Climate Change Impacts on Agroecosystems in China:Processes,Mechanisms and Prospects

Building a more resilient response system to climate change for sustainable development and reducing uncertainty in China’s food markets,requires access to historical research gaps and mapping future research progress for decision making.However,the lack of quantitative and objective analyses to ensure the stability and development of agroecosystems increases the complexity of agro-climatic mechanisms,which leads to uncertainty and undesirable consequences.In this paper,we review the characteristics of climate change in China(1951–2020),reveal the mechanisms of agroecosystem structure in response to climate,and identify challenges and opportunities for future efforts in the context of research progress.The aim is to improve the scientific validity and relevance of future research by clarifying agro-climatic response mechanisms.The results show that surface temperature,precipitation,and frequency of extreme weather events have increased to varying degrees in major agricultural regions of China in 1951–2020.And they have strong geographic variation,which has resulted in droughts in the north and floods in the south.Moreover,climate change has complicated the mechanisms of soil moisture,Net Primary Productivity(NPP),soil carbon pool,and crop pest structure in agroecosystems.This lends to a reduction in soil water holding capacity,NPP,soil carbon content,and the number of natural enemies of diseases and insects,which in turn affects crop yields.However,human interventions can mitigate the deterioration of these factors.We have also realized that the methodology and theory of historical research poses a great challenge to future agroecosystem.Historical and projected climate trends identified current gaps in interdisciplinary integration and multidisciplinary research required to manage diverse spatio-temporal climate change impacts on agroecosystems.Future efforts should highlight integrated management and decision making,multidisciplinary big data coupling,and numerical simulations to ensure sustainable agricultural development,ecological security,and food security in China.

Estimation of USLE crop and management factor values for crop rotation systems in China

Soil erosion on cropland is a major source of environmental problems in China ranging from the losses of a non-renewable resource and of nutrients at the source to contamination of downstream areas. Regional soil loss assessments using the Universal Soil Loss Equation (USLE) would supply a scientiifc basis for soil conservation planning. However, a lack of in-formation on the cover and management (C) factor for cropland, one of the most important factors in the USLE, has limited accurate regional assessments in China due to the large number of crops grown and their complicated rotation systems. In this study, single crop soil loss ratios (SLRs) were col ected and quantiifed for 10 primary crops from past studies or re-ports. The mean annual C values for 88 crop rotation systems in 12 cropping system regions were estimated based on the combined effects of single crop SLRs and the percentage of annual rainfal erosivity (R) during the corresponding periods for each system. The C values in different cropping system regions were compared and discussed. The results indicated that the SLRs of the 10 primary crops ranged from 0.15 to 0.74. The mean annual C value for al 88 crop rotation systems was 0.34, with a standard deviation of 0.12. The mean C values in the single, double and triple cropping zones were 0.37, 0.36 and 0.28, respectively, and the C value in the triple zone was signiifcantly different from those in single and double zones. The C values of dryland crop systems exhibited signiifcant differences in the single and triple cropping system regions but the differences in the double regions were not signiifcant. This study is the ifrst report of the C values of crop rotation systems in China at the national scale. It wil provide necessary and practical parameters for accurately assessing regional soil losses from cropland to guide soil conservation plans and to optimize crop rotation systems.

Do Land Characteristics Affect Farmers' Soil Fertility Management?

Soil fertility management （SFM） has important implications for sustaining agricultural development and food self-sufifciency. Better understanding the determinants of farmers’ SFM can be a great help to the adoption of effective SFM practices. Based on a dataset of 315 plots collected from a typical rice growing area of South China, this study applied statistical method and econometric models to examine the impacts of land characteristics on farmers’ SFM practices at plot scale. Main results showed that in general land characteristics affected SFM behaviors. Securer land tenure arrangements facilitated effective practices of SFM through more diversiifed and more soil-friendly cropping pattern choices. Plot size signiifcantly reduced the intensities of phosphorus and potassium fertilizer application. Given other factors, 1 ha increase in plot size might reduce 3.0 kg ha-1 P2O5 and 1.8 kg ha-1 K2O. Plots far from the homestead were paid less attention in terms of both chemical fertilizers and manure applications. Besides, plots with better quality were put more efforts on management by applying more nitrogen and manure, and by planting green manure crops. Signiifcant differences existed in SFM practices between the surveyed villages with different socio-economic conditions. The ifndings are expected to provide important references to the policy-making incentive for improving soil quality and crop productivity.

