2012 Vol. 20, No. 3

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New dimensions in agroecology
LIN Wen-Xiong, CHEN Ting, ZHOU Ming-Ming
2012, 20(3): 253-264. doi: 10.3724/SP.J.1011.2012.00253
Abstract(2496) PDF(2992)
Abstract:
The authors reviewed the developmental history and characteristics of agroecology, and pointed out that the research areas of agroecology were broadening in both macroscopic and microscopic aspects, and the researches were going more deeply. On the macroscopic level, the investigation of agroecology was expanding from a pure macroscopic study of agricultural biology to a sociological study concerning the issues related to agriculture, farmer and rural areas. The research works shifted from the relationships between structure and function of agroecosystem to the food system. The major task was to study the impacts of the energy and material flow in agroecosystem on the social and economic development, and the regulation of food system by policy and laws from the eco-economic perspective. Modern agroecology emphasized the awakening of social ecological consciousness and the important role of ecological consciousness which played great roles in the protection of argoecosystem and the promotion of pollution-free production. Therefore, in western countries, community movements or actions were important ways that agroecologists relied on to make government, production units, sell units and administrations accept the agroecological concepts, act in compliance with agroecological laws and ensure the health and efficiency of the food system. These activities had become essential subjects in the education, research and practice of modern agroecology, which involved all processes in agroecology, including scientific research, demonstration and its extension of experiments, promotion by society or association actions, spontaneous participation of publics. All these efforts embodied the feature of the modern agroecology. On the microscopic level, modern agroecology was entering the age of molecular agroecology. Molecular agroecology employed the state-of-art techniques of modern biology and introduced the theories and assays from systems biology to unveil the underlying relationships and mechanisms of the structure and function of agroecosystem. With the development of modern biology techniques, especially the breakthroughs of environmental (meta-) genomics and proteomics, molecular agroecology largely enriched our knowledge of the unknown biological world. The ability to analyze biodiversity and genetic diversity in depth enabled molecular agroecology to examine the processes and mechanisms underlying ecosystem development on the molecular level, which fueled the transformation of agroecology from a qualitative and half-quantitative study into a quantitative and mechanism study. This change urged the agroecologists to keep pace with the times. The agroecologists needed to improve their knowledge structure and scientific research ability in order to follow the transformation of agroecology from traditional science into modern science. This article took many case-studies as examples to demonstrate the necessity and importance of this scientific development, and aimed at inspiring introspection and thinking among peers.
Characteristics of nutrient return and uptake in rice-duck mutualism ecosystem of double rice cropping season
ZHANG Fan
2012, 20(3): 265-269. doi: 10.3724/SP.J.1011.2012.00265
Abstract(1880) PDF(1387)
Abstract:
aising ducks in paddy fields is a traditional agricultural model in China. Field experiments were conducted in rice-duck mutualism ecosystems in the double rice cropping region of Hunan Province during May to October of 2010. A conventional rice field was used as the control. The characteristics of nutrient return and uptake by rice in the rice-duck mutualism ecosystem were analyzed. The main objectives of the study were to provide theoretical and practical bases for further development and utilization of this classical agricultural technique. Results showed that feeding duck in paddy fields respectively increased C, N and P by 229.87 kg·hm-2, 18.22 kg·hm-2 and 17.75 kg·hm-2 of duck feces during double rice cropping season. During double rice cropping season, the return of C, N and P to soil in the rice-duck mutualism ecosystem was in the order of C > N > P. The measured values of C, N and P were 1 491.21 kg·hm-2, 66.02 kg·hm-2 soils under the rice-duck mutualism ecosystem increased by 20.43% (P > 0.05), 55.81% (P < 0.05) and 379% (P < 0.05), respectively. While C and N returns were largely from rice root system, P return was mostly from duck feces. In contrast with conventional rice system, rice-duck symbiosis system increased soil total N by 5.73%, significantly increased soil total P by 6.25%. The rice-duck symbiosis increased root and straw total N and P and seed total P during double cropping rice season. It also increased straw N and P uptake, root P uptake and decreased yield and seed N and P uptake during double cropping rice season. Rice P uptake and content were better than N under rice-duck mutualism ecosystem.
