M.L. Jat

Productivity and Sustainability of the Rice–Wheat Cropping System in the Indo-Gangetic Plains of the Indian subcontinent: Problems, Opportunities, and Strategies

Abstract Rice and wheat are the staple foods for almost the entire Asian population and therefore they occupy a premium position among all food commodities. The era of the Green Revolution started during the early 1970s with wheat and rice and since then the rice–wheat cropping system of the Indo-Gangetic Plains has played a significant role in the food security of the region. However, recent years have witnessed a significant slowdown in the yield growth rate of this system and the sustainability of this important cropping system is at risk due to second-generation technology problems and mounting pressure on natural resources. Traditional cultivars and conventional agronomic practices are no longer able to even maintain the gains in productivity achieved during the past few decades. Demand for food is increasing with the increasing population and purchasing power of consumers. The rice–wheat cropping system is labor-, water-, and energy-intensive and it becomes less profitable as these resources become increasingly scarce and the problem is aggravated with deterioration of soil health, the emergence of new weeds, and emerging challenges of climate change. Therefore, a paradigm shift is required for enhancing the systems productivity and sustainability. Resource-conserving technologies involving zero- or minimum-tillage in wheat, dry direct seeding in rice, improved water- and nutrient-use efficiency, innovations in residue management to avoid straw burning, and crop diversification should assist in achieving sustainable productivity and allow farmers to reduce inputs, maximize yields, increase profitability, conserve the natural resource base, and reduce risk due to both environmental and economic factors. A number of technological innovation and diversification options have been suggested to overcome the systems sustainability problems but some of them have not been fully embraced by the farmers as these are expensive, knowledge-intensive, or do not fit into the system and have resulted in some other unforeseen problems. Different concerns and possible strategies needed to sustain the rice–wheat cropping system are discussed in this review on the basis of existing evidence and future challenges.

Simulation of resource-conserving technologies on productivity, income and greenhouse gas GHG emission in rice-wheat system

The Rice-wheat (RW) cropping system is one of the major agricultural production systems in four IndoGangetic Plains (IGP) countries: India, Pakistan, Bangladesh and Nepal of South Asia covering about 32% of the total rice area and 42% of the total wheat area. The excessive utilization of natural resource bases and changing climate are leading to the negative yield trend and plateauing of Rice-wheat (RW) system productivity. The conservation agriculture based efficient and environmental friendly alternative tillage and crop establishment practices have been adopted by the farmers on large scale. A few tools have been evolved to simulate the different tillage and crop establishment. In the present study, InfoRCT (Information on Use of Resource Conserving Technologies), a excel based model integrating biophysical, agronomic, and socioeconomic data to establish input-output relationships related to water, fertilizer, labor, and biocide uses; greenhouse gas (GHG) emissions; biocide residue in soil; and Nitrogen (N) fluxes in the rice-wheat system has been validated for farmer participatory practices. The assessment showed that double no-till system increased the farmer’s income, whereas raised-bed systems decreased it compared with the conventional system. The InfoRCT simulated the yield, wateruse, net income and biocide residue fairly well. The model has potential to provide assessments of various cultural practices under different scenarios of soil, climate, and crop management on a regional scale.

ON-FARM ECONOMIC AND ENVIRONMENTAL IMPACT OF ZERO-TILLAGE WHEAT: A CASE OF NORTH-WEST INDIA

Conducting farmers participatory field trials at 40 sites for 3 consecutive years in four rice-wheat system dominated districts of Haryana state of India, this paper tested the hypothesis that zero tillage (ZT) based crop production emits less greenhouse gases and yet provide adequate economic benefits to farmers compared to the conventional tillage (CT). In each farmers field, ZT and CT based wheat production were compared side by side for three consecutive years from 2009–10 to 2011–12. In assessing the mitigation potential of ZT, we examined the differences in input use and crop management, especially those contributing to GHGs emissions, between ZT wheat and CT wheat. We employed Cool Farm Tool (CFT) to estimate emission of GHGs from various wheat production activities. In order to assess economic benefits, we examined the difference in input costs, net returns and cost-benefit analysis of wheat production under CT and ZT. Results show that farmers can save approximately USD 79 ha −1 in terms of total production costs and increase net revenue of about USD 97.5 ha −1 under ZT compared to CT. Similarly, benefit-cost ratio under ZT is 1.43 against 1.31 under CT. Our estimate shows that shifting from CT to ZT based wheat production reduces GHG emission by 1.5 Mg CO 2 -eq ha −1 season −1 . Overall, ZT has both climate change mitigation and economic benefits, implying the win-win outcome of better agricultural practices.

