中国生态农业学报(中英文)

CH₄ flux characteristics and influencing factors in six land use patterns in the Loess Plateau

LIU Huan, LIU Mengyun, LIU Liwen, ZHAO Guoqing, ZHANG Jie, ZHANG Mengmeng, LI Xiaoran

2018, 26(7): 937-947. doi: 10.13930/j.cnki.cjea.171124

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Abstract:
Change in land use can influence soil micro-environment along with microbial, physiological and biochemical processes, significantly affecting the generation and emission of greenhouse gases. At present, researches on greenhouse gas flux from land use transformation have mainly focused on carbon dioxide (CO₂), largely neglecting methane (CH₄) generation and emission. This study determined the characteristics of soil CH₄ fluxes and the influencing factors, also highlighting the critical factors of different land use patterns (cultivated land, natural grassland, shrub land, arbor and shrub land, arbor land and orchard). The study laid the basis for predicting the contribution of land-use-driven transformation to greenhouse effects in the Loess Plateau region. The study was conducted in Malian Forest Farm of Yongshou County, Shaanxi Province. In the study, soil CH₄ fluxes in different land use types were measured during the period from April 2015 to March 2016 using static chamber chromatograph techniques. The related environmental factors were recorded, including soil temperature, soil moisture, surface temperature and soil total nitrogen content. The results indicated that soils were CH₄ sink under different land use types. There were significant differences (P < 0.05) in CH₄ uptake fluxes in different land use types. Soil CH₄ fluxes in six land use types had similar seasonal variations, higher in summer and autumn than in winter and spring. Average soil CH₄ uptake was in the order of arbor and shrub land (51.24 μg·m^-2·h^-1) > arbor land (44.80 μg·m^-2·h^-1) > shrub land (31.52 μg·m^-2·h^-1) > natural grassland (25.89 μg·m^-2·h^-1) > orchard (18.97 μg·m^-2·h^-1) > cultivated land (14.89 μg·m^-2·h^-1). Soil CH₄ uptake fluxes in different land use types were positively correlated with soil temperature, surface temperature and total nitrogen, and negatively correlated with soil moisture. Soil temperature at the 0-20 cm soil layer was the main layer of production of soil CH₄ fluxes in six land use types. The uptake CH₄ under natural soil conditions was significantly higher than that in agricultural soils. The transformation of cultivated land to forest land increased CH₄ uptake, enhancing the mitigation of greenhouse effect of soil.

Climate suitability grading and planting zoning of soybean in Northeast Inner Mongolia

WANG Yanping, YIN Xiuxia, ZHANG Fang, ZHANG Xuming, WU Changshun

2018, 26(7): 948-957. doi: 10.13930/j.cnki.cjea.171128

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Abstract:
In northeast of Inner Mongolia, soybean production is faced with two problems. The first is that soybean planting area is zoned with ≥ 10℃ accumulative temperature without non clear division between soybean and maize region. The second is the use efficiencies of heat and water in the area are low in the area. In order to efficiently make use of water and heat resources in soybean cultivation and promote soybean production in cool area, we used meteorological observation data and soybean crop growing phrases data in years from 1987 to 2016 in Hulun Buir, Xing'an League in Northeast Inner Mongolia, and surrounding areas in Heilongjiang Province to analyze the climate suitability of soybean in Hulun Buir. In the study, temperature suitability, precipitation suitability of soybean were calculated, respectively, with the "three basis points" of temperature and water demand in each growth phase of soybean, while the climate suitability was calculated with the comprehensive hydrothermal suitability model. Furthermore, planting zoning of soybean cultivation in Hulun Buir was conducted according the comprehensive hydrothermal suitability level in GIS environment. The results showed that for the temperature suitability and comprehensive hydrothermal suitability, ≥ 0.6, 0.4-0.6 and ≤ 0.4 were classified as most suitable, more suitable and unsuitable. For precipitation suitability, ≥ 0.7 was most suitable, 0.6-0.7 more suitable and ≤ 0.6 unsuitable. The most suitable areas for planting soybean were in the southeast of Daxing'anling farming region, more suitable areas at the edge of the planting region in eastern Daxing'anling, then unsuitable areas were in the north woodland and western pastoral of Hulun Buir. Agroforestry ecotone in the south of forest region where accumulated temperature exceeded 10℃ was 1 900-2 100℃, which was not suitable for cultivating corn, but could be developed vigorously for cultivating soybean. This area was considered for increased soybean acreage during structural crop adjustment. The results provided reference for soybean production in the cool area in Northeast China.