Effect of no-tillage on soil aggregate and organic carbon storage
JIANG Xue-Bing, LI Yun-Sheng, OUYANG Zhu, HOU Rui-Xing, LI Fa-Dong
2012, 20(3): 270-279. doi: 10.3724/SP.J.1011.2012.00270
Abstract(2117) PDF(1892)
Abstract:
No-tillage (NT) is an increasingly agronomic practice in China. Tillage practices deeply affect soil quality and organic carbon (SOC) accumulation. The effect of NT, as a form of conservation tillage, on soil organic carbon storage had remained highly contentious. To shed further view on the effect of NT on soil structure and quality in the Huang-Huai-Hai Plain (HP), a long-term no-tillage experimental site for the main crop rotation — winter wheat (Triticum aestivum L.) and summer maize (Zea Mays L.) — was investigated. The experimental site belongs to the Yucheng Comprehensive Experimental Station (YCES) of Chinese Academy of Sciences (CAS) and has been used in studying the changes in soil aggregates and organic carbon storage under different tillage systems for 7 years now. NT, no-tillage with removed residue and organic fertilization (NTRR) and conventional tillage (CT) treatments were set up in the study. The impact of the three tillage systems on total soil organic carbon content and storage, water-stable aggregate stability, water-stable aggregate SOC content and storage, and relationship between total SOC content and water-stable aggregate SOC content were analyzed. Compared with CT, SOC content and storage, and water-stable aggregate mean weight diameter (MWD) and geometric mean diameter (GMD) along with macro-aggregate organic carbon content and storage in the 0~20 cm soil layer significantly increased in NT and NTRR treatments. This was possibly due to reduced soil disturbances and residue mulch and organic fertilizer applications. No tillage plots with residue mulch stored more SOC and macro-aggregate organic carbon than those with applied organic fertilizer. For the treatments, the order of the content of SOC and macro-aggregate organic carbon in the 20~60 cm soil depth was NT < NTRR < CT. In comparison with NT and NTRR, CT limited deep-soil organic carbon accumulation. Compared with straw mulch, the application of organic fertilizer enhanced deep-soil organic carbon accumulation under no tillage. On the average, SOC storage in NT and NTRR was lower than in CT in the 0~60 cm soil depth. There was a significant positive correlation between SOC and 0.25~2 mm aggregate organic carbon, indicating that the 0.25~2 mm soil macro-aggregates could be used as a proxy for changes in SOC. In conclusion therefore, no-tillage significantly improved the distribution and stability of surface soil water-stable aggregates. While no-tillage significantly increased the storage of surface total SOC in the 0.25~2 mm soil aggregates, reduced it in deep soil layers. Compared with organic manure, straw mulch promoted the accumulation of SOC in surface soils and reduces it in deep soils under no tillage practice.
Soil enzyme activity under organic versus conventional vegetable production systems
YE Jun, WANG Xiao-Li, Gonzalez Perez Pablo, LIU Xiao-Song, HUANG Dan-Feng
2012, 20(3): 279-284. doi: 10.3724/SP.J.1011.2012.00279
Abstract(1650) PDF(1171)
Abstract:
There has been a growing trend in using soil enzymes as indicators for changes in soil quality under different management practices. Although literature on this subject has tremendously grown in the last 10 years, most of the studies have focused on cultivated fields. However, research on cultivated vegetable soils also has significant implications. Experiments were conducted at two close-by fields (one under organic farming and the other under conventional farming) in Shanghai to investigate the influence of different horticultural farm management practices on soil enzyme activities. Four combinations of field type and management system — organic management in greenhouse (GO), conventional management in greenhouse (GC), organic management in open-field (LO) and conventional management in open-field (LC) conditions — were evaluated. Soil sampled at the 0~20 cm depth were analyzed using the traditional soil analysis method. Furthermore, proteinase, urease, dehydrogenase, β-glucosidase and nitrate reductase activities were determined. The results presented here fostered an in-depth understanding of the impacts of management practices on soil enzyme activities. Soil electrical conductivity (EC) under organic managements was less than that under conventional management by averages of 12% and 16% in greenhouse and open-field conditions, respectively. The levels of microbial biomass C and N under organic managements were higher than those under conventional managements. Significant differences were noted in proteinase and prease activities among the different management practices. Proteinase, urease, dehydrogenase and β-glucosidase activities were comparatively high under organic management, while nitrate reductase activity was low. Management practices significantly affected proteinase and urease activities with P values of 0.006 8 and 0.012 4 respectively. Environmental conditions of cultivation significantly influenced proteinase, urease, β-glucosidase and nitrate reductase activities. Enzyme activities were higher in organic managements under greenhouse conditions than in other treatments. Analysis showed that proteinase, urease, dehydrogenase and β-glucosidase activities were closely correlated (at significant levels) with total dissolved nitrogen, microbial biomass C and microbial biomass N. In summary, organic systems significantly improved soil microbial characteristics and increased soil organic C, which in turn enhanced soil enzyme activities. Moreover, proteinase, urease, dehydrogenase and β-glucosidase activities were suitable indicators for soil fertility. Further studies that focus on determining the relationship between soil microbial diversity and specific enzyme activities under different management systems using the DGGE (denaturing gradient gel electrophoresis) technique were therefore recommended.
Effect of organic management on soil fertility and melon production in irrigated oasis farmlands
ZHANG Zheng, DAI Chun-Yan, CHEN Nian-Lai, ZHANG Yu-Xin, SUN Xiao-Mei, HUANG De-Zhi, ZHAO Na
2012, 20(3): 285-290. doi: 10.3724/SP.J.1011.2012.00285
Abstract(1461) PDF(1188)
Abstract:
Organic management is an effective strategy for producing safe fruits and vegetables. To evaluate the effect of organic management on soil quality and melon production in dry regions, an open-field experiment was conducted in the lower reaches of the Shiyanghe River Basin. Melon yield and quality, soil nutrients, enzyme activities and quantities of microorganisms were determined in plots after different years of organic management. The results showed that organic management significantly increased soil organic matter and available N, P and K contents. After one, two and three years of organic management, soil organic matter content increased by 36.48%, 71.54%, 124.21% compared with traditional management, respectively. In three-year organic management plots, soil available N, P and K contents were significantly higher than that in traditional management plots. Compared with traditional management plots, soil available N, P and K contents in three-year organic management plots increased by 49.04 mg·kg-1, 65.68 mg·kg-1 and 214.62 mg·kg-1, respectively. Also compared with traditional management plots, soil fungi, bacteria and actinomycetes and activities of urease and alkaline phosphatase in organic management plots increased significantly. While no significant difference was noted in melon fruit yield between the two management practices, total soluble solids in melon flesh was significantly higher in organic management plots than in traditional management plots. These results suggested that organic management improved soil fertility, enhanced soil microorganism community, and increased soil enzyme activity and melon fruit quality.