Improving Water Productivity of Wheat-Based Cropping Systems in South Asia for Sustained Productivity

Abstract Serious water deficits are threatening agricultural sustainability in many regions of the South Asia (SA). While the increase in crop production of irrigated rice–wheat system in SA has been impressive since the 1970s, the low water productivity (WP) has led to the depletion of surface water and groundwaters. In this chapter we have discussed the availability of water resources in SA, identified the positive effects of soil and water management and crop genetic improvement on WP, and then described knowledge gaps and research priorities to further improve the WP with special emphasis on wheat-based cropping systems in irrigated and rainfed regions of SA. A single approach would not be able to tackle the forthcoming challenge of producing more food and fiber with limited or even reduced available water. Integrating irrigation water-saving techniques (water-saving irrigation methods, deficit irrigation, modernization of irrigation system, etc.) with agronomic and soil manipulations viz., optimum irrigation scheduling, direct-seeded rice, alternate wetting and drying in puddle transplanted rice, raised bed planting, crop diversification, conservation tillage, crop residue management, and conjunctive use of good quality (canal) water. Improved soil water management practices for rainfed regions include reducing runoff, rainwater harvesting and recycling, conserving rainwater in the root zone by reducing evaporation losses, and optimal nutrient management. The low WP in farmer’s fields compared with well-managed experimental sites indicates the need for more efforts to transfer water-saving technologies to the farmers. In future we need to increase scientific understanding of the effects of agronomic management on WP across various soil and climate conditions; improve irrigation practices (timing and amounts) and methods (drip and sprinkler) based on real-time monitoring of water status in soil-crop systems; and maximize WP by managing water resources and allocation at regional scales in wheat-based cropping systems.

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

Abstract 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 CO 2 , N 2 O and CH 4 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.

Tillage, residue and nitrogen management effects on methane and nitrous oxide emission from rice–wheat system of Indian Northwest Indo-Gangetic Plains

Abstract Zero-tillage, residue management and precision nutrient management techniques are being promoted in the rice–wheat (RW) production system of Indo-Gangetic Plains (IGPs) to enhance climate change adaptation and increase food production. These management practices may also influence greenhouse gas emissions through their effects on various soil processes such as oxidation-reduction and nitrification–denitrification. We measured soil fluxes of CH4 and N2O in RW system under three tillage and residue management systems layered with four nitrogen (N) management treatments. The tillage and residue management systems comprised: conventional tillage (CT), zero-tillage without residue retention (ZT − R) and ZT with full residue retention (ZT + R) for both the crops. The four N management treatments for rice were: (a) basmati cultivar with recommended dose of nitrogen (RDN) applied in three splits, (b) basmati cultivar with 80% RDN as basal dose followed by Green Seeker (GS) guided N application, (c) hybrid cultivar with RDN applied in three splits and (d) hybrid with 80% RDN as basal dose followed by GS guided N application. The four N management treatments for wheat comprised combinations of RDN with and without relay green gram (GG), and 80% of RDN as basal dose followed by GS guided N application with and without relay GG. We employed the static chamber method to collect gas samples from the experimental plots which were subsequently analysed using gas chromatograph. Significant CH4 emissions were detected only in the CT rice system during the initial phase of continuous flooding, irrespective of N management strategies. N fertilization management affected the pattern of N2O emission with higher emission rates during crop establishment phase under 80% RDN as basal followed by GS guided N application than conventional RDN. In case of wheat, 80% RDN as basal followed by GS guided N application also induced higher cumulative N2O emissions than applying RDN at three regular splits. In rice, ZT-based RW system emitted more N2O than CT-based system. Overall ZT-based RW system reduced CH4 emission but this benefit is counterbalanced by higher N2O production compared to CT-based RW system.

