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Measurement, spatial spillover and influencing factors of agricultural carbon emissions efficiency in China
WU Haoyue, HUANG Hanjiao, HE Yu, CHEN Wenkuan
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Effects of tillage and straw returning method on the distribution of carbon and nitrogen in soil aggregates
ZHANG Yuming, HU Chunsheng, CHEN Suying, WANG Yuying, LI Xiaoxin, DONG Wenxu, LIU Xiuping, PEI Lin, ZHANG Hui
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Relationship between policy incentives, ecological cognition, and organic fertilizer application by farmers: Based on a moderated mediation model
SANG Xiance, LUO Xiaofeng, HUANG Yanzhong, TANG Lin
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Spatio-temporal evolution of carbon stocks in the Yellow River Basin based on InVEST and CA-Markov models
YANG Jie, XIE Baopeng, ZHANG Degang
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Effects of straw returning and fertilization on soil bacterial and fungal community structures and diversities in rice-wheat rotation soil
ZHANG Hanlin, BAI Naling, ZHENG Xianqing, LI Shuangxi, ZHANG Juanqin, ZHANG Haiyun, ZHOU Sheng, SUN Huifeng, LYU Weiguang
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2015 Vol. 23, No. 12
Display Method:
2015, 23(12): 1491-1501.
doi: 10.13930/j.cnki.cjea.150462
Abstract:
Inter-specific interactions in cereal-vegetable strip intercropping system mainly occur at border-row areas. It is meaningful to know more about the differences in the growths of belowground (root) and aboveground (shoot) of crop systems between border-row and middle-row crops for establishment of a sustainable strip intercropping system. Two fertilization methods — chemical fertilization (CF) and combined application of organic materials and chemical fertilizers (OMFC), were used in a cereal-vegetable strip intercropping system (spring maize intercropped first with dwarf bean then with autumn Chinese cabbage, expressed as spring maize||bush beanautumn Chinese cabbage) and then yield, biomass, root and soil available NPK of border row, sub-border row and middle row of crops tested in relation to border effects on crops. The results showed that compared with middle row, aboveground biomass and yield of maize in border row increased significantly by 58.7% and 40.8% under the CF and OMCF fertilization methods, respectively. In contrast, vegetable growth in the border row was suppressed. However, aboveground biomass and yield of border row and sub-border row of bush bean under different fertilization conditions were less than those of middle row. Specifically, border row and sub-border row bush bean yields decreased by 49.7% and 45.6% under CF treatment, respectively. At silking stage of spring maize, the depth of maize root in border row was deeper than that in middle row, and growth direction of all the roots was partial to vegetable strip. Compared with CF treatment, maize root length and weight in the 015 cm soil layer in border row under OMCF treatment increased by 104.3% and 77.5%, respectively, while bush bean root length in the border row significantly decreased. Conversely, the roots of border row bush bean were inhibited when compared with middle row bush bean, which was much more severe under OMCF treatment. OMCF treatment strengthened intra-specific competition between spring maize and vegetable crops. In addition, the competitive advantage in nutrient absorption of border rows of spring maize significantly decreased soil available NPK contents in border row areas.
Inter-specific interactions in cereal-vegetable strip intercropping system mainly occur at border-row areas. It is meaningful to know more about the differences in the growths of belowground (root) and aboveground (shoot) of crop systems between border-row and middle-row crops for establishment of a sustainable strip intercropping system. Two fertilization methods — chemical fertilization (CF) and combined application of organic materials and chemical fertilizers (OMFC), were used in a cereal-vegetable strip intercropping system (spring maize intercropped first with dwarf bean then with autumn Chinese cabbage, expressed as spring maize||bush beanautumn Chinese cabbage) and then yield, biomass, root and soil available NPK of border row, sub-border row and middle row of crops tested in relation to border effects on crops. The results showed that compared with middle row, aboveground biomass and yield of maize in border row increased significantly by 58.7% and 40.8% under the CF and OMCF fertilization methods, respectively. In contrast, vegetable growth in the border row was suppressed. However, aboveground biomass and yield of border row and sub-border row of bush bean under different fertilization conditions were less than those of middle row. Specifically, border row and sub-border row bush bean yields decreased by 49.7% and 45.6% under CF treatment, respectively. At silking stage of spring maize, the depth of maize root in border row was deeper than that in middle row, and growth direction of all the roots was partial to vegetable strip. Compared with CF treatment, maize root length and weight in the 015 cm soil layer in border row under OMCF treatment increased by 104.3% and 77.5%, respectively, while bush bean root length in the border row significantly decreased. Conversely, the roots of border row bush bean were inhibited when compared with middle row bush bean, which was much more severe under OMCF treatment. OMCF treatment strengthened intra-specific competition between spring maize and vegetable crops. In addition, the competitive advantage in nutrient absorption of border rows of spring maize significantly decreased soil available NPK contents in border row areas.
2015, 23(12): 1502-1510.
doi: 10.13930/j.cnki.cjea.150533
Abstract:
Cropping patterns and fertilizer management are critical for soil phosphorus (P) use efficiency. In order to explore the dynamic changes of inorganic P fractions in crop rhizosphere soils and to establish theoretical basis for optimal P management in maize/soybean relay intercropping, we designed a pot experiment where aboveground biomass and P uptake of maize and soybean, and available P and inorganic P fraction concentrations in rhizosphere and non-rhizosphere soils were determined. The experiment included three cropping patterns of maize/soybean relay intercropping (M/S), maize monoculture (MM) and soybean monoculture (SS). There were also three fertilization treatments, including non-fertilization (CK), nitrogen and potassium fertilization (NK) and then nitrogen, phosphorus and potassium fertilization (NPK). The results showed that grain yield of intercropped maize was significantly higher than that of mono-cropped maize under the same fertilization treatment. P fertilization significantly increased grain yield of mono-cropped maize whereas it had no significant effect on grain yield of intercropped maize. Stalk biomass and grain yield of intercropped soybean were all higher than those of mono-cropped soybean, regardless of fertilization application. Shoot P accumulation of intercropped maize and soybean per plant was significantly higher than that of mono-cropped system under all fertilization treatments. At maturity stage of maize, rhizosphere soil available P concentrations under intercropped maize were respectively 54.2% and 71.8% higher than those of mono-cropped maize under CK and NK treatments. At the start of blooming stage of soybean, rhizosphere soil available P concentration under intercropped soybean was 19.8% higher than that of mono-cropped soybean under NPK treatment. At maturity stage of soybean, rhizosphere soil available P concentrations of intercropped soybean were respectively 23.8% and 108.0% higher than that of mono-cropped soybean under NK and NPK treatments. Al-P concentrations in rhizosphere soils were lower than those of non-rhizosphere soils under both intercropped and monocultured maize for all the three fertilization treatments. Al-P concentrations in rhizosphere soils under monoculture maize were respectively 1.19 and 1.22 times those under intercropped maize for both CK and NK treatments. Fe-P concentration in rhizosphere soils under monoculture maize was 1.21 times that under intercropped maize for NPK treatment. Under the CK, NK and NPK fertilization treatments, Al-P concentrations in rhizosphere soils under monoculture soybean were respectively 1.12, 1.30 and 1.25 times those under intercropped soybean. Also Al-P concentrations in non-rhizosphere soils of monoculture soybean were respectively 1.22, 1.30 and 1.06 times those under intercropped soybean for CK, NK and NPK treatments. Similarly, Fe-P concentrations in rhizosphere soils under monoculture soybean were respectively 1.47 and 1.12 times those under intercropped soybean for CK and NK treatments. In conclusion, maize/soybean relay intercropping was favorable for soil Al-P and Fe-P dissolution and uptake under low P dose, compared with monoculture systems.