Effects of continuous straw return to soil on maize growth and soil chemical and physical characteristics
MU Ping, ZHAN EN-He, WANF Han-Ning, WAN Yong-Feng
2012, 20(3): 291-296. doi: 10.3724/SP.J.1011.2012.00291
Abstract(2546) PDF(1874)
Abstract:
As it significantly improves the physical and chemical characteristics of farmland plow layer soil, straw return is an efficient strategy to enhance soil fertility. To understand the effects of different straw return methods on soil fertility and maize growth, experiments were conducted from 2002 to 2010 in Pingliang Maize Breeding Experimental Station (PMBES) of Gansu Agricultural University. Soil chemical and physical characteristics, and maize plant root growth and yield were determined for three straw return treatments — 3-year straw return (H3, 2007—2010), 6-year straw return (H6, 2005—2010) and 9-year straw return (H9, 2002—2010) — and non-straw return used as the control (0-year straw return, CK). The results showed that soil contents of organic matter, total nitrogen, total phosphorus, alkali-hydrolysis N and available K in the 0~30 cm soil layer significantly improved with increasing years of straw return. Soil bulk density reduced significantly in the 20~50 cm soil layer with increasing years in the order of 9 < 6 < 3 < 0 years. Root weight density, total length and activity significantly improved with increasing years of maize straw return. Especially during later growth stage, maize root characteristics in deep soil exhibited significant differences among different straw return treatments. Root activity in the 40~60 cm soil layer in H9, H6 and H3 treatments were higher than in CK treatment by 54.8%, 29.1% and 16.3%, respectively. Root weight density and total length in H9 treatment increased respectively by 44.3% and 79.3% over CK. The root weight density and total length increased by 30.8% and 58.9% in H6, and by 18.8% and 47.7% in H3 treatments over CK, respectively. Under CK, maize root rapidly recession in the fields. Plant height, ear height of maize increased with increasing years of straw return. Ear height of H9, H6 and H3 was 11.1 cm, 5.3 cm and 0.7 cm higher than that of CK respectively. The maize yield improved with increasing years of straw return too. 100-seed weigh and yield of H9, H6, H3 increased by 17.4%, 10.2%, 7.5%, and 15.4%, 10.3%, 4.5%, respectively, over the CK. The findings suggested that straw return delayed root consenescence, enhanced root nutrient uptake at the later growth stage and increased maize yield.
Decomposition characteristics of returned rapeseed straw in soil and effects on soil fertility
HU Hong-Xiang, CHEN Yan, MA You-Hua, YU Xue-Sheng, XIANG Jin-Xia
2012, 20(3): 297-302. doi: 10.3724/SP.J.1011.2012.00297
Abstract(2884) PDF(1689)
Abstract:
The burning of straw in open air, straw stacking or abandoning are not only resource-wasting, but also seriously impact surrounding environments, traffic safety, social production and people lives. Although the promotion of rapeseed straw decomposition and rural crop straw utilization limits the negative impacts of straw burning on the environment and improves soil fertility, so far not much research has been conducted on rapeseed straw decomposition rate of rice-rapeseed rotation system in Jiang-Huai area. Different amounts of rapeseed straw were returned to soil at various buried depths in nylon net bags in the experiment. The decomposition characteristics of the returned rapeseed straws and the effect on soil fertility and crop yield were determined. The results showed that the decomposition ratio of rapeseed straw after being returned to the field increased with time. The decomposition rate of rapeseed straw was faster at the initial stage of decomposition but then slowed down right through the final stage of decomposition. Straw decomposition rate was negatively correlated with the amount of returned rapeseed straw to the field. The order of decomposition rate was entire amount straw returned to soil < 2/3 amount straw returned to soil < 1/2 amount straw returned to soil < 1/3 amount straw returned to soil. The decomposition rate of returned rapeseed straw on surface soil was faster than that in the 20 cm soil depth. Also the decomposition rate of returned rapeseed straw in the 10 cm soil depth was the lowest. Returning straw to soil improved soil physical and chemical properties. Not only did it reduce soil bulk density, but it also enhanced soil organic matter and nutrients in comparison with control treatment (KC) at P < 0.05. Returning rapeseed straw to soils increased rice yield. Yield of CK treatment was 7 725 kg·hm-2. Also compared with CK, yields of different returned straw-to-soil treatments increased in the range of 6.02%~21.17% (P< 0.01). The study therefore provided the basis for controlling rapeseed straw decomposition rates to promote straw resource utilization and improve agricultural eco-environment.
