Search

It is of great significance to study agroecosystem health in major grain producing areas based on the theory and method of ecosystem health. This paper selected Jilin Province as the study area, and an evaluation index system of agroecosystem health was built based on the SSI-VOR conceptual framework model. Using the optimal combined weights method, comprehensive evaluation assessment, GIS spatial analysis and grey slope similarity incidence models, the spatial-temporal pattern of agroecosystem health and influence factors were analyzed from 2000 to 2011 in Jilin Pro-vince. The results indicated that, temporally, the composite index of agroecosystem health showed a rising trend in Jilin Province from 1995 to 2011, and the agroecosystem health level changed from not healthy to relatively healthy; spatially, the spatial discrepancy of agroecosystem health level tended to become larger, which remained unchanged in central area, while was gradually improved in southeast and west. The main contributors which improved the agroecosystem health level were economic driving force, environmental management and social development, while the main 'dragging' factors were ecological pressure, organization structure and input capacity. Finally, relevant measures were put forward to improve the agroecosystem health condition.

Eco-services provided by non-agricultural organisms are the basis of ecosystem to keep its stability in agricultural landscapes. With the strengthening of agricultural intensification, the ongoing loss of biodiversity is one of the most extrusive issues in the development of modern agriculture. In this paper, the study area was set up in Gongyi County, a typical agricultural region in the middle and lower reaches of the Yellow River. According to its typical topography (mountain-hilly-plain) type, we explored the effects of landscape heterogeneity on the diversity of pollinators at three different scales, which were geomorphic categories, landscape and habitat. Pan traps were used to obtain pollinators in this study. The effects of agricultural landscape heterogeneity at multi-scales on the diversity of pollinators were analyzed by using multivariable ANOVA. The results showed that a total of 67012 pollinator individuals that belonged to 86 classes and 7 subjects were classified. The dominant groups inclu-ded Syrphidae and Anthomyiidae. The common groups included Drosophilidae, Calliphoridae, Bombyliidae, Pipunculidae, Cantharidae, Cynipidae, Vespidae, Chalalcididae, Megachilidae and Apidae. Geomorphic categories showed the most significant impact on pollinators (P<0.001), suggesting that hilly and mountainous areas were the pollinators' ground of nectar. It was followed by habitat scale (P<0.05), with non-significant effect on the scales of landscape and the interaction between scales. The effect of landscape heterogeneity on the diversity of pollinators in hilly and mountainous areas provided a theoretical support for landscape planning and biodiversity conservation on the local area with different geomorphic categories.

Drought is the greatest agro-meteorological disaster. Risk assessment of drought is of great guiding significance to improve the regional risk management and decision-making level, and to further reduce agricultural loss. In this paper, drought risk of summer maize was analyzed accor-ding to natural disaster risk theory, using the data of weather, planting area and yield of summer maize, and local effective irrigation area of 69 stations in Huanghuaihai area. The assessing indices and models of drought risk were established from the aspects of danger, vulnerability, exposure, and disaster prevention and mitigation capacity. The results showed that, in Huanghuaihai area, the most dangerous periods for drought during summer maize season (June-September) were the follo-wing two stages: sowing to emergence and milky to maturity. Spatially, the highest drought risk was mainly distributed in central and southern Hebei, western and northern Henan. After weighting the vulnerability, exposure, and disaster prevention and mitigation capacity, the integrated highest drought risk was mainly distributed in the west and southwest of Henan Province. The sub-high risk area was distributed in the south of Henan, Cangzhou and Xingtai of Hebei, and Dezhou of Shandong. The lowest risk area was located in south of Shandong, north of Anhui, and Xinyang of Henan. The other areas were at moderate risk.

To objectively evaluate and compare the stability and sustainability of different planting patterns of typical watersheds in Loess Plateau of China after the Grain for Green Project, this paper used the emergy analysis method to quantify the emergy inputs and outputs of three watersheds with different planting patterns, i.e., both grains and fruit trees (Gaoxigou watershed), mainly grains (Wuliwan watershed) and mainly fruit trees (Miaozuigou watershed). In addition, an emergy analysis system was established to evaluate the suitability of the three patterns from the perspectives of natural resources pressure as well as social and economic development levels. More than 75% of the total emergy inputs of all the three watersheds were purchased, and nonrenewable emergy inputs had a much larger contribution than renewable emergy inputs, indicating the characteristic of low emergy self-sufficient ratio and considerable high environmental loading ratio. The pattern of planting grains had high emergy inputs but low emergy outputs, while the patterns of planting fruit trees and planting both had high emergy inputs and outputs. The energy densities of all three patterns reached two times of the average of agricultural systems in China. Especially, the net emergy of planting grains pattern was the lowest while that of planting both grains and fruit trees was the highest. The environmental sustainability index (ESI) of planting grains pattern was less than 1 and both emergy and ESI were much lower than national averages. The ESI of planting both grains and fruit trees pattern was the highest. In summary, comparison of the three patterns showed that planting both grains and fruit trees had better sustainability and high stability and the emergy production efficiency was high. Thus, it was suggested to change the agricultural development from watershed based units to multi-industry integrated mode.

The precipitation exiguity and water deficiency are the major factors limiting crop growth in dry farming regions of northern China. Dual-mulching of ridges and furrows, which have been widely concerned both domestically and internationally, could increase the utilization efficiency of precipitation and crop yield. In this paper, we reviewed the concept and model of dual-mulching of ridges and furrows, its supporting farm machinery and implements as well as its ecological effects on soil and crops. Based on the current research progress of cultivation techniques using harvested rainfall in ridge and furrow, priority of future research aspects of the dual-mulching of ridges and furrows were suggested as follows: 1) to establish the suitable ridge-furrow ratios for different crops in different types of dry farming regions of northern China; 2) to pay more attention to the study of coupling effects of soil moisture with temperature, fertility and other factors; 3) to explore better environment-friendly mulching materials; 4) to enhance the research on technical evaluation and popularization, and the design of supporting farm machinery and implements.

Greenhouse gases (GHGs) emission from arable field is a hot topic recently, adopting appropriate cropping systems is an effective way to reduce GHGs emission. This paper reviewed the impacts and mechanisms of intercropping on soil CO 2 and N 2 O emissions in upland field. Rational intercropping systems could increase soil organic carbon (SOC), promote the transformation of straw to SOC, slow down mineralization rate of SOC, and hence reduce soil CO 2 emissions. The Poaceae intercropping with legume could maintain the stability of yield while reducing synthetic N inputs, formation of inorganic N by residue decomposition and soil mineral N, and further reducing soil N 2 O emission. In addition, crop interactions in intercropping system and filed microclimate were important factors on GHGs emission as well. It is necessary to extent the period of researches in field GHGs emission in order to fully understand the underlying mechanisms of GHGs emission in farm land, especially the function of soil microorganisms at molecular level. It would provide theoretical knowledge in building environment-friendly agricultural system in the future.

