Powlson et al. reply-In our recent Perspective 1 , we concluded that no-till agriculture offered ... more Powlson et al. reply-In our recent Perspective 1 , we concluded that no-till agriculture offered only limited potential for mitigating climate change through soil carbon (C) sequestration, in contrast to the claims made in the agriculture chapter of the 2013 UNEP Emissions Gap Report 2. The authors of the UNEP report disagree with our conclusion and we are happy to respond to their comments 3. They are correct that we concentrated totally on no-till rather than other agricultural practices as a means of mitigating climate change. This was deliberate because current uptake of notill-and its probable rate of adoption in the medium term-is far greater than for the other practices mentioned, such as agroforestry and biochar applications to soil. And we have no disagreement with their comments on climate change mitigation through improved water and nutrient management and reduced use of fossil fuels-in fact, alterations to water and nutrient management are probably the most effective approaches in all agricultural systems, not only rice production. We agree with Neufeldt et al. 3 that estimating soil C accumulation following adoption of no-till using a 'bottom-up' approach is, in principle, preferable to the 'top-down' method we used. In their Correspondence, Neufeldt et al. 3 accomplish bottom-up estimations of avoided emissions for specific countries by multiplying the area under no-till by a climate-relevant value for the annual rate of increase in soil organic C under the practice. They acknowledge the considerable uncertainty in rates of accumulation under no-till: for example, their estimate for Australia ranges from over 400 MtCO 2 e saved from past notill adoption to additional emissions of over 200 MtCO 2 e compared with conventional cultivation 3. In the face of such uncertainty the strong promotion of no-till as an effective means of climate change mitigation in the UNEP Emissions Gap Report 2 looks distinctly unjustified.
In water scarce regions of South Asia, diversification of rice with maize is being advocated towa... more In water scarce regions of South Asia, diversification of rice with maize is being advocated towards sustainability of cereal-based cropping systems. Adoption of innovative agronomic management practices, i.e., conservation agriculture (CA) and sub-surface drip irrigation (SSDI) are considered as key strategies for much needed interventions to address the challenges of water scarcity under projected climate change. Benefits from CA and SSDI concerning water economy are well-established, however, information about their complementarity and water budgeting in cereal-based systems are lacking. A field study was conducted with process-based model (HYDRUS-2D) to understand water transport, root water uptake and components of soil water balance in maize grown in rotation with wheat after five years of continuous adoption of conservation agriculture. In this study, altogether eight treatments comprising of 6 CA+ treatments (CA coupled with SSDI); permanent beds using sub-surface drip (PB-S...
Abstract The crucial link between agricultural growth and the Sustainable Development Goals (SDGs... more Abstract The crucial link between agricultural growth and the Sustainable Development Goals (SDGs) set by the United Nations Development Programme is established through efficient use of nitrogen in the cereal production systems. Nitrogen, mostly in its reactive form as fertilizer or synthetic N, governs the food production, and reconciles the productivity with economic and environmental considerations. However, N flows in the production system involves a large N leaking to the environment resulting in abysmally low nitrogen use efficiencies and environmental adversity. Agricultural system with sub-optimal N application is characterized with low crop productivity, spiraling into the vicious cycle of poverty, malnutrition and poor economy, a case most common in the sub-Saharan Africa. These essentially relate to SDG 1 (no-poverty), 2 (zero-hunger), 3 (good health and well-being), 8 (decent work and economic growth) and 15 (life on land). Excess or imbalanced fertilizer N in most of China and parts of India led to serious environmental hazards, degradation of land and economic loss. Balancing the amount of N input in these regions will contribute in achieving the SDG 13 (climate action). Meeting some of the SDGs (5, gender equality; 6, clean water and sanitation; 10: reduced inequalities; etc.) requires optimum N application, which will also ensure “responsible consumption and production” (SDG 12). The quest for an appropriate N management needs accounting for the N surplus in a production system, and evolving strategies for increasing the nitrogen use efficiency. Much effort has been made to this effect with varying success. Cutting-edge technological options are although available on the horizon, the success lies in improved awareness among the policy makers, stakeholders and farmers, and better research to quantify the linkage between N management and the SDGs, taking collectively.