Bioavailability and mechanism of modified rock phosphate in calcareous soil
LI Ya-Juan, YANG Cui-Hong, CHEN Bo, QIUN Hui-Zhen
2012, 20(3): 303-309. doi: 10.3724/SP.J.1011.2012.00303
Abstract(2155) PDF(1382)
Abstract:
Phosphorus is among the most plant essential nutrient elements. High yields and good qualities of crops are efficiently promoted by the application of plenty soluble phosphorus fertilizers. Utilization efficiency of soluble phosphorus fertilizers, however, remains generally low because of its unique chemical properties. This has posed a significant challenge for natural resources of phosphorus and rock phosphate. Furthermore, the use of rock phosphate resources as high concentration phosphorus and compound fertilizers was limited in China. It was therefore important to develop the most efficient utilization technique for the sustainable usage of rock phosphate resource with meaningful economic benefits of phosphorus fertilizer incorporation. Rock phosphate activation to release efficient, non-acid-driven phosphorus and utilizable byproducts in industries and agriculture was one such technique. Although few current studies conducted in acid soils indicated high bioavailability of new phosphorus fertilizers derived from activated rock phosphorus (the so-called modified rock phosphate), less studied was conducted in calcareous soils. This paper explored the availability of modified rock phosphate in calcareous soils of North China and the possible mechanisms of activation effects. The findings of the study could enhance industrial production and application of modified rock phosphate in different soil conditions. In this paper, rock phosphates from different producing areas [Kunming City of Yunnan Province (RPⅠ), Deyang City of Sichuan Province (RPⅡ), Mianzhu City of Sichuan Province (RPⅢ), Kaiyang City of Guizhou Province (RPⅣ)] were activated by both organic and inorganic activators to get modified rock phosphate. The P bioavailability of the modified rock phosphates in calcareous soils were also tested for spring wheat in pot experiments. Compared with the rock phosphates, the results showed improvements in available and soluble P in modified rock phosphates. Also while the use of inorganic activator improved available P, organic activator largely improved soluble P. Modified rock phosphate improved dry matter content, and P uptake and utilization efficiency of spring wheat in calcareous soils. Modifying rock phosphates with organic activator had more significant effect on spring wheat growth. Measured structures using the Infrared Spectrogram (IS) technique showed significant changes in rock phosphate structures after activation. Compared with normal rock phosphates, increased characteristic H2PO4- and HPO42- spectrograms were noted. The increasing effects varied among rock phosphates producing areas and activator types. This indicated that activation promoted release of available P in rock phosphates. Rock phosphates from different areas were different in chemical components such as phosphorus, calcium, iron, aluminum and magnesium. Chemical measurements showed that activation effects were related with rock phosphate oxide content. In the four rock phosphates, RPIII showed the best activation effect. MgO content of RPIII was the highest and total oxide content was the lowest. This was the possible reason behind the best effect produced by RPIII — i.e., the higher MgO content induced a higher solubility of rock phosphates. Different activators exhibited different activation effects even for the same rock phosphate. Although IS structure measurement suggested that inorganic activator was better, soil plant experiments showed that organic activator was better. Due to these contrasting results, further studies were recommended in this direction.
Effects of water, nitrogen and phosphorus coupling on starch paste properties of winter wheat
ZHENG Zhi-Song, WANG Chen-Yang, ZHANG Mei-Wei, ZHANG Jie, YAO Yu-Qing, NIU Jun-Yi
2012, 20(3): 310-314. doi: 10.3724/SP.J.1011.2012.00310
Abstract(1610) PDF(1469)
Abstract:
A field experiment was conducted under rain-shelter conditions in Luoyang (Henan Province) during the 2009—2010 and 2010—2011 cropping seasons by using “Luohan 2” winter wheat cultivar. The objective of the experiment was to evaluate the effects of irrigation and nitrogen/phosphorus fertilization on grain quality of winter wheat in the semiarid region of West Henan Province. The experiment was a factorial combination of 5 irrigation, nitrogen and phosphorus application rates, each in 3 replicas. The effects of water, nitrogen and phosphorus application rates and interactions on starch paste parameters of winter wheat were determined. The results showed that the application of nitrogen and phosphorus fertilizers had significant effects on starch paste properties of winter wheat (P≤0.05 or P≤0.01). Main starch viscosity parameters (peak viscosity, initial viscosity and final viscosity) increased significantly as nitrogen application increased from 0 kg·hm-2 to 105 kg·hm-2, and after peaking at 105 kg·hm-2 decreased with nitrogen application rate. Starch viscosity parameters reached the highest values at phosphorus application rate of 168 kg·hm-2. Irrigation had no significant effect on starch paste properties. However, irrigation and nitrogen interactions significantly influenced some starch paste properties. Overall, combined treatments of nitrogen, phosphorus and water at N105P168W217.5 — i.e., 105 kg(N)·hm-2, 168 kg(P2O5-2 and 217.5 mm irrigation — produced the best starch quality. Statistical analysis indicated a significant positive correlation between starch paste properties and grain yield in the 2009—2010 cropping season and not in the 2010—2011 crop season. This suggested that there existed the possibility for improvement of both grain yield and starch paste quality in the region.