Spatiotemporal evolution of rice production geographical agglomeration in Chongqing based on spatial statistics

TANG Rongli, YAO Xiong, WANG Chunping, WU Hong, LIN Qing, LEI Kairong

2018, 26(7): 958-970. doi: 10.13930/j.cnki.cjea.171183

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Abstract:
Knowledge about dynamic changes of geographical planting patterns of crops is a critical basis for planting adjustments and optimal configurations. Using ordered and spatial statistical methods, the spatial distributions, temporal evolutions, key production area transformations and geographical concentrations of rice production in Chongqing municipality were determined. Also the spatial evolution patterns and dynamics of rice production from 2000 to 2015 were quantified. The results showed that the cultivated area and rice production in Chongqing decreased before 2007, but gradually increased after 2008. During the study period, the spatial distribution patterns of yield per unit area, planting area ratio and total yield in Chongqing were all higher in the west than in the east, and then higher in the south than in the north. Using administrative districts as study unit, rice production areas were divided into 4 typical zones-large area with high yield, small area with high yield, large area with low yield and small area with low yield. From 2000 to 2015, the counties belonging to the large area with high yield type and large area with low yield was stable with some changed in rank of counties. However, the type of small area with high yield changed greatly, the counties number decreased from 8 in 2000 to 4 in 2015. The counties of the small area and low yield type most located in the hill area where the light, water conditions were relative poor. With the expansion of Chongqing City, some counties once were in the small area with high yield changed to the type of small area with low yield. Rice production center was located in the southwest of Chongqing and gradually moved to the northeast. While the degree of geographical aggregation of rice industry decreased gradually over time, the degree of spatial homogenization improved. Regional natural factors, social economy, planting technology development and government planning were the influencing factors of the patterns of rice industry. In future, different cultivation planning and optimal management measures were needed for different planting areas.

Evaluation of spatial differences in tourism resources values in Honghe Hani Rice Terrace Systems

ZHANG Yongxun, MIN Qingwen, LI Xiande

2018, 26(7): 971-979. doi: 10.13930/j.cnki.cjea.180001

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Abstract:
Tourism, as a type of non-pollution industry with low cost and short return period on investment, has become the first choice of local governments for economic development. Agricultural heritage site, as a kind of traditional rural area, has obvious advantages in terms of its abundant tourism resources. However, agricultural heritage site usually covers a big region including many counties or towns. There is the need that each sub-region develops different types of tourism, depending on its resource advantages, to avoid competition between sub-regions. Honghe Hani Rice Terrace System (HHRTS) enjoys a lot of natural and cultural landscapes and the titles of globally and nationally important agricultural heritage and world cultural heritage systems, but is located in impoverished counties. Tourism development in this area now is imbalanced in space. Thus, in this study, a scientific assessment of the resources in Hani Terrace area was conducted, on which basis a tourism development route for the area was proposed. In the study, the qualities of tourism resources in 8 towns of HHRTS site were assessed using the AHP-Fuzzy method. Based on the differences among the natural and human landscapes, an evaluation index system for resource characteristics and impact were constructed, which included 6 indexes (appreciation value, rare degree, scale, diversity, popularity and grade) for the natural landscape and 7 indexes (history, scale, cultural value, art value, popularity, originality and protection grade) for the human landscape. The weight and value of each index was marked by tourism experts. The assessment of tourism resources in 8 towns were done by researchers with long-term experience in Hani Terraces. The results showed that in the natural landscape resources, Maandi Town had an overwhelming advantage. Adebo Town and Sanmeng Town had an advantage over other towns due to their national-level natural reserves. Jiayin Town also had an advantage due to its good mix of water and plant landscapes. Panzhihua Town, Xinjie Town, Jiayin Town and Baohua Town had huge advantage over other towns because of the famous terraced landscape and advertisement. Then other towns had higher evaluation because of the human landscape, such as terraces, ancient villages and traditional cultures. In summary, the human landscape value was higher than the natural landscape value for HHRTS. Actually, the natural landscape also had a high value, but it still was not fully developed. The development level of tourism in Hani Terraces area varied in space. Therefore, different tourism development strategies for 8 towns were proposed, driven by tourism resource advantages of each town. Jiayin Town and Baohua Town were good for tourism in terraced agricultural activities because of special tourism villages and agricultural handicrafts. Xinjie Town, Panzhihua Town and Niujiaozhai Town were good for tourism in Hani terraced sightseeing and cultural experience of minority to make use of the ethnic culture and terraced landscapes. Sanmeng Town should develop minority festival experience and health-keeping traveling because of its good environment and ethnic culture. Then Adebo Town was to develop leisure agriculture and eco-tourism based on farming culture and natural reserves. Finally, Ma'andi Town was to build tourism in mountain and water sightseeing and artistic creation because of the fantastic natural sceneries.

Influence of artificial lodging at grain-filling stage on plant growth, yield and quality of super rice

ZHAO Xinyong, SHAO Zaisheng, WU Yanzhen, ZHAO Yipeng, WANG Yulong, WANG Yunxia, YANG Lianxin