The hedgerows, also called vegetative barriers, are defined as strips of grass, trees or shrubs or combinations of herbaceous and woody plants established along the contour lines of slopes, the edge of fields, streams, ditches or other water bodies, which can play outstanding roles in soil structure improvement, such as soil texture, porosity, bulk density, and some other physical properties. Its mechanical resistance can delay and intercept runoff effectively, facilitate rainwater infiltration, and reduce the denudation power of runoff on surface land. Moreover, the hedgerows can change sloping topography through constant sediment accumulation at the upper sides of the strips. The international and domestic researches across different ecological zones and geographical regions were summarized and analyzed in this paper. On the basis of such analysis, the hedgerows were confirmed to play a positive role in soil physical and chemical properties, rainfall infiltration, erosion processes, vegetation restoration, biodiversity conservation, landscape optimization and other important ecosystem services. Meanwhile, two problems in the current research of hedgerows were put forward: the planting pattern and structure of hedgerows, species selection, and management practices should be systematized for application, while the mechanisms of hedgerows on vegetation restoration and ecological succession should be further explored in scientific research.

Carbon emissions due to land use change have an important impact on global climate change. Adjustment of regional land use patterns has a great scientific significance to adaptation to a changing climate. Based on carbon emission/absorption parameters suitable for Liaoning Province, this paper estimated the carbon emission of land use change in the city and town concentrated area of central Liaoning Province. The results showed that the carbon emission and absorption were separately 308.51 Tg C and 11.64 Tg C from 1997 to 2010. It meant 3.8% of carbon emission. was offset by carbon absorption. Among the 296.87 Tg C net carbon emission of land use change, carbon emission of remaining land use type was 182.24 Tg C, accounting for 61.4% of the net carbon emission, while the carbon emission of land use transformation was 114.63 Tg C, occupying the rest 38.6% of net carbon emission. Through quantifying the mapping relationship between land use change and carbon emission, it was shown that during 1997-2004 the contributions of remaining construction land (40.9%) and cropland transform ation to construction land (40.6%) to carbon emission were larger, but the greater contributions to carbon absorption came from cropland transformation to forest land (38.6%) and remaining forest land (37.5%). During 2004-2010, the land use types for carbon emission and absorption were the same to the period of 1997-2004, but the contribution of remaining construction land to carbon emission increased to 80.6%, and the contribution of remaining forest land to carbon absorption increased to 71.7%. Based on the carbon emission intensity in different land use types, we put forward the low-carbon regulation countermeasures of land use in two aspects. In carbon emission reduction, we should strict control land transformation to construction land, increase the energy efficiency of construction land, and avoid excessive development of forest land and water. In carbon sink increase, we should improve forest coverage rate, implement cropland, grassland transform to forest land, strengthen forest land and water protection, and adjust cropland internal structure and scientifically implement cropland management.

This paper investigated the genus diversity of soil nematodes of different agricultural areas in Jiangsu Province, analyzed the relationship between soil nematodes and soil environmental factors, and discussed the roles of soil nematodes as biological indicators of soil health. The results showed that, a total of 41 nematode genera were found in all six agricultural areas, belonging to 19 families, 7 orders, 2 classes. The numbers and community compositions of nematodes were obviously influenced by soil texture, fertilization and tillage practices. In all six agricultural areas, the numbers of nematodes in coastal agricultural area (400 individuals per 100 g dry soil) were significantly larger than that in Xuhuai, Ningzhenyang, and riverside agricultural areas. While the smallest number of nematodes was found in Yanjiang agricultural area (232 individuals per 100 g dry soil), which might be due to the differences in soil texture, annual rainfall and annual air temperature and other factors. The dominant genera of nematodes were similar in the adjacent agricultural areas. Correlation analysis showed that there was a significant positive correlation between the number of soil nematodes and levels of soil nutrients (soil organic matter, total nitrogen, available nitrogen, available potassium and available phosphorus). Redundancy analysis (RDA) indicated the total nitrogen, available potassium and pH obviously affected some soil nematode genera. The analysis of spatial distribution characteristics of soil nematode community in farmland of Jiangsu Province could provide data for health assessment of agricultural ecosystems.

Taking winter wheat cultivar 'Tainong 18' as test material, this paper set three treatments, local farmer's traditional cultivation pattern (FP), super high yield pattern (SH) and high yield high efficiency pattern ( HH) to investigate the effects of cultivation patterns on the intercepted photosynthetically active radiation (IPAR), PAR use efficiency (RUE), dry matter (DM) accumulation, harvest index (HI), grain yield and fertilizers' partial factor productivity (PFP) in 2012-2013. The results showed that IPAR, RUE and DM accumulation of the total growth stage and grain yield under SH pattern were significantly higher than those under FP pattern. IPAR of the total growth stage under HH pattern was lower than that under FP pattern, but RUE, DM accumulation and HI were significantly higher than that under FP pattern, so grain yield was higher than that under FP pattern. The grain yields under HH pattern were respectively decreased by 3.8% and 2.8% under high and low fertility levels compared that under SH pattern, while the PFP of N, P and K under HH pattern were averagely 26.4%, 68.5% and 92.6% higher than those under SH pattern, respectively. In conclusion, HH pattern, with the characteristics of 'reducing fertilizer', 'increasing planting density' and 'delaying sowing date', was the recommended cultivation pattern under the condition similar to this experiment balancing the grain yield, radiation use and fertilizer use.

Nitrogen use efficiency (NUE) has received worldwide concern in the sphere of agronomic science and environmental science, and it is fundamentally important for evaluating N utilization status and optimizing N fertilization management in cultivated lands. In recent years, in consideration of low values and great variations of NUE in China' s cultivated lands, some scholars have discussed on the traditional concept and calculating method of NUE, and also have proposed some substituted NUE calculating methods. In this paper, we summarized some disadvantages of both conventional concept and calculating method of NUE, i.e. the subtraction method and the 15N labeling method. Furthermore, we particularly introduced several substituted NUE calculation methods and discussed research directions in the future. In summary, we strongly suggested the establishment of a comprehensive evaluation index system of N utilization in good accordance with the current agricultural production status in China, based on a correct understanding of the dialectical relationships among N application rate, crop yield, N utilization and N loss.

Social economy in Huaihe River Basin had undergone enormous changes during 1990-2010. The grain yield had increased by 58%, from 64.14 million tons to 101.21 million tons, and the urbanization rate had increased by 22%, from 13% to 35%. Assessing the negative impacts of these high intensive human activities caused by rapid social development on terrestrial ecosystem would serve as a scientific basis for quantitative management of regional ecology. This paper estimated the spatial and temporal distribution of net anthropogenic nitrogen input (NANI) in Huaihe River Basin during 1990-2010. The results showed that there was an increasing trend in NANI in the period of 1990-2001, and after that this trend was slower. The NANI increased from approximately 17232 kg N · km(-2) · a(-1) in 1990 to a peak of 28771 kg N · km(-2) · a(-1) in 2003, and then declined to 26415 kg N · km(-2) · a(-1) in 2010. Chemical fertilizer and atmospheric deposition were the largest two sources of NANI, followed by food & feed import and biological nitrogen. Contributions from both chemical fertilizer and atmospheric deposition had been increasing continuously, respectively from 64% and 16% in 1990 to 77% and 19%. Our findings implied that the shift from fertilizer-supported agriculture and fossil fuel-supported industry to sci-tech lead economic development is urgently needed.