Cropping patterns and fertilizer management are critical for soil phosphorus (P) use efficiency. In order to explore the dynamic changes of inorganic P fractions in crop rhizosphere soils and to establish theoretical basis for optimal P management in maize/soybean relay intercropping, we designed a pot experiment where aboveground biomass and P uptake of maize and soybean, and available P and inorganic P fraction concentrations in rhizosphere and non-rhizosphere soils were determined. The experiment included three cropping patterns of maize/soybean relay intercropping (M/S), maize monoculture (MM) and soybean monoculture (SS). There were also three fertilization treatments, including non-fertilization (CK), nitrogen and potassium fertilization (NK) and then nitrogen, phosphorus and potassium fertilization (NPK). The results showed that grain yield of intercropped maize was significantly higher than that of mono-cropped maize under the same fertilization treatment. P fertilization significantly increased grain yield of mono-cropped maize whereas it had no significant effect on grain yield of intercropped maize. Stalk biomass and grain yield of intercropped soybean were all higher than those of mono-cropped soybean, regardless of fertilization application. Shoot P accumulation of intercropped maize and soybean per plant was significantly higher than that of mono-cropped system under all fertilization treatments. At maturity stage of maize, rhizosphere soil available P concentrations under intercropped maize were respectively 54.2% and 71.8% higher than those of mono-cropped maize under CK and NK treatments. At the start of blooming stage of soybean, rhizosphere soil available P concentration under intercropped soybean was 19.8% higher than that of mono-cropped soybean under NPK treatment. At maturity stage of soybean, rhizosphere soil available P concentrations of intercropped soybean were respectively 23.8% and 108.0% higher than that of mono-cropped soybean under NK and NPK treatments. Al-P concentrations in rhizosphere soils were lower than those of non-rhizosphere soils under both intercropped and monocultured maize for all the three fertilization treatments. Al-P concentrations in rhizosphere soils under monoculture maize were respectively 1.19 and 1.22 times those under intercropped maize for both CK and NK treatments. Fe-P concentration in rhizosphere soils under monoculture maize was 1.21 times that under intercropped maize for NPK treatment. Under the CK, NK and NPK fertilization treatments, Al-P concentrations in rhizosphere soils under monoculture soybean were respectively 1.12, 1.30 and 1.25 times those under intercropped soybean. Also Al-P concentrations in non-rhizosphere soils of monoculture soybean were respectively 1.22, 1.30 and 1.06 times those under intercropped soybean for CK, NK and NPK treatments. Similarly, Fe-P concentrations in rhizosphere soils under monoculture soybean were respectively 1.47 and 1.12 times those under intercropped soybean for CK and NK treatments. In conclusion, maize/soybean relay intercropping was favorable for soil Al-P and Fe-P dissolution and uptake under low P dose, compared with monoculture systems.
2015, 23(12): 1511-1519.
doi: 10.13930/j.cnki.cjea.150489
Abstract:
The process of water regulation during the growing period of adzuki bean under experimental pot conditions was studied in order to determine the effects of combining different water (drought stress and normal irrigation) and nitrogen fertilizer (N application rates of 0 g·kg-1, 0.1 g·kg-1, and 0.3 g·kg-1) conditions on the root physio-ecological indices and yield. The results showed that: 1) Under drought stress condition, plant height, stem diameter, shoot dry weight, total root length, root area, root volume, average root diameter, max root length, root dry weight and seedling index initially increased and then decreased with increasing nitrogen application rate. Also root soluble protein content at seedling stage, Pn, Tr and Gs at blooming/pod-setting stage, transverse diameter, weight per pod and seeds per pod, 100-seed weight at mature stage initially increased and then decreased with increasing nitrogen application rate. Furthermore, the activities of SOD and POD in root increased with increasing nitrogen rate while soluble sugar content decreased initially and then increased with increasing nitrogen application rate. However, root MDA content, pod length and pods per plant did not significantly change in response to different nitrogen fertilizer treatments. Under normal irrigation, with increasing nitrogen application rate, maximum root length decreased. Also while SOD activity, POD activity and Gs increased, MDA content and soluble sugar content decreased initially and then increased with increasing nitrogen application. Then pods per plant did not change for three nitrogen treatments while the other indices mentioned above changed parabolically with increasing nitrogen application rate. 2) Under equal nitrogen fertilizer treatments, normal irrigation decreased SOD and POD activities, soluble sugar content and soluble protein content as opposed to drought stress treatment. However, MDA content, transverse diameter and pods per plant had no significant difference for both drought and normal irrigation conditions. The other above indices increased under normal irrigation treatment compared with drought stress treatment. 3) Among the three nitrogen levels, yield of adzuki bean was highest under 0.1 g·kg-1 nitrogen application. It increased respectively by 95.2% and 118.3% compared with 0 g·kg-1 and 0.3 g·kg-1 nitrogen treatments under drought stress condition. It also increased respectively by 63.8% and 137.1% compared with 0 g·kg-1 and 0.3 g·kg-1 nitrogen treatments under normal irrigation condition. In addition, yield of adzuki bean was higher in normal irrigation treatment. It increased by 84.5% and 198.7%, respectively, compared to drought stress treatment under equally nitrogen fertilizer treatment. The results suggested that reasonable application of nitrogen fertilizer and water enhanced the growth and yield of adzuki bean, furthermore, adzuki bean was more suitable for production at low soil moisture (35%–45% of field water capacity) and suitable fertilizer condition (0.1 g·kg-1 N application) in the hilly area of Loess Plateau of Shanxi Province.
The process of water regulation during the growing period of adzuki bean under experimental pot conditions was studied in order to determine the effects of combining different water (drought stress and normal irrigation) and nitrogen fertilizer (N application rates of 0 g·kg-1, 0.1 g·kg-1, and 0.3 g·kg-1) conditions on the root physio-ecological indices and yield. The results showed that: 1) Under drought stress condition, plant height, stem diameter, shoot dry weight, total root length, root area, root volume, average root diameter, max root length, root dry weight and seedling index initially increased and then decreased with increasing nitrogen application rate. Also root soluble protein content at seedling stage, Pn, Tr and Gs at blooming/pod-setting stage, transverse diameter, weight per pod and seeds per pod, 100-seed weight at mature stage initially increased and then decreased with increasing nitrogen application rate. Furthermore, the activities of SOD and POD in root increased with increasing nitrogen rate while soluble sugar content decreased initially and then increased with increasing nitrogen application rate. However, root MDA content, pod length and pods per plant did not significantly change in response to different nitrogen fertilizer treatments. Under normal irrigation, with increasing nitrogen application rate, maximum root length decreased. Also while SOD activity, POD activity and Gs increased, MDA content and soluble sugar content decreased initially and then increased with increasing nitrogen application. Then pods per plant did not change for three nitrogen treatments while the other indices mentioned above changed parabolically with increasing nitrogen application rate. 2) Under equal nitrogen fertilizer treatments, normal irrigation decreased SOD and POD activities, soluble sugar content and soluble protein content as opposed to drought stress treatment. However, MDA content, transverse diameter and pods per plant had no significant difference for both drought and normal irrigation conditions. The other above indices increased under normal irrigation treatment compared with drought stress treatment. 3) Among the three nitrogen levels, yield of adzuki bean was highest under 0.1 g·kg-1 nitrogen application. It increased respectively by 95.2% and 118.3% compared with 0 g·kg-1 and 0.3 g·kg-1 nitrogen treatments under drought stress condition. It also increased respectively by 63.8% and 137.1% compared with 0 g·kg-1 and 0.3 g·kg-1 nitrogen treatments under normal irrigation condition. In addition, yield of adzuki bean was higher in normal irrigation treatment. It increased by 84.5% and 198.7%, respectively, compared to drought stress treatment under equally nitrogen fertilizer treatment. The results suggested that reasonable application of nitrogen fertilizer and water enhanced the growth and yield of adzuki bean, furthermore, adzuki bean was more suitable for production at low soil moisture (35%–45% of field water capacity) and suitable fertilizer condition (0.1 g·kg-1 N application) in the hilly area of Loess Plateau of Shanxi Province.
2015, 23(12): 1520-1528.
doi: 10.13930/j.cnki.cjea.150551
Abstract:
Root residues in fields after harvesting crops are the basic materials for soil organic carbon (C). Root residues are critical for the maintenance of organic matter and improvement of soil fertility. The application of inorganic fertilizers not only increases crop yield, but also affects the allocation of photosynthate in aboveground and belowground systems of crops. The effect of different fertilization on returned crop root biomass into soil has widely been studied. Nitrogen (N) fertilizer accounts for the largest fertilizer use in agricultural production. However, it has still not been clear whether the chemical composition and decomposition dynamics of crop root residues were affected by N level. Meanwhile, soil nutrient cycle may also be affected by root decay. Consequently, a field experiment was conducted to evaluate soil organic C decay under different levels of N fertilizer application to maize. The experiment also studied the dynamics of soil available C and N contents affected by the addition of maize roots in black loessial soils. In October 2010, maize roots in the 020 cm soil depth were collected from three N fertilization treatments in a 7-year-long field experiment. Maize roots gathered from the plots under the 0 kg(N)·hm-2, 120 kg(N)·hm-2 and 240 kg(N)·hm-2 treatments were marked as R0, R120 and R240, respectively. After mixing with soil at 15 cm and 45 cm depths at 2% proportion, the decomposition characteristics of the three N-fertilized roots were determined for 368 days after buried in soil. The results showed that in contrast to the control treatment (without root addition), the contents of soil microbial biomass C, soluble organic C and mineral N increased significantly under addition of N-treated maize roots at both soil depths. However, there was no obvious difference between R0, R120, and R240 treatments. The specific absorbance at 280 nm (UV280) increased with increasing decomposition time, which suggested that the portion of aromatic and complex compounds in soil organic matter increased. After one year of decomposition, residual ratios of C in roots under R0, R120 and R240 treatments were respectively 44.4%, 35.3% and 34.9% at 15 cm depth, and 53.3%, 44.3% and 42.5% at 45 cm soil depth. Root decomposition ratio and decay rate constant were significantly higher at 15 cm than that at 45 cm soil depth. Simulated equations of remaining maize root C with the first order kinetics fitting indicated that the time to reach 95% root C decomposition under R0, R120 and R240 prolonged, respectively, by 3.2, 2.3 and 1.9 years at 45 cm soil depth, compared with that at 15 cm soil depth. It was concluded that the effect of decomposition of crop residues on soil C and N accumulation and cycle in farmland soils need more attention in the study of soil carbon sequestration.