2018, 26(7): 980-989. doi: 10.13930/j.cnki.cjea.171180

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Abstract:
Rice lodging has been one of the main constraints to high yield and good quality rice production in China. Because lodging not only makes mechanized harvesting difficult, it also impedes assimilate, water and nutrient transport in grains, limiting the realization of rice yield potential. Lodging conditions under high humidity are prone to diseases and pests, resulting in poor grain quality. In recent years, the potential risk of rice lodging has been increasing because of the release of high-yielding varieties characterized by large panicle, increased nitrogen fertilizer application and shifts from labor-intensive to simplified planting techniques such as direct-seeding or seedling broadcasting. In addition, extreme weather conditions, such as typhoon accompanied with heavy rains at late growth stage, has been another main reason behind lodging, often affecting large areas of croplands. Therefore, it was of utmost importance to further study the mechanisms of lodging-resistance of rice and the related regulation strategies. In this experiment, the effect of artificial lodging at grain-filling stage on plant growth, yield and grain quality of super rice ('Nanjing 9108') was investigated by comparing plants with normal growth (CK), artificial lodging after 30 days of heading (AL30) and artificial lodging after 15 days of heading (AL15). Compared with CK, AL30 and AL15 artificial lodging treatments decreased dry matter production of aboveground organs of 'Nanjing 9108', which resulted in decrease in total dry matter production by 7.3% (P < 0.05) for AL30 and 24.3% (P < 0.01) for AL15. The proportion of biomass distribution in reproductive organs decreased for AL15, but had no significant change for AL30. AL30 and AL15 artificial lodging treatments decreased grain yield by 8.3% (P < 0.05) and 36.4% (P < 0.01), respectively. Yield loss caused by lodging at grain-filling stage was mainly associated with decreases in filled-grain rate and 1000-full-grain weight. Filled-grain rate and 1000-full-grain weight decreased by 5.6% (P < 0.05) and 3.3% (P < 0.05) for AL30, and by 30.8% (P < 0.01) and 6.7% (P < 0.01) for AL15. Lodging-induced decrease in grain weight was mainly associated with smaller brown rice, which was attributed to poorer grain filling at grain-filling stage. Head rice rate decreased by 7.5% (P < 0.05) for AL30 and 14.7% (P < 0.01) for AL15. AL30 treatment had no effect on protein or amylose contents of rice grain, but AL15 increased protein content by 20.2% (P < 0.05). Artificial lodging had no significant effect on RVA profile of rice grain. The results suggested that the effect of plant lodging at late grain-filling stage (30 days after heading) on yield and grain quality of 'Nanjing 9108' super rice was relatively small. In contrast, plant lodging at early grain-filling stage (15 days after heading) inhibited dry matter production and grain-filling process, resulting in yield loss and grain quality deterioration.

Effect of floating dust weather on leaf photosynthesis and water potential of grapes in Karakash River Basin

ZHANG Fuchun, PAN Mingqi, MEMETABLA·Memettursun, ZHANG Wen, ZHONG Haixia, LI Tuanjie, GAO Dahui, WU Xinyu

2018, 26(7): 990-998. doi: 10.13930/j.cnki.cjea.170769

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Abstract:
Grape provides an important source of income for farmers in Karakash River Basin in Xinjiang. However, floating dust weather conditions are frequent in spring and summer. Thus grape production in the region is greatly influenced by both the floating dust weather and spring water scarcity. In order to determine the effects of floating dust weather conditions on grape photosynthesis and leaf water potential in the Karakash River Basin and on the adaptability of different grapevine varieties to the local climatic conditions, a study was conducted based on the analyses of the occurrence of floating dust weather during 2011-2017 in Karakax County in Karakash River Basin. Using 'Hotan Red', 'Munake', 'Thompson' and 'Centennial Seedless' as experimental materials, the effects of spring floating dust weather and natural cover of dust on photosynthesis and water potential of grape leaves were analyzed. The results showed that the floating dust days in Karakax County during the period from April to May were up to 23.7 days, accounting for 38.9% of the whole period. For floating dust days, average photosynthetically active radiation (PAR) in the area declined by 71.8% at 10:00-20:00 local time during day time. Also net photosynthetic rate (P_n) of grape leaf decreased significantly for all varieties at afternoon (12:00 local time), except for "Munake". For sunny days, the trend in water potential of grape leaf first increased before decreasing later. Leaf water potential change was non-obviously different during floating dust days and was lower than for sunny days. The change in transpiration rate (T_r) in floating dust days was similar to that in sunny days, but with a slight delay. Grape leaf was covered by dust during continuous dusty weather. The amount of dust retention per unit area of canopy of 'Thompson' and 'Centennial Seedless' were respectively 8.64 g·m^-2 and 10.93 g·m^-2. Dust cover dropped significantly P_n in 'Thompson' and 'Centennial Seedless', but increased intercellular CO₂ concentration (C_i). Dust cover also increased saturation intensity, compensation point, intrinsic quantum efficiency, apparent quantum yield and dark respiration rate of leaves of 'Thompson' and 'Centennial Seedless'. Conclusion therefore, dusty weather conditions reduced photosynthetically active radiation intensity, with grape leaves covered in dust, further reducing leaves P_n. At the same time, dust cover significantly increased dark breathing rate. The study suggested that cleaning dust on the surface of grape leaves effectively improved photosynthesis. Under floating dust weather conditions, grape leaf T_r decreased and leaf water potential was maintained. Thus floating dust weather conditions in Karakash River Basin delayed spring water deficit, and alleviated the conflict between supply and use of water in the area.