Grass growing in orchard is implemented in most fruit cultivation advanced countries, but only China carries out grass weeding. To effectively resolve the puzzle on harmful or beneficial effect on fruit production imparted by grass growing, and promote grass growing management in orchard in China, more and more domestic research was reported in recent years. Combined the results of our research and domestic related research, we reviewed the latest research progress about the effect of growing grass on soil, microclimate, fruit tree diseases and insect pests, tree growth and fruit quali- ty, etc. in this paper. We pointed out that grass growing in orchard must consider the local conditions, economic efficiency, the critical period, and the supporting technique.

Based on the concept and methods of landscape character assessment (LCA) in England, this paper applied a complete process of landscape character assessment with a case study in Qiaokou Town, which is located in a typical southern paddy fields area in Changsha City. We drew the landscape character map of Qiaokou Town through desk classification and field survey, identified and compared the key characters of each character area, and proposed suggestions on the improvement and stewardship of landscape characters. The results showed that Qiaokou could be divided into 2 landscape character types and 7 landscape character areas with the main differences in cropland and vegetation pattern as well as aesthetic characters. The case study indicated that LCA could be a critical tool to identify the characteristics in rural area, and provide helpful guidance to protect, restore and maintain the unique culture and characters of rural landscape, which is useful for targeted rural landscape development. In the future, we suggested that the assessment on the effects of landscape construction measures on the ecosystem services should be incorporated in LCA research as well.

Effects of long-term cropping patterns on the activities of peroxidase, invertase, arylsulfatase, dehydrogenase and protease were investigated in this paper. Four long-term cropping patterns included (1) 10 years continuous cropping of corn, (2) 8 years continuous cropping of wheat followed by 10 years continuous cropping of cotton, (3) 15 years continuous cropping of cotton, and (4) 6 years continuous cropping of cotton followed by 6 years of wheat/sunflower rotation. The responses of soil bacteria, fungi, ammonia oxidizing bacteria (AOB) , and the ammonia oxidizing archaea (AOA) to different copping patterns were analyzed. The results showed that cropping patterns significantly affected the activities of soil peroxidase, arylsulfatase, dehydrogenase and protease, while had no significant effect on soil invertase activity. The cropping patterns significantly influenced the diversity index of AOA, but had no significant influence on that of soil bacteria, fungi and AOB. The community structures of soil fungi and AOB were more sensitive to cropping patterns than soil bacteria and AOA. In conclusion, long-term continuous cropping of cotton decreased the activities of soil enzymes activities and soil microbial diversity in oasis farmland, while crop rotation could alleviate the negative influence.

Based on the 1961-2010 ground surface data from 90 meteorological stations, this paper analyzed the spatiotemporal change characteristics of agricultural climate resources (e.g. sunshine hours, thermal resources and water) for the growth season of winter wheat and summer maize in Shandong Province. Results indicated that temperature indicators showed a significant rising tendency especially in the winter wheat growth season. Both evapotranspiration and sunshine hours declined obviously, especially for the evapotranspiration in the summer maize growth season, while there was no clear change evidence in rainfall and aridity. Regarding the spatial distribution characteristics, agro-climatic resources presented meridional or zonal increment or decrement in the winter wheat and summer maize growth seasons. In different areas, variation features of agro-climatic resources appeared with distinct differences. In the western Shandong area, temperature indicators showed a slight rising tendency while evapotranspiration and aridity declined significantly. Sunshine hours decreased most significantly in the middle and west southern areas. Precipitation increment was relatively obvious in the winter wheat growth season in the middle and east southern areas and in the summer maize growth season in the middle and southern areas. Thermal resource increases benefited the growth of winter wheat in every phase during the growth period. However, it brought high risks of plant diseases and hot disaster as well. The decrease of sunshine hours was adverse to crop photosynthesis in the growth period while evapotranspiration decrement profited the water retention of soil.

Agricultural policy in China's rural heartland is driving profound changes to traditional farming systems. A case study covering four decades mapped and recorded farming patterns and processes in Shizuitou Village, a rural village in northwest Shanxi. An integrated geospatial methodology from geography and anthropology was employed in the case study to record the changing dynamics of farming systems in Shizuitou Village to discover the long-term impacts of China's agricultural policies on village farming systems. Positive and negative impacts of agricultural policies on village farming systems were mapped, inventoried and evaluated using Participatory Geographic Information Systems (PGIS). The results revealed traditional polycultures are being gradually replaced by industrialized monocultures. The driving forces behind these farming changes come from a series of government agricultural policies aiming at modernization of farming systems in China. The goal of these policies was to spur rapid development of industrial agriculture under the guise of modernization but is leading to the decay of traditional farming systems in the village that maintained local food security with healthy land for hundreds of years. The paper concluded with a recommendation that in future, agricultural policy makers should strike a more reasonable balance between short-term agricultural profits and long-term farming sustainability based on the principles of ecological sustainable development under the context of global changes.

Controlling soil nutrient leaching in farmland ecosystems has been a hotspot in the research field of agricultural environment. Biochar has its unique physical and chemical properties, playing a significant role in enhancing soil carbon storage, improving soil quality and increasing crop yield. As a kind of new exogenous material, biochar has the potential in impacting soil nutrient cycling directly or indirectly, and has profound influences on soil nutrient leaching. This paper analyzed the intrinsic factors affecting how biochar affects soil nutrient leaching, such as the physical and chemical properties of biochar, and the interaction between biochar and soil organisms. Then the latest literatures regarding the external factors, including biochar application rates, soil types, depth of soil layer, fertilization conditions and temporal dynamics, through which biochar influences soil nutrient (especially nitrogen and phosphorus) leaching were reviewed. On that basis, four related action mechanisms were clarified, including direct adsorption of nutrients by biochar due to its micropore structure or surface charge, influencing nutrient leaching through increasing soil water- holding capacity, influencing nutrient cycling through the interaction with soil microbes, and preferential transport of absorbed nutrients by fine biochar particles. At last future research directions for better understanding the interactions between biochar and nutrient leaching in the soil were proposed.

