保护性耕作对农田碳、氮效应的影响研究进展

作物产量的高低主要取决于土壤肥力,如何保持并提高土壤肥力是确保我国粮食安全和农业可持续发展的重要任务,也是众多学者关注的焦点。土壤有机碳和氮素是评价土壤质量的重要指标,其动态平衡直接影响土壤肥力和作物产量。随着全球气候变化及环境污染问题的愈加突出,农田土壤固碳及提高氮效率成为各界科学家研究的热点。目前,保护性耕作已成为发展可持续农业的重要技术之一,对土壤固碳及氮素的利用具有很大的影响。深入了解保护性耕作对土壤有机碳固持与氮素利用效率提高的影响机制,对于正确评价土壤肥力有着重要意义。但由于气候、土壤及种植制度等条件不一致,关于保护性耕作对农田碳、氮效应结论不一。阐述了国际上保护性耕作对农田系统土壤有机碳含量变化及其分解排放(如CO₂和CH₄)、氮素变化及其矿化损失(如NH₃挥发、N₂O排放与氮淋失)和碳氮素相互关系(如C/N层化率)影响的研究进展,并分析了其影响因素和相关机理。尽管国内保护性耕作的研究已进行30 多年,但在土壤有机碳与氮素方面与国外相比依然有较大的差距。保护性耕作对土壤固碳与氮素利用的影响机制,碳素和氮素在土壤-植株-大气系统中的转移变化,及结合农事管理等综合评价其生态效应的研究很少。在此基础上,提出未来我国保护性耕作在土壤有机碳固定和氮素利用方面的重点研究方向:(1)在定位试验基础上进一步探讨保护性耕作对土壤有机碳及氮素利用的影响机制;(2)深入研究土壤有机碳和氮素的相互关系及其对土壤肥力的影响;(3)结合环境保护与土壤可持续管理对保护性耕作农田土壤固碳及氮素高效利用的系统评价研究;(4)加强保护性耕作对农田碳、氮效应的宏观研究,合理评价保护性耕措施下对农田碳、氮综合效应。     

环境友好型农业生态补偿实践进展

环境友好型农业是兼顾生产和环境保护的农业生产方式,具有典型的正外部性。发达国家通过生态补偿措施来激励农民采取环境友好型农业生产方式,政策措施实用且有效,推动了可持续农业的快速发展。系统综述了国内外开展环境友好型农业生态补偿的实践及其效果,并基于我国在保护性耕作、测土配方施肥、土壤有机质提升、生态农业和生态标记等方面的生态补偿实践,指出了制约我国环境友好型农业生态补偿发挥更积极作用的主要因素是补偿金额、补偿期限和补偿方式。同时,通过借鉴国外发达国家的经验,提出了建立环境友好型农业技术清单等政策建议,对于加快我国环境友好型农业生态补偿进程具有重要的意义。     

Conservation tillage

Conservation production systems combine tillage and planting practices to reduce soil erosion and loss of water from farmland. Successful conservation tillage practices depend on the ability of farm managers to integrate sound crop production practices with effective pest management systems. More scientific information is needed to determine the relations between tillage practices and physical, chemical, and biological soil factors that affect plant and pest ecology. There is a need to devise improved pest management strategies for conservation tillage and to better understand the impact of conservation tillage on water-quality, especially as it is related to use of agricultural chemicals. While savings in fuel, labor, and soil have induced many farmers to adopt conservation tillage, improved methods and equipment should increase adoption even more.     

中国保护性耕作研究分析-保护性耕作与作物生产

 保护性耕作（conservation tillage，CT）是实现农业可持续发展的重要手段，本研究通过收集中国公开发表的与保护性耕作相关的研究论文，整理前人研究提供的试验数据，分析保护性耕作措施对作物生产的影响，为保护性耕作条件下的作物稳产丰产研究提供支持。研究发现，保护性耕作对作物的生长发育、病虫害发生、水分利用等都有不同程度的影响，以当地传统耕作模式为对照，实施保护性耕作技术的作物产量平均增加12.51%。但有10.92%数据显示减产，表明保护性耕作减产是客观存在的，文章归纳了影响保护性耕作条件下作物产量的主要原因。中国自“六五”期间开始进行保护性耕作的研究工作，在理论研究和生产实践中取得了一定的成绩。随着对保护性耕作概念的深入理解，中国保护性耕作的研究和应用工作得到了长足发展，作为实践性较强的应用型研究，保护性耕作要充分重视理论研究和应用过程中存在的问题，利用新型研究技术和研究手段，明确保护性耕作影响作物生产的机制，为保护性耕作技术的创新和推广应用提供理论基础。     