Estimation of leaf area index of rapeseed and rice based on deflection angle and spectral retrieval algorithm

LIU Yichen, MA Yi, TONG Chunyan, DUAN Bo, JIANG Qi

2018, 26(7): 999-1010. doi: 10.13930/j.cnki.cjea.170846

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Abstract:
Leaf area index (LAI) provides insight into productivity, physiological and phenological status of vegetation. The quick and accurate estimation of LAI contributes to growth status diagnosis and yield prediction. A variety of methods have been used for the estimation of LAI, however, the specific spectral bands applied differ widely among the methods and data used. Based on the general shape of the canopy reflectance curve, the spectral angles are found to be of great importance for the LAI estimation. The general objectives of this study were (i) to find informative spectral angles extracted by deflection angle based spectral retrieval (DABSR) and spectral bands retained in the other two common methods, vegetation indices (Ⅵ) and principle component analysis (PCA), for estimating LAI in rapeseed and rice; (ii) to compare the accuracy of the three methods as well as determine whether a robust algorithm for LAI estimation of two various crops can be devised. As the two main crops in China, rapeseed and rice, with different leaf structures as well as canopy architecture, were taken as the experimental subjects. Different nitrogen application rates (0, 45, 90, 135, 180, 225, 270, 360 kg×hm^-2) and planting treatments (directed sowing and transplanting) were set for rapeseed, while 45 varieties of rice under the same growing environment were employed in the experiment. It was revealed that, for LAI estimation of rapeseed, the model built with DABSR performed the best as the coefficient of determination (R²), root mean square error (RMSEP) and mean normalized bias (MNB) of the predictive model were 0.74, 0.47 and 0.16 respectively; the model built with PCA was of medium accuracy with 0.73, 0.48 and -0.04 for R², RMSEP and MNB, respectively. The selected Ⅵ models were of significantly poorer accuracy with 0.61, 0.57 and 0.17 for R², RMSEP and MNB respectively, as a result of the effect induced by flowers and pods on canopy reflectance spectrum. From the perspective of rice, the relationship model based on DABSR-STEPWISE was of the best accuracy, as the R², RMSEP and MNB could reach up to 0.70, 0.80 and 0.05. The models built with VIs performed the worst among three methods (R² ≤ 0.61, RMSEP ≤ 0.92 and MNB ≤ 0.04), while the PCA model performed in between with 0.63, 0.88 and 0.04 for R², RMSEP and MNB individually. The red edge and the NIR bands were selected in most models and considered the most informative. Among the three methods, DABSR-STEPWISE, proposed on the basis of spectral angle, was the most suitable for estimating LAI of two kinds of crops under different growing environments. The analysis allowed development of universal algorithms for LAI estimation in various crops. Being of high accuracy and high computational efficiency, these findings have significant implications on the development of uniform and robust algorithms, which is crucial for LAI estimation of specie-specific crops.

Effects of PEG, NaCl and Na₂CO₃ stresses on Suaeda glauca and Suaeda salsa seed germination

LI Jinsong, GUO Kai, LI Xiaoguang, FENG Xiaohui, LIU Xiaojing

2018, 26(7): 1011-1018. doi: 10.13930/j.cnki.cjea.171033

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Abstract:
Suaeda glauca and S. salsa are native halophytes in China with a key role in the improvement and restoration of salt marsh ecologies. There is a lot of works on the response of Suaeda plants to salinity, but works are limited about the effects of drought and alkali stress on S. glauca and S. salsa, especially at germination stage. The aim of this study was to evaluate the impacts of PEG, NaCl and Na₂CO₃ stress on the germination of S. glauca and S. salsa seeds. The in-vitro seed germination test was carried out with various solutions of PEG-6000 (29 mmol·L^-1, 38 mmol·L^-1, 45 mmol·L^-1and 50 mmol·L^-1), NaCl (100 mmol·L^-1, 200 mmol·L^-1, 300 mmol·L^-1 and 400 mmol·L^-1) and Na₂CO₃ (70 mmol·L^-1, 140 mmol·L^-1, 210 mmol·L^-1and 280 mmol·L^-1) in iso-osmotic concentrations (-0.46 MPa, -0.92 MPa, -1.38 MPa and -1.84 MPa). We measured the germination rate, germination index, mean germination time, early seedling growth after 7-day treatment and final germination rate after another 7-day recovery. The results showed that with increasing osmotic stress intensity, the germination rates of two species were depressed under PEG, NaCl and Na₂CO₃ treatments, while -0.46 MPa treatment did not differ significantly from that of the control (fresh water). The negative effect of NaCl on S. glauca seed germination was less than iso-osmotic PEG and Na₂CO₃ treatments. By contrast, the effects of iso-osmotic PEG, NaCl or Na₂CO₃treatments on S. salsa seed germination were not significantly different. The germination rate of S. salsa was positively related to osmotic potential. Recovery study indicated that PEG, NaCl and Na₂CO₃ stress had no negative effects on the final germinate rate of S. glauca and S. salsa, meaning that the inhibition of PEG, NaCl and Na₂CO₃ stress on seed germination was due to osmotic pressure rather than ion toxicity. In addition, mild NaCl treatments (-0.46 MPa for S. glauca, and -0.46 and -0.92 MPa for S. salsa) promoted S. glauca and S. salsa seedling elongation, while PEG and Na₂CO₃ treatments inhibited it. In iso-osmotic conditions, radicle and hypocotyl lengths of S. glauca and S. salsa seedlings under NaCl treatment were greater than those under PEG and Na₂CO₃ treatments. Compared with S. glauca, S. salsa seedlings grew better under -0.46 MPa and -0.92 MPa NaCl treatments, but worse under -0.46 MPa Na₂CO₃ treatment. The findings suggested that, 1) S. salsa seeds exhibited strong resistance to PEG, NaCl and Na₂CO₃ stress, and its resistance to PEG and Na₂CO₃ stress was greater than that of S. glauca. 2) S. salsa had stronger capacity to establish seedlings under NaCl stress than S. glauca, but its tolerance to mild Na₂CO₃ stress was weaker than that of S. glauca.

