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A large database of individual farmer field data (n = 4,107) for rice production in the Northwestern Indo-Gangetic Plains of India was used to decompose rice yield gaps and to investigate the scope to reduce nitrogen (N) inputs without compromising yields. Stochastic frontier analysis was used to disentangle efficiency and resource yield gaps, whereas data on rice yield potential in the region were retrieved from the Global Yield Gap Atlas to estimate the technology yield gap. Rice yield gaps were small (ca. 2.7 t ha−1, or 20% of potential yield, Yp) and mostly attributed to the technology yield gap (ca. 1.8 t ha−1, or ca. 15% of Yp). Efficiency and resource yield gaps were negligible (less than 5% of Yp in most districts). Small yield gaps were associated with high input use, particularly irrigation water and N, for which small yield responses were observed. N partial factor productivity (PFP-N) was 45–50 kg grain kg−1 N for fields with efficient N management and approximately 20% lower for the fields with inefficient N management. Improving PFP-N appears to be best achieved through better matching of N rates to the variety types cultivated and by adjusting the amount of urea applied in the 3rd split in correspondance with the amount of diammonium-phosphate applied earlier in the season. Future studies should assess the potential to reduce irrigation water without compromising rice yield and to broaden the assessment presented here to other indicators and at the cropping systems level.

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-SSD) with (WR) and without (WOR) crop residue at different N rates, 0, 120 and 150 kg N ha−1 were compared with CA (PB using furrow irrigation-FI with crop residue-120 kg N ha−1) and conventional tillage practices (CT) (CT using FI without crop residue-120 kg N ha−1). Results showed that the model could simulate the daily changes in profile soil water content with reasonable accuracy in all the treatments. Simulated soil water balance indicated higher cumulative root water uptake (CRWU), lower cumulative evaporation (CE) and higher soil water retention in CA+ (PB-SSD+ crop residue at 150 and 120 kg N ha−1) than CA and CT plots. Hydrus-2D model efficiency > 0, RMSE between 0.009–0.026 and R2 value between 0.80–0.92 at P

In the scenario of global climate change, the enhancement and stabilization of soil organic carbon holds prime importance. In this context, conservation agriculture (CA) based practices i.e., diversified cropping systems and permanent bed (PB) holds great potential. In this article, we have compared the dynamics of soil organic carbon under mustard and wheat based systems [MMuMb, maize-mustard-mungbean and MWMb, maize-wheat-mungbean)] planted on PB, with and without residue (PB + R and PB - R) along with four nitrogen (N) management options [Un-fertilized, N through prilled urea (PU), N through sulphur coated urea (SCU), and N through neem coated urea (NCU)]. After 5-years of experimentation, to assess the medium-term impact of full CA (PB + R) in comparison to partial CA (PB-R) on SOC dynamics under mustard and wheat based systems with diverse N sources, we had conducted an incubation study at three temperature levels (27, 32 and 37 °C) in a sandy loam soil (Typic Haplustept) of north-western Indo- Gangetic Plains (IGP) of India. Wheat-based cropping system (MWMb) resulted in higher values of less labile, non-labile as well as total SOC, as compared with mustard-based system (MMuMb). On the other hand, MMuMb registered higher amount of very labile and labile SOC, with enhanced decay rate. The cumulative C mineralization (Ct) was 11–17% higher under MMuMb compared with MWMb, from all the soil depths at 27 °C. Retention of crop residue in PB increased total SOC by 11.5 to 19.5% compared with PB-R, across the soil depths. The Ct were significantly higher under full CA plots with lower decay rate (Kc), as compared to plots under partial CA. Application of N fertilizers registered a significant hike in total SOC compared to un-fertilized control plots. At the same time, the coated N sources i.e., SCU and NCU failed to cause any significant improvements in total SOC as compared with uncoated PU plots. On the other hand, coated urea treated plots registered significantly higher C mineralization compared with uncoated PU plots. Between the two coated urea products, the NCU application registered significantly higher C mineralization compared with SCU across the sampling events and temperature regimes from all the soils layers. Cropping system or residue addition/removal did not affect temperature sensitivity of SOC mineralisation. At the same time, addition of N-fertilizers, irrespective of sources lowered the Q10 compared with no-N fertilization.