Root residues in fields after harvesting crops are the basic materials for soil organic carbon (C). Root residues are critical for the maintenance of organic matter and improvement of soil fertility. The application of inorganic fertilizers not only increases crop yield, but also affects the allocation of photosynthate in aboveground and belowground systems of crops. The effect of different fertilization on returned crop root biomass into soil has widely been studied. Nitrogen (N) fertilizer accounts for the largest fertilizer use in agricultural production. However, it has still not been clear whether the chemical composition and decomposition dynamics of crop root residues were affected by N level. Meanwhile, soil nutrient cycle may also be affected by root decay. Consequently, a field experiment was conducted to evaluate soil organic C decay under different levels of N fertilizer application to maize. The experiment also studied the dynamics of soil available C and N contents affected by the addition of maize roots in black loessial soils. In October 2010, maize roots in the 020 cm soil depth were collected from three N fertilization treatments in a 7-year-long field experiment. Maize roots gathered from the plots under the 0 kg(N)·hm-2, 120 kg(N)·hm-2 and 240 kg(N)·hm-2 treatments were marked as R0, R120 and R240, respectively. After mixing with soil at 15 cm and 45 cm depths at 2% proportion, the decomposition characteristics of the three N-fertilized roots were determined for 368 days after buried in soil. The results showed that in contrast to the control treatment (without root addition), the contents of soil microbial biomass C, soluble organic C and mineral N increased significantly under addition of N-treated maize roots at both soil depths. However, there was no obvious difference between R0, R120, and R240 treatments. The specific absorbance at 280 nm (UV280) increased with increasing decomposition time, which suggested that the portion of aromatic and complex compounds in soil organic matter increased. After one year of decomposition, residual ratios of C in roots under R0, R120 and R240 treatments were respectively 44.4%, 35.3% and 34.9% at 15 cm depth, and 53.3%, 44.3% and 42.5% at 45 cm soil depth. Root decomposition ratio and decay rate constant were significantly higher at 15 cm than that at 45 cm soil depth. Simulated equations of remaining maize root C with the first order kinetics fitting indicated that the time to reach 95% root C decomposition under R0, R120 and R240 prolonged, respectively, by 3.2, 2.3 and 1.9 years at 45 cm soil depth, compared with that at 15 cm soil depth. It was concluded that the effect of decomposition of crop residues on soil C and N accumulation and cycle in farmland soils need more attention in the study of soil carbon sequestration.
2015, 23(12): 1529-1535.
doi: 10.13930/j.cnki.cjea.150417
Abstract:
Intercropping systems have been proved to be sustainable, boosted crop productivity and increased resource utilization. However, little has been known about the effect of intercropping on greenhouse gas emissions in field soils. Intensive mono-cropping of sweet corn along with N fertilizer overuse induces nitrous non-point pollution in South China. Cereal-legume intercropping can reduce N application while maintaining crop yield. The objective of this study was to determine the effect of sweet corn and soybean intercropping under reduced N fertilizer on soil N2O emission and crop yield. A field experiment was conducted in South China Agriculture University during three seasons (autumn of 2013, spring of 2014 and autumn of 2014), two N fertilizer levels (N0: 300 kg·hm-2 and N1: 360 kg·hm-2) and three planting patterns [sweet corn||soybean intercropping system with line ratios of sweet corn to soybean of 2︰3 (S2B3) and 2︰4 (S2B4), sole sweet corn (SS)] were used. N2O emission in the field was determined using the static chamber/gas chromatographic technique. Results showed that reduced N application significantly decreased Global Warming Potential of N2O (GWPN2O, kg·hm-2), with treatment of S2B4-N0 producing the lowest GWPN2O, respectively 66.31%, 84.08% and 51.31% less than S2B4-N1 during the three seasons. However, no significant difference in GWPN2O was noted among different planting patterns. In addition, reduced N application did not reduce crop yield and land equivalent ratio (LER) was greater than one in every intercropping systems. As the yield of intercropping system was higher than that of mono- cropping of sweet corn and reduced N application decreased soil N2O emission, intercropping and reduced N application significantly decreased Greenhouse Gas Intensity of N2O (GHGIN2O = GWPN2O/yield, kg·t-1). The lowest GHGIN2O was observed under S2B4-N0 treatment. During the three seasons, the average GHGIN2O under S2B4-N0 treatment dropped by 71.60% and 71.21% compared with that under SS-N0 and S2B4-N1 treatments, respectively. The study demonstrated that intercropping with reduced N application was an efficient strategy for maintaining crop yield, increasing land use rate and reducing N2O emissions. The S2B4-N0 had the best effect.
Intercropping systems have been proved to be sustainable, boosted crop productivity and increased resource utilization. However, little has been known about the effect of intercropping on greenhouse gas emissions in field soils. Intensive mono-cropping of sweet corn along with N fertilizer overuse induces nitrous non-point pollution in South China. Cereal-legume intercropping can reduce N application while maintaining crop yield. The objective of this study was to determine the effect of sweet corn and soybean intercropping under reduced N fertilizer on soil N2O emission and crop yield. A field experiment was conducted in South China Agriculture University during three seasons (autumn of 2013, spring of 2014 and autumn of 2014), two N fertilizer levels (N0: 300 kg·hm-2 and N1: 360 kg·hm-2) and three planting patterns [sweet corn||soybean intercropping system with line ratios of sweet corn to soybean of 2︰3 (S2B3) and 2︰4 (S2B4), sole sweet corn (SS)] were used. N2O emission in the field was determined using the static chamber/gas chromatographic technique. Results showed that reduced N application significantly decreased Global Warming Potential of N2O (GWPN2O, kg·hm-2), with treatment of S2B4-N0 producing the lowest GWPN2O, respectively 66.31%, 84.08% and 51.31% less than S2B4-N1 during the three seasons. However, no significant difference in GWPN2O was noted among different planting patterns. In addition, reduced N application did not reduce crop yield and land equivalent ratio (LER) was greater than one in every intercropping systems. As the yield of intercropping system was higher than that of mono- cropping of sweet corn and reduced N application decreased soil N2O emission, intercropping and reduced N application significantly decreased Greenhouse Gas Intensity of N2O (GHGIN2O = GWPN2O/yield, kg·t-1). The lowest GHGIN2O was observed under S2B4-N0 treatment. During the three seasons, the average GHGIN2O under S2B4-N0 treatment dropped by 71.60% and 71.21% compared with that under SS-N0 and S2B4-N1 treatments, respectively. The study demonstrated that intercropping with reduced N application was an efficient strategy for maintaining crop yield, increasing land use rate and reducing N2O emissions. The S2B4-N0 had the best effect.
2015, 23(12): 1536-1543.
doi: 10.13930/j.cnki.cjea.150539
Abstract:
The concentrations of nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) at 7 cm, 15 cm, 30 cm and 50 cm soil depths under bare fallow, rotation field?Ⅰ (rotation of celery-tung choy-baby bok choy-amaranth) and rotation field?Ⅱ (rotation of choy sum-celery-tung choy-bok choy) were monitored using a special in situ soil gas collection device and gas chromatography to explore the distribution characteristics of N2O, CH4 and CO2 in soil profiles. The results showed great variations in annual concentrations of N2O, CH4 and CO2 within the 0-50 cm soil depth with respective values of 0.63 1 657.0 μL(N2O)L-1, 0.872.5 μL(CH4)L-1 and 0.4136.6 mL(CO2)L-1. N2O concentrations under rotation?Ⅰ?and rotation?Ⅱ increased with increasing soil depth. Also N2O concentration under bare fallow increased with increasing soil depth within the 030 cm soil layer, while it decreased with increasing depth within the 3050 cm soil layer. Average N2O concentrations of two vegetable rotational fields were significantly higher than that of bare fallow. Different N fertilizers application to the two vegetable rotational fields did not significantly change N2O concentration for the same soil layer. The orders of both CH4 and CO2 concentrations in soil profile were 50 cm > 30 cm > 15 cm > 7 cm. N fertilizer application had no significant effect on CH4 concentration. Average CH4 concentration under the two vegetable rotations in the 015 cm soil depth was higher than that under bare fallow. However, CH4 concentration at the 1550 cm soil depth was higher under field rotation Ⅰ but lower under field rotation Ⅱ than that under bare fallow. CO2 concentration had a clear seasonal variation. Average CO2 concentration under the two vegetable rotations was lower than that in corresponding soil layers under bare fallow, except for the 50 cm soil depth under field rotation Ⅰ. The results suggested that soil N2O, CH4 and CO2 concentrations of vegetable rotational fields with high nitrogen input and frequent tillage had greater temporal and spatial variability. The effect of nitrogen application on N2O was stronger than that on CH4 and CO2. Nitrogen application and tillage slightly affected the distribution of CH4 concentration in the soil. CO2 concentration was significantly affected by soil temperature and tillage. Other factors affected the distribution of N2O, CH4 and CO2 in the soil can be the focus of further research.