Effect of no-tillage on pore distribution in soil profile

YANG Yonghui, WU Jicheng, MAO Yongping, HE Fang, ZHANG Jiemei, GAO Cuimin, PAN Xiaoying, WANG Yue

2018, 26(7): 1019-1028. doi: 10.13930/j.cnki.cjea.171093

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Abstract:
Soil pore structure plays an important role in soil water movement in both topsoil and subsoil, and it is closely related to soil surface runoff and permeability. CT scanning has accurately revealed the number, size and location of macro-pores (> 1 mm in diameter). Long-term tillage can greatly influence the physical properties of soil profile, while non-tillage can improve soil structure, increase soil fertility and soil porosity, and thereby decrease soil bulk density and promote crop growth. Studies of non-tillage effects on soil pore have mostly been focused on the ploughed layer. Further study is needed to determine the impact of long-term non-tillage on soil pore volume, size and distribution along soil profile by using the CT scanning method and combining with soil structure, soil bulk density and soil moisture parameters investigation by using conventional method, especially for the deep soil (0-100 cm) layer. Thus in order to determine the effect of long-term no-tillage measure on pore characteristics, structure and water parameters of soil, CT scanning was used to quantitatively analyze soil pore volume (80-1 000 μm, > 1 000 μm and > 80 μm), porosity, and pore distribution of the 0-100 cm soil profile under long-term no-tillage and conventional tillage conditions in this study. A conventional method was adopted to determine macro-aggregate amount, bulk density, field water capacity, effective water content and saturated hydraulic conductivity. The results showed that no-tillage treatment increased numbers and porosities of soil pores > 1 000 μm, 80-1 000 μm and > 80 μm. The numbers increased respectively by 55.3%, 58.2% and 57.9%, while porosities increased by 97.4%, 39.4% and 72.6% of > 1 000 μm, 80-1 000 μm and > 80 μm pores under non-tillage treatment compared with the conventional tillage treatment. It was also found that pore shape and pore circularity improved under non-tillage treatment. For different soil layers, no-tillage treatment increased numbers of 80-1 000 μm pores and > 80 μm pores in the 0-25 cm and 80-100 cm soil layers, and number of > 1 000 μm soil pore in the 0-45 cm soil layer. Furthermore, there were significantly increases in porosities > 1 000 μm and > 80 μm soil pores in the 0-20 cm and 25-40 cm soil layers, and porosity of 80-1 000 μm soil pores in the 0-20 cm soil layer under non-tillage treatment compared with those under conventional tillage treatment. In addition, long-term no-tillage increased water content in the 0-25 cm soil layer, saturated hydraulic conductivity and content of water stable aggregates (> 0.25 mm) in the 0-55 cm soil layer. Then long-term no-tillage treatment reduced soil bulk density in the 0-55 cm soil layer compared with conventional tillage treatment. Correlation analysis showed that CT scanning well showed soil pore characteristics, which was related with soil physical parameters measured by conventional method. Also micro-cosmic soil pore characteristics could be used to characterize macroscopic physical properties of the soil. In summary, long-term non-tillage practice was beneficial for improvement of soil structure and pore, and increased soil water availability.

Effects of maize residue decomposition on aggregate composition and organic carbon distribution of different fertilities Brown soils

XU Yingde, WANG Jingkuan, WANG Siyin, SUN Xuebing, LI Junwei, ZHANG Mingyao, GAO Xiaodan

2018, 26(7): 1029-1037. doi: 10.13930/j.cnki.cjea.171087

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Soil aggregate and organic carbon are two major indices for assessing soil fertility. Besides, crop residue return is an effective agricultural way to supplement soil carbon pool and promote soil aggregate formation. However, how soil fertility level and residue type affect soil aggregate stability and organic carbon distribution is not clearly understood yet. In this study, a field incubation experiment was carried out by adding maize (Zea mays L.) root or stem and leaf to brown soil of different fertility levels. The samples of low fertility (LF) and high fertility (HF) soils were collected from a long-term (29 years) fertilization experiment. Six treatments were set, which were low fertility soil with maize root (LF+R), low fertility soil with maize stem and leaf (LF+S), high fertility soil with maize root (HF+R), high fertility soil with maize stem and leaf (HF+S), low or high fertility soil without maize residues (LF or HF). The objective of the study was to explore the dynamics of soil aggregate composition and allocation of organic carbon after residue incorporation. The study could have significant implications for developing residue management and reduce soil erosion in agro-ecosystems. The results showed that soil fertility significantly affected aggregates composition and organic carbon allocation of soil with crop residue incorporation. The addition of maize residue increased mean weight diameter, geometric mean diameter of soil aggregates and contribution rate of organic carbon in larger aggregates (> 2 mm and 1-2 mm) in LF soil compared to those in HF soil. The results suggested that LF soil was more sensitive to organic matter input and had a rapid rate of transformation to macro-aggregate. 2) At the end of experiment, the addition of maize stem and leaf to HF soil had a more pronounced effect on soil aggregate stability compared to the addition of root. Then the addition of root had a more pronounced effect on organic carbon content in soil aggregates than the addition of stem and leaf. However, there was no significant difference between soil aggregate stability and organic carbon content in LF soil aggregate supplemented with different maize parts. The results further suggested that soil fertility level could change the effects of different parts of crop residues addition on soil aggregate stability and organic carbon distribution. 3) The proportion of > 2 mm, 1-2 mm aggregates and soil aggregate stability sharply increased during the first 360 days. This then tended to stable during the later incubation period of 360-720 days. This indicated that the effect of maize residue on the formation of soil aggregate gradually weakened with time. It was concluded that the effects of maize residue addition on soil aggregates composition and organic carbon distribution were dependent on both soil fertility and residue part. Besides, crop residue addition had more obvious effect on improving the structure and stability of aggregates in LF soils.