Assessment of temperature sensitivity of soil organic carbon (SOC) mineralization from soils of long-term precision conservation agriculture (CA) plots is essential to forecast soil C dynamics. Under CA, varying quantity of inorganic nutrient application had differential impact on SOC. At the same time study of SOC mineralization at different simulated temperatures is important as global climate change affects C-cycle of an agro-ecosystem. To assess the impact of tillage and nutrient management on SOC build-up, a long-term study (five year old) with 3-tillage practices [ZT-zero tillage; PB-permanent beds, & CT-conventional tillage] in main plot and 4-nutrient management strategies [unfertilized, farmer fertilizer practice-FFP, recommended fertilizers-Ad-hoc and a site specific nutrient management-SSNM] in sub-plot in a maize-wheat-mungbean system was chosen. To measure the build-up and thermal sensitivity of SOC, soil samples from 3- depths (0–7.5, 7.5–15 and 15–30 cm) were collected. The kinetics of C-mineralisation was studied through laboratory incubation at 3-temperatures (27, 32 and 37 °C) for 90 days. The PB/ZT and SSNM had significantly higher SOC compared with CT and unfertilized plots, respectively. Although the cumulative C mineralization after 90-days of incubation followed the trend of SOC content among the treatments, while decay rates of SOC mineralization showed somewhat different trend. In all the tillage treatments the percentage of SOC mineralised ranged between 3.3–5.8% at 27 °C, 5.2–8.1% at 32 °C and 7.3–10.9% at 37 °C. At higher temperature, higher SOC decay rates were observed under CT and unfertilized plots compared with PB/ZT and SSNM plots, respectively. The SOC from lower soil depth in CT and unfertilized plots was more temperature sensitive (Q10 = 4.03 and 4.89, respectively) compared to those under CA-based PB/ZT (Q10 = 2.63–2.82) and SSNM (Q10 = 2.15) based balanced nutrition, respectively. The SOC in lower soil depth (7.5–15 and 15–30 cm) is 1.3 and 2.1 times more temperature sensitive respectively than surface soil depth of 0–7.5 cm soil depth. Higher proportion of less labile SOC under CT and unfertilized plots might be the reason for higher temperature sensitivity. In the inevitable and impending global climate change scenario, we might lose a sizeable amount of sequestered C, which is otherwise stable at present ambient temperature.

A greater energy grant in diesel-fed machinery driven farming substantiate the higher GHGs emission along with improper input (fertilizer, pesticide and irrigation) use and intensive soil management. Practicing conservation tillage, residue retention and diversified crop rotations were advocated because of their multiple benefits. Hence we explored the energy requirement and carbon footprint of conservation agriculture (CA) based maize production systems. Coated N fertilizer [sulphur coated urea (SCU) and neem coated urea (NCU)] were compared with unfertilized and uncoated prilled urea (PU) in the scenario of with and without residue retention on permanent beds (PB) under diversified maize systems [MMuMb, maize-mustard-mungbean and MWMb, maize-wheat-mungbean] in search of a sustainable and energy efficient production system with lesser C-footprint. Results of the 4-year study showed that crops planted on permanent bed with crop residue (PB+R) registered 11.7% increase in system productivity compared to PB without residue (PB−R). N management through Neem coated urea (NCU) recorded 2.3 and 10.9% higher system productivity compared with non-coated prilled urea plot under PB−R and PB+R, respectively. MMuMb was marginally superior than MWMb system in terms of cropping sequence yield, profitability, and energy and carbon use efficiency. Crop residue retention in zero tilled PB increased cost of cultivation by 125 and 147 USD/ha in MMuMb and MWMb systems, respectively. The quantified carbon footprint value was higher in MWMb system. In CA-based practices, crop residues management contributed the highest energy input (61.5–68.4%) followed by fertilizer application (17–20%). Among N management practices, neem coated urea (NCU) significantly improved system productivity and profitability in all the residue applied plots compared to un-fertilized and prilled urea (PU) applied plots. Similarly, higher energy output was also observed in NCU treated plots. However, carbon footprint value was higher in PU (268–285 CO2-e kg/Mg) plots than NCU (259–264 CO2-e kg/Mg) treated plots. Thus, the study supports and recommends that the CA-based MMuMb system with efficient N management through NCU is an environmentally safe, clean and energy efficient one, hence can reduce carbon footprint, will ensure food security and will mitigate climate change.