保护性耕作研究现状、发展趋势及对策

借鉴国外保护性耕作的概念，根据具体情况，提出了我国保护性耕作的概念。在此基础上，将保护性耕作划分为3种类型，并详细阐述了保护性耕作是通过“少动土”、“少裸露”保持“适度湿润”和“适度粗糙”等土壤状态，达到保土、培肥、节水、增产、增效。系统地总结了国际保护性耕作技术发展的历程，提出了未来国际的发展趋势，并结合我国的实际情况，论述了我国保护性耕作存在的区域匹配差、规范性差、配套技术落后等问题，提出要正确认识保护性耕作，加强联合攻关等发展保护性耕作的对策和建议。     

土壤保持耕作——全球农业可持续发展优先领域

 从农业活动对全球变化以及对农业可持续发展的影响进而导致全球性土壤保持需求的迫切性增加出发，追踪了国外土壤保持耕作领域的研究和发展动态；对中国该领域研究发展现状和研究水平，从时间、深度、方法、生产应用等方面与国外进行了比较分析。中国是一个水土流失和耕地退化严重的农业大国，而从全球统计数字来看，中国土壤保持耕作面积目前仅占全球保持耕作面积的0.2%，仅占全国耕地面积的0.1%， 其现状与中国耕地资源和环境的继续退化以及对土壤保持耕作需求的增加极不相符。加强中国土壤保持耕作系统研究和土壤保持耕作"节能固碳"长期建设不仅对中国而且对全球变化及农业可持续发展具有重大意义。鉴于中国土壤保持耕作领域研究和发展所存在的不足和所面临的更大挑战，以及该领域研究涉及到复杂的农业系统"耕作管理-生物过程-环境变化"相互作用及其系统能流-碳流循环过程，尤其农业生态系统碳汇/源估量尚存在诸多不确定性因素等科学问题，有必要运用综合的系统性研究分析方法，借助国外长期试验和理论研究经验，以及系统模型模拟研究手段等多学科和交叉学科知识，加速提升中国土壤保持耕作领域的科研实力和水平，为实现碳汇/源科学调控管理、减缓农业对温室效应贡献、促进农业可持续发展提供科学依据。     

华北平原一年两熟区保护性耕作技术研究进展

冬小麦-夏玉米一年两熟的种植方式在华北平原区的农业生产中占有极为重要的地位,但传统耕作方式使该区的农业生产不可持续。保护性耕作是一种先进的保水保土的生产技术,对该区的农业可持续发展作用甚大。阐述了保护性耕作的定义、原理及保护性耕作的历史与发展,归纳总结了保护性耕作对播种、出苗、田间杂草、作物生长发育及作物产量等方面的影响研究。以期为华北平原一年两熟区的保护性耕作研究提供一定的参考。     

保护性耕作对土壤团聚体、微生物及线虫群落的影响研究进展

保护性耕作具有良好的生态效益，有利于农业生态系统的可持续发展。本文对比分析了国内外有关常规耕作和保护性耕作措施对土壤团聚体、土壤有机碳、土壤微生物及土壤线虫影响的研究进展。结果表明：保护性耕作减少土壤大团聚体的破坏，降低团聚体周转速率，提高土壤结构的稳定性；保护性耕作提高表层土壤总有机碳及活性有机碳含量；保护性耕作可以提高耕层微生物生物量，尤其对真菌生物量影响显著；保护性耕作不同程度地提高了团聚体中微生物量和微生物多样性，但并未改变微生物在团聚体中的分布模式；保护性耕作可提高土壤线虫多度，提高原状土壤和土壤各粒级团聚体中线虫群落的成熟度指数和结构指数，但并未改变线虫总数、营养类群、功能团及生态指数在团聚体中的分布模式。针对目前国内外研究现状，展望了保护性耕作今后的研究重点，以期为因地制宜选取保护性耕作措施提供理论支持，推进我国农业可持续发展。     

