Alternative tillage and rice establishment options should aim at less water and labor to produce similar or improved yields compared with traditional puddled-transplanted rice cultivation. The relative performance of these practices in terms of yield, water input, and economics varies across rice-growing regions. A global meta and mixed model analysis was performed, using a dataset involving 323 on-station and 9 on-farm studies (a total of 3878 paired data), to evaluate the yield, water input, greenhouse gas emissions, and cost and net return with five major tillage/crop establishment options. Shifting from transplanting to direct-seeding was advantageous but the change from conventional to zero or reduced tillage reduced yields. Direct-seeded rice under wet tillage was the best alternative with yield advantages of 1.3–4.7% (p < 0.05) and higher net economic return of 13% (p < 0.05), accompanied by savings of water by 15% (p < 0.05) and a reduction in cost by 2.4–8.8%. Direct-seeding under zero tillage was another potential alternative with high savings in water input and cost of cultivation, with no yield penalty. The alternative practices reduced methane emissions but increased nitrous oxide emissions. Soil texture plays a key role in relative yield advantages, and therefore refinement of the practice to suit a specific agro-ecosystem is needed.

outh Asian agriculture is a global 'hotspot' for contemporary and future climate vulnerability. Further, 1.7 billion people live in South Asia, and by 2050, that number is expected to rise to 2.4 billion. Although the region enjoys high economic growth, it suffers from extreme poverty, undernourishment and the deterioration of natural resources 1 . South Asia has more than 42% of the world's poor (earning less than US$1.90 per day), about 21% of the population is undernourished, and more than 41% of children are underweight 2 . Rapid population growth will increase the demand for cereals by about 43% between 2010 and 2050. Meeting this projected need is doubly challenging considering 94% of the land suitable for farming is already in production and 58% of agricultural areas face multiple climatic hazards such as water shortage and extreme heat stress 3 . The present situation is anticipated to worsen with climate change, with rising temperatures and changing monsoon rainfall patterns projected to cost India 2.8% of gross domestic product 4 . Although global crop productivity has more than doubled during the past decades, negative impacts on environment, biodiversity, soil quality and air quality are common 5,6 .Future food production in South Asia requires new management approaches that are efficient and climate smart to make tangible contributions to the United Nations' Sustainable Development Goals (SDGs). Conservation agriculture (CA) has emerged as an alternative to an inefficient tillage-based conventional agriculture. CA is an ecosystem approach to regenerative sustainable agriculture and land management based on three interlinked principles: (1) continuous no or minimum mechanical soil disturbance, (2) permanent maintenance of soil mulch (crop biomass and cover crops) and (3) diversification of cropping system (economically, environmentally and socially adapted rotations including legumes and cover crops), along with other complementary good agricultural production and land management practices 7 . CA helps in managing agroecosystems for improved and sustained productivity, increased profits and food

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Food security involves the sustainable utilization of soil and land resources. Zero‐tillage (ZT) practice is a proponent of better resource utilization, to improve soil physical condition, and a potential sink to atmospheric carbon. However, the impact varies across climates, over the ZT history, cropping systems, and soil depths. A meta‐analysis was performed, based on 4,131 paired data from 522 studies spread globally, to evaluate the effect of ZT in comparison to conventional tillage, on soil physical condition (bulk density; mean weight diameter of aggregates; field capacity water content; and steady‐state infiltration rate), soil organic carbon (SOC) content, and the root response (root length density). Zero‐tillage significantly improved mean weight diameter of aggregates and field capacity water content at surface and subsurface layers by 19–58% and 6–16%, respectively, and resulted in no change in bulk density in either of the layers, but infiltration rate increased by 66%. Surface 0‐ to 5‐ and 5‐ to 10‐cm layers had significantly higher SOC content under ZT, whereas in other layers, the SOC content either reduced or did not change, resulting in a small and insignificant variation in the SOC stock (~1.1%) in favor of ZT. The root length density improved by ~35% in ZT only at 0‐ to 5‐cm soil depth. Effect of climate, soil type, or cropping system could not be broadly recognized, but the impact of ZT certainly increased over time. Improvements in soil aggregation and hydraulic properties are highly convincing with the adoption of ZT, and therefore, this practice leads to the better and sustainable use of soil resources.

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