The concentrations of nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) at 7 cm, 15 cm, 30 cm and 50 cm soil depths under bare fallow, rotation field?Ⅰ (rotation of celery-tung choy-baby bok choy-amaranth) and rotation field?Ⅱ (rotation of choy sum-celery-tung choy-bok choy) were monitored using a special in situ soil gas collection device and gas chromatography to explore the distribution characteristics of N2O, CH4 and CO2 in soil profiles. The results showed great variations in annual concentrations of N2O, CH4 and CO2 within the 0-50 cm soil depth with respective values of 0.63 1 657.0 μL(N2O)L-1, 0.872.5 μL(CH4)L-1 and 0.4136.6 mL(CO2)L-1. N2O concentrations under rotation?Ⅰ?and rotation?Ⅱ increased with increasing soil depth. Also N2O concentration under bare fallow increased with increasing soil depth within the 030 cm soil layer, while it decreased with increasing depth within the 3050 cm soil layer. Average N2O concentrations of two vegetable rotational fields were significantly higher than that of bare fallow. Different N fertilizers application to the two vegetable rotational fields did not significantly change N2O concentration for the same soil layer. The orders of both CH4 and CO2 concentrations in soil profile were 50 cm > 30 cm > 15 cm > 7 cm. N fertilizer application had no significant effect on CH4 concentration. Average CH4 concentration under the two vegetable rotations in the 015 cm soil depth was higher than that under bare fallow. However, CH4 concentration at the 1550 cm soil depth was higher under field rotation Ⅰ but lower under field rotation Ⅱ than that under bare fallow. CO2 concentration had a clear seasonal variation. Average CO2 concentration under the two vegetable rotations was lower than that in corresponding soil layers under bare fallow, except for the 50 cm soil depth under field rotation Ⅰ. The results suggested that soil N2O, CH4 and CO2 concentrations of vegetable rotational fields with high nitrogen input and frequent tillage had greater temporal and spatial variability. The effect of nitrogen application on N2O was stronger than that on CH4 and CO2. Nitrogen application and tillage slightly affected the distribution of CH4 concentration in the soil. CO2 concentration was significantly affected by soil temperature and tillage. Other factors affected the distribution of N2O, CH4 and CO2 in the soil can be the focus of further research.
2015, 23(12): 1544-1551.
doi: 10.13930/j.cnki.cjea.150687
Abstract:
Biogas slurry, the by-product of biogas engineering comprised of agricultural residue and livestock/poultry waste, is a leading source of agricultural non-point pollution. Biogas slurry is also most difficult to be dealt with in the protection of water environment. To study the safety of the technology of biogas slurry application in paddy fields, 4 treatments of biogas slurry application and two control treatments were designed. The treatments included irrigation 1 000 t.hm-2 of biogas slurry with zero nitrogen urea application at tillering stage of rice (BS10); replacements of 100%, 200% and 300% of nitrogen urea, respectively, with 211.76 t.hm-2, 423.53 t.hm-2 and 635.29 t.hm-2 of biogas slurry at tillering stage of rice (100%BS, 200%BS and 300%BS). The control treatments were conventional fertilization at 180 kg(N).hm-2 of nitrogen urea (CF) at tillering stage of rice, and no-fertilization treatment (CK) at tillering stage of rice. Then the changes in total nitrogen, ammonium nitrogen and nitrate nitrogen contents in field surface water were monitored after 1 day, 2 days, 3 days, 5 days and 7 days of biogas slurry application. The same changes were also monitored in percolated soil water at 40 cm and 60 cm depths. The results showed that biogas slurry application at rice tillering stage obviously increased total nitrogen and ammonia nitrogen contents in field surface water. Both total nitrogen and ammonia nitrogen contents increased with increasing amount of biogas slurry application. Ammonia nitrogen was the main form of nitrogen in every field surface water treatment, and the content significantly dropped over time. Compared with the first day after biogas slurry application, total nitrogen decreased by 46.67%73.26% on the third day, where in BS10, 300%BS, 200%BS and 100%BS treatments the reduction in total nitrogen were higher than that in CF treatment by 26.59%, 26.43%, 24.38% and 10.25%, respectively. Also compared with the first day after biogas slurry application, total nitrogen decreased by 69.15%86.43% on the seventh day, where in BS10, 300%BS, 200%BS and 100%BS treatments the reduction in total nitrogen were higher than CF treatment by 13.16%, 12.27%, 11.60% and 5.96%, respectively. Ammonia nitrogen decreased by 47.52%67.60% on the third day, and 75.25%83.73% on the seventh day, respectively, compared with the first day after biogas slurry application. And in BS10, 300%BS, 200%BS and 100%BS treatments, the reduction in ammonia nitrogen were higher than CF treatment by 14.73%, 17.29%, 20.08% and 6.47% on the third day, and by 6.05%, 6.21%, 8.48% and 3.55% on the seventh day, respectively. Thus the first three days after application was the critical period for biogas slurry dissolution in paddy fields. It was also the key period to limit nitrogen loss through surface drainage which in turn reduced agricultural non-point source pollution. Compared with conventional fertilization treatment, there was no obvious effect of BS10, 300%BS, 200%BS and 100%BS treatments on total nitrogen and ammonia nitrogen contents of percolated soil water at 40 cm soil depth, however, total nitrogen and ammonia nitrogen contents obviously increased at 60 cm soil depth. Total nitrogen under BS10, 300%BS, 200%BS and 100%BS treatments was higher than that under CF treatment by 0.37 mg?L1, 0.67 mg?L1, 0.13 mg.L-1 and 0.23 mg?L1 at 60 cm soil depth, respectively, on the seventh day after treatment. Ammonia nitrogen under BS10 and 200%BS treatments was higher than that under CF treatment by 0.02 mg.L-1 and 0.36 mg.L-1, respectively. The impact of treatment 100%BS on total nitrogen and ammonia nitrogen contents was weakest both in field surface water and in percolated soil water at three days after biogas slurry application. Duplicate values of total nitrogen concentration of percolated soil water at 40 cm and 60 cm soil depths under each treatment had considerably large range of variations. Analysis of variance of total nitrogen concentration in percolated soil water showed no significant difference at 0.05 level between 40 cm and 60 cm soil depths. Combined with rice production safety, it was recommended to limit biogas slurry application to less than 211.76 t.hm-2 during tillering stage.