Effects of combined application of potassium silicate and Streptomyces pctum bio-control agents on growth, yield and quality of strawberry under continuous cropping in greenhouse
SHEN Guang-Hui, XUE Quan-Hong, CHEN Qin, WANG Ling-Na, ZHAO Juan, XUE Lei
2012, 20(3): 315-321. doi: 10.3724/SP.J.1011.2012.00315
Abstract(1903) PDF(1375)
Abstract:
Continuous cultivation of strawberry generally leads to stunted growth, yield loss and reduced fruit quality. These problems could be overcome by integrated management approaches such as combined biological, chemical and other control practices. In this study, the effects of single or combined application of potassium silicate (Si) and Streptomyces pctum (Act12) bio-control agents on the growth, yield and quality of strawberry (“Hongtaihou” variety) under continuous cropping in greenhouse conditions were evaluated. The experiment was conducted from Sep. 2008 to Apr. 2009 in greenhouse with continuously cropped strawberry. The results showed that combined Si and Act12 bio-control agents significantly enhanced strawberry health and growth under continuous cropping. The ratio of “I” growth-scale strawberry plant increased by 44.7% and that of “III” growth-scale decreased by 58.3% in the third year of continuous cropping. The death rate of strawberry reduced to almost 0% under Si+Act12 treatment in the fourth year of continuous cropping. Plant fresh weight, root fresh weight, leaf number and leaf fresh weight of strawberry in the third year of continuous cropping significantly (P < 0.05) increased by 73.7%, 71.3%, 11.1% and 38.7%, respectively. Continuous cropping strawberry for three consecutive years under Act12+Si treatment antedated blooming for 10 days compared with the control. The bud number was also significantly (P< 0.05) enhanced by 17.0% under Si+Act12 treatment. Fruit number, single fruit weight and per-plant yield under Si+Act12 treatment increased by 18.6%, 90.6% and 126.2%, respectively. Compared with the control, fruit contents of total soluble solid, sugar-to-acid ratio and vitamin C at full fruit stage increased by 21.7%, 36.2% and 27.0%, respectively. Leaf soluble protein increased by 67.4% and leaf PPO activity related with disease resistance at full fruit stage significantly (P< 0.05) increased by 101.0% under Act12+Si treatment. The combined application of Si+Act12 agents significantly improved single fruit weight and per-plant fruit yield of strawberry in the fourth year of continuous cropping by 194.7% and 359.1%, respectively. These results suggested that the combined application of Si and Act12 bio-control agents not only promoted strawberry growth and yield and quality of fruit, but also enhanced plant disease resistance. It was concluded that the application of Si+Act12 agents had the potential for alleviating the adverse effects of continuous cropping of strawberry in greenhouse conditions.
Changes in soil nitrogen and microbial activity during Robinia pseudoacacia recovery period in the Loess Hilly-Gully region
LIU Dong, HUANF Yi-Mei, AN Shao-Shan
2012, 20(3): 322-329. doi: 10.3724/SP.J.1011.2012.00322
Abstract(1467) PDF(1384)
Abstract:
This study determined the effect of Robinia pseudoacacia plantation age (10, 15, 30 and 38 years) on soil properties?in the Zhifanggou Basin, Ansai, Shaanxi Province. Soil samples were collected in the typical hilly region of the Loess Plateau from the 0~10 cm, 10~30 cm and 30~60 cm depths and analyzed for nitrogen (N) content, microbial biomass carbon (Cmic), microbial biomass phosphorus (Pmic), microorganism quotient and basal respiration. Additional physical and chemical properties of soil were also determined. The results showed that soil NH4+-N, NO3--N, and organic N contents gradually increased with increasing plantation age and decreased with increasing soil depth. Soil bulk density decreased with increasing plantation age and increased with increasing soil depth. Total soil N in the 0~10 cm depth increased from 0.40 g·kg-1 in the 10-year-old plantation to 0.87 g·kg-1 in the 30-year-old plantation. On soil N fertility scale, this represented an increase, from level-7 to level-5.?Soil Cmic and Pmic were significantly higher in R. pseudoacacia plantations than in abandoned lands (CK). Both soil Cmic and Pmic increased with increasing plantation age and decreased with increasing soil depth.?Microorganism quotient for all three soil layers was significantly greater in R. pseudoacacia plantations than in abandoned lands. Furthermore, the microorganism quotient [Cmic to TOC (total organic carbon) ratio] increased significantly with increasing plantation age.?Soil respiration quotient (basic respiration to Cmic ratio) for all three soil layers decreased significantly with increasing plantation age. Soil microorganism quotient was positively correlated with organic N, total N and NO3---N (P < 0.05). R. pseudoacacia plantations also improved some other soil physical and chemical properties.?Organic C and available P increased significantly with increasing plantation age. However, C to N ratio decreased with increasing plantation age. R. pseudoacacia trees not only increased carbon availability to soil microorganisms, but also enhanced soil carbon utilization. Moreover, increase in microbial activity increased soil organic N content and overall soil fertility.