Assessing soil properties and nutrient availability under conservation agriculture practices in a reclaimed sodic soil in cereal-based systems of North-West India

ABSTRACT Soil quality degradation associated with resources scarcity is the major concern for the sustainability of conventional rice-wheat system in South Asia. Replacement of conventional management practices with conservation agriculture (CA) is required to improve soil quality. A field experiment was conducted to assess the effect of CA on soil physical (bulk density, penetration resistance, infiltration) and chemical (N, P, K, S, micronutrients) properties after 4 years in North-West India. There were four scenarios (Sc) namely conventional rice-wheat cropping system (Sc1); partial CA-based rice-wheat-mungbean system (RWMS) (Sc2); CA-based RWMS (Sc3); and CA-based maize-wheat-mungbean (Sc4) system. Sc2 (1.52 Mg m−3) showed significantly lower soil bulk density (BD). In Sc3 and Sc4, soil penetration resistance (SPR) was reduced and infiltration was improved compared to Sc1. Soil organic C was significantly higher in Sc4 than Sc1. Available N was 33% and 68% higher at 0–15 cm depth in Sc3 and Sc4, respectively, than Sc1. DTPA extractable Zn and Mn were significantly higher under Sc3 and Sc4 compared to Sc1. Omission study showed 30% saving in N and 50% in K in wheat after four years. Therefore, CA improved soil properties and nutrient availability and have potential to reduce external fertilizer inputs in long run.

Effects of conservation agriculture on crop productivity and water-use efficiency under an irrigated pigeonpea–wheat cropping system in the western Indo-Gangetic Plains

In search of a suitable resource conservation technology under pigeonpea ( Cajanus cajan L.)–wheat ( Triticum aestivum L.) system in the Indo-Gangetic Plains, the effects of conservation agriculture (CA) on crop productivity and water-use efficiency (WUE) were evaluated during a 3-year study. The treatments were: conventional tillage (CT), zero tillage (ZT) with planting on permanent narrow beds (PNB), PNB with residue (PNB + R), ZT with planting on permanent broad beds (PBB) and PBB + R. The PBB + R plots had higher pigeonpea grain yield than the CT plots in all 3 years. However, wheat grain yields under all plots were similar in all years except for PBB + R plots in the second year, which had higher wheat yield than CT plots. The contrast analysis showed that pigeonpea grain yield of CA plots was significantly higher than CT plots in the first year. However, both pigeonpea and wheat grain yields during the last 2 years under CA and CT plots were similar. The PBB + R plots had higher system WUE than the CT plots in the second and third years. Plots under CA had significantly higher WUE and significantly lower water use than CT plots in these years. The PBB + R plots had higher WUE than PNB + R and PNB plots. Also, the PBB plots had higher WUE than PNB in the second and third years, despite similar water use. The interactions of bed width and residue management for all parameters in the second and third years were not significant. Those positive impacts under PBB + R plots over CT plots were perceived to be due to no tillage and significantly higher amount of estimated residue retention. Thus, both PBB and PBB + R technologies would be very useful under a pigeonpea–wheat cropping system in this region.

Nutrient Management and Use Efficiency in Wheat Systems of South Asia

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.

Relay planting of wheat in cotton: an innovative technology for enhancing productivity and profitability of wheat in cotton-wheat production system of South Asia

SUMMARY Cotton–wheat (CW) is the second most important cropping system after rice–wheat in South Asia. Sowing of wheat after cotton is usually delayed due to late pickings coupled with time needed for seedbed preparation, resulting in low wheat yield. Lack of suitable machinery is a major constraint to direct drilling of wheat into the heavy cotton stubbles. An innovative approach with much promise is the ‘2-wheel tractor-based self-propelled relay seeder’ with seed-cum-fertilizer attachment. On-farm trials were conducted at four locations during 2009–2010 and at 10 locations during 2010–2011 to evaluate the following four wheat establishment methods in CW-dominated areas of south-western Punjab, India: (1) zero till seeding in standing cotton using a self-propelled relay seeder, (2) relay seeding in standing cotton with a manual drill without prior tillage (2010 only), (3) relay broadcast seeding in standing cotton following light manual tillage and (4) conventional sowing of wheat after cotton harvest (conventional tillage and sowing with a seed–fertilizer drill). Planting of wheat under conventional practice was delayed by 20–44 days compared with relay seeding. Seed cotton yield was also significantly higher with relay seeding due to opportunity for one additional picking. Yield of wheat sown with the self-propelled relay seeder was 41.2% and 11.8% higher than with conventional practice in 2009–2010 and 2010–2011 respectively. The increase in wheat yield under relay seeding of wheat was primarily due to higher spike density and more grains per spike. The net income from the CW system was 28.2% higher for the self-propelled relay seeder than with conventional sowing.