Biogas slurry, the by-product of biogas engineering comprised of agricultural residue and livestock/poultry waste, is a leading source of agricultural non-point pollution. Biogas slurry is also most difficult to be dealt with in the protection of water environment. To study the safety of the technology of biogas slurry application in paddy fields, 4 treatments of biogas slurry application and two control treatments were designed. The treatments included irrigation 1 000 t.hm-2 of biogas slurry with zero nitrogen urea application at tillering stage of rice (BS10); replacements of 100%, 200% and 300% of nitrogen urea, respectively, with 211.76 t.hm-2, 423.53 t.hm-2 and 635.29 t.hm-2 of biogas slurry at tillering stage of rice (100%BS, 200%BS and 300%BS). The control treatments were conventional fertilization at 180 kg(N).hm-2 of nitrogen urea (CF) at tillering stage of rice, and no-fertilization treatment (CK) at tillering stage of rice. Then the changes in total nitrogen, ammonium nitrogen and nitrate nitrogen contents in field surface water were monitored after 1 day, 2 days, 3 days, 5 days and 7 days of biogas slurry application. The same changes were also monitored in percolated soil water at 40 cm and 60 cm depths. The results showed that biogas slurry application at rice tillering stage obviously increased total nitrogen and ammonia nitrogen contents in field surface water. Both total nitrogen and ammonia nitrogen contents increased with increasing amount of biogas slurry application. Ammonia nitrogen was the main form of nitrogen in every field surface water treatment, and the content significantly dropped over time. Compared with the first day after biogas slurry application, total nitrogen decreased by 46.67%73.26% on the third day, where in BS10, 300%BS, 200%BS and 100%BS treatments the reduction in total nitrogen were higher than that in CF treatment by 26.59%, 26.43%, 24.38% and 10.25%, respectively. Also compared with the first day after biogas slurry application, total nitrogen decreased by 69.15%86.43% on the seventh day, where in BS10, 300%BS, 200%BS and 100%BS treatments the reduction in total nitrogen were higher than CF treatment by 13.16%, 12.27%, 11.60% and 5.96%, respectively. Ammonia nitrogen decreased by 47.52%67.60% on the third day, and 75.25%83.73% on the seventh day, respectively, compared with the first day after biogas slurry application. And in BS10, 300%BS, 200%BS and 100%BS treatments, the reduction in ammonia nitrogen were higher than CF treatment by 14.73%, 17.29%, 20.08% and 6.47% on the third day, and by 6.05%, 6.21%, 8.48% and 3.55% on the seventh day, respectively. Thus the first three days after application was the critical period for biogas slurry dissolution in paddy fields. It was also the key period to limit nitrogen loss through surface drainage which in turn reduced agricultural non-point source pollution. Compared with conventional fertilization treatment, there was no obvious effect of BS10, 300%BS, 200%BS and 100%BS treatments on total nitrogen and ammonia nitrogen contents of percolated soil water at 40 cm soil depth, however, total nitrogen and ammonia nitrogen contents obviously increased at 60 cm soil depth. Total nitrogen under BS10, 300%BS, 200%BS and 100%BS treatments was higher than that under CF treatment by 0.37 mg?L1, 0.67 mg?L1, 0.13 mg.L-1 and 0.23 mg?L1 at 60 cm soil depth, respectively, on the seventh day after treatment. Ammonia nitrogen under BS10 and 200%BS treatments was higher than that under CF treatment by 0.02 mg.L-1 and 0.36 mg.L-1, respectively. The impact of treatment 100%BS on total nitrogen and ammonia nitrogen contents was weakest both in field surface water and in percolated soil water at three days after biogas slurry application. Duplicate values of total nitrogen concentration of percolated soil water at 40 cm and 60 cm soil depths under each treatment had considerably large range of variations. Analysis of variance of total nitrogen concentration in percolated soil water showed no significant difference at 0.05 level between 40 cm and 60 cm soil depths. Combined with rice production safety, it was recommended to limit biogas slurry application to less than 211.76 t.hm-2 during tillering stage.
2015, 23(12): 1552-1561.
doi: 10.13930/j.cnki.cjea.150642
Abstract:
The dry-raising technique at rice seedling stage is an important cultivation method of rice that not only saves water, but also favors high yield production. To study the ecological characteristics of rice rhizosphere soils of dry-raised seedlings, the plant morphological index, ecological factor, soil nutrient effectiveness and bacterial community diversity of rhizosphere soils were investigated in a paddy field. The results showed that compared with moist-raised seedlings, shoot dry weight, root length, root dry weight, root-shoot ratio and white root number of dry-raised seedlings increased by 3.02%, 21.99%, 18.93%, 15.10% and 200.00%, respectively, but plant height decreased by 32.31%. Monitoring of ecological factor showed that soil water content of dry-raised seedlings was 15%17%. Under dry-raising condition, soil pH was decreased by 7.94% and electrical conductivity and temperature were decreased soil by 244.62% and 23 ℃, respectively, compared with those under moist-raising condition. The activities of phosphatase, invertase, urease, catalase and dehydrogenase in rhizosphere soils also increased by 166.66%, 518.85%, 131.98%, 102.70% and 84.36%, respectively, under dry-raised system at rice seedling stage, while nitrate reductase decreased by 72.95%. Dry-raising condition favored the conversion of soil organic matter and energy. This in turn increased soil organic matter, NO3-N, NH4+-N, available K and available P in rhizosphere soil of dry-raised seedlings respectively by 89.27%, 320.11%, 56.95%, 50.85% and 184.75%. Finally, 16sRNA high-throughput sequencing analysis showed that Chao1 and Shannon-Wiener index for bacterial was higher in rhizosphere soil of dry-raised seedlings than those of moist-raised seedlings. Analysis of soil microorganism biota revealed that the proportions of Alphaproteobacteria, Gammaproteobacteria, Bacteroidetes, Chloroflexi, Nitrospirae, Acidobacteria, Gemmatimonadetes, Planctomycetes and Actinobacteria increased in rhizosphere soil of dry-raised seedlings, while the proportions of Firmicutes and Betaproteobacteria decreased. Function analysis on dominant populations of rhizospheric bacterial community showed that dry-raising system at rice seedling stage accelerated the growth of soil nutrient conversing bacteria. This included nitrifying bacteria, azotobacter, ammonia oxidizing bacteria, photosynthetic bacteria, phosphorus and potassium-solubilizing bacteria. In addition, the ratio of bacillales, pfseudomonas and rhizobium containing large amounts of plant growth-promoting rhizobacteria also increased significantly in rice rhizosphere soil of dry-raised seedling, which favored root growth. In summary, the cultivation of dry-raised seedling by controlling soil moisture content changed the pH, electric conductivity, temperature and bacteria diversity of rhizosphere soils of rice seedlings. This in turn favored the development of strong seedlings.
The dry-raising technique at rice seedling stage is an important cultivation method of rice that not only saves water, but also favors high yield production. To study the ecological characteristics of rice rhizosphere soils of dry-raised seedlings, the plant morphological index, ecological factor, soil nutrient effectiveness and bacterial community diversity of rhizosphere soils were investigated in a paddy field. The results showed that compared with moist-raised seedlings, shoot dry weight, root length, root dry weight, root-shoot ratio and white root number of dry-raised seedlings increased by 3.02%, 21.99%, 18.93%, 15.10% and 200.00%, respectively, but plant height decreased by 32.31%. Monitoring of ecological factor showed that soil water content of dry-raised seedlings was 15%17%. Under dry-raising condition, soil pH was decreased by 7.94% and electrical conductivity and temperature were decreased soil by 244.62% and 23 ℃, respectively, compared with those under moist-raising condition. The activities of phosphatase, invertase, urease, catalase and dehydrogenase in rhizosphere soils also increased by 166.66%, 518.85%, 131.98%, 102.70% and 84.36%, respectively, under dry-raised system at rice seedling stage, while nitrate reductase decreased by 72.95%. Dry-raising condition favored the conversion of soil organic matter and energy. This in turn increased soil organic matter, NO3-N, NH4+-N, available K and available P in rhizosphere soil of dry-raised seedlings respectively by 89.27%, 320.11%, 56.95%, 50.85% and 184.75%. Finally, 16sRNA high-throughput sequencing analysis showed that Chao1 and Shannon-Wiener index for bacterial was higher in rhizosphere soil of dry-raised seedlings than those of moist-raised seedlings. Analysis of soil microorganism biota revealed that the proportions of Alphaproteobacteria, Gammaproteobacteria, Bacteroidetes, Chloroflexi, Nitrospirae, Acidobacteria, Gemmatimonadetes, Planctomycetes and Actinobacteria increased in rhizosphere soil of dry-raised seedlings, while the proportions of Firmicutes and Betaproteobacteria decreased. Function analysis on dominant populations of rhizospheric bacterial community showed that dry-raising system at rice seedling stage accelerated the growth of soil nutrient conversing bacteria. This included nitrifying bacteria, azotobacter, ammonia oxidizing bacteria, photosynthetic bacteria, phosphorus and potassium-solubilizing bacteria. In addition, the ratio of bacillales, pfseudomonas and rhizobium containing large amounts of plant growth-promoting rhizobacteria also increased significantly in rice rhizosphere soil of dry-raised seedling, which favored root growth. In summary, the cultivation of dry-raised seedling by controlling soil moisture content changed the pH, electric conductivity, temperature and bacteria diversity of rhizosphere soils of rice seedlings. This in turn favored the development of strong seedlings.