Change characteristics of soil phosphorus and phosphorus fertilizer efficiency in Black Loessial soil of dryland in the Loess Plateau under long-term fertilization

WANG Shuying, FAN Tinglu, DING Ningping, ZHAO Gang, ZHANG Jianjun, LI Shangzhong, WANG Lei, DANG Yi, CHENG Wanli, TANG Xiaoming

2018, 26(7): 1038-1047. doi: 10.13930/j.cnki.cjea.171002

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Abstract:
Using a long-term fertilization experiment set up in 1978 in Pingliang, Gansu Province, changes in soil phosphorus (P) and P fertilizer efficiency (PFE) were determined and used to guide rational application of P fertilizer in dry farmlands. Six fertilizer treatments-no fertilizer (CK), chemical nitrogen (N), chemical nitrogen and phosphorus (NP), straw plus chemical NP (SNP), farmyard manure (M) and farmyard manure plus chemical NP (MNP)-were used in the cropping system of 4-year continues winter wheat followed by 2-year spring corn. After 38 years, the total soil phosphorus and Olsen-P contents in CK and N treatments decreased, and phosphorus activation coefficient dropped. Total soil phosphorus contents under NP, SNP, M and MNP treatments increased respectively by 22.8%, 14.0%, 38.6% and 56.1%. Then Olsen-P contents increased respectively by 99.1%, 48.4%, 206.4% and 375.6%, while P activation coefficients were 1.7, 1.3, 2.2 and 3.1 times as that in 1978. Total soil P contents in N and SNP treatments were negatively correlated with the number of experimental years with annual decline rates of 1.9 mg·kg^-1 and 2.6 mg·kg^-1, respectively. Total soil P contents under NP, M and MNP treatments were positively correlated with the number of experimental years, with annual increase rates of 1.2 mg·kg^-1, 1.9 mg·kg^-1 and 2.8 mg·kg^-1, respectively. Total soil P contents under CK remained basically unchanged with the number of experimental years. Soil available P contents under CK and N treatments decreased with increasing number of experimental years, and the annual decline rates were respectively 0.03 mg·kg^-1 and 0.09 mg·kg^-1. Soil available P contents under NP, SNP, M and MNP treatments were positively correlated with the number of experimental years, with annual increase rates of respectively 0.29 mg·kg^-1, 0.24 mg·kg^-1, 0.46 mg·kg^-1 and 0.89 mg·kg^-1. Crop yield was positively correlated with soil available P (wheat R²=0.116 9, n=132; corn R²=0.332 4, n=54). P using rate (PUR), P recovery rate (PRR) and P agronomic efficiency (PAE) of corn were greater than those of wheat for all 4 P treatments (NP, SNP, M and MNP), but P physiological efficiency (PPE) of wheat was greater than that of corn. The ranked order of above four indexes of P fertilizer efficiency (PFE) for different treatments was SNP > NP > MNP > M. The four indexes of PFE of maize were positively correlated with the number of experimental years. Compared with MNP treatment, P input with M decreased 14.2%. Wheat and corn PFE decreased by 14.3%-69.5% and 0.8%-75.5%, respectively. In summary, combined application of organic and inorganic fertilizers was optimal choice for improving soil fertility, increasing crop yield and enhancing resource use efficiency in Heilu soil of the Loess Plateau dryland.

Effect of long-term conservation tillage on arbuscular mycorrhizal fungi diversity

ZHANG Guiyun, ZHANG Liping, WEI Mingfeng, LIU Zhen, FAN Qiaolan, LYU Beibei, YAO Zhong, CHAI Yuejin