Climate change will significantly affect agricultural production in China. The combination of the integral regression model and the latest climate projection may well assess the impact of future climate change on crop yield. In this paper, the correlation model of maize yield and meteorological factors was firstly established for different provinces in China by using the integral regression method, then the impact of climate change in the next 40 years on China's maize production was evaluated combined the latest climate prediction with the reason be ing analyzed. The results showed that if the current speeds of maize variety improvement and science and technology development were constant, maize yield in China would be mainly in an increasing trend of reduction with time in the next 40 years in a range generally within 5%. Under A2 climate change scenario, the region with the most reduction of maize yield would be the Northeast except during 2021-2030, and the reduction would be generally in the range of 2.3%-4.2%. Maize yield reduction would be also high in the Northwest, Southwest and middle and lower reaches of Yangtze River after 2031. Under B2 scenario, the reduction of 5.3% in the Northeast in 2031-2040 would be the greatest across all regions. Other regions with considerable maize yield reduction would be mainly in the Northwest and the Southwest. Reduction in maize yield in North China would be small, generally within 2%, under any scenarios, and that in South China would be almost unchanged. The reduction of maize yield in most regions would be greater under A2 scenario than under B2 scenario except for the period of 2021-2030. The effect of the ten day precipitation on maize yield in northern China would be almost positive. However, the effect of ten day average temperature on yield of maize in all regions would be generally negative. The main reason of maize yield reduction was temperature increase in most provinces but precipitation decrease in a few provinces. Assessments of the future change of maize yield in China based on the different methods were not consistent. Further evaluation needs to consider the change of maize variety and scientific and technological progress, and to enhance the reliability of evaluation models.

In recent years, some scholars from China have deeply discussed about the concept, connotation and calculating method of nitrogen use efficiency (NUE), and have raised questions and also put forward some improved methods for NUE calculation in cultivated lands. In this paper, we compared advantages and disadvantages of these improved NUE calculation methods by using the data from a 5-year positioning field experiment under a wheat-maize rotation system. The results indicated that it made mistakes when the traditional subtraction method was used to calculate NUE for wheat season and maize season separately, since the soil fertility level of experimental plots had differed significantly from each other after several seasons or years of different fertilization managements. Additionally, the calculated NUE increased markedly with the cropping season going, thus making it difficult to mirror the actual situation of N utilization in cultivated lands. For the wheat-maize rotation system, the cumulative NUE calculation method considered wheat season and maize season as a whole part, and skillfully avoided mistakes which could be caused by inhomogeneity of soil fertility levels between experimental plots. Moreover, the calculated NUE were comparably smaller, with smaller coefficient variations (CVs), in contrast with the traditional subtraction method. The NUE calculated by using the ratio method were bigger, with the smallest CVs, than that computed by using the cumulative calculation method. The soil N balance method took a thoughtful consideration about the budgets and losses of soil nutrients before and after crop growth, but obtained the largest values of NUE and CVs within these methods.

Taking Jinjing Town in Dongting Lake area as a case, this paper analyzed the evolution of rural landscape patterns by means of life cycle theory, simulated the evolution cycle curve, and calculated its evolution period, then combining CA-Markov model, a complete prediction model was built based on the rule of rural landscape change. The results showed that rural settlement and paddy landscapes of Jinjing Town would change most in 2020, with the rural settlement landscape increased to 1194.01 hm2 and paddy landscape greatly reduced to 3090.24 hm2. The quantitative and spatial prediction accuracies of the model were up to 99.3% and 96.4%, respectively, being more explicit than single CA-Markov model. The prediction model of rural landscape patterns change proposed in this paper would be helpful for rural landscape planning in future.

By using geographic information system technology (GIS) and geostatistics methods, this paper studied the spatial variability of soil properties and available nutrients in the new regulation area units located in Qingjiangyuan modern tobacco agriculture science and technology park (Enshi, Hubei), suburb of Enshi City and the Baiyang base of Lichuan City, and further evaluation of the soil fertility suitability index (SFI) was carried out by use fuzzy mathematics. The results indicated that the effects of land restoration on the soil available phosphorus content variability and spatial distribution were very obvious, possibly due to the landform characteristics and restoration extent. The effect of land restoration on soil pH was small, however, serious soil acidification was detected in the soil sampled from Baiyang (pH < 5.5). Low SFI was found in 77.6%, 17.1% and 31.4% of the soils taken from the suburb, Baiyang and Qingjiangyuan, respectively. In conclusion, attentions should be paid on soil acidification in Baiyang, soil fertility and equalization in the suburb, and soil fertility in the region of Qingjiangyuan with low SFI.

In order to manifest lower energy consumption and less labor employment, and provide the theoretical basis for constructing environmentally friendly modem tobacco agriculture, this paper analyzed gas composition of the chimney from a bulk-curing barn and the dispersion of sulfur dioxide (SO2) around the workshop cluster using ecom-J2KN flue gas analyzer and air sampler. During curing, the concentrations of carbon dioxide (CO2) and SO2 in the chimney were both highest at 38 degrees C, while the concentration of nitrogen oxides (NOx) was highest at 42 degrees C. The emission concentration of SO2 from the chimney was 1327.60-2218.40 mg x m(-3). Average SO2 emission would decrease by 49.7% through adding 4.0% of a sulfur-fixed agent. The highest concentrations of SO2 in the surface soil appeared at the yellowing stage. SO2 concentration in horizontal direction localized at 43-80 m exceeded 0.5 mg x m(-3). The highest concentration of SO2 (0.57 mg x m(-3)) was observed at 50 m. At 50 m in the downstream wind direction of the workshop cluster, SO2 concentration in vertical direction localized at 0.9-1.8 m exceeded 0.5 mg x m(-3), and the highest concentration of SO2 in vertical direction was 0.65 mg x m(-3) at 1.6 m. During curing, the average concentration of SO2 was decreased by 0.43 mg x m(-3) by using the sulfur-fixed agent. The polluted boundary was localized at 120 m in the downstream wind direction of the workshop cluster.

According to the cultivated land ecological security in major grain production areas of Northeast China, this paper selected 48 counties of Jilin Province as the research object. Based on the PSR-EES conceptual framework model, an evaluation index system of cultivated land ecological security was built. By using the improved TOPSIS, Markov chains, GIS spatial analysis and obstacle degree models, the spatial-temporal pattern of cultivated land ecological security and the obstacle factors were analyzed from 1995 to 2011 in Jilin Province. The results indicated that, the composite index of cultivated land ecological security appeared in a rising trend in Jilin Province from 1995 to 2011, and the cultivated land ecological security level changed from being sensitive to being general. There was a pattern of 'Club Convergence' in cultivated land ecological security level in each county and the spatial discrepancy tended to become larger. The 'Polarization' trend of cultivated land ecological security level was obvious. The distributions of sensitive level and critical security level with ribbon patterns tended to be dispersed, the general security level and relative security levels concentrated, and the distributions of security level scattered. The unstable trend of cultivated land ecological security level was more and more obvious. The main obstacle factors that affected the cultivated land ecological security level in Jilin Province were rural net income per capita, economic density, the proportion of environmental protection investment in GDP, degree of machinery cultivation and the comprehensive utilization rate of industrial solid wastes.