2015, 23(12): 1562-1570.
doi: 10.13930/j.cnki.cjea.150596
Abstract:
A field experiment was conducted to determine the effects of nitrogen (N) fertilization on fluorine (F) contents in tea garden soils and tea shoots. The rates of nitrogen application were respectively 0 kg(N)hm-2 (CK), 360 kg(N)hm-2 (T1) and 720 kg(N)hm-2 (T2). The dynamic changes of soil pH and contents of NH4+-N, NO3--N and F in different?forms in tea garden soil were studied and F contents of shoots with one bud and four leaves, and shoots with one bud and five leaves were measured in spring, summer and autumn, respectively. The results showed that: 1) N application significantly decreased the content of water soluble F (FW) and slightly decreased the content of exchangeable F (FEx) and FFe/Mn oxide-bound F (FEx/Mn) in tea garden soil in 20 to 30 days after N application. In 4550 days after N fertilization, the reduction in FW slowed down while the contents of FEx and FEx/Mn increased. Compared with CK, the contents of various forms F in the 020 cm soil layer decreased under T1 treatment, while they increased under T2 treatment at the end of the experiment 164 days after N application. 2) Correlation analyses showed that for the 020 cm soil layer, NH4+-N content was significantly negatively correlated with FW and positively correlated with FFe/Mn (P < 0.01). Then for the 2040 cm soil layer, NO3--N content was significantly positively correlated with FW and negatively correlated with FEx (P < 0.01). Soil pH had a significantly negative correlation with FW (P < 0.01), but no significant correlation with the other three forms of F. FFe/Mn was significantly positively correlated with FEx and organic matter-bound F (FOr) at P < 0.01, but no significantly correlated with FW. 3) N application before and after spring tea harvest reduced F content in new shoots with one bud and four leaves and shoots with one bud and five leaves in spring, summer and autumn. However, the effect was not significant among different treatments. Under T1 condition, the largest reduction in F content in tea shoots was in summer tea (25.1527.95 mgkg-1), followed by autumn tea (21.0624.31 mgkg-1) and spring tea (18.5821.03 mgkg-1). Under T2 condition, the largest reduction in F content in tea shoots was in autumn tea (18.6422.34 mgkg-1), followed by summer tea (7.7914.14 mgkg-1) and then spring tea (3.527.30 mgkg-1). F content in tea shoots was mainly affected by soil inorganic N in the 020 cm soil layer and by soil pH in the 2040 cm soil layer. N application influenced tea root absorption of F and tea leaf accumulation of F, which regulated F content in new tea shoots. The study laid the theoretical basis for N fertilizing management in order to reduce F content in tea garden soils and in tea shoots.
A field experiment was conducted to determine the effects of nitrogen (N) fertilization on fluorine (F) contents in tea garden soils and tea shoots. The rates of nitrogen application were respectively 0 kg(N)hm-2 (CK), 360 kg(N)hm-2 (T1) and 720 kg(N)hm-2 (T2). The dynamic changes of soil pH and contents of NH4+-N, NO3--N and F in different?forms in tea garden soil were studied and F contents of shoots with one bud and four leaves, and shoots with one bud and five leaves were measured in spring, summer and autumn, respectively. The results showed that: 1) N application significantly decreased the content of water soluble F (FW) and slightly decreased the content of exchangeable F (FEx) and FFe/Mn oxide-bound F (FEx/Mn) in tea garden soil in 20 to 30 days after N application. In 4550 days after N fertilization, the reduction in FW slowed down while the contents of FEx and FEx/Mn increased. Compared with CK, the contents of various forms F in the 020 cm soil layer decreased under T1 treatment, while they increased under T2 treatment at the end of the experiment 164 days after N application. 2) Correlation analyses showed that for the 020 cm soil layer, NH4+-N content was significantly negatively correlated with FW and positively correlated with FFe/Mn (P < 0.01). Then for the 2040 cm soil layer, NO3--N content was significantly positively correlated with FW and negatively correlated with FEx (P < 0.01). Soil pH had a significantly negative correlation with FW (P < 0.01), but no significant correlation with the other three forms of F. FFe/Mn was significantly positively correlated with FEx and organic matter-bound F (FOr) at P < 0.01, but no significantly correlated with FW. 3) N application before and after spring tea harvest reduced F content in new shoots with one bud and four leaves and shoots with one bud and five leaves in spring, summer and autumn. However, the effect was not significant among different treatments. Under T1 condition, the largest reduction in F content in tea shoots was in summer tea (25.1527.95 mgkg-1), followed by autumn tea (21.0624.31 mgkg-1) and spring tea (18.5821.03 mgkg-1). Under T2 condition, the largest reduction in F content in tea shoots was in autumn tea (18.6422.34 mgkg-1), followed by summer tea (7.7914.14 mgkg-1) and then spring tea (3.527.30 mgkg-1). F content in tea shoots was mainly affected by soil inorganic N in the 020 cm soil layer and by soil pH in the 2040 cm soil layer. N application influenced tea root absorption of F and tea leaf accumulation of F, which regulated F content in new tea shoots. The study laid the theoretical basis for N fertilizing management in order to reduce F content in tea garden soils and in tea shoots.
2015, 23(12): 1571-1579.
doi: 10.13930/j.cnki.cjea.150285
Abstract:
The footprint of flux is effective for observation of the contribution of turbulent exchange to the atmosphere. It is closely related to the exchange of flux between the atmosphere and ecosystem. However, in practice, the complexity of the underlying surface increases the difficulty and uncertainty in calculating flux. Evaluation of flux footprint can solve the problem of spatial representativeness of flux, which makes it easy to calculate flux exchange. In order to study the variation in flux footprint for complete growth seasons of maize in semiarid area, flux footprint and source area functions were calculated from continuous flux measurements for the period from 1st January 2014 to 31st December 2014 using the eddy covariance system driven by FSAM model. The eddy covariance system was in the maize field in the Experiment Station of Agro-ecosystem in Semiarid Area (ESASA) of Lanzhou University, which is in a hilly area of the Loess Plateau. The flux measurement in the agro-ecosystem in semiarid area was spatially representative. The results showed that the prevailing wind direction in the research area was 90°180°. Wind frequencies in that direction during active growth and non-growing seasons of maize were respectively 59.11% and 55.28% of the total wind frequency. The second main wing direction was 270°360°. In the prevailing wind direction, the upwind footprint tail of the growing season was longer than that of non-growing season. However, the reverse was the case for the vertical upwind direction. The comparison between non-growing season 1 (January 1 to March 31) and non-growing season 2 (November 1 to December 31) showed a stable area of flux footprint for the non-growing season. In the prevailing wind direction, flux footprint decreased from seedling stage to tasseling stage while it increased from tasseling stage to maturity stage of maize. The farthest point of flux source area was significantly affected by aerodynamic roughness. Under stable stratification, source areas were larger than those under unstable conditions. The horizontal upwind range of source areas was 892 m and vertical upwind range of source areas was 35+35 m at 0.9 level under stable stratification. Then under unstable stratification, source area upwind range was 783 m and source area vertical upwind range was 25+25 m. There was no obvious difference between the areas of flux footprint between 90°180° direction and 270°360° direction, suggesting that flux footprint was not closely related with wind direction. Daytime flux source area was smaller than that of night-time, which was caused by different atmospheric stabilities for day-time and night-time. Comparison with other research results suggested that aerodynamic roughness and atmospheric stability influenced agro-ecosystem flux footprint by changing flux source length. Also δv/u* was the main factor driving flux source width. This study suggested that the flux footprint measured with FSAM adequately revealed the characteristics of surface flux in agro-ecosystems in semiarid areas.
The footprint of flux is effective for observation of the contribution of turbulent exchange to the atmosphere. It is closely related to the exchange of flux between the atmosphere and ecosystem. However, in practice, the complexity of the underlying surface increases the difficulty and uncertainty in calculating flux. Evaluation of flux footprint can solve the problem of spatial representativeness of flux, which makes it easy to calculate flux exchange. In order to study the variation in flux footprint for complete growth seasons of maize in semiarid area, flux footprint and source area functions were calculated from continuous flux measurements for the period from 1st January 2014 to 31st December 2014 using the eddy covariance system driven by FSAM model. The eddy covariance system was in the maize field in the Experiment Station of Agro-ecosystem in Semiarid Area (ESASA) of Lanzhou University, which is in a hilly area of the Loess Plateau. The flux measurement in the agro-ecosystem in semiarid area was spatially representative. The results showed that the prevailing wind direction in the research area was 90°180°. Wind frequencies in that direction during active growth and non-growing seasons of maize were respectively 59.11% and 55.28% of the total wind frequency. The second main wing direction was 270°360°. In the prevailing wind direction, the upwind footprint tail of the growing season was longer than that of non-growing season. However, the reverse was the case for the vertical upwind direction. The comparison between non-growing season 1 (January 1 to March 31) and non-growing season 2 (November 1 to December 31) showed a stable area of flux footprint for the non-growing season. In the prevailing wind direction, flux footprint decreased from seedling stage to tasseling stage while it increased from tasseling stage to maturity stage of maize. The farthest point of flux source area was significantly affected by aerodynamic roughness. Under stable stratification, source areas were larger than those under unstable conditions. The horizontal upwind range of source areas was 892 m and vertical upwind range of source areas was 35+35 m at 0.9 level under stable stratification. Then under unstable stratification, source area upwind range was 783 m and source area vertical upwind range was 25+25 m. There was no obvious difference between the areas of flux footprint between 90°180° direction and 270°360° direction, suggesting that flux footprint was not closely related with wind direction. Daytime flux source area was smaller than that of night-time, which was caused by different atmospheric stabilities for day-time and night-time. Comparison with other research results suggested that aerodynamic roughness and atmospheric stability influenced agro-ecosystem flux footprint by changing flux source length. Also δv/u* was the main factor driving flux source width. This study suggested that the flux footprint measured with FSAM adequately revealed the characteristics of surface flux in agro-ecosystems in semiarid areas.