A study was conducted to design productive, profitable, irrigation water¸ nitrogen and energy use... more A study was conducted to design productive, profitable, irrigation water¸ nitrogen and energy use efficient intensive cereal systems (rice-wheat; RW and maize-wheat; MW) in North-West India. Bundling of conservation agriculture (CA) with sub-surface drip irrigation termed as CA+ were compared with CA alone and conventional tillage based and flood irrigated RW rotation (farmer’s practice; ScI). In contrast to conventional till RW rotation which consumed 1889 mm ha−1 irrigation water (2-yr mean), CA+ system saved 58.4 and 95.5% irrigation water in RW and MW rotations, respectively. CA+ practices saved 45.8 and 22.7% of irrigation water in rice and maize, respectively compared to CA with flood irrigation. On a system basis, CA+ practices saved 46.7 and 44.7% irrigation water under RW (ScV) and MW (ScVI) systems compared to their respective CA-based systems with flood irrigation (ScIII and ScIV). CA+ in RW system recorded 11.2% higher crop productivity and improved irrigation water prod...
The Emissions Gap Report 2013 from the United Nations Environment Programme restates the claim th... more The Emissions Gap Report 2013 from the United Nations Environment Programme restates the claim that changing to no-till practices in agriculture, as an alternative to conventional tillage, causes an accumulation of organic carbon in soil, thus mitigating climate change through carbon sequestration. But these claims ignore a large body of experimental evidence showing that the quantity of additional organic carbon in soil under no-till is relatively small: in large part apparent increases result from an altered depth distribution. The larger concentration near the surface in no-till is generally beneficial for soil properties that often, though not always, translate into improved crop growth. In many regions where no-till is practised it is common for soil to be cultivated conventionally every few years for a range of agronomic reasons, so any soil carbon benefit is then lost. We argue that no-till is beneficial for soil quality and adaptation of agriculture to climate change, but its role in mitigation is widely overstated. agriculture. If, as we maintain, the contribution through promoting no-till practices is substantially less than claimed, there is even more pressure to deliver mitigation through other approachesboth in agriculture and in other sectors.
outh Asian agriculture is a global 'hotspot' for contemporary and future climate vulnerability. F... more 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 security while preserving and enhancing the resource base and the environment. It is estimated that a partial CA-based system (at least one crop has no till, with or without residue retention) is spread to over 2.5 million ha in South Asia (M.L. Jat, personal communication). Numerous favourable impacts have been reported in the global literature on CA, including for crop yields, resource (labour, water, energy) use efficiencies, timeliness of cropping practices, soil quality and ecosystem services 8-13. Nevertheless, a meta-analysis of global yield data from 48 crops across 63 countries reported limited yield gains with full CA or with some components of CA 14 , a result that has drawn into question the wisdom of making CA a sustainable intensification priority for agricultural development programs. Although the benefits derived from CA have been broadly questioned, there has been gradual increase in adoption of CA over time. Zero-tillage (ZT) wheat has been adopted on a significant area in the rice-wheat system of the northwestern Indo-Gangetic Plains 15 and in the Eastern Gangetic Plain 16 with positive impacts on wheat yield, profitability and resource-use efficiencies 17,18. The national governments in South Asia are actively promoting CA to address sustainability problems. Although numerous on-station and on-farm studies have been carried out during the past two decades to evaluate CA in South Asia, a systematic synthesis of evidence is lacking. To clarify the regional potential of CA as a full package or combination of its components in South Asia, this study presents a comprehensive meta-analysis on data from on-station (1996-2016) and on-farm (2010-2014) studies in South Asia's dominant cereal-based cropping systems. Performance parameters considered in the analyses included (1) grain yield, (2) protein-equivalent yield (PEY), (3) water use efficiency, (4) cost of cultivation and net economic return, and (5) emission of GHGs (methane and nitrous oxide) and global warming potential (GWP). Results are contrasted with conventional best practices and contextualized with respect to