Influence of preceding crop and tillage system on forage yield and quality of selected summer grass and legume forage crops under arid conditions

Among the crop production factors, preceding crop and tillage management affect the sustainable use of soil resources and ultimately crop growth and productivity. This study aimed at investigating the impact of preceding winter crops (grass or legume) and different tillage systems on forage yield, quality and nutritive values of three summer grass (Sudan grass, pearl millet and teosinte) and two legume forage crops (cowpea and guar) under arid conditions. The results exhibited that growing forage crops after legumes (as berseem clover) produced the highest fresh and dry forage yields and quality attributes compared with grasses (as wheat) with the exception of crude fiber content, which was decreased. Moreover, tillage practices showed positive impact on forage yields and quality attributes. The maximum forage yields and quality parameters were recorded under conventional tillage (CT) practice compared with reduced tillage (RT) and no-tillage (NT) systems. Among the evaluated crops, the highest yields of fresh forage, dry forage, crude fiber, crude protein and total digestible nutrient were exhibited by grass forage crops (Sudan grass, pearl millet and teosinte), whereas the highest crude protein content and the digestible energy values were produced by legume forage crops (cowpea and guar). The maximum fresh forage, dry forage, crude fiber, crude protein, total digestible nutrient and digestible crude protein yields were produced by pearl millet followed by Sudan grass under CT and RT after berseem clover. The highest net return was recorded by sowing pearl millet after berseem clover and applying CT followed by RT practices, which could be recommended for the commercial production. Moreover, it could be assumed that the combination of growing grass forage crops after legume crops under CT or RT systems could enhance forage crop yield and quality with an improvement in soil properties for sustainable agriculture with low cost and the highest net income.     

黄土高原不同耕作方式对土壤理化性质及作物产量的影响

黄土高原属干旱、半干旱雨养农业区,过去以传统耕作方式为主。作物秸秆不还田以及对耕地直接进行翻耕,导致耕地表土裸露,因而加快了土壤有机质的矿化速率。土壤侵蚀、土壤养分流失、耕地质量下降,为此,以保护环境、提高水肥资源高效利用和实现农业可持续发展为目的保护性耕作在该地区逐渐展开。比较分析深松、免耕、传统翻耕等不同耕作方式对土壤理化性质、作物产量的影响,以期为该区域创建合理有效的耕作方式提供理论指导。     

免耕播种与深耕播种对小麦产量影响研究

保护性耕作技术就是按照农作物栽培要求,采取少耕或免耕方法,利用作物秸秆及残茬覆盖保护土壤,保护农业生态环境,实现农业可持续发展的技术体系。     

东北地区保护性耕作对土壤及作物生长的影响

阐述了保护性耕作的重要性,深入研究了保护性耕作对土壤、作物生长发育及病虫害的影响,旨在形成适合东北地区的保护性耕作技术模式,推进东北地区的农业向持续高效的方向发展。     

Soil conservation in Cuba: A key to the new model for agriculture

Most aspects of agriculture in Cuba prior to 1989 were comparable to California: a high energy input, conventional agriculture (based on what the Cubans now call the “classical model”) in which little was done to protect the nation's soils from erosion, loss of fertility, salinization, and other forms of degradation. In stark contrast the new “Alternative Model,” which has been rapidly replacing the previous model since 1989, emphasizes soil conservation and rehabilitation and the general improvement of the nation's soils as the key to sustaining low-input production and attainment of food security. One of the first steps in implementing the new model was the launching of an ambitious program to reclassify, evaluate, and map the nation's soils in great detail, and to interpret the maps for management of sustainable production. A main feature of this program is coordinated fertility trials to determine, for each combination of crop and soil, the minimum quantity of plant nutrients needed to produce the crop. The build up and maintenance of soil fertility and productivity is being accomplished with various organic and mineral amendments and biofertilizers, produced or mined within the country (locally, where possible) and through rational management utilizing cover crops, green manures, crop successions (intercropping and rotations), and other appropriate technologies. Rehabilitation of degraded soils, tillage reduction, reforestation, vermiculture, vermicomposting, and other forms of waste cycling are other features of the new model that are important to soil conservation and maintenance for sustainable production.     