Elevation, Slope Aspect and Integrated Nutrient Management Effects on Crop Productivity and Soil Quality in North-west Himalayas, India

On farm bio-resource recycling has been given greater emphasis with the introduction of conservation agriculture specifically withclimate change scenarios in the mid-hills of the north-west Himalaya region（NWHR）. Under this changing scenario, elevation, slope aspect and integrated nutrient management（INM） may affect significantly soil quality and crop productivity. A study was conducted during 2009-2010 to 2010-2011 at the Ashti watershed of NWHR in a rainfed condition to examine the influence of elevation, slope aspect and integrated nutrient management（INM） on soil resource and crop productivity. Two years of farm demonstration trials indicated that crop productivity and soil quality is significantly affected by elevation, slope aspect and INM. Results showed that wheat equivalent yield（WEY） of improved technology increased crop productivity by -20%-37% compared to the conventional system. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-17%. North aspect and higher elevation increased crop productivity by 15%-25% compared to south aspect and low elevation（except paddy）. Intercropping of maize with cowpea and soybean enhanced yield by another 8%-15%. Irrespective of slope, elevation and cropping system, the WEY increased by -30% in this region due to INMtechnology. The influence of elevation, slope aspect and INM significantly affected soil resources（SQI） and soil carbon change（SCC）. SCC is significantly correlated with SQI for conventional（R2 = 0.65＊）, INM technology（R2 = 0.81＊） and for both technologies（R2 = 0.73＊）. It is recommended that at higher elevation.（except for paddy soils） with a north facing slope, INM is recommended for higher crop productivity; conservation of soil resources is recommended for the mid hills of NWHR; and single values of SCC are appropriate as a SQI for this region.

Effects of Different Agricultural Managements on Characteristics of Soil Microbial Community under Continuous Cropped Strawberry(Fragaria ananassa Duchesne)

[Objective] The objective of this study was to investigate the effects of different agricultural managements on soil microbial population,activity,functional diversity and soil enzyme activity in continuous mono-cropping field of strawberry.[Method]A field plot experiment was carried out to evaluate characteristics of soil microbial community by soil enzyme analysis,microbial cultivation and Biolog analysis.[Result]The results showed that bacteria population proportion,the ration of bacteria to fungi,microorganism amount,AWCD,soil dehydrogenase activity,the Shannon,Simpson,and Mcintosh indices of soil microbial communities were obviously increased under strawberry-rice rotation,soil solarization with rice bran,and calcium cyanamide（CaCN2）treatments,in addition,soil urease activity was significantly increased under strawberry-rice rotation and soil solarization with rice bran treatment,when compared with no fertilization.When compared with conventional fertilization treatment,strawberry-rice rotation and soil solarization with rice bran both significantly increased AWCD and Mcintosh index of soil microbial communities,meanwhile respectively increased soil urease and dehydrogenase activity.PCA analyses suggested that carbon utilization of soil microbial communities under strawberry-rice rotation,soil solarization with rice bran,and calcium cyanamide treatment was obviously different from that of conventional fertilization and no fertilization treatment.[Conclusion] strawberry-rice rotation and soil solarization with rice bran were effective agricultural managements to control soil biological degradation under Continuous Cropped Strawberry.

Fuzzy Synthetic Evaluation of Wetland Soil Quality Degradation:A Case Study on the Sanjiang Plain,Northeast China

Wetland soil quality degradation caused by large-scale agricultural reclamation on the Sanjiang Plain of Northeast China has been widely reported. A relative soil quality evaluation (RSQE) model and a projection pursuit evaluation (PPE) model based on real-coded accelerating genetic algorithm were introduced to evaluate quality variations in top layers of the main wetland soils on the Sanjiang Plain in 1999 and 2003, respectively. As soil quality degradation boundaries were vague, this study established two fuzzy synthetic evaluation (FSE) models based on the original data and criteria used in the RSQE and PPE models. The outputs of the two FSE models were obtained by choosing two fuzzy composite operators M(∧, ∨) and M(·, ⊕). Statistical analysis showed that the results of the FSE, RSQE, and PPE models were correlated. In particular, outputs of the FSE model using M(·, ⊕) were significantly correlated with those of the RSQE model with r = 0.989 at P < 0.01. Compared with RSQE and PPE models, the FSE model may be more objective in showing soil quality variations and was closer to the natural situation, showing the feasibility and applicability of the FSE model in evaluating soil quality degradation. However, the choice of composite operator was of critical importance. The study of wetland soil quality degradation on the Sanjiang Plain was of scientific and practical significance for protection and management of soils and for sustainable development of agriculture in this area in the future.