2015, 23(12): 1580-1587.
doi: 10.13930/j.cnki.cjea.150445
Abstract:
Diverted water volume from the Yellow River to Ningxia irrigation area has continued to drop since 2000, having a significant impact on the development of irrigation in Ningxia. In order to determine the effect of decreasing diverted water volume on pollution of irrigation return flow in the region, the Yinbei Irrigation Area comprising of two typical drains (Yinxin and the Fifth drains) was used as a case study. Firstly, the yearly regularity of the amount of farmland irrigation return flow and the sources of pollution in the Yinxin and Fifth drains were determined. Furthermore, the evolution of ammonia nitrogen and total phosphorus concentrations during irrigation period in the drains were analyzed using the Mann-Kendall method. Meanwhile, farmland pollution load was calculated using a hydrology statistical analysis method. Finally, the effect of the decrease in water diversion on pollution of irrigation return flow in Yinbei Irrigation Area was analyzed and discussed. The results showed that the discharge processes in the drains were consistent with water diversion processes in the irrigation area, while irrigation return flow pollution mainly occurred in the stage of irrigation. Since 2000, the amount of irrigation return flow fell significantly in the Yinxin and Fifth drains. This change was largely in line with the diverted water volume from the Yellow River to the irrigation area. Furthermore, the water quality of irrigation return flow was improved during irrigation period in the Yinxin and Fifth drains. For the Yinxin drain, the concentration of total phosphorus apparently decreased and the concentration dynamics of ammonia nitrogen stabilized during irrigation period. Similarly, there were decreasing trends in the concentrations of ammonia nitrogen and total phosphorus in the Fifth drain during irrigation period. Compared with the period prior to 2004, ammonia nitrogen and total phosphorus load in the Yinxin drain dropped respectively by 35.3% and 41.7%, while that in the Fifth drain dropped by 71.2% and 63.7%. Correlation analysis revealed that non-point pollution load from farmlands was positively related with the volumes of irrigation return flow in the Yinxin and the Fifth drains. It was concluded that the control of the diversion of water volume and the adoption of agricultural water-saving techniques contributed to the control of pollution of farmland irrigation return flow in Yinbei Irrigation Area.
Diverted water volume from the Yellow River to Ningxia irrigation area has continued to drop since 2000, having a significant impact on the development of irrigation in Ningxia. In order to determine the effect of decreasing diverted water volume on pollution of irrigation return flow in the region, the Yinbei Irrigation Area comprising of two typical drains (Yinxin and the Fifth drains) was used as a case study. Firstly, the yearly regularity of the amount of farmland irrigation return flow and the sources of pollution in the Yinxin and Fifth drains were determined. Furthermore, the evolution of ammonia nitrogen and total phosphorus concentrations during irrigation period in the drains were analyzed using the Mann-Kendall method. Meanwhile, farmland pollution load was calculated using a hydrology statistical analysis method. Finally, the effect of the decrease in water diversion on pollution of irrigation return flow in Yinbei Irrigation Area was analyzed and discussed. The results showed that the discharge processes in the drains were consistent with water diversion processes in the irrigation area, while irrigation return flow pollution mainly occurred in the stage of irrigation. Since 2000, the amount of irrigation return flow fell significantly in the Yinxin and Fifth drains. This change was largely in line with the diverted water volume from the Yellow River to the irrigation area. Furthermore, the water quality of irrigation return flow was improved during irrigation period in the Yinxin and Fifth drains. For the Yinxin drain, the concentration of total phosphorus apparently decreased and the concentration dynamics of ammonia nitrogen stabilized during irrigation period. Similarly, there were decreasing trends in the concentrations of ammonia nitrogen and total phosphorus in the Fifth drain during irrigation period. Compared with the period prior to 2004, ammonia nitrogen and total phosphorus load in the Yinxin drain dropped respectively by 35.3% and 41.7%, while that in the Fifth drain dropped by 71.2% and 63.7%. Correlation analysis revealed that non-point pollution load from farmlands was positively related with the volumes of irrigation return flow in the Yinxin and the Fifth drains. It was concluded that the control of the diversion of water volume and the adoption of agricultural water-saving techniques contributed to the control of pollution of farmland irrigation return flow in Yinbei Irrigation Area.
2015, 23(12): 1588-1596.
doi: 10.13930/j.cnki.cjea.150869
Abstract:
Agricultural production conditions have undergone major changes because of climatic change. This has threatened not only food security, but also the farmers’ income. This study investigated the characteristics of household heads, families and social capital, which influenced farmers’ adaptive behavior to climate change, in order to understand famers’ adaptive behavior to climate change and provide a reference for government to make policy scientifically. In this study, rice producing areas of Jiangsu and Anhui Provinces were investigated through interpersonal interviews of 364 households. Using the Poisson Regression model in STATA statistical software, the paper analyzed the factors influencing the farmers’ adaptive behaviors to climate change. According to the survey data, adaptive measures to climate change most likely used by farmers was planting excellent rice varieties, which was orderly followed by turning to off-farm employments, repairing irrigation channels, changing irrigation frequency, adjusting planting and sowing time, buying agricultural insurance, adopting conservation farming techniques, diversified planting, adjusting fertilizer and pesticide application pattern and switching to other crops. The number of adaptive measures taken by farmers ranged from 0 to 8, with an average of 4.49. The main reason for giving up taking adaptive measures to climate change for famers was high costs, followed by unawareness of any adaption methods and labor shortage. Model results indicated that the gender and education of household head, family size, income structure, planting scale, social capital, meteorological information and agricultural extension services significantly impacted the adaptive behaviors of farmers to climate change. In order to enhance the adaptive capacity of farmers, it was essential for government to increase agricultural subsidies, improve agricultural insurance, rural infrastructure and transfer of arable land, guarantee food purchase price, and strengthen agricultural technology extension system. Furthermore, the farmers should to strengthen themselves through the construction of social network, social trust and social norms, which also contributed to enhance their ability to cope with natural risks.
Agricultural production conditions have undergone major changes because of climatic change. This has threatened not only food security, but also the farmers’ income. This study investigated the characteristics of household heads, families and social capital, which influenced farmers’ adaptive behavior to climate change, in order to understand famers’ adaptive behavior to climate change and provide a reference for government to make policy scientifically. In this study, rice producing areas of Jiangsu and Anhui Provinces were investigated through interpersonal interviews of 364 households. Using the Poisson Regression model in STATA statistical software, the paper analyzed the factors influencing the farmers’ adaptive behaviors to climate change. According to the survey data, adaptive measures to climate change most likely used by farmers was planting excellent rice varieties, which was orderly followed by turning to off-farm employments, repairing irrigation channels, changing irrigation frequency, adjusting planting and sowing time, buying agricultural insurance, adopting conservation farming techniques, diversified planting, adjusting fertilizer and pesticide application pattern and switching to other crops. The number of adaptive measures taken by farmers ranged from 0 to 8, with an average of 4.49. The main reason for giving up taking adaptive measures to climate change for famers was high costs, followed by unawareness of any adaption methods and labor shortage. Model results indicated that the gender and education of household head, family size, income structure, planting scale, social capital, meteorological information and agricultural extension services significantly impacted the adaptive behaviors of farmers to climate change. In order to enhance the adaptive capacity of farmers, it was essential for government to increase agricultural subsidies, improve agricultural insurance, rural infrastructure and transfer of arable land, guarantee food purchase price, and strengthen agricultural technology extension system. Furthermore, the farmers should to strengthen themselves through the construction of social network, social trust and social norms, which also contributed to enhance their ability to cope with natural risks.