Improved crop protection and biodiversity of the agroecosystem by reduced tillage in rice paddy fields in southern China

Agricultural sustainability has benefited from the broad adoption of conservation agriculture (CA) practices for decades, in which the reduction of mechanical disturbances to soil (also known as reduced tillage, RT) is one of the most essential principles for CA implementation. Many studies have recommended the advantages of CA practices in the promotion of biodiversity, but the integrated impacts on crop productivity and biodiversity remain unclear. Since CA has been applied in rice production in the subtropical area of southern China for several years, the effects of CA, particularly the RT methods, need to be evaluated for the local and long-term adoption. In this study, we established an integrated network to illustrate how the reduction of tillage intensity influenced organisms including invertebrates (such as rice pests and their predators), pathogens and weeds, and then led to an impact on rice yield. The two-year study demonstrated that major rice pests, such as rice planthoppers, stem borers and apple snails, were effectively controlled by RT practice. Similarly, the occurrence of common diseases declined with less tillage. Compared to the conventional tillage (CT) treatment, the density of weeds in paddy fields deceased significantly in the RT treatment. In addition, the diversity and richness of pest predators increased remarkably in paddy fields where either reduced or no tillage was applied, which highlighted the significance of a CA strategy for the promotion of biodiversity in the agroecosystem. More importantly, the rice yield gradually increased after the two-year reduction of tillage. Taken together, our results suggest that the reduction of tillage intensity is beneficial for the protection of rice crops from various pests, and facilitates the sustainability of the agroecosystem and rice yield, which provides a solid basis and novel insights for the establishment of sustainable agroecosystems by CA-related practices in rice production in southern China.     

Possible adoption of precision agriculture for developing countries at the threshold of the new millennium

The concept of precision agriculture, based on information technology, is becoming an attractive idea for managing natural resources and realizing modern sustainable agricultural development. It is bringing agriculture into the digital and information age. The practice has smoothly extended into some developing countries. The basic principle of managing soil and crop variability within a field is certainly not new. It was named ‘intensive and meticulous cultivation’ by the Chinese people and has been long regarded as the cream of Chinese conventional agriculture. Toward the new millennium, China is preparing to follow the experience of the developed world and is starting to investigate the new technology. This paper considers the possible adoption of precision agriculture for developing countries and ideas in conducting the practice in China.     

农业机械化与可持续发展初探

笔者通过从农业可持续发展中存在的问题,提出农业机械化对于农业可持续发展的作用,以及保护性耕作、节水农业技术的应用等农业生产环节与农业可持续发展的关系。     

中国保护性耕作试验研究的产量效应分析

【目的】明确中国目前开展的保护性耕作研究的产量效应以及具体分布情况。【方法】收集公开发表的涉及保护性耕作的研究论文,对有关数据进行整理和分析。【结果】研究发现,中国保护性耕作研究具有明显的地域特色：少耕研究集中在东北地区,免耕研究集中在长江下游及东南地区,秸秆处理和综合型措施的研究以西北地区最多。中国保护性耕作的产量研究结果多为增产,但也有10.92%的减产数据见诸于各地的报道,其中黄淮海、华北平原、西北内陆、青藏高原、黄土高原区的减产概率比较高;少耕和免耕处理的减产概率较高;小麦减产概率最高,玉米减产概率最小。不同区域、不同作物对保护性耕作措施的反应不同：小麦在黄淮海、华北平原及西北地区的减产发生频率较高,少耕处理的减产概率最大,但在西南地区的稳产性能较好;水稻在西南地区减产概率高,在长江中下游和东南地区的稳产性能较好,秸秆处理减产概率高,而免耕稳产性能较好。少、免耕和秸秆处理相结合的综合型保护性耕作措施减产概率很低,且在所有区域对所有作物的表现相同,值得重点研究。【结论】保护性耕作是实现农业可持续发展的重要手段,但保护性耕作措施的选择应因地制宜,根据生产条件采用最具生产价值的耕作模式。本研究的结果能够为我国保护性耕作的稳产丰产研究和推广应用提供指导。     