Influence of drip irrigation under plastic film mulching on concentrations of CO2 and CH4 in soil
TAO Li-Jia, WANG Feng-Xin, GU Xiao-Xiao
2012, 20(3): 330-336. doi: 10.3724/SP.J.1011.2012.00330
Abstract(1602) PDF(1576)
Abstract:
A pot experiment was conducted in a greenhouse to compare the influences of flood (F) and drip (D) irrigations on soil concentrations of CO2 and CH4 during potato cropping season using the static opaque chamber and gas chromatography technique. Two agronomic measures were evaluated for each irrigation regime under mulched (M) and non-mulched conditions. Three more treatments were set under mulched drip irrigation (MD) based on different wet ratio (P) — P1 (P=25%), P2 (P=33%) and P3 (P=50%). There were six treatments altogether, denoted as DP1, MDP1, MDP2, MDP3, FC and MF. Bare soils with (MBS) and without (BS) plastic film mulching were set as control treatments. Results suggested that mulching treatments increased soil CO2 concentration by 10.4%~94.5% due to plastic film mulching increasing effect on temperature and moisture, and barrier effects on natural air transmission of the soil-atmosphere system. Mulching treatments decreased soil CH4 concentration by 5.1%~47.4%. Because of dry-wet alternation under drip-irrigation and decreased soil aeration under flood irrigation, CO2 concentration was 7.4%~49.7% higher under flood irrigation and CH4 concentration 6.6%~68.2% lower under drip irrigation. Soil moisture influenced greenhouse gas emission by altering soil aeration and soil dissolved organic matter. The higher the wet ratio under MD, the lower was CO2 concentration. However, the effect of wet ratio on CH4 concentration was not clear. Soil temperature was the main driving factor of soil respiration, which also regulated CH4 oxidation processes. The greenhouse gas concentration in soils after DP1 irrigation showed a significant positive correlation between soil temperature and soil CO2 concentration. Also after DP1 irrigation, a significant negative correlation existed between soil temperature and soil CH4 concentration while a significant negative correlation was noted between soil CO2 and CH4 concentrations.
Effect of water content on composition of water hyacinth Eichhornia crassipes (Mart.) Solms residue and greenhouse gas emission
SHI Lin-Lin, SHEN Ming-Xing, CHEN Zhi-Zhou, WANG Hai-Hou, LU Chang-Ying, CHEN Feng-Sheng, SONG Jie
2012, 20(3): 337-342. doi: 10.3724/SP.J.1011.2012.00337
Abstract(1280) PDF(1288)
Abstract:
Although, residue of water hyacinth, Eichhornia crassipes (Mart.) Solms, is better compost because it has a smaller volume and a higher dry matter content after being extruded, not much research exists on it. To determine suitable compost water content of water hyacinth, an experiment that focused mainly on the effects of water on compost and environment factors was conducted. Static compost piles were set at 65%, 70%, 75%, and 80% water content through controlling mixing proportion of water hyacinth residue and rice straw. The temperature, pH, carbon, nitrogen and greenhouse gas of the composts were determined. The results showed that pH, humic acid (after composting for 7 d) and fulvic acid contents of the compost were not significantly affected (P > 0.05) by water content. However, temperature, Kjeldahl-N, soluble carbon, humic acid (after composting for 50 d), nitrate-N and ammonium-N were significantly affected (P< 0.05) by water content of the compost. The 75% water content treatment was especially attractive in temperature-rising of the composts and reached the highest temperature of 53.4 °C just after 6 d. On the 50th d, the Kjeldahl-N, nitrate-N and ammonium-N of the 75% water content treatment were higher (P < 0.05) than those of 65% and 70% water content treatments. Compared with at the 7th d under the 75% water content treatment, at the 50th d, Kjeldahl-N content decreased by 21.1% (the highest change), nitrate-N increased by 434% (the highest change), and ammonium-N decreased by 14.1% (the lowest change). Although no significant differences in CH4 emission fluxes among the water content treatments were noted, differences in N2O and CO2 emission fluxes were pronounced. N2O emission flux in 80% water content treatment was 3.9~23.1 times higher than in other treatments. CO2 flux in 75% water content treatment was 1.9~2.5 times higher than in other treatments. The study therefore suggested that using water hyacinth residue and rice straw compost at 75% water content was the best in terms of compost efficiency and quality better in the term of environment.
Effects of Ca2+ on membrane lipid peroxide, antioxidation enzymes and thermal dissipation of squash seedlings under high temperature and light intensity
QIN Shu-Hao, ZHANG Jun-Lian, KONG Ling-Juan, ZHANG Wen-Li
2012, 20(3): 343-347. doi: 10.3724/SP.J.1011.2012.00343
Abstract(1346) PDF(1299)
Abstract:
Vegetable growth and development have suffered restraints and damages by high temperatures and strong lights under rising global temperatures in recent years. The yield, quality and economic benefits of summer vegetables substantially reduced due to dual stresses of high temperatures and strong lights. Therefore an experiment was carried out in 2009 to explore the methods of alleviating of high temperature/light adversities in vegetable production. In the experiment, a squash (Cucurbitapepo L.) variety of “Alan” was used to study Ca2+ effects on the characteristics of chlorophyll fluorescence, membrane lipid peroxide and antioxidation enzymes of squash seedlings by exogenous application of CaCl2+ solution under the stresses of high temperature and light intensity. The results showed that squash seedlings under the application of 5~20 mmol·L-1 of Ca2+ had higher superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) activities and GSH content than the control experiment (CK). However, the contents of malondialdehyde (MDA), H22O2, and relative electrical conductivity were lower than those of over-40 mmol·L-1 Ca2+ and CK treatments. The maximum PSII efficiency (Fv /Fm), actual PSII efficiency (ΦPSⅡ) and photochemical queching coefficient (qP) improved under the 5~20 mmol·L-1 Ca2+ treatment. However, non-phochemical fluorescence quenching coefficient (NPQ) decreased under the 5~20 mmol·L-1 Ca2+ treatment. This indicated that the 5~20 mmol·L-1 Ca2+ treatment remarkably buffered damages caused by high temperatures and light intensity stresses and decreased excitation energy of dissipation. The best buffer effect for high temperatures and strong lights occurred under 10 mmol·L-1 Ca2+ application. No buffer effect was noted when Ca2+ concentration was more than 40 mmol·L-1.