Understanding the impacts of climate change on agriculture production and the underlying mechanism in North China Plain is important to take effective adaptations for national food security. Using Hybrid-Maize model, this paper investigated the impacts of climate change on summer maize yield potential and famers' adaptation by changing varieties with longer growth periods from 1981 to 2010 in Xingtai County, Hebei Province. Results showed a significant warming trend with the average temperature increasing by 0.49 degrees C x 10 a(-1) since the 1980s. Both solar radiation and sunshine hours decreased significantly since the 1980s. The sunshine hours decreased by 0.56 h x d(-1) x 10 a(-1) and the solar radiation decreased by 265.1 MJ x m(-2) x 10 a(-1), while the precipitation kept constant with large variation among years since 1981. Yield potentials of both irrigated and rainfed maize were simulated to decrease by 0.63-0.64 Mg x hm(-2) x 10 a(-1) since 1981 if varieties were assumed fixed with the 1980s. This was mainly due to the decrease of solar radiation during the maize growth season and the shortened growth stage by warming, and around 60% of grain yield decrease was attributed to the decreased solar radiation. In practice, by changing varieties with longer growth periods, the growing degree days of varieties adopted by local farmers since the 2000s increased by 19% (280 degrees C) compared to the 1980s, and consequently the yield potential was simulated to increase by 34%-40% (2.73-3.40 Mg x hm(-2)) for both irrigated and rainfed maize.

This paper studied the effects of different mulching modes on the soil moisture in a semi-arid rainfed area of Loess Plateau, Northwest China. Seven treatments were installed, i. e., mulching plastic film in summer (T1), mulching plastic film in autumn (T2), mulching 5 cm long wheat straw in summer (T3), mulching whole wheat straw in summer (T4), mulching plastic film in summer plus wheat straw (T5), mulching used plastic film after harvest (T6), and un-mulching (CK). In T6, the soil moisture in different layers at different crop growth stages was all higher than that in CK. In the other five mulching treatments, the soil moisture in 0-90 cm layer before flowering stage was obviously higher, but that in 0-90 cm layer after flowering stage and in 90-200 cm layer during the whole growth season was lower than that of CK. The soil moisture in 0-200 cm layer in T6 during the whole growth period was significantly higher than that in CK, with a difference of 0.9%, but the soil moisture in 0-200 cm layer in other mulching treatments was lower. As compared with plastic film mulching, straw mulching increased the soil moisture in 0-200 cm layer. The soil moisture under mulching with used plastic film after harvest was higher than that under mulching with new plastic film. As compared to CK, the grain yield of winter wheat with plastic film mulching was increased by 20.3%-29.0%, and that With straw mulching was increased by 5.0%-16.7%. There was a significant positive correlation between the crop productivity and the soil water consumption during the growth period (r = 0.77*).

This paper studied the changes of organic soil substrate properties with increasing cultivation years and their effects on the cucumber growth in solar greenhouse. The results showed that with increasing cultivation years, the physical and chemical properties of organic soil substrate deteriorated, which was manifested in the increase of bulk density and the decrease of total porosity, pH, and available nutrient contents. The numbers of bacteria and actinomycetes in the substrate decreased with increasing cultivation years, while that of fungi was in reverse. The cucumber growth was also affected to a certain extent, manifesting in the decrease of plant height and leaf area, the decline of photosynthetic efficiency, and the decrease of yield and quality. It would be necessary to restore the fertility of organic soil substrate after 3-year cultivation.

Based on a long term field experiment, this paper studied the effects of different multiple cropping systems on the weed community composition and species diversity under paddy-upland rotation. The multiple cropping rotation systems could significantly decrease weed density and inhibited weed growth. Among the rotation systems, the milk vetch-early rice-late maize --> milk vetchearly maize intercropped with early soybean-late rice (CCSR) had the lowest weed species dominance, which inhibited the dominant weeds and decreased their damage. Under different multiple cropping systems, the main weed community was all composed of Monochoia vaginalis, Echinochloa crusgalli, and Sagittaria pygmae, and the similarity of weed community was higher, with the highest similarity appeared in milk vetch-early rice-late maize intercropped with late soybean --> milk vetch-early maize-late rice (CSCR) and in CCSR. In sum, the multiple cropping rotations in paddy field could inhibit weeds to a certain extent, but attentions should be paid to the damage of some less important weeds.

Taking the vegetable solar greenhouses having been planted for 2, 4, 6, 11, 13, 16, and 19 years as test objects, and with the open vegetable field as the control, this paper studied the variations of soil microbial flora and enzyme activities. With the increasing years of planting, the numbers of soil bacteria, actinomycetes, and total microbes in vegetable solar greenhouses decreased after an initial increase, and reached the maximum in the greenhouse of 11 years planting, with a significant increment of 54.8%, 63.7%, and 55.4%, respectively, as compared to the control. The number of soil fungi in the vegetable solar greenhouses increased steadily with increasing planting years, being about 2.2 times higher in the greenhouse of 11 years planting. Among the microbial physiological groups, the numbers of aerobic cellulose-decomposer, aerobic azotobacter, nitrite bacteria, denitrifier, and sulphur reducer showed the same variation trend as the soil bacteria's, and those in the greenhouse of 11 years planting being 1.5, 1.6, 1.9, 1.4, and 1.1 times of the control, respectively. The number of ammonifiers increased after an initial decrease, reached the minimum in the greenhouse of 13 years planting, being only 56.0% of the control. The enzyme activities of soil urease, polyphenol oxidase, sucrase, protease, cellulase, and alkaline phosphatase increased firstly and then decreased with the increasing years of planting, but soil catalase activity was relatively stable. Correlation analysis showed that the numbers of soil bacteria, actinomycetes, and total microbes were significantly positively correlated with all test soil enzyme activities, while the number of soil fungi had significant negative correlation with the activity of soil catalase.

Taking two winter wheat cultivars Ji' nan 17 and Shannong 8355 as test materials, this paper measured the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and the malondialdehyde (MDA) and soluble protein contents in the functional leaves and sheaths of the tillers at different positions at stem elongation stage under low temperature stress, and then, the freezing resistance of the tillers was comprehensively evaluated by the methods of principal component analysis and cluster analysis. The results showed that under low temperature stress, the SOD, POD, and CAT activities in the functional leaves and sheaths of each tiller at stem elongation stage increased, but the MDA and soluble protein contents increased or decreased to some extent. By using principal component analysis and cluster analysis, the tillers of each cultivar were grouped into three kinds of freezing resistance type. For Ji' nan 17, the main stem, tiller I, and tiller II belonged to high freezing resistance type, the tiller III, tiller IV, and tiller I p belonged to medium freezing resistance type, and the tiller II p belonged to low freezing resistance type. For Shannong 8355, the main stem, tiller I, tiller II, and tiller III belonged to high freezing resistance type, the tiller IV and tiller I p belonged to medium freezing resistance type, and the tiller II p belonged to low freezing resistance type. It was concluded that the freezing resistance of the winter wheat tillers at different positions at stem elongation stage differed, with the lower position tillers being more resistant than the higher position tillers.