Under the present scenario of resource degradation, shortage of water & labour, growing production cost, falling water tables as well as farm profitability and climate-change; the sustainability of traditional rice-wheat (RW) system became a major challenge in Indo-Gangetic Plains (IGP). Therefore, to address these issues in India’s, north-western IGP, RW system need to be diversified with conservation agriculture (CA) based profitable and sustainable systems. Full CA based crop production technologies may furnish more yield, reduce water need and enhance farm profitability, without hampering the sustainability of natural resources. So in an established on-going long term study (since 2012), we assessed the medium term-impact of four different nitrogen management practices [Un-fertilized, N through Prilled urea (PU), N through Sulphur coated urea (SCU) and N through Neem coated urea (NCU)] in residue retained permanent bed (PB + R) vs. residue removed permanent bed (PB-R) plots under maize-mustard-mungbean (MMuMb) and maize-wheat-mungbean (MWMb) crop rotations. Results showed that, the maize, wheat and mustard yields were statistically similar in first year of study irrespective of residue retention or removal, whereas during subsequent years, yields of maize, wheat and mustard were significantly (P

The rising economic and environmental costs of mineral fertilizers associated with lower nutrient use efficiency, and the need to respond the limitations of N fertilization under residue retained condition of conservation agriculture (CA) motivate the research for alternative N placement methods. The third principle of CA, i.e., residue retention on the soil surface hinders the right placement of split applied nitrogen (N). To address this issue, we assessed the impact of three N placement methods, i.e., NPM1: both the N splits were surface band placed, NPM2: the first split of N was sub-surface point placed and second N split (late vegetative stage) was surface band applied, and NPM3: both the N splits were sub-surface point placed, under 4-long-term tillage and residue management (+R) options, i.e., permanent raised bed (PB+R), zero-till flat (ZT+R) conventional till flat (CT+R) and first time zero till flat sowing of the crop on last 10-year fallow land (FZT+R), in an on-going long-term study (since 2008) in maize for three consecutive years (2018–2020). Results showed that sub-surface point placement of both the N splits (NPM3) increased maize grain yield by 4.7, 7.0 and 6.0% (3-years mean basis) compared to NPM2, under CA-based PB, ZT, and FZT plots, respectively. The peak growth rate in the CA-based PB+R plot was advanced by 4-days with a 9.2% higher growth rate compared to CT+R. Similarly, the peak growth rate in NPM3 was 20% higher than NPM1 plots. The changes in soil properties under CA altered the crop growth behavior, while sub-surface point placement of split applied nitrogen (N) increased the grain N content and altered the peak growth rate of maize. The variability in maize grain yield was best described by cob length and number of cobs in long-term tillage and by cob length in N management plots. The cob length and grains per cob were increased by 4.8–8.7 and 8.6–12.8% under CA-based plots compared to CT+R, respectively. The amount of vegetative stage accumulated N remobilized to maize grain was 21.2% higher under PB+R compared to CT+R plots, while the N remobilization in NPM3 was 22.9% higher compared to NPM1 plots. Similarly, the contribution of reproductive stage N uptake to grain was 9–12% higher in CA-NPM3 compared to CT-NPM1 plots. Further, the early and vigorous growth of maize resulted in a higher accumulation of N and its remobilization to the grains in CA-based and N point placed plots. The sub-surface point placement of N (NPM3) resulted in a 12.8, 14.5 and 9.2% higher benefit-cost ratio compared to NPM1 plots in 11th (2018), 12th (2019) and 13th (2020) years of experimentation, respectively. Therefore, the present study visualizes the impact of a decade-long CA and efficient N management on crop growth behavior, N uptake and remobilization and crop productivity and water use efficiency. This study provides evidence to popularize this technology in the CA-systems of Indo-Gangetic Plains and other similar agro-ecologies.