Agricultural pollution pressure in the Taihu Lake Basin
LI Jing, MIN Qing-Wen, LI Zi-Jun, JIAO Wen-Jun, YAN Zheng, LUN Fei
2012, 20(3): 348-355. doi: 10.3724/SP.J.1011.2012.00348
Abstract(1855) PDF(2058)
Abstract:
The serious water environment quality deterioration in the Taihu Lake Basin (TLB) has been largely blamed on agricultural pollution. The pollutants were mainly from the processing of plant, livestock and poultry and aquacultural products. This paper developed an agricultural pollution model that calculates the pressure index of agricultural pollution based on the cultivation of plants and the breeding of livestock, poultry and aquaculture. The results showed that nitrogen and phosphorus pollutants largely contributed to water pollution with pollution pressure index value greater than one. Spatial distributions of agricultural pollution pressure index differed not only with different cultivation and breeding practices, but also with region. Although fertilizer and pesticide dose per unit area decreased, it was still far above the upper limit of safety usage. For example, the lowest fertilizer dose in Changzhou City during 2000—2008 was 452.71 kg·hm-2 (in 2008), which was still above the 225 kg·hm-2 upper safe limit. The findings in this paper served as important reference for sustainable usage of water resources and water environment management in terms of the influence of agriculture pollution on the water environment.
Spatio-temporal variations of winter wheat water requirement and climatic causes in Huang-Huai-Hai Farming Region
YANG Xiao-Lin, SONG Zhen-Wei, WANG Hong, SHI Quan-Hong, CHEN Fu, CHU Qing-Quan
2012, 20(3): 356-362. doi: 10.3724/SP.J.1011.2012.00356
Abstract(2412) PDF(1981)
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Information on crop water requirement and the changes in this factor in time and space are critical for irrigation schemes, water resources planning and decision-making. Based on observed daily meteorological data in 50 weather stations in 7 sub-zones of Huang-Huai-Hai Farming Region (HFR) in 1960—2009, winter wheat water requirement and irrigation amount were simulated using the modified SIMETAW model. Results showed that winter wheat water requirement decreased from 1960 to 2009, with a significant decrease of 9.21~18.90 mm from 1970 to 1999. Winter wheat perennial average water requirement was 452.4 mm, coupled rainfall degree for winter wheat growing season was only 0.40. Winter wheat irrigation amount varied among different sub-zones, it increased at the rate of 10.02~13.48 mm per decade in western Henan Province and central Shanxi and Shaanxi Provinces. With regard to spatial distribution, water requirement and irrigation amount during winter wheat growing season were higher in the peripheral than in the central regions. Both water requirement and irrigation amount were highest in the west Henan Province with values of 457.32 mm and 335.33 mm. However, winter wheat water requirement and irrigation amount were lowest in the lower Haihe Plain with values of 363.24 and 247.51 mm. While temperature significantly increased, wind speed, humidity and solar radiation significantly decreased and also with an insignificant decrease in precipitation from 1960 to 2009. The negative trend in winter wheat water requirement in HFR was mainly attributed to declining solar radiation, which was in turn driven by some other climatic factors. Correlation analysis showed that temperature, sunshine hour and wind speed were positively correlated with winter wheat water requirement, while relative humidity was negatively correlated with it.
Response of corn growth to climate warming in Tianshui City, Gansu Province
ZHAO Guo-Liang, GAO Qing, YAO Xiao-Ying, WEN Hong-Chang, QIANG Yu-Zhu, WANG Juan
2012, 20(3): 363-368. doi: 10.3724/SP.J.1011.2012.00363
Abstract(1542) PDF(1344)
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Global climate warming is having a significant impact on crop growth and development. Using information on air temperature and days of high temperature for 1968—2009 in Tianshui City, Gansu Province, the trends and characteristics of temperature in recent decades were analyzed for the region. This dataset was combined with that on corn growth for 1980—2005 (provided by Tianshui Institute of Agricultural Sciences) to perform statistical analysis and correlation analysis by the DPS system. Regression model equations were then constructed (by analyzing the relationships and trends between corn growth and temperature) to determine the response of corn to climate warming, followed by discussing the periods and appropriate belts for sowing the crop. This provided a theoretical basis for adjustments of planting structures and food security. The results indicated that annual average temperature in Tianshui City steadily increased at a rate of 0.469 °C·10a-1. Positive trends were also noted in both the annual and seasonal average temperatures. Winter and spring temperatures obviously increased and days with annual temperatures above 30 °C and 35 °C gradually increased. While corn sowing and seedling operations delayed, sprouting, silking and maturity phenologies occurred early with warming temperatures. Sowing delayed by 2.7 d·a-1, seedling extend by 0.1 d·10a-1, and sprouting, silking and maturity occurred early by 3.3 d·10a-1, 4.4 d·10a-1 and 8.7 d·10a-1, respectively. At various stages of corn growth, the days from sowing to seedling delayed by 0.1 d·10a-1, and seedling to sprouting, sprouting to silking and silking to maturity periods shortened by 3.4 d·10a-1, 1.0 d·10a-1 and 4.4 d·10a-1, respectively. Corn growth accelerated, development occurred early and growth period shortened with increasing temperature. The average 1000-kernel weight of corn from 1980 to 2005 declined. Extreme high temperatures greatly impacted the growth period and 1000-kernel weight of corn in the region.
