Abstract Of late, intensive farming for higher food production is often associated with many negative implications for soil systems, such as decline of soil organic matter (SOM), increase in risks of soil erosion by wind and/or water, decline in soil biological diversity, increase in degradation of soil physical quality, lower nutrient-use efficiency, high risks of groundwater pollution, falling water tables, increasing salinization and waterlogging, in-field burning of crop residues, pollution of air and emission of greenhouse gases (GHG), leading to global warming, and decline in factor productivity. These negative implications necessitate an objective review of strategies to develop sustainable management practices, which could not only sustain soil health and ensure food security, but also enhance carbon sequestration, decrease GHG emissions, and offer clean and better ecosystem services. Conservation agriculture (CA), that includes reduced or no-till practices along with crop residue retention and mixed crop rotations, offers multiple benefits. Adoption of a system-based CA conserves water, improves and creates more efficient use of natural resources through the integrated management of available soil nutrients, water, and biological resources, and enhances use efficiency of external inputs. Due to apparent benefits of CA, it is increasingly being adopted and now covers about 180 million hectares (Mha) worldwide. However, in South Asia its spread is low (<5 Mha), mostly concentrated in the Indo-Gangetic Plains (IGP). In this region, one of the serious issues is “residue burning” with severe environmental impacts. A huge amount of crop residue left over after the combine harvest of rice has forced farmers to practice widespread residue burning (∼140 M tonnes) to cope with excessive stubble and also for timely planting/sowing of succeeding crops. In rice-wheat cropping systems, which cover more than 10 Mha in the IGP, CA practices are relatively more accepted by farmers. In these systems, any delay in sowing leads to yield penalty of 1–1.5% per day after the optimum sowing date of wheat. The strong adoption of CA practices in IGP is mainly to overcome delayed sowing due to the field preparation and control of weeds, timely planting, and also escape from terminal heat during the grain-filling stage. Major challenges to CA adoption in South Asia are small land holdings (<1 ha), low technological reach to farmers, nonavailability of suitable farm implements for small farm holders, and the staunch conventional farming mind-set. South Asia region consists of many countries of diverse agro-ecologies with contrasting farming systems and management. This region, recently known for rapid economic growth and increasing population, necessitates higher food production and also hot-spots for adoption of CA technologies. Therefore, in this review critically explores the possibility, extent of area, prospects, challenges, and benefits of CA in South Asia. HIGHLIGHTS Conservation agriculture (CA), consisting of reduced or no-tillage and crop residue retention, is a self–sustainable system which offers an alternative to crop residue burning. The CA approach improves soil health by increasing soil organic carbon (SOC) and aggregation and also conserves soil, water and energy than conventional farming systems. South Asian countries are suitable for adoption of CA practices but the area under CA remains low (<5 Mha) as compared to the global area (180 Mha). Adoption of CA in South Asia has skewed distribution, mainly in Indo-Gangetic Plains (IGP) in India, Pakistan, Nepal and Bangladesh in South Asia. Development of herbicide-resistant weed species and weed shift by continuous application of herbicides are the major challenges in adoption of CA. The traditional-farming mind-set, socio-economic conditions, small farm-holdings, weed and residue management, and non-availability of suitable machinery are key constraints to the low adoption of CA practices in South Asia.