Based on the 7-year field experiment on the dryland of east Gansu of Northwest China in 2005-2011, this paper analyzed the variations of soil moisture content, bulk density, and nutrients content at harvest time of winter wheat and of the grain yield under no-tillage and conventional tillage and five fertilization modes, and approached the effects of different tillage and fertilization modes on the soil water storage and conservation, soil fertility, and grain yield under winter wheat/ spring corn rotation. In 2011, the soil moisture content in 0-200 cm layer and the soil bulk density and soil organic matter and available nitrogen and phosphorus contents in 0-20 cm and 20-40 cm layers under different fertilization modes were higher under no-tillage than under conventional tillage. Under the same tillage modes, the contents of soil organic matter and available nitrogen and available phosphorus were higher under the combined application of organic and inorganic fertilizers, as compared with other fertilization modes. The soil available potassium content under different tillage and fertilization modes decreased with years. The grain yield under conventional tillage was higher than that under no-tillage. Under the same tillage modes, the grain yield was the highest under the combined application of organic and inorganic fertilizers, and the lowest under no fertilization. In sum, no-tillage had the superiority than conventional tillage in improving the soil water storage and conservation and soil fertility, and the combined application of organic and inorganic fertilizers under conventional tillage could obtain the best grain yield.

Taking bare land as the control, this paper studied the effects of different planting modes on the soil permeability of sloping farmlands in purple soil area. For the test six planting modes, the soil permeability was in the order of Eriobotrya japonica > Citrus limon > Vetiveria zizanioides hedgerows +corn >Leucaena leucocephala hedgerows + corn> Hemerocallis fulva > corn> bare land, and decreased with increasing depth. The eigenvalues of soil infiltration were in the order of initial infiltration rate> average infiltration rate> stable infiltration rate. The soil permeability had significant positive linear correlations with soil total porosity, non-capillary porosity, initial moisture content, water holding capacity, and organic matter content, and significant negative linear correlation with soil bulk density. The common empirical infiltration model could well fit the soil moisture infiltration processes under the six planting modes, while the Kostiakov equation could not.

Taking a rice-wheat rotation system in the suburb of Nanjing, Jiangsu Province of East China as test object, this paper studied the fluxes of CH4 and N2O and their annual dynamics under different farming managements in 2010-2011, and the field observation data were applied to validate the process-based model, denitrification-decomposition (DNDC) model, aimed to approach the applicability of the model to this rotation system, and to use this model to simulate the effects of different environmental factors and farming managements on the global warming potentials (GWPs) of CH4 and N2O. The results showed that except in the treatment control and during wheat growth season, the simulated cumulative emissions of CH4 and N2O from the rotation system in all treatments were basically in coincide with the observed data, the relative deviations being from 7. 1% to 26.3%, and thus, the DNDC model could be applied to simulate the GWPs of cumulative emissions of CH4 and N2O as affected by various environmental factors or management practices. The sensitivity test showed that the GWPs of CH4 and N2O varied significantly with the changes of environmental factors such as the mean annual air temperature, soil bulk density, soil organic carbon, soil texture, and soil pH. Farming managements such as N fertilization, straw returning, and duration of mid-season drainage also had significant effects on the GWPs of CH4 and NO20. Therefore, the above-mentioned environmental factors and farming managements should be taken into account to estimate the greenhouse gases emission from the rice-wheat cropping system on site-specific or regional scale.

Potato-sunflower intercropping is a prevailing cropping system in the agricultural and pastoral ecotone in China. To precisely simulate the crop phenology in the intercropping system is of significance for the assessment and optimization of intercropping systems. In this paper, the simulation model for the development stages of sunflower and potato in monoculture and intercropping was established, based on the crop's physiological development time, and validated with the field experimental data from 2010 to 2011. A good fitness was observed between the simulated and observed values of the crop's development stages. The root mean square error (RMSE) of the development stages from sowing to emergence, emergence to flowering, flowering to mature, and from sowing to mature was 1.2, 2.9, 2.4 and 2.6 d, respectively, with the prediction error lower than 5%. The model was strong on mechanistic, explanation and adaptability, and could be applied as a good tool in the researches of crop growth and development.

Under the conditions of applying water soluble fertilizer and its bulk blending with controlled release fertilizer (BB-CRF), and by using micro-lysimeter, this paper quantitatively studied the nitrogen (N) uptake by mustard, the soil N losses from N2O emission, leaching and others, and the N residual in soil in three rotations of continuously cropped mustard. In the treatment of BB-CRF with 25% of controlled release nitrogen, the N uptake by mustard increased with rotations, and the yield by the end of the experiment was significantly higher than that in the treatment of water soluble fertilizer. The cumulated N2O emission loss and the N leaching loss were obviously higher in treatment water soluble fertilizer than in treatment BB-CRF. NO3(-)-N was the primary form of N in the leachate. In relative to water soluble fertilizer, BB-CRF altered the fates of fertilizer nitrogen, i.e., the N uptake by mustard and the N residual in soil increased by 75.4% and 76.0%, and the N leaching loss and other apparent N losses decreased by 27.1% and 66.3%, respectively. The application of BB-CRF could be an effective way to reduce the various losses of fertilizer N while increase the fertilizer N use efficiency, and the controlled release fertilizer is the environmentally friendly fertilizer with the property of high N use efficiency.

Traditional agronomy, as a discipline or specialty, is originated from the reductionism thinking of neoteric experimental sciences and motivated by the great success of industrialized revolution, but loses the ensemble grasp of the relationships between agricultural organisms and their resources and environment, i.e., agroecosystem mechanism. Moreover, due to the excessively relying on exogenous fossil energy input and the monoculture with a few highly productive crop cultivars, the agricultural interior sustainability has unceasingly lost, making our mankind facing the double crises of grain security and food safety. Therefore, it is imperative to reconstruct the traditional agronomy and its educational system. In this paper, the author proposed to link traditional agronomy with ecology, establishing agroecology as the core subject and agroecosystem management as the core applied system, and in particular, establishing 'production ecology' to fill up the wide gap between the crop cultivation and farming system and the crop genetics and breeding, the two second grade disciplines under agronomy. Ideologically and methodologically, this proposal could provide disciplinary, scientific, and educational bases to authentically implement the strategy of sustainable development of agriculture.

Based on the multi-disciplinary researches, and in terms of the transformation efficiency of surface water to soil water, availability of cropland soil water, crop canopy structure, total irrigation volume needed on a given area, and crop yield, this paper discussed the water-saving mechanisms of intercropping system in improving cropland water use efficiency. Intercropping system could promote the full use of cropland water by plant roots, increase the water storage in root zone, reduce the inter-row evaporation and control excessive transpiration, and create a special microclimate advantageous to the plant growth and development. In addition, intercropping system could optimize source-sink relationship, provide a sound foundation for intensively utilizing resources temporally and spatially, and increase the crop yield per unit area greatly without increase of water consumption, so as to promote the crop water use efficiency effectively.