To contain the COVID-19 pandemic, India imposed a national lockdown at the end of March 2020, a d... more To contain the COVID-19 pandemic, India imposed a national lockdown at the end of March 2020, a decision that resulted in a massive reverse migration as many workers across economic sectors returned to their home regions. Migrants provide the foundations of the agricultural workforce in the 'breadbasket' states of Punjab and Haryana in Northwest India.There are mounting concerns that near and potentially longer-term reductions in labor availability may jeopardize agricultural production and consequently national food security. The timing of rice transplanting at the beginning of the summer monsoon season has a cascading influence on productivity of the entire rice-wheat cropping system. To assess the potential for COVID-related reductions in the agriculture workforce to disrupt production of the dominant rice-wheat cropping pattern in these states, we use a spatial ex ante modelling framework to evaluate four scenarios representing a range of plausible labor constraints on the timing of rice transplanting. Averaged over both states, results suggest that rice productivity losses under all delay scenarios would be low as compare to those for wheat, with total system productivity loss estimates ranging from 9%, to 21%, equivalent to economic losses of USD $674 m to $1.48 billion. Late rice transplanting and harvesting can also aggravate winter air pollution with concomitant health risks. Technological options such as direct seeded rice, staggered nursery transplanting, and crop diversification away from rice can help address these challenges but require new approaches to policy and incentives for change.
The future of the South Asia's rice-wheat (RW) production system is at stake due to continuously ... more The future of the South Asia's rice-wheat (RW) production system is at stake due to continuously depleting aquifers and increasing pressure on underground water under projected climate change scenario. Conventional management factors such as flood irrigation, intensive tillage and residue burning are threatening sustainability of RW system. With increasing adoption of conservation agriculture (CA), sub-surface drip fertigation (SSDF) provides an exceptional opportunity for complementing irrigation water saving benefits. Presently, there is no research evidence on optimum spacing and depth for drip laterals in a CA (direct drilling and residue mulch) based RW system around the globe. This study was therefore, planned to evaluate effects of residue mulch, different spacing and depths of laterals for SSDF on crop yield, irrigation water productivity (WPi), nitrogen use efficiency (NUE) and net returns for CA based RW system in a silt loam soil in northwestern India. Drip laterals were spaced either at 33.75 cm or 67.5 cm, and installation depths were 0, 15 or 20 cm beneath the soil surface and compared with conventional and zero tillage based flood-irrigated RW systems. Grain yield and irrigation water input in rice and wheat were generally similar under different SSDF treatments. Irrigation water savings were 48-53% in rice and 42-53% in wheat under combination of SSDF and CA compared to flood irrigation system. A similar trend in WPi was recorded in both the crops. Residue mulch contributed to higher irrigation water savings, wheat yield and WPi compared to no mulch. Both rice and wheat needed 20% less N fertilizer under SSDF system to obtain grain yields similar to that under flood irrigated crops. Net returns from SSDF system with 67.5 cm lateral spacing were significantly higher compared to flood irrigation system. In conclusion, SSDF system having laterals spaced at 67.5 cm and installed at 15 cm depth provides tangible benefits for substantial saving in irrigation water and energy and increasing NUE and net income for CA based RW system in South Asia.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Emerging evidence supports the intuitive link between chronic health conditions associated with a... more Emerging evidence supports the intuitive link between chronic health conditions associated with air pollution and the vulnerability of individuals and communities to COVID-19. Poor air quality already imposes a highly significant public health burden in Northwest India, with pollution levels spiking to hazardous levels in November and early December when rice crop residues are burned. The urgency of curtailing the COVID-19 pandemic and mitigating a potential resurgence later in the year provides even more justification for accelerating efforts to dramatically reduce open agricultural burning in India.