2015, 23(12): 1597-1604.
doi: 10.13930/j.cnki.cjea.150606
Abstract:
In order to study the dynamic evolution of the vulnerability of rural water resources system in Hengyang Basin, an evaluation index system with 8 indicators was built. The indicators included average precipitation, drought index (July September), slope index, soil water storage index, vegetation index, land use index, water availability index and human activity index. The index-driven evaluation system was used to determine the vulnerability of rural water resources system in Hengyang Basin from 1990 to 2010. A mathematical model was constructed in GIS to analyze the spatial-temporal evolution and changing trends in rural water resources system vulnerability in Hengyang Basin in the last two decades. The model analyzed data were mainly from Remote Sensing (RS) satellites and processed on computer platform. After careful research and detailed analysis, the study concluded as follows: 1) In the last two decades, the vulnerability of rural water resources system in Hengyang Basin was low for the border regions, high for central regions, strong for the north and weak for the south of the basin. 2) In the last two decades, the vulnerability of rural water resources system in Hengyang Basin increased with an obvious spatial difference. The regions of enhanced vulnerability of water resources system were distributed mainly along the south and north while weakened regions of vulnerability of water resources system distributed mainly along the east and west. From the perspective of change in time, the vulnerability of rural water resources system in Hengyang Basin increased at the start and end of the study period, and weakened midway of the study period. 3) From the point of view of full time change, the vulnerability of rural water resources system in Hengyang Basin increased significantly in Hengshan, Hengyang and Hengdong Counties, weakened significantly in Leiyang and Qidong Counties, and had equilibrium distribution for different changes in the vulnerability of rural water resources system in Hengnan and Changning Counties. 4) The spatial differentiation characteristics of the change in vulnerability index was roughly classified into four types — fluctuating change, growing significantly after weakening, decreasing significantly after increasing and recovery growth after significant decrease. 5) From the trend of change in vulnerability in different years, the fluctuating change was the main type, followed by equilibrium state, and then the two types of increase (slow increase and slow decrease) were rare. In the last two decades, the overall intensity of the vulnerability of rural water resources in Hengyang Basin increased. Rural water resources vulnerability index had an obvious spatial and temporal variability. It was urgent to strengthen scientific management of water resources system in Hengyang Basin.
In order to study the dynamic evolution of the vulnerability of rural water resources system in Hengyang Basin, an evaluation index system with 8 indicators was built. The indicators included average precipitation, drought index (July September), slope index, soil water storage index, vegetation index, land use index, water availability index and human activity index. The index-driven evaluation system was used to determine the vulnerability of rural water resources system in Hengyang Basin from 1990 to 2010. A mathematical model was constructed in GIS to analyze the spatial-temporal evolution and changing trends in rural water resources system vulnerability in Hengyang Basin in the last two decades. The model analyzed data were mainly from Remote Sensing (RS) satellites and processed on computer platform. After careful research and detailed analysis, the study concluded as follows: 1) In the last two decades, the vulnerability of rural water resources system in Hengyang Basin was low for the border regions, high for central regions, strong for the north and weak for the south of the basin. 2) In the last two decades, the vulnerability of rural water resources system in Hengyang Basin increased with an obvious spatial difference. The regions of enhanced vulnerability of water resources system were distributed mainly along the south and north while weakened regions of vulnerability of water resources system distributed mainly along the east and west. From the perspective of change in time, the vulnerability of rural water resources system in Hengyang Basin increased at the start and end of the study period, and weakened midway of the study period. 3) From the point of view of full time change, the vulnerability of rural water resources system in Hengyang Basin increased significantly in Hengshan, Hengyang and Hengdong Counties, weakened significantly in Leiyang and Qidong Counties, and had equilibrium distribution for different changes in the vulnerability of rural water resources system in Hengnan and Changning Counties. 4) The spatial differentiation characteristics of the change in vulnerability index was roughly classified into four types — fluctuating change, growing significantly after weakening, decreasing significantly after increasing and recovery growth after significant decrease. 5) From the trend of change in vulnerability in different years, the fluctuating change was the main type, followed by equilibrium state, and then the two types of increase (slow increase and slow decrease) were rare. In the last two decades, the overall intensity of the vulnerability of rural water resources in Hengyang Basin increased. Rural water resources vulnerability index had an obvious spatial and temporal variability. It was urgent to strengthen scientific management of water resources system in Hengyang Basin.
2015, 23(12): 1605-1613.
doi: 10.13930/j.cnki.cjea.150370
Abstract:
Although the study of land carrying capacity assessment methods has involved a variety of factors in the past decades, few research studies have deeply focused on a particular aspect. Using the supply of ecological service value combined with population needs of ecological service value, a land carrying capacity assessment method was constructed for an effective quantitative test of land carrying capacity. A land cover classification was carried out using satellite remote sensing images as basic data source. Using the Costanza’s ecosystem service value evaluation method as a reference point (namely the unit area ecological service value coefficient), the ecological services value of a certain area was calculated. Combined with population need, the ecological services value was quantified. Finally, a method for evaluating the carrying capacity of land resources in Yunnan Province based on the supply value of ecological services was established to make extension and supplement for existing land carrying capacity assessment methods. Based on the analysis of Yunnan Province, it was helpful to improve the existing land resources carrying capacity assessment methods. The remote sensing technology used in this study to acquire land cover and land use data for Yunnan Province was critical for developing more effective methods. Combined with the Costanza’s theory of ecosystem service value, the supply of ecological service value in Yunnan Province was calculated. Based on the local statistical population data, total food consumption in different regions and cities of Yunnan Province was calculated. Finally, a land carrying capacity assessment parameters and standards based on the supply of ecosystem services was built for Yunnan Province. From the characteristics of the study area and the research goals, land cover/use types in Yunnan Province were divided into 6 classes: farmland, woodland, grassland, wetland, artificial surfaces and unused land. Based on TM Landsat remote sensing image data and the research area (the whole Yunnan Province) for 2010, the object oriented automatic classification method was used to obtain the overall distribution of the 6 land cover types in Yunnan Province on eCognition 8.7 classification platform. The results showed that given the supply of land resources and regional population food consumption, the situation of land resources in the region was optimistic. This was noted for Diqing, Nujiang and Lijiang in northern Yunnan Province and also those sparsely populated areas in southern Xishuangbanna and Pu’er. In other areas, however, land supply service was very inadequate relative to the population need. This was due to the long development history, large population, etc. The evaluation method of land carrying capacity constructed based on ecological services supply was a significant improvement over existing ones, with the potential to benefit land resource carrying capacity assessments elsewhere. It had the potential to contribute to the assessment of regional land resources and to lay a solid scientific basis for sustainable development planning.
Although the study of land carrying capacity assessment methods has involved a variety of factors in the past decades, few research studies have deeply focused on a particular aspect. Using the supply of ecological service value combined with population needs of ecological service value, a land carrying capacity assessment method was constructed for an effective quantitative test of land carrying capacity. A land cover classification was carried out using satellite remote sensing images as basic data source. Using the Costanza’s ecosystem service value evaluation method as a reference point (namely the unit area ecological service value coefficient), the ecological services value of a certain area was calculated. Combined with population need, the ecological services value was quantified. Finally, a method for evaluating the carrying capacity of land resources in Yunnan Province based on the supply value of ecological services was established to make extension and supplement for existing land carrying capacity assessment methods. Based on the analysis of Yunnan Province, it was helpful to improve the existing land resources carrying capacity assessment methods. The remote sensing technology used in this study to acquire land cover and land use data for Yunnan Province was critical for developing more effective methods. Combined with the Costanza’s theory of ecosystem service value, the supply of ecological service value in Yunnan Province was calculated. Based on the local statistical population data, total food consumption in different regions and cities of Yunnan Province was calculated. Finally, a land carrying capacity assessment parameters and standards based on the supply of ecosystem services was built for Yunnan Province. From the characteristics of the study area and the research goals, land cover/use types in Yunnan Province were divided into 6 classes: farmland, woodland, grassland, wetland, artificial surfaces and unused land. Based on TM Landsat remote sensing image data and the research area (the whole Yunnan Province) for 2010, the object oriented automatic classification method was used to obtain the overall distribution of the 6 land cover types in Yunnan Province on eCognition 8.7 classification platform. The results showed that given the supply of land resources and regional population food consumption, the situation of land resources in the region was optimistic. This was noted for Diqing, Nujiang and Lijiang in northern Yunnan Province and also those sparsely populated areas in southern Xishuangbanna and Pu’er. In other areas, however, land supply service was very inadequate relative to the population need. This was due to the long development history, large population, etc. The evaluation method of land carrying capacity constructed based on ecological services supply was a significant improvement over existing ones, with the potential to benefit land resource carrying capacity assessments elsewhere. It had the potential to contribute to the assessment of regional land resources and to lay a solid scientific basis for sustainable development planning.
Editor-in-chief：LIU Changming
Competent Authorities：Chinese Academy of Sciences
Sponsored by：Institute of Genetics and Developmental Biology, Chinese Academy of Sciences; China Ecological Economics Society
Organizer：Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences
ISSN 2096-6237
CN 13-1432/S
- Chinese core periodicals
- Core Chinese Sci-Tech Periodicals
- China's Top Science and Technology Periodicals
- Covered by Chinese Science Citation Database (CSCD)
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