Agro-ecosystem is the most basic system for human beings survival, while the analysis of the structure and function of the system is the key to solve the problems of agro-ecological environment. In this paper, emergy theory and related economic measurement methods including data envelopment analysis, cointegration test, and error correction model were applied to quantitatively analyze the operation dynamics, environmental loading, operation efficiency, and input-output relation of the agro-ecosystems in Sichuan Province and its 21 cities in 1997-2009. In the study period, Sichuan Province was in the transition period from traditional agriculture to modern agriculture. The agricultural mechanization level of the Province improved constantly, resources utilization efficiency enhanced continually, overall structural dominant degree was better, but the over-reliance on economic emergy input caused the sustainability of the system weakened gradually. The development status of the agro-ecosystems in the Province varied among regions. Chengdu Plain and Western Sichuan Highland were either in overexploited or in underutilized, while the hilly areas were full of vitality and development potential, tended to be the important areas for the future development of Sichuan agriculture. Generally, the operation efficiency of the agro-ecosystems in the Province was relatively low, with the situation differed in different regions due to the lower technical efficiency or improper scale. There was a long-term equilibrium between the economic emergy indices and output emergy, but the short-term emergy input didn't reach the ideal output.

This paper studied the variations of soil microbial biomass C, N, and P contents and soil hydrolase activities under different cropping modes, i.e., corn + sweet potato intercropping (CS), soybean mono-cropping (SM), continuous cropping of ginger (CG), and rice-milk vetch rotation (RM) , after ginger planting in the purple soil area at the lower reaches of Minjiang River. Ginger planting decreased the soil microbial biomass C, N and P contents significantly. The decrement of the soil microbial biomass C and N contents after ginger planting was lesser under CS and RM than under SM and CG, but the soil microbial biomass P content was in adverse. Ginger planting also decreased the soil acid phosphatase activity significantly, and the decrement was the greatest under CS but the least under RM. The soil invertase activity decreased significantly under CG, and the soil urease activity had a significant decrease under SM, CG and RM. After ginger planting, the soil urease and intervase activities under CS were higher, as compared with those under the other cropping modes.

Stand establishment is the most difficult step for cotton planting on coastal saline-alkali soil. To establish and improve the techniques for stand establishment is the key in the production of high-yielding cotton on saline-alkali soil. Based on the previous studies and our own research progress in this field, this paper reviewed the effects and the underlying mechanisms of making unequal salt distribution in root zone, increasing soil moisture and temperature, establishing under-mulching greenhouse, and introducing seed coating agent in promoting stand establishment of cotton on saline-alkali soil. It was suggested that under the conditions of the average salt content in topsoil being not able to reduce, improving at least partial root zone environment through the induction of unequal salt distribution in the root zone and increasing soil moisture and temperature could significantly reduce salt injury and improve stand establishment. Flat seeding under plastic mulching on low-salinity soil, furrow seeding with mulching on moderate- or high-salinity soil, early mulching before sowing on rain-fed saline soil, and late sowing of short-season cotton in heat-limited area were the efficient techniques for improving the stand establishment of cotton on coastal saline-alkali soil. This review could provide full guarantee for the cotton stand establishment on coastal saline-alkali soil.

Taking an eight-year field experiment site in Dehui County of Jilin Province, Northeast China as test object, this paper studied the effects of different tillage modes (no tillage and ploughing in autumn) on the penetration resistance and bulk density of black soil. No tillage increased the soil penetration resistance, especially at the soil depth of 2.5-17.5 cm. In the continuous cropping of maize and the rotation of maize-soybean, the maximum soil penetration resistance at planting zone under no tillage and ploughing in autumn was 2816 and 1931 kPa, and 2660 and 2051 kPa, respectively, which had no restriction on the crop growth. The curve of soil penetration resistance under ploughing in autumn changed with ridge shape, while that under no tillage changed less. Comparing with ploughing in autumn, no tillage increased the bulk density of 5-20 cm soil layer significantly. Under no tillage, the bulk density of 5-30 cm soil layer changed little, but under ploughing in autumn, soil bulk density increased gradually with increasing soil depth. There was no significant correlation between soil bulk density and soil penetration resistance.

In a long-term site-specific experiment with rice straw return (RSR) and in a short-term experiment with different RSR modes, this paper studied the effects of RSR on the soil organic carbon (SOC) sequestration, methane emission, and net carbon sink in a double season paddy field. RSR increased the SOC content, and the annual increasing rate of soil carbon sink in plow layer (0-15 cm) under long-term RSR was 0.07 t C x hm(-2) x a(-1). With the increasing amount of RSR, the apparent SOC transformation rate decreased. RSR promoted the methane emission from the paddy field significantly, and the methane emission flux in treatment RSR plus NPK during early- and late rice growth seasons increased by 75.0% and 251.5% (P < 0.01), respectively, compared with that in treatment NPK. The methane emission increased with the increasing amount of RSR. Under the similar tillage mode and rice yield, the rice straw returned had the similar apparent methane transformation rate. Considering the soil carbon sequestration and the net carbon sink after methane emission in the paddy field comprehensively, treatment RSR plus NPK had significant negative effect on the carbon sink which was basically approached to the bio-fixation of carbon by rice and increased by 158.3%, as compared with treatment NPK. Among different RSR modes, rice straw mulching plus no tillage decreased soil methane emission significantly, with the net carbon sink decreased by 50.9% as compared with the treatment high stubble plus tillage, and benefited the high and stable yielding of rice.

Rice productivity is the key factor affecting rice production and its sustainable development. Based on the gradation of cultivated land quality at county-level, this paper evaluated the rice productivity in Fuyang County of Zhejiang Province, and, through selected sampling field investigation and according to the land productivity index of paddy field quality, a model for assessing rice achievable productivity was established, aimed to analyze the regional rice productivity and its achievable productivity. In the study area, there was a positive correlation between the land productivity index and rice yield. For single cropping rice, its achievable productivity was 1.70 x 10(5) t, being 1.6 times of its realistic productivity (1.04 x 10(5) t). In 2009, the realistic rice productivity per unit area was 7676 kg x hm(-2), and the achievable productivity was 8831 kg x hm(-2), with a production potentiality of +15%, a big potential of rice production capacity in the county. Through the analyses of rice productivity, relative superiority of rice production scale, and its growth potential index in the villages and towns, the rice production of Fuyang County was divided into three regions, i. e., key enhancement region, optimization construction region, and development protection region.

Taking a 2-year-old tea garden in Qingdao of Shandong Province as test object, this paper studied the effects of different mulching modes on the soil water and nutrient dynamics and tea plant growth. Four treatments were installed, i.e., no mulching (CK), straw mulching (T1), plastic film mulching (T2), and straw plus plastic film mulching (T3). Comparing with CK, mulching could keep the soil water content at a higher level, and enhance the water use efficiency. In treatments T1 and T3, the tea growth water use efficiency and yield water use efficiency increased by 43%-48% and 7%-13%, respectively, compared with CK. Also in treatments T1 and T3, the contents of soil organic matter, available-N, nitrate-N, and ammonium-N increased significantly, with the soil fertility improved, and the leaf nitrate-N content and nitrate reductase activity increased, which promoted the tea growth and yield (12%-13% higher than CK) and made the peak period of bud growth appeared earlier. Considering the tea growth and yield, water and nutrient use efficiency, environment safety and economic benefit, straw mulching could be an effective ground surface mulching mode for young tea garden.