Food insecurity in the Sahelian environment was extensively shown to be a result of low soil fert... more Food insecurity in the Sahelian environment was extensively shown to be a result of low soil fertility and high climate risks. But decisions and recommendations made from the great wealth of research have little been adopted by farmers. Soil water crop models (SWCM) can assist researchers and development actors in this environment if they can appropriately deal with the constraints and mainly farmers' agricultural development goals. We reviewed the Sahelian agricultural constraints and farmer management practices with an emphasis on Niger and pearl millet. Significant results derived from research works to improve crop productivity are presented and analyzed with regard to the main agricultural constraints. Potential and currently used SWCMs are presented and compared for relevance for use in such a particular environment for decision support (DS). This shows that crop modeling in millet-based agricultural system of the Sahel should be addressed with an integrated approach that can handle the multiple and usually connected agricultural constraints of the region: low soil fertility and spatial variability, time and space rainfall variability. Recommendations were made regarding the relevant and minimum aspects that SWCM should take into account for a successful and reliable use for DS in the complex Sahelian environment.
ABSTRACT With the advent of Green Revolution era in the mid-1960s, high-yielding wheat (Triticum ... more ABSTRACT With the advent of Green Revolution era in the mid-1960s, high-yielding wheat (Triticum aestivum L.) varieties and chemical fertilizers were introduced in South Asia. Fertilizer consumption is continuously increasing since then, but the productivity of wheat is relatively stagnant during the last decade. In South Asia, fertilizers have been applied to wheat as blanket recommendations for regions with similar climate and landform. There exists a large variation in nutrient use efficiencies in wheat because of following blanket recommendations for nitrogen, phosphorus, and potassium in fields differing greatly in nutrient-supplying capacity of the soil. Research carried out in South Asia suggests that further improvement in nutrient use efficiency will become possible by balanced use of nitrogen, phosphorus, and potassium fertilizers, and by rational use of organic manures in wheat systems. Long-term fertility experiments also confirm the need of balanced use of nutrients to produce high sustainable yield levels of wheat. In saline alkali soils, wheat needs to be supplied with higher amounts of nutrients, particularly N, than in normal soils. Band placement of fertilizers, particularly phosphorus, leads to improved fertilizer use efficiency, but appropriate machinery is lacking. Recently introduced site-specific nutrient management strategies for wheat take into account field-to-field variability and can help increase fertilizer use efficiency more than that achieved by following blanket fertilizer recommendations. Conservation agricultural practices consisting of reduced tillage and residue retention in wheat fields have already been introduced in South Asia. Nutrient management strategies for these wheat-growing environments are also being actively worked out. Yield gap analysis shows that productivity of wheat as well as nutrient use efficiencies can be further improved.
Understanding the diversity of current states, life cycles and past trajectories of households an... more Understanding the diversity of current states, life cycles and past trajectories of households and agroecosystems is essential to contextualise the co-design of more sustainable agroecosystems. The objective of this paper was to document and analyse current states, trajectories of changes and their major drivers of households in a highly populated maize-based agroecosystem of Western Kenya. In 2013, we revisited 20 rural households that were surveyed, analysed and categorised 10 years ago (2003) in order to describe major changes in livelihood strategies, land use and soil fertility status. The household-level analysis was complemented with the analysis of secondary data on changes in drivers at the national level for the study period. The diachronic study showed a close association between drivers such as market and transport development, and the structure of rural households in terms of demographic shifts, land and labour exchanges, increased costs of agricultural inputs and better connectivity to markets. Between 2003 and 2013, the surveyed households experienced an increase in non-agricultural income by 30 %; intensity of land cultivation by 60 %; use of hybrid maize seeds by 35 %; and of synthetic fertilisers by almost 50 %. Local households increase their number of crossbred livestock in detriment of local breeds and used less manure to fertilise their soils. In contrast, there were few changes in terms of food self-sufficiency (around 9 months per year) and in soil conditions (soil fertility was already poor in 2003). In terms of livelihood strategies, betterendowed households tended to diversify and acquire land that enabled them to adapt and benefit from the major changes observed in external drivers. In contrast, more vulnerable households sold labour and land to cope with such changes, remaining in a poverty trap. Households combine and explore diverse strategies to act, cope and adapt to fast-changing local and regional drivers. Policy or development programmes need to account for such diversity and dynamics to support the co-development of more adaptive and sustainable smallholder agroecosystems.