The effect of total carbon on microscopic soil properties and implications for crop production

Soil structure is a dynamic property affected by physical, chemical, and microbiological processes. Addition of organic matter to soils and the use of different management practices have been reported to impact soil structure and crop production. Moderation in soil temperature and increases in microbial activity and soil water retention are often suggested as reasons for the rise in crop yield when organic matter is added to the soil. Less is known about the direct effect of changes in soil structure on crop production. A field experiment was conducted to study the effect of summer cover crop and in-season management system on soil structure. The experiment was a nested design with summer cover crop as the main plot and management system as the subplot. Summer cover crop treatments included cowpea （Vigna unguiculata L. Walp.） incorporated into the soil in the fall （CI）, cowpea used as mulch in the fall （CM）, sudangrass （Sorghum vulgare） incorporated into the soil in the fall （S）, and dry fallow or bare ground （B）. Management systems were organic （ORG） and conventional （CNV） systems. Lettuce （Lactuca sativa L.） and cantaloupes （Cucumis melo L.） were cultivated in rotation in the plots for three consecutive years using the same cover crops and management systems for each plot. Disturbed and undisturbed soil cores were collected at the end of the third year and used for laboratory experiments to measure physical, chemical, and hy- draulic properties. Image analysis was used to quantify soil structure properties using a scanning electron micro- scope on thin sections prepared from the undisturbed soil cores. We found that total soil carbon was correlated with porosity, saturation percentage, and pore roughness. Pore roughness was correlated with crop production in gen- eral and with marketable production in particular. We found that the higher the complexity of the pore space, the more water retained in the soil, which may increase soil water residence and reduce plant water stress.

Evaluation of C and P Factors in Universal Soil Loss Equation on Trapping Sediment: Case Study of Santubong River

Universal Soil Loss Equation (USLE) is the most comprehensive technique available to predict the long term average annual rate of erosion on a field slope. USLE was governed by five factors include soil erodibility factor (K), rainfall and runoff erodibility index (R), crop/vegetation and management factor (C), support practice factor (P) and slope length-gradient factor (LS). In the past, K, R and LS factors are extensively studied. But the impacts of factors C and P to outfall Total Suspended Solid (TSS) and % reduction of TSS are not fully studied yet. Therefore, this study employs Buffer Zone Calculator as a tool to determine the sediment removal efficiency for different C and P factors. The selected study areas are Santubong River, Kuching, Sarawak. Results show that the outfall TSS is increasing with the increase of C values. The most effective and efficient land use for reducing TSS among 17 land uses investigated is found to be forest with undergrowth, followed by mixed dipt. forest, forest with no undergrowth, cultivated grass, logging 30, logging 10^6, wet rice, new shifting agriculture, oil palm, rubber, cocoa, coffee, tea and lastly settlement/cleared land. Besides, results also indicate that the % reduction of TSS is increasing with the decrease of P factor. The most effective support practice to reduce the outfall TSS is found to be terracing, followed by contour-strip cropping, contouring and lastly not implementing any soil conservation practice.

Response of Soil Microbial Properties to Long-Term Application of Organic and Inorganic Amendments in a Tropical Soil (Saria, Burkina Faso)

Soil microbial biomass carbon (MBC), β-glucosidase, acid phosphatase and fluorescein diacetate (FDA) activities and bacterial community structure were assessed in a long-term (26 years) experiment, at physiological stages of sorghum growth, comparing different management methods for organic (manure, straw residues) and inorganic (urea) amendments at the INERA field station in Saria (Burkina Faso). Annual application of manure led to the highest soil microbial biomass and enzyme activities. Investigations indicated that only microbial biomass and β-glucosidase activities were affected during the cropping season. Phosphatase and FDA enzyme activities did not depend on the crop development stages. The application of N fertilizer modified phosphatase and FDA enzyme activities, the activities being higher in soils amended with N fertilizer. The bacterial community structure was analyzed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) targeting the eubacterial 16S rRNA gene. Cluster analysis of PCR-DGGE patterns showed two major clusters, the first containing the mineral fertilization and straw treatments and the second, the straw + urea, manure and manure + urea treatments. Sorghum grain yields were the highest for manure treatments. In this long-term experiment, applying straw did not produce a better grain yield than that obtained in the un-amended plot.