Coupling relationship between agricultural industry and resources in the loess hilly region on the background of conservation of water and soil— Based on the perspective of farmers-behavior
XIA Zi-Lan, WANG Ji-Jun, YAO Wen-Xiu, LVY Ming-Quan
2012, 20(3): 369-377. doi: 10.3724/SP.J.1011.2012.00369
Abstract(1355) PDF(1503)
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The present structure and coupling situation of agricultural system in the loess hilly region was formed under the influence of soil and water conservation policy. Agricultural ecological economic system may develop to a certain direction and form a new coupling situation through regulating the present coupling relationship between agricultural industry and resources. It had a practical significance to comprehensively clarify and assess the coupling interactions of the two important factors of the agricultural economic system. Due to multi-external policies and human interventions that acted on the agricultural ecological economic system, the indexes characterizing policy and farmers’ decision and behavior in the system were not directly observable (latent variables). Traditional models (e.g., coupled dynamic systems model, coupled degree model, gray system analysis, etc.) either ignored or partially treated these indexes. The complex interactions and feedbacks among the system indexes were not adequately explained by these models. This paper employed the structure equation model to explore the interactive relationships and functional paths across agricultural industry and resources under the influence of soil/water conservation policies in the loess hilly region, with a proxy farmer-survey from Wuqi County, Shaanxi Province, as the data resource. First, soil/water conservation policy, farmer behavior, agricultural resource and environment, agricultural industry development and coupling situation of agriculture system were set as 5 latent variables. And the correspondingly measurable indexes were selected. Then, 9 hypotheses about coupling relationship between agricultural industry and resources of the studied area were advanced. On this base, the model of agricultural industry-resources system coupling relationship was established. Fit test of the model showed desired effects. The model results showed that soil/water conservation policies improved regional agricultural resources conditions (with path coefficient of 0.62). This suggested that the policies were consistent with ecological targets. However, the policies inhibited positive farmer behavior in terms of resource utilization and industry management (with path coefficient of -0.22). This implied that the policies were some sort of disincentive and incompatible with farmer activity. Farmer behavior not only affected the state of system coupling directly (with path coefficient of 0.42), but also indirectly through promoting agro-industry development (with indirect path coefficient of 0.61×0.35 = 0.21). This also suggested that farmers’ production and decision-making behavior was a critical factor in the coupling of the system. Because of the policy mandatory provisions for resources utilization and inhabitation of farmer behavior, the regional agricultural resources environment was not supportive of agro-industry development (with path coefficient of -0.24). That is to say it induced a detestable local situation between agro-industry development and agro-resources environment. To optimize agro-industry and resources coupling of the loess hilly region, a full utilization of the present resources environment was recommended.
Development and security of follow-up industries in returned farmland to forest/grass lands in Western Region of Shanxi Province
ZHAO Yi-Xue
2012, 20(3): 378-383. doi: 10.3724/SP.J.1011.2012.00378
Abstract(1301) PDF(965)
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Follow-up industries for the project of returned farmland to forest/grass lands has existed for about 10 years. Protecting achievements and benefits of the developed follow-up industries and the related programs was critical to the success of the projects. This paper analyzed the present trends and questions about safeguarding and developing follow-up industries via comparisons and syntheses with five typical counties in Western Region of Shanxi Province as the cases. Based on the results, the course of developing follow-up industries were divided into three stages — retrogressive development (2000—2003), accelerated development (2003—2006) and quick development (2006—2009). The results were analyzed on the basis of two factors. The first was quality of farmland and changes in follow-up industrial developments in terms of cultivation, population, grain, etc. The second was the question of grains and developments of follow-up industries in any given region. The analysis results of the typical counties showed trends of increasing in farmland quality and sustainable development of follow-up industries under the conditions of farmland decrease and population growth. However, the individual case of the typical counties showed negative growth in total and per cap. grain production in some certain periods. It indicated serious problems in development of follow-up industries. The paper put forward further analytical questions about the amount of farmlands and per-person availability of grains. These factors remained stable in the project regions in Western Shanxi Province.
Phytotoxicity and oxidative stress of laundry detergents on maize
CAO Ling-Xian
2012, 20(3): 384-386. doi: 10.3724/SP.J.1011.2012.00384
Abstract(1120) PDF(1155)
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