Powlson et al. reply-In our recent Perspective 1 , we concluded that no-till agriculture offered ... more Powlson et al. reply-In our recent Perspective 1 , we concluded that no-till agriculture offered only limited potential for mitigating climate change through soil carbon (C) sequestration, in contrast to the claims made in the agriculture chapter of the 2013 UNEP Emissions Gap Report 2. The authors of the UNEP report disagree with our conclusion and we are happy to respond to their comments 3. They are correct that we concentrated totally on no-till rather than other agricultural practices as a means of mitigating climate change. This was deliberate because current uptake of notill-and its probable rate of adoption in the medium term-is far greater than for the other practices mentioned, such as agroforestry and biochar applications to soil. And we have no disagreement with their comments on climate change mitigation through improved water and nutrient management and reduced use of fossil fuels-in fact, alterations to water and nutrient management are probably the most effective approaches in all agricultural systems, not only rice production. We agree with Neufeldt et al. 3 that estimating soil C accumulation following adoption of no-till using a 'bottom-up' approach is, in principle, preferable to the 'top-down' method we used. In their Correspondence, Neufeldt et al. 3 accomplish bottom-up estimations of avoided emissions for specific countries by multiplying the area under no-till by a climate-relevant value for the annual rate of increase in soil organic C under the practice. They acknowledge the considerable uncertainty in rates of accumulation under no-till: for example, their estimate for Australia ranges from over 400 MtCO 2 e saved from past notill adoption to additional emissions of over 200 MtCO 2 e compared with conventional cultivation 3. In the face of such uncertainty the strong promotion of no-till as an effective means of climate change mitigation in the UNEP Emissions Gap Report 2 looks distinctly unjustified.
In water scarce regions of South Asia, diversification of rice with maize is being advocated towa... more In water scarce regions of South Asia, diversification of rice with maize is being advocated towards sustainability of cereal-based cropping systems. Adoption of innovative agronomic management practices, i.e., conservation agriculture (CA) and sub-surface drip irrigation (SSDI) are considered as key strategies for much needed interventions to address the challenges of water scarcity under projected climate change. Benefits from CA and SSDI concerning water economy are well-established, however, information about their complementarity and water budgeting in cereal-based systems are lacking. A field study was conducted with process-based model (HYDRUS-2D) to understand water transport, root water uptake and components of soil water balance in maize grown in rotation with wheat after five years of continuous adoption of conservation agriculture. In this study, altogether eight treatments comprising of 6 CA+ treatments (CA coupled with SSDI); permanent beds using sub-surface drip (PB-S...
Abstract The crucial link between agricultural growth and the Sustainable Development Goals (SDGs... more Abstract The crucial link between agricultural growth and the Sustainable Development Goals (SDGs) set by the United Nations Development Programme is established through efficient use of nitrogen in the cereal production systems. Nitrogen, mostly in its reactive form as fertilizer or synthetic N, governs the food production, and reconciles the productivity with economic and environmental considerations. However, N flows in the production system involves a large N leaking to the environment resulting in abysmally low nitrogen use efficiencies and environmental adversity. Agricultural system with sub-optimal N application is characterized with low crop productivity, spiraling into the vicious cycle of poverty, malnutrition and poor economy, a case most common in the sub-Saharan Africa. These essentially relate to SDG 1 (no-poverty), 2 (zero-hunger), 3 (good health and well-being), 8 (decent work and economic growth) and 15 (life on land). Excess or imbalanced fertilizer N in most of China and parts of India led to serious environmental hazards, degradation of land and economic loss. Balancing the amount of N input in these regions will contribute in achieving the SDG 13 (climate action). Meeting some of the SDGs (5, gender equality; 6, clean water and sanitation; 10: reduced inequalities; etc.) requires optimum N application, which will also ensure “responsible consumption and production” (SDG 12). The quest for an appropriate N management needs accounting for the N surplus in a production system, and evolving strategies for increasing the nitrogen use efficiency. Much effort has been made to this effect with varying success. Cutting-edge technological options are although available on the horizon, the success lies in improved awareness among the policy makers, stakeholders and farmers, and better research to quantify the linkage between N management and the SDGs, taking collectively.