中文翻译：

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南亚免耕农业和保护性农业——问题、挑战、前景和收益

摘要 最近，为提高粮食产量而进行的集约化耕作通常会对土壤系统产生许多负面影响，例如土壤有机质 (SOM) 减少、风和/或水侵蚀土壤的风险增加、土壤生物多样性下降。 , 土壤物理质量退化加剧、养分利用效率降低、地下水污染风险高、地下水位下降、盐渍化和内涝加剧、作物残留物的田间燃烧、空气污染和温室气体排放，导致全球变暖，要素生产率下降。这些负面影响需要对制定可持续管理做法的战略进行客观审查，这不仅可以维持土壤健康和确保粮食安全，还可以加强碳固存，减少温室气体排放，并提供清洁和更好的生态系统服务。保护性农业 (CA) 包括减少耕作或免耕做法以及作物残留物保留和混合作物轮作，可提供多种好处。采用基于系统的 CA 可以节约用水，通过对可用土壤养分、水和生物资源的综合管理来改善和提高自然资源的利用效率，并提高外部投入的利用效率。由于 CA 的明显优势，它越来越多地被采用，现在全球覆盖约 1.8 亿公顷 (Mha)。然而，在南亚，它的传播范围很小（<5 Mha），主要集中在印度恒河平原（IGP）。在该地区，严重的问题之一是对环境造成严重影响的“残渣焚烧”。水稻联合收割后剩余的大量作物残茬迫使农民进行广泛的残茬焚烧（约 1.4 亿吨），以应对过多的残茬，并及时种植/播种后茬作物。在 IGP 中覆盖超过 10 Mha 的稻麦种植系统中，CA 做法相对更被农民接受。在这些系统中，播种的任何延迟都会导致在小麦最佳播种日期之后每天减产 1-1.5%。在 IGP 中大力采用 CA 做法主要是为了克服由于田间准备和控制杂草、及时播种以及在灌浆阶段逃避末期热量而导致的延迟播种。南亚采用 CA 的主要挑战是土地面积小（<1 公顷）、农民的技术覆盖率低、小农场主没有合适的农具，以及坚定的传统农业心态。南亚地区由许多农业生态不同的国家组成，农业系统和管理各不相同。该地区最近以经济快速增长和人口增长而闻名，需要更高的粮食产量，也是采用 CA 技术的热点。因此，在这篇综述中，批判性地探讨了 CA 在南亚的可能性、范围、前景、挑战和好处。亮点 保护性农业 (CA) 包括减耕或免耕和作物残留物保留，是一种自我可持续的系统，可替代作物残留物燃烧。CA 方法通过增加土壤有机碳 (SOC) 和聚集来改善土壤健康并保护土壤，与传统农业系统相比，水和能源。南亚国家适合采用 CA 实践，但与全球面积（180 Mha）相比，CA 下的面积仍然很低（<5 Mha）。南亚采用 CA 的分布偏斜，主要是在南亚的印度、巴基斯坦、尼泊尔和孟加拉国的印度恒河平原 (IGP)。开发抗除草剂的杂草品种和持续使用除草剂导致的杂草转移是采用 CA 的主要挑战。传统农业观念、社会经济条件、小农场经营、杂草和残留物管理以及合适机械的不可用是南亚采用 CA 做法的关键制约因素。南亚国家适合采用 CA 实践，但与全球面积（180 Mha）相比，CA 下的面积仍然很低（<5 Mha）。南亚采用 CA 的分布偏斜，主要是在南亚的印度、巴基斯坦、尼泊尔和孟加拉国的印度恒河平原 (IGP)。开发抗除草剂的杂草品种和持续使用除草剂导致的杂草转移是采用 CA 的主要挑战。传统农业观念、社会经济条件、小农场经营、杂草和残留物管理以及合适机械的不可用是南亚采用 CA 做法的关键制约因素。南亚国家适合采用 CA 实践，但与全球面积（180 Mha）相比，CA 下的面积仍然很低（<5 Mha）。南亚采用 CA 的分布偏斜，主要是在南亚的印度、巴基斯坦、尼泊尔和孟加拉国的印度恒河平原 (IGP)。开发抗除草剂的杂草品种和持续使用除草剂导致的杂草转移是采用 CA 的主要挑战。传统农业观念、社会经济条件、小农场经营、杂草和残留物管理以及合适机械的不可用是南亚采用 CA 做法的关键制约因素。南亚的尼泊尔和孟加拉国。开发抗除草剂的杂草品种和持续使用除草剂导致的杂草转移是采用 CA 的主要挑战。传统农业观念、社会经济条件、小农场经营、杂草和残留物管理以及合适机械的不可用是南亚采用 CA 做法的关键制约因素。南亚的尼泊尔和孟加拉国。开发抗除草剂的杂草品种和持续使用除草剂导致的杂草转移是采用 CA 的主要挑战。传统农业观念、社会经济条件、小农场经营、杂草和残留物管理以及没有合适的机械是南亚采用 CA 做法的关键制约因素。