Microbiological Assessment of Soil Planted with Cover Crops, and Soybean and Maize in Succession

This study aimed to assess the population density of nematodes and mycorrhizal soil fungi, in areas cultivated with oats, brachiaria, forage and white lupine, as well as in maize and soybean crops in succession, in order to generate a microbiological indicator of soil quality. In order to assess nematode and arbuscular mycorrhizal fungi (AMF) population densities, the experiment was performed in two stages: the first assessment was performed in the area where different cover crops were planted, in five seasons (0, 60, 90, 120, 150 days after sowing—DAS). In the second stage, soybean and maize crops in succession were assessed. According to the results, free-living nematodes and arbuscular mycorrhizal fungi population densities were not affected by the cover crop species used and, therefore, these can be grown prior to soybean and corn crops, without impact to free-living nematodes and AMF. The largest population of saprophyte nematodes and AMF occurred at 90 days. The cultivation of soybean and corn did not influence the number of free-living nematodes, but influenced the number of arbuscular mycorrhizal fungi. The highest numbers of mycorrhizal fungi Gigaspora margarita and Glomus macrocarpum were found in maize.

Effect of Soil on the Growth and Quality of Pepper during Different Durations of Continuous Planting

With the greenhouse soil that had been planted with cucumber as the control,the greenhouse soil that had been planted with pepper for 3,7,10 and 15 consecutive years was collected,and the effects of continuous cropping on plant height,stem diameter,leaf area,yield,photosynthetic pigment content and fruit quality of pepper were investigated by pot experiment. The results showed that with the extension of continuous cropping duration,the plant height,stem diameter and yield of pepper decreased significantly compared with the control; and the mass fraction of photosynthetic pigments declined,and the mass fractions of chlorophyll a and total chlorophyll were significantly lower than those of the control. Under the condition of continuous cropping,the fruit quality of pepper decreased significantly,and the mass fractions of soluble solids and soluble protein were significantly lower than those of the control.

山水林田湖草沙系统治理与水土保持高质量发展

[目的]中国水土流失治理已由“全面治理,重点治理”迈向“系统治理,攻坚克难”的新阶段。分析山水林田湖草沙系统治理的内涵、准则及其与水土保持的关系,旨在丰富新时代水土保持理论体系,引领水土保持高质量发展。[方法]在长期理论探索和实践验证的基础上,梳理山水林田湖草沙系统治理理念的发展过程,阐明其内涵、目标与实践准则。[结果]水土流失长期治理实践总结提升形成的以小流域为单元的综合治理技术路线是山水林田湖草沙生命共同体系统思想最朴素的实践体现。小流域综合治理的系统性主要体现为治理对象的系统协调,总体布局的系统统筹,治理措施的系统考量,治理成效的多效益兼顾,实施和管理的多部门协同和多主体参与的共治共享6个方面。水土保持高质量发展实践需要遵循的基于系统治理理念的具体举措包括:利用系统思维理解水土保持高质量发展的内涵和要求,精准诊断山水林田湖草沙系统短板及其控制性要素,构建山水林田湖草沙多层次全方位立体化防控体系,构筑完备的水土保持管理与技术保障体系。[结论]在新的历史时期,应该完整准确理解并全面贯彻落实山水林田湖草沙系统治理的理念,探索整体提升水土保持学术研究水平和治理效能的新路径、新模式、新机制。同时应结合区域或流域实际,对农田、水利、牧业、林业及生产建设活动进行全面综合系统的规划和治理,推动水土保持高质量发展。

黄河流域生态治理与生态经济协同发展模式研究进展

为了给黄河流域生态保护和高质量发展重大国家战略的实施及乡村振兴等提供科技支撑,对多年来黄河流域生态治理与生态经济协同发展的研究成果、关键技术及典型模式进行系统归纳,分析了当前存在的突出问题,并提出了相应的对策建议。黄河流域生态治理与生态经济协同发展模式是随着水土保持工作不断发展和生态文明建设、乡村振兴等多项国家战略的实施而逐步建立和不断丰富完善的,多年来黄河流域各地区针对严重的水土流失探索了多种生态治理与生态经济协同发展模式,包括水土保持-地貌-生态经济高适配生态经济型综合治理模式、水土保持型生态农业经济模式、风沙区水土保持-生态经济融合发展模式、砒砂岩区生态治理-衍生产业协同发展模式、半干旱区乡村能源生态型良性循环模式、黄土高塬水土保持型生态经济带治理模式等。当前存在的突出问题有:生态治理-生态经济协同发展的理念薄弱,二者的协同性不高且耦合协调的空间不均衡,发展模式结构单一、规模效益不高等。建议:创新生态治理-生态经济协同发展的理论与关键技术;建立多元化投入机制,创建以高质量发展为目标的新型生态治理与经济协同发展模式及其生产与产业体系,探索“全托全链”的推广机制;构建适宜的技术体系、产业体系、经营体系和人才支撑体系;建立生态治理与生态经济协同发展先行试验示范县,引领和优化区域现代生态治理与经济的协同发展。