A study was conducted to design productive, profitable, irrigation water¸ nitrogen and energy use... more A study was conducted to design productive, profitable, irrigation water¸ nitrogen and energy use efficient intensive cereal systems (rice-wheat; RW and maize-wheat; MW) in North-West India. Bundling of conservation agriculture (CA) with sub-surface drip irrigation termed as CA+ were compared with CA alone and conventional tillage based and flood irrigated RW rotation (farmer’s practice; ScI). In contrast to conventional till RW rotation which consumed 1889 mm ha−1 irrigation water (2-yr mean), CA+ system saved 58.4 and 95.5% irrigation water in RW and MW rotations, respectively. CA+ practices saved 45.8 and 22.7% of irrigation water in rice and maize, respectively compared to CA with flood irrigation. On a system basis, CA+ practices saved 46.7 and 44.7% irrigation water under RW (ScV) and MW (ScVI) systems compared to their respective CA-based systems with flood irrigation (ScIII and ScIV). CA+ in RW system recorded 11.2% higher crop productivity and improved irrigation water prod...
The Emissions Gap Report 2013 from the United Nations Environment Programme restates the claim th... more The Emissions Gap Report 2013 from the United Nations Environment Programme restates the claim that changing to no-till practices in agriculture, as an alternative to conventional tillage, causes an accumulation of organic carbon in soil, thus mitigating climate change through carbon sequestration. But these claims ignore a large body of experimental evidence showing that the quantity of additional organic carbon in soil under no-till is relatively small: in large part apparent increases result from an altered depth distribution. The larger concentration near the surface in no-till is generally beneficial for soil properties that often, though not always, translate into improved crop growth. In many regions where no-till is practised it is common for soil to be cultivated conventionally every few years for a range of agronomic reasons, so any soil carbon benefit is then lost. We argue that no-till is beneficial for soil quality and adaptation of agriculture to climate change, but its role in mitigation is widely overstated. agriculture. If, as we maintain, the contribution through promoting no-till practices is substantially less than claimed, there is even more pressure to deliver mitigation through other approachesboth in agriculture and in other sectors.
outh Asian agriculture is a global 'hotspot' for contemporary and future climate vulnerability. F... more 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 security while preserving and enhancing the resource base and the environment. It is estimated that a partial CA-based system (at least one crop has no till, with or without residue retention) is spread to over 2.5 million ha in South Asia (M.L. Jat, personal communication). Numerous favourable impacts have been reported in the global literature on CA, including for crop yields, resource (labour, water, energy) use efficiencies, timeliness of cropping practices, soil quality and ecosystem services 8-13. Nevertheless, a meta-analysis of global yield data from 48 crops across 63 countries reported limited yield gains with full CA or with some components of CA 14 , a result that has drawn into question the wisdom of making CA a sustainable intensification priority for agricultural development programs. Although the benefits derived from CA have been broadly questioned, there has been gradual increase in adoption of CA over time. Zero-tillage (ZT) wheat has been adopted on a significant area in the rice-wheat system of the northwestern Indo-Gangetic Plains 15 and in the Eastern Gangetic Plain 16 with positive impacts on wheat yield, profitability and resource-use efficiencies 17,18. The national governments in South Asia are actively promoting CA to address sustainability problems. Although numerous on-station and on-farm studies have been carried out during the past two decades to evaluate CA in South Asia, a systematic synthesis of evidence is lacking. To clarify the regional potential of CA as a full package or combination of its components in South Asia, this study presents a comprehensive meta-analysis on data from on-station (1996-2016) and on-farm (2010-2014) studies in South Asia's dominant cereal-based cropping systems. Performance parameters considered in the analyses included (1) grain yield, (2) protein-equivalent yield (PEY), (3) water use efficiency, (4) cost of cultivation and net economic return, and (5) emission of GHGs (methane and nitrous oxide) and global warming potential (GWP). Results are contrasted with conventional best practices and contextualized with respect to