2018, 26(7): 1048-1055. doi: 10.13930/j.cnki.cjea.171119

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Abstract:
To verify the effect of long-term conservation tillage and subsoiling on arbuscular mycorrhizal fungi (AMF) diversity in dry areas in northern China, a comparative analysis of species richness, spore density, Shannon diversity index and colonization rate of AMF among no-till with straw mulching (NTS), no-till with straw mulching after subsoiling (SNTS) and traditional tillage treatment (TT) were conducted in 2014 at a long-term (22 years) positioning test base for conservation tillage in Linfen, Shanxi Province. In the study, 9 AMF species belonging to 7 genera were isolated and identified in soil samples of NTS and SNTS treatments, including two species each of Rhizophagus and Funneliformis and one species each of Glomus, Claroideoglomus, Acaulospora, Sclerocystis and Septoglomus. Also 8 AMF species belonging to 6 genera were isolated and identified in soil samples of TT treatment. The AMF species in the TT treatment were the same with those in NTS and SNTS treatments, except that there was no Acaulospora.The dominant species of AMF in NTS, SNTS and TT treatments were the same. The dominant species of AMF in the 0-40 cm soil layer were mainly Fu. mosseae and G. versiforme, the 40-80 cm soil layer were Fu. mosseae, G. versiforme and Rh. aggregatum, and the 80-120 cm soil layer was Rh. aggregatum. Below the 120 cm soil layer, the dominant AMF species was Rh. aggregatum, which was found only under NTS and SNTS treatments. Species richness, spore density and Shannon diversity index of AMF in NTS and SNTS treatments in the same soil layers were higher than those in TT treatment, and those in SNTS treatment were higher than those in NTS treatment. Species richness, spore density and Shannon diversity index of AMF decreased with increasing of soil depth under the same treatment. The maximum species richness, spore density and Shannon diversity index of AMF were all in the 0-20 cm shallow soil layer. The colonization rate and spore density of AMF at different growth stages of wheat in NTS and SNTS treatments were all significantly higher than that in TT treatment. Colonization rate of AMF in NTS, SNTS and TT treatments was the highest at jointing stage of wheat and was respectively 14.9%, 16.1% and 10.6%. AMF spore density of soil was the highest at maturity stage of wheat and was respectively 111.7 spores·(100g)^-1, 125.0 spores·(100g)^-1 and 90.3 spores·(100g)^-1. The study showed that long-term no-till with straw mulching improved AM fungi diversity, especially under no-till with straw mulching after subsoiling. The results provided the scientific basis for the full play of AMF role and reasonable application of conservation tillage in dry farmland ecosystems in northern China.

Effects of species-combined exogenous decomposing micro-organisms on soil microbial community structure and metabolic activity

ZHOU Xuan, LI Yuming, CONG Cong, WANG Qianqian, JIANG Heng, YUE Longkai, YAO Shuihong

2018, 26(7): 1056-1066. doi: 10.13930/j.cnki.cjea.171216

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Abstract:
An incubation experiment was conducted to study the effects of species combination of exogenous decomposing micro-organisms on soil microbial community structure and metabolic activity. The objective of the study was to lay the basis for the optimization of population configuration of decomposing microbial agents. In the study, three microbe species-Paenibacillus pabuli (P), Streptomyces violaceorubidus (S) and Trichoderma aureoviride (T)-were selected. For the experiments, in addition to single P, S and T microbe strains, the microbes were merged to produce two species (PT, PS and ST) and three species (PST) combinations of decomposing microorganisms (forming a total of 7 microbial agents). These microbial agents were then added to red soil sampled from Jiangxi Province in South China. Moreover, a control treatment of red soil added with sterile peat was set to the experimental design. During the incubation period, temporal changes in soil respiration rate and microbial biomass carbon were monitored. Additionally, the changes in total PLFAs content and in the proportion of characteristic microbial population in different treatments after 30 days of incubation were determined. The PLFAs percentages of microbial communities showed the total microbial biomass and composition of soil microbial communities. The results showed that, except for ST and PST, most treatments showed that total microbial biomass increased from 17.2% to 121.6% (P < 0.05). Compared with the control, the proportion of fungus in all the treatments increased by 8.8%-50.6% (P < 0.05). However, the proportion of bacteria in PLFAs remained basically unchanged, increasing from 79.6% to 83.1%. For most of the treatments, except for P and ST, the proportion of actinomyces decreased from 9.4% to 69.8%. Principal component analysis (PCA) of PLFAs data indicated that soil microbial community structure was influenced by different decomposing micro-organisms agents. The change in microbial community structure varied with treatment type, among which single P, S and T microbe strains were smallest and their trio-combination (PST) biggest, compared with the control. The results of soil respiration rate showed the growth of micro-organisms. Treatments of single P and T microbe strains and binary combination of micro-organisms S and T (ST) affected logarithmic growth of soil microbes in the short-term, increasing peak soil respiration rate by 48.7% (P), 53.7% (T) and 78.7% (ST), respectively. Additionally, with increasing number of species of decomposing micro-organisms, it took more time for soil microbes to enter latent phase. From long-term impact of exogenous decomposing micro-organisms on soil fertility, these micro-organisms changed soil microbial metabolic activity, which led to a change in the amount of soil carbon mineralization. The addition of ST combination of microorganisms increased soil microbial metabolic quotient by 28.9%, consequently, the amount of soil carbon mineralization increased by 11.1%. The addition of single S microbe strain decreased soil microbial metabolic quotient by 32.4%, while the amount of soil carbon mineralization only decreased by 7.3%. However, under PS and PST combinations, microbial metabolic activity remained unchanged, while the amount of soil carbon mineralization decreased by 5.8% and 8.7%, separately. There was the need for further study on these treatment combinations. In conclusion, the addition of exogenous decomposing micro-organisms changed soil microbial community structure and growth trajectory. Furthermore, with increasing number of species of decomposing micro-organisms, change in microbial community structure increased. Finally, the study failed to account for any relationship between soil microbial metabolic activity and the number of species of decomposing micro-organisms.