This paper studied the effects of alternative furrow irrigation and nitrogen (N) application rate (no N, optimal N, and conventional N) on the photosynthesis, growth characteristics, yield formation, and fruit quality of cucumber (Cucumis sativus) cultivar Jinyu No. 5 in a solar greenhouse in winter-spring growth season and autumn-winter season. Under alternative furrow irrigation, the net photosynthetic rate of upper, middle, eand lower leaves was appreciably lower and the transpiration rate decreased significantly, and the transient water use efficiency of upper and middle leaves improved, as compared with those under conventional irrigation. Stomatal factor was the limiting factor of photosynthesis under alternative furrow irrigation. The photosynthesis and transient water use efficiency of functional leaves under alternative furrow irrigation increased with increasing N application rate. Comparing with conventional irrigation, alternative furrow irrigation decreased leaf chlorophyll content and plant biomass, but increased root biomass, root/shoot ratio, and dry matter allocation in root and fruit. The economic output under alternative furrow irrigation was nearly the same as that under conventional irrigation, whereas the water use efficiency for economic yield increased significantly, suggesting the beneficial effects of alternative furrow irrigation on root development and fruit formation. With the increase of N application rate, the leaf chlorophyll content, chlorophyll a/b, specific leaf mass, plant biomass, economic yield, and fruit Vc and soluble sugar contents under alternative furrow irrigation increased, but no significant difference was observed between the treatments optimal N and conventional N. N application had little effects on the water use efficiency for economic yield. The economic yield and biomass production of the cucumber were significantly higher in winter-spring growth season than in autumn-winter growth season.

Taking the solar greenhouse heavy loam soil having been planted vegetables for different years at Yunyang Town in Jingyang County of Shaanxi Province as test objects, and with the uncovered vegetable soil adjacent to the greenhouse as the control, this paper studied the effects of solar greenhouse vegetable cultivation on soil physical quality. Solar greenhouse vegetable cultivation had greater effects on the bulk density of 0-30 cm soil layer (an increase in 0-10 cm soil layer and a decrease in 10-30 cm soil layer), but little effects on that of 30-40 cm soil layer. In 0-40 cm solar greenhouse soil profile, the contents of < 0.01 mm physical clay and < 0.001 mm clay were lower in upper layer than in deeper layer, indicating their downward movement, and this phenomenon was more obvious with increasing year of solar greenhouse vegetable cultivation. Within the first 5 years of solar greenhouse vegetable cultivation, soil field water capacity decreased significantly, with a decrement of 13.8%, but remained relatively stable after then.

By using the CERES-Maize crop model and Century soil model in Decision Support System of Agrotechnology Transfer (DSSAT) model, this paper studied the effects of crop management parameters, fertilizer N application rate, soil initial N supply, and crop residue application on the maize growth, crop-soil N cycling, and soil organic C and N ecological balance in black soil (Mollisol) zone of Jilin Province, Northeast China. Taking 12,000-15,000 kg x hm(-2) as the target yield of maize, the optimum N application rate was 200-240 kg N x hm(-2). Under this fertilization, the aboveground part N uptake was 250-290 kg N x hm(-2), among which, 120-140 kg N x hm(-2) came from soil, and 130-150 kg N x hm(-2) came from fertilizer. Increasing the N application rate (250-420 kg N x hm(-2)) induced an obvious increase of soil residual N (63-183 kg x hm(-2)); delaying the N topdressing date also induced the increase of the residual N. When the crop residue application exceeded 6000 kg x hm(-2), the soil active organic C and N could maintain the supply/demand balance during maize growth season. To achieve the target maize yield and maintain the ecological balance of soil organic C and N in black soil zone of Jilin Province, the chemical N application rate would be controlled in the range of 200-240 kg N x hm(-2), topdressing N should be at proper date, and the application amount of crop residue would be up to 6000 kg x hm(-2).

Taking the energy-saving solar greenhouses with the same infrastructure but different sunken depths (0, 0.5, 1.0, and 1.5 m) in Tai' an of Shandong Province as test objects, this paper analyzed the intercepted amount of direct solar radiation energy, and studied the diurnal variation and spatial distribution patterns of environmental factors in the greenhouses on winter solstice (December 20-24, 2009) and summer solstice (June 19-23, 2010). With the increase of sunken depth, the shadow areas in the greenhouses caused by sunken profiles increased gradually, the direct solar radiation energy into the interior of the greenhouses shifted from south to north, and the ratio of ground radiation to back wall radiation decreased gradually. Within the range of 0-1.0 m sunken depth, the air temperature and soil temperature in the greenhouses increased significantly with increasing sunken depth; but when the sunken depth was 1.5 m, the warming effect declined significantly, and the deviation of the lowest soil temperature increased. The deeper the sunken depth, the lower the light intensity and the higher the relative humidity in the greenhouses were. In considering of both lighting and heat preservation, the appropriate sunken depth of energy-saving sunlight greenhouses with a span of 10 m in Tai' an region should be less than 1.0 m.

Based on the observation data from the meteorological stations and agricultural experimental stations in Jiangxi Province, this paper studied the change trend of the growth period of double cropping rice in the province, and, by using the indices growing degree-days (GDD), cool degree-days (CDD), and heat degree-days (HDD), the change trends of the heat resources at each growth stage of the double cropping rice in 1981-2007 were analyzed. Under the background of climate warming, the mean air temperature, mean minimum air temperature, mean maximum air temperature during the growth period of the double cropping rice all had an increasing trend, leading to the shortening of double cropping rice growth season, with the most obvious decrease of vegetative growth phase and the prolonged reproductive growth phase. In the vegetative growth phase, the GDD and HDD increased, while the CDD decreased. In 1981-2007, the effective heat resources of double cropping rice in Jiangxi Province increased, low temperature risk reduced, while high temperature risk increased. The increment of the effective heat resources for double cropping rice was higher in northeast Jiangxi than in southwest Jiangxi, low temperature risk was higher in south Jiangxi than that in north Jiangxi, and high temperature risk was the highest in middle Jiangxi.

Agricultural land consolidation is a strong disturbance to farmland ecosystem. In traditional agricultural land consolidation, the main technical and economic indices for the design of ditches include the convenience for production and transportation, the allocation of water resources, and the improvement of water utilization, but short of ecological consideration, which has already affected the spread of agricultural species, caused the degradation of bio-habitat, and given obvious negative effects on the bio-competition mechanism, buffering and compensation capacity, and insect pests-resistance of farmland ecosystem. This paper summarized the functions of ecological ditches, and introduced the recent progress on the formations and construction designs of ecological ditches, tests of ecological engineering methods, and technologies and methods of choosing correct ecological materials. It was suggested that the future research should focus on the different functional requirements and specifications for different roads and ditches, and the characteristics and habitats of all the organisms and animals should be considered by the designers and constructors. Moreover, a comprehensive design which meets the ecological demands for the ditches' formations, structures, and regulatory sizes should be taken into account to solve the most of the problems listed above.