To contain the COVID-19 pandemic, India imposed a national lockdown at the end of March 2020, a d... more To contain the COVID-19 pandemic, India imposed a national lockdown at the end of March 2020, a decision that resulted in a massive reverse migration as many workers across economic sectors returned to their home regions. Migrants provide the foundations of the agricultural workforce in the 'breadbasket' states of Punjab and Haryana in Northwest India.There are mounting concerns that near and potentially longer-term reductions in labor availability may jeopardize agricultural production and consequently national food security. The timing of rice transplanting at the beginning of the summer monsoon season has a cascading influence on productivity of the entire rice-wheat cropping system. To assess the potential for COVID-related reductions in the agriculture workforce to disrupt production of the dominant rice-wheat cropping pattern in these states, we use a spatial ex ante modelling framework to evaluate four scenarios representing a range of plausible labor constraints on the timing of rice transplanting. Averaged over both states, results suggest that rice productivity losses under all delay scenarios would be low as compare to those for wheat, with total system productivity loss estimates ranging from 9%, to 21%, equivalent to economic losses of USD $674 m to $1.48 billion. Late rice transplanting and harvesting can also aggravate winter air pollution with concomitant health risks. Technological options such as direct seeded rice, staggered nursery transplanting, and crop diversification away from rice can help address these challenges but require new approaches to policy and incentives for change.
The future of the South Asia's rice-wheat (RW) production system is at stake due to continuously ... more The future of the South Asia's rice-wheat (RW) production system is at stake due to continuously depleting aquifers and increasing pressure on underground water under projected climate change scenario. Conventional management factors such as flood irrigation, intensive tillage and residue burning are threatening sustainability of RW system. With increasing adoption of conservation agriculture (CA), sub-surface drip fertigation (SSDF) provides an exceptional opportunity for complementing irrigation water saving benefits. Presently, there is no research evidence on optimum spacing and depth for drip laterals in a CA (direct drilling and residue mulch) based RW system around the globe. This study was therefore, planned to evaluate effects of residue mulch, different spacing and depths of laterals for SSDF on crop yield, irrigation water productivity (WPi), nitrogen use efficiency (NUE) and net returns for CA based RW system in a silt loam soil in northwestern India. Drip laterals were spaced either at 33.75 cm or 67.5 cm, and installation depths were 0, 15 or 20 cm beneath the soil surface and compared with conventional and zero tillage based flood-irrigated RW systems. Grain yield and irrigation water input in rice and wheat were generally similar under different SSDF treatments. Irrigation water savings were 48-53% in rice and 42-53% in wheat under combination of SSDF and CA compared to flood irrigation system. A similar trend in WPi was recorded in both the crops. Residue mulch contributed to higher irrigation water savings, wheat yield and WPi compared to no mulch. Both rice and wheat needed 20% less N fertilizer under SSDF system to obtain grain yields similar to that under flood irrigated crops. Net returns from SSDF system with 67.5 cm lateral spacing were significantly higher compared to flood irrigation system. In conclusion, SSDF system having laterals spaced at 67.5 cm and installed at 15 cm depth provides tangible benefits for substantial saving in irrigation water and energy and increasing NUE and net income for CA based RW system in South Asia.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Emerging evidence supports the intuitive link between chronic health conditions associated with a... more Emerging evidence supports the intuitive link between chronic health conditions associated with air pollution and the vulnerability of individuals and communities to COVID-19. Poor air quality already imposes a highly significant public health burden in Northwest India, with pollution levels spiking to hazardous levels in November and early December when rice crop residues are burned. The urgency of curtailing the COVID-19 pandemic and mitigating a potential resurgence later in the year provides even more justification for accelerating efforts to dramatically reduce open agricultural burning in India.