Construction potential of high-standard farmland based on landform factors

LI Chunmei, SHAO Jing'an, GUO Yue, CAO Fei, TAN Shaojun

2018, 26(7): 1067-1079. doi: 10.13930/j.cnki.cjea.171122

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Abstract:
The construction of high-standard farmland is important for scientific, efficient and sustainable use of land resources, and the potential study is the basic work in the construction of high-standard farmland. In view of the experience and problems in the construction of high-standard farmland during the "12^th Five-Year" period, this study hypothesized that "high-standard" not only focused on the quality improvement, but also the enhancement of mechanization and scale of cultivated land. Moreover, differentiation was necessary in planning and design for various natural, social and economy conditions. There are complex and diverse landform types in Chongqing. Driven by the law of regional differentiation, significant differences in social-economy and industrial development arose in space. Thus this article used landforms as the basis for evaluation of high-standard farmland construction potential with Dianjiang County in Chongqing as the research area. The study analyzed the potential of using basic farmlands to build high-standard farmlands and isolated the limiting factors for building high-standard farmlands in different landform types. Hence it was expected that the study will provide the theoretical basis for the planning and construction of new high-standard farmlands in Dianjiang County, Chongqing. Based on the four landform areas of Dianjiang County (shallow and low hill area, low middle hill area, high hill with flat area, and low mountain and deep hill area), we established an index system to evaluate the construction potential of high-standard farmlands. Furthermore, the entropy weight method was used to calculate the weights of indicators in each geographic area. The comprehensive index method was further used to determine the potential score of each evaluation unit. The results showed that:1) about 80% of the basic farmlands in Dianjiang County had the potential to be transformed into high-standard farmlands. Among these, the area basically meeting the construction criteria covered 28.57% of the total basic farmland, the area needing improvement accounted for 24.13%, and the area needing comprehensive renovation made up 26.92%. 2) The potential for the construction of high-standard farmlands in four types of landform was ranked as:shallow and low hill area > low middle hill area ≈ high hill with flat area > low mountain and deep hill area. 3) There were different limiting factors to high-standard farmland construction in different landform areas. The restricting factors in the shallow and low hill area were soil organic matter content and farmland protective acreage. The limitations in low middle hill area were effective soil layer thickness, soil organic matter content, and irrigation and drainage conditions. The restrictive factors in the high hills with flat area were soil organic matter content, irrigation and drainage conditions, and distance of field to main road. The limiting factors in low mountains and deep hill area were effective soil layer thickness, soil organic matter content, pH, irrigation and drainage condition, farmland tractor-plowing ability, and distance of field to residential area. In the planning and implementation of high-standard farmland construction projects, there was need for project layout to be closely developed around different physiognomy type restriction factors and local agricultural industry development direction. At the same time, there was need for project layouts to focus on leading industries and to eliminate or reduce the role of limiting factors, to carry out different high-standard farmland constructions.

Permanent prime farmland demarcation in city periphery in peninsula hill areas: A case of Haiyang City in Shandong Province

ZHANG Yaqin, YAN Hongwen, ZHAO Xianfeng, SUN Shiqing

2018, 26(7): 1080-1088. doi: 10.13930/j.cnki.cjea.171003

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Abstract:
The red lines of prime farmlands constitute the top priority of the "Tri-Line" demarcation of general land use planning. The demarcation of permanent prime farmlands in city periphery has been of great significance for controlling city unlimited sprawl, stabilizing farmland area and ensuring food security of the country. Using Haiyang City in Shandong Province as a case study, this study developed a land planning strategy for the study area based on the "Tri-Line"-coordinating demarcation process. The study adopted procedures of ecological priority, strict construction land evidence, positive demarcation of high-quality cultivated land and market resources allocation to integrate ecological safety network, suitable evaluation of construction land and comprehensive evaluation of cultivated land to demarcate the permanent prime farmland in the study area. To comprehensively evaluate the cultivated land quality, the land evaluation and site assessment (LESA) method was improved, and ArcGIS was used to analyze spatial distribution of cultivated land patch. The results showed that the area of cultivated lands in ecological safety network was 12.11 hm², and those in the priority construction region and important construction region was 154.99 hm², both were not suitable for permanent prime farmland. The cultivated land in the city periphery was divided into 4 grades based on comprehensive quality scores. The priority area and suitable area were designated as permanent prime farmland, where the natural quality and site condition were superior. Then the controlled area and reserved area were not included in this division. About 458.05 hm²land was in the priority region, of which 427.82 hm² of the cultivated land was classified as permanent prime farmland. About 771.83 hm² land was classified as suitable area, of which 500.67 hm² was permanent prime farmland. After demarcation, the area of permanent prime farmland around Haiyang City was 1 305.22 hm², of which newly cultivated land formed 928.49 hm², accounting for 60.26% of the total cultivated land around the city. Overall, permanent prime farmland protection rate increased by 42.66%. The average use index of cultivated land in permanent prime farmland (9.04) was higher than that of cultivated land in the whole city (9.56), and the slope of the permanent prime farmland was less than 15°. 4) The layout of ecological security land, permanent prime farmland and construction land around the city was more optimized in favor of the orderly development of the city and the sustainable use of the land. In summary, based on the improved LESA evaluation method and comprehensive consideration of layout space of ecological security land, permanent prime farmland and construction land, the study enriched the demarcation method of permanent prime farmlands and achieved permanent prime farmland demarcation in Haiyang City. At the same time, the results of the study were practicable and provided the scientific basis for the protection of permanent prime farmlands and the application of "Tri-Line" demarcation in general land use planning.

2018 Vol. 26, No. 7