发展机械化保护性耕作实现农业的可持续发展

农业可持续发展是中国农业发展的重大课题,保持农业的可持续发展是农业产业结构调整的首要问题,保护性耕作是实现农业可持续发展和环境保护的重要措施。“改革传统耕作方法,发展保护性耕作技术,对于改善农业生产条件和生态环境具有重要意义”。     

Procedures of soil farming allowing reduction of compaction

Evaluation of new technologies using guidance systems is very important and can help producers with choosing the right equipment for their applications. Without using satellite navigation during field operations, there is a tendency for passes to overlap. That results in waste of fuel and pesticides, longer working times and also environmental damage. When utilising satellite guidance for field operations, there is a close connection with controlled traffic farming (CTF) as well. CTF is currently a quite quickly developing farming system based on fixed layout of machinery passes across a field. Tracks precisely set out for a machine’s tyres in the field could be a tool for minimising soil compaction risk which is another threat to the environment. The purpose of this paper was to evaluate the accuracy of currently available guidance systems for agricultural machines. Real pass-to-pass errors (omissions and overlaps) in a field were measured. Consequently, comparison between observed guidance systems was made regarding final working accuracy. Further, intensity of machinery passes, percentage of wheeled area and repeated passes in fields were monitored. These measurements were made in fields under real operating conditions using a conventional tillage system with ploughing and also a conservation tillage system, both systems with randomly organized traffic. Finally, the same parameters were monitored in fields where fixed machinery tracks were used for all operations and passes but only under a conservation tillage system. Pass-to-pass accuracy was measured for the evaluation of different guidance systems. Size of missed areas or overlaps was evaluated statistically. Concerning intensity of machinery passes and total field area affected by machinery passes, the following facts were found out. The experiments with randomized traffic showed a significant difference of the parameters mentioned above between a conventional tillage system with ploughing and a conservation tillage system. Wheeled area was 86 and 64%, respectively which proves benefits of conservation tillage. The experiments with a fixed track system showed that the total run-over area by machinery tyres decreased even more (up to 31%) in comparison to randomized traffic in a field (only fields under conservation tillage system were monitored and evaluated). The following statements based on our results can be made. The navigation and therefore possibility for better accuracy of machinery passes in fields together with permanent machinery tracks utilization could help with soil condition improvement and also energy savings which would result from that. The CTF system will help with further development of a system for soil compaction protection which is currently a real necessity.     

Climate change adaptation,greenhouse gas mitigation and economic profitability of conservation agriculture: Some examples from cereal systems of Indo-Gangetic Plains

Achieving sustainability of the cereal system in the Indo-Gangetic Plains(IGP)of India under progressive climate change and variability necessitates adoption of practices and technologies that increase food production,adaptation and mitigation in a sustainable way.This paper examines conservation agriculture(CA)from the perspective of:(i)increased yield and farm income,(ii)adaptation to heat and water stresses,and(iii)reduction in greenhouse gas(GHGs)emissions.The analyses and conclusions are based on the literature and evidences from a large number of on-station as well as farmers’field trials on CA in the cereal systems of IGP.Our analyses show that CA-based system substantially reduces the production cost(up to 23%)but produces equal or even higher than conventional system;thereby increasing economic profitability of production system.CA-based production systems also moderated the effect of high temperature(reduced canopy temperature by 1–4°C)and increased irrigation water productivity by 66–100%compared to traditional production systems thus well adapting to water and heat stress situations of IGP.Our continuous monitoring of soil flux of CO2,N2O and CH4 revealed that CA-based rice-wheat systems emit 10–15%less GHGs than conventional systems.This is the first time that CA and its components are synthesized and analyzed from food security-climate change nexus.From this holistic analysis,we suggest that wide-scale promotion of suitable CA practices by integrating into national agriculture development strategy is a way forward to address food security,climate change adaptation and mitigation challenges faced by present agriculture.