Food insecurity in the Sahelian environment was extensively shown to be a result of low soil fert... more Food insecurity in the Sahelian environment was extensively shown to be a result of low soil fertility and high climate risks. But decisions and recommendations made from the great wealth of research have little been adopted by farmers. Soil water crop models (SWCM) can assist researchers and development actors in this environment if they can appropriately deal with the constraints and mainly farmers' agricultural development goals. We reviewed the Sahelian agricultural constraints and farmer management practices with an emphasis on Niger and pearl millet. Significant results derived from research works to improve crop productivity are presented and analyzed with regard to the main agricultural constraints. Potential and currently used SWCMs are presented and compared for relevance for use in such a particular environment for decision support (DS). This shows that crop modeling in millet-based agricultural system of the Sahel should be addressed with an integrated approach that can handle the multiple and usually connected agricultural constraints of the region: low soil fertility and spatial variability, time and space rainfall variability. Recommendations were made regarding the relevant and minimum aspects that SWCM should take into account for a successful and reliable use for DS in the complex Sahelian environment.
ABSTRACT With the advent of Green Revolution era in the mid-1960s, high-yielding wheat (Triticum ... more ABSTRACT With the advent of Green Revolution era in the mid-1960s, high-yielding wheat (Triticum aestivum L.) varieties and chemical fertilizers were introduced in South Asia. Fertilizer consumption is continuously increasing since then, but the productivity of wheat is relatively stagnant during the last decade. In South Asia, fertilizers have been applied to wheat as blanket recommendations for regions with similar climate and landform. There exists a large variation in nutrient use efficiencies in wheat because of following blanket recommendations for nitrogen, phosphorus, and potassium in fields differing greatly in nutrient-supplying capacity of the soil. Research carried out in South Asia suggests that further improvement in nutrient use efficiency will become possible by balanced use of nitrogen, phosphorus, and potassium fertilizers, and by rational use of organic manures in wheat systems. Long-term fertility experiments also confirm the need of balanced use of nutrients to produce high sustainable yield levels of wheat. In saline alkali soils, wheat needs to be supplied with higher amounts of nutrients, particularly N, than in normal soils. Band placement of fertilizers, particularly phosphorus, leads to improved fertilizer use efficiency, but appropriate machinery is lacking. Recently introduced site-specific nutrient management strategies for wheat take into account field-to-field variability and can help increase fertilizer use efficiency more than that achieved by following blanket fertilizer recommendations. Conservation agricultural practices consisting of reduced tillage and residue retention in wheat fields have already been introduced in South Asia. Nutrient management strategies for these wheat-growing environments are also being actively worked out. Yield gap analysis shows that productivity of wheat as well as nutrient use efficiencies can be further improved.
Understanding the diversity of current states, life cycles and past trajectories of households an... more Understanding the diversity of current states, life cycles and past trajectories of households and agroecosystems is essential to contextualise the co-design of more sustainable agroecosystems. The objective of this paper was to document and analyse current states, trajectories of changes and their major drivers of households in a highly populated maize-based agroecosystem of Western Kenya. In 2013, we revisited 20 rural households that were surveyed, analysed and categorised 10 years ago (2003) in order to describe major changes in livelihood strategies, land use and soil fertility status. The household-level analysis was complemented with the analysis of secondary data on changes in drivers at the national level for the study period. The diachronic study showed a close association between drivers such as market and transport development, and the structure of rural households in terms of demographic shifts, land and labour exchanges, increased costs of agricultural inputs and better connectivity to markets. Between 2003 and 2013, the surveyed households experienced an increase in non-agricultural income by 30 %; intensity of land cultivation by 60 %; use of hybrid maize seeds by 35 %; and of synthetic fertilisers by almost 50 %. Local households increase their number of crossbred livestock in detriment of local breeds and used less manure to fertilise their soils. In contrast, there were few changes in terms of food self-sufficiency (around 9 months per year) and in soil conditions (soil fertility was already poor in 2003). In terms of livelihood strategies, betterendowed households tended to diversify and acquire land that enabled them to adapt and benefit from the major changes observed in external drivers. In contrast, more vulnerable households sold labour and land to cope with such changes, remaining in a poverty trap. Households combine and explore diverse strategies to act, cope and adapt to fast-changing local and regional drivers. Policy or development programmes need to account for such diversity and dynamics to support the co-development of more adaptive and sustainable smallholder agroecosystems.
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Papers by Bruno Gerard