不同处理对大棚草莓连作土壤理化性质和果实品质的影响

为了探讨不同处理对大棚草莓连作土壤和果实品质的影响,以未处理为对照(CK),研究了甜玉米轮作、棉隆消毒、生物炭利用、菌渣混土等7个不同修复技术对处理后土壤理化性质、植株生长、果实品质、产量的影响。结果表明:甜玉米轮作处理(T1)土壤含水量、容重最高,EC值最低,养分含量除了全氮、全钾、碱解氮、有效锌外最低,盐分离子含量均低于CK;小麦秸秆炭处理(T3)土壤含水量、容重较低,EC值最高,pH值高于CK,有机质、全磷、有效磷、有效铜、有效锌含量最高,盐分离子含量除了F-和Cl-外均高于CK;T1草莓植株生长指标高于CK,单果重、单株产量高,果实硬度大,可溶性固形物含量高,糖酸比、固酸比最高。综上所述,T3可有效改善土壤板结和酸化,减少养分损失;T1土壤保水性好,养分利用率高,可消耗部分过多养分,减轻土壤富营养化,减缓连作土壤次生盐渍化,促进植株健康生长,提高果实品质和产量。

中药渣有机肥对作物生长、土壤化学性状及酶活性的Meta分析

以中药渣有机肥为研究对象,采用Meta分析的方法,共筛选出32篇文献,包含388组相对独立的数据,研究了中药渣有机肥对作物生长发育和土壤化学性质及酶活性影响的综合效应,以期为实现我国中药渣资源的合理利用与绿色低碳发展提供参考依据。结果表明:施用中药渣有机肥能够显著促进作物产量、叶绿素含量和土壤pH、土壤蔗糖酶和过氧化氢酶活性等指标,比不施肥分别增加了15.30%、25.90%、14.50%、40.70%和14.80%;随着施用中药渣有机肥时间的延长,植物总生物量呈逐渐增长的趋势(P<0.01),但土壤脲酶的效应值则呈先增加后降低的趋势;中药渣有机肥对药用植物土壤性状的正效应要优于农作物和蔬菜。综上,合理地施用中药渣有机肥能较显著促进植物生长发育并改善土壤理化性状。

微生物肥料改土培肥研究进展

微生物肥料是一种以活性微生物为主要成分的新型肥料产品,能提高土壤肥力、促进植物生长发育、增强植物抗性。文章归纳了微生物肥料的国内外发展历程,介绍了微生物肥料对土壤物理、化学、生物性质以及植物生长发育、产量、品质、抗性的影响,并对其应用前景进行了展望,旨在为后续微生物肥料的合理应用提供参考。

秸秆粉碎技术对土壤环境及作物生长的提升机理

秸秆粉碎技术是指将农田或农作物种植后残留的秸秆、稻草等植物秸秆进行机械粉碎处理,在有效处理秸秆的同时秸秆中的有机物质和养分为土壤提供营养,有助于改善土壤质量。该文分析了秸秆粉碎对土壤环境的影响,包括改善土壤结构、增加土壤有机质和提高土壤保水保肥能力等方面的正面影响。同时探讨了秸秆粉碎技术可能带来的负面影响,如对土壤微生物和生物多样性的影响等,阐述了秸秆粉碎对作物生长中提供养分、改善土壤温度、减轻土壤压实等方面的作用机理,并结合实际案例和研究成果,总结秸秆粉碎技术在提升土壤环境质量和促进作物生长方面的重要意义和发展趋势,研究内容旨在对农业生产具有重要意义。

作物轮作栽培措施对土壤有机碳和氮素累积及作物产量的影响

农作物轮作系统是一种普遍应用的作物种植模式,通过这一模式能够提高对土地资源的高效利用,提高土壤肥力和生物活性,还能有效降低病虫害的发生率。在农作物轮作系统实施中还需要采取有效的栽培管理措施,保证土壤有机碳和氮素累积,进而提高农作物的产量。结合已有文献报道,分析栽培管理措施对农作物轮作系统土壤有机碳和氮素累积及作物产量的影响,以在农作物轮作系统中合理采取栽培管理措施,促进土壤营养成分的累积,保证作物的整体产量。

静宁县胡家塬苹果重茬建园经验

老化果园更新是苹果主产区面临的突出问题之一。淘汰老化果园后,在旧园址上重茬建园时,会出现一系列问题,不利于新栽苹果树的生长结果。静宁县在治平镇雷沟村胡家塬进行老化果园挖除,在旧址上重茬建园试验示范,积累了较成熟的经验。该文介绍胡家塬苹果重茬建园示范园的基本情况,从土壤处理及配套措施两方面总结经验,供苹果重茬建园者参考。

乘势而上砥砺奋进扎实推动河北水土保持工作高质量发展

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