SUMMARY: Conservation agriculture (CA) practices such as zero tillage (ZT) and permanent raised beds (PB) accelerate deposition of soil organic matter and augment associated biological properties of soil through enhanced inputs of organic carbon. However, the potential benefit of CA under intensive cereal‐based systems for key soil health indicators (such as carbon pools and biological activities) is only partially known. Therefore, we analysed the effect of three medium‐term tillage practices and four intensive crop rotations on selected soil organic carbon pools and microbial properties. The tillage practices consist of ZT, PB and conventional tillage (CT) in main plots and four crop rotations (MWMb, maize–wheat–mungbean; MCS, maize–chickpea–Sesbania; MMuMb, maize–mustard–mungbean; MMS, maize–maize–Sesbania) in subplots. The experimental design was split‐plot with three replications. After 6 years, we observed a significant positive effect of CA practices on soil organic carbon (SOC) content, labile SOC fractions, soil microbial biomass carbon (MBC) and dehydrogenase activity (DHA). The total organic carbon (TOC) was greatly affected by medium‐term tillage and diversified cropping systems; it was larger for CA and MCS and MWMb systems. The interaction effect between tillage and cropping systems for SOC content was not significant at all soil depths. Significantly larger contributions (8.5–25.5%) of labile SOC pools to TOC at various soil depths were recorded in PB and ZT. There was a significant positive effect of CA practices and diversified crop rotations on MBC and DHA at all the soil depths and sampling times, but the interaction effect between tillage and cropping systems was not significant. Thus, our medium‐term (≥ 5‐years) study showed that the combination of CA (PB and ZT) practices and appropriate choice of rotations (MCS and MWMb) appears to be the most appropriate option for restoration and improvement of the soil health of light‐textured Inceptisols through the accumulation of soil organic matter (SOM) and improvement in soil biological properties. HIGHLIGHTS: Effect of conservation agriculture (CA) on soil labile carbon inputs and biological properties. Observed changes in SOC stock and C‐pools at different soil depths after 6 years. Significant effects of tillage and crop rotations observed for labile‐C pools. Adoption of ZT and PB enhanced SOC stock, C‐pools and microbial activity compared to CT.

Conventional tillage practices and imbalanced use of inorganic fertilizers is well known to result in poor soil health. Alternative tillage and precision nutrient management are important strategies for tackling the issues of soil health deterioration, particularly in cereal-based intensive cropping systems. Therefore, we conducted a 4-year study with the objective of (a) monitoring the changes in soil physical, biological and chemical properties and crop productivity, (b) development of soil quality index-SQI, and monitor its’ changes against system productivity as management goal, and (c) studying the changes in soil organic carbon-SOC in relation to annual C input. The experiment was laid out in a split-plot design with 3-tillage practices [zero tillage-ZT; permanent beds-PB; and conventional tillage-CT] and 4-nutrient management strategies [Control (unfertilized), farmers’ fertilizer practice-FFP, recommended fertilizers doses-Ad-hoc and site specific nutrient management-SSNM] under a continuous maize (Zea mays L.) - wheat (Triticum aestivum L.)- mungbean (Vigna radiata L. Wilczek) rotation in a sandy loam soil (Typic Haplustept) of north-western Indo-Gangetic plains (NW-IGP) of India. The ZT/PB with SSNM/Ad-hoc nutrient management resulted in higher values of a) physical parameters viz., water stable aggregates >250 μm, saturated hydraulic conductivity (Ksat) and mean weight diameter-MWD, b) chemical parameters viz., SOC, available N, P, and K, and c) biological parameters viz., microbial biomass carbon and enzyme activities (fluorescein diacetate hydrolase, dehydrogenase, s-glucosidase and alkaline phosphatase) compared with CT and unfertilized treatments. The CA practices recorded an increase in WSA (12–21%), MWD (14–29%), and Ksat (11–14%) compared with CT at the 0-0.15 m and 0.15–0.30 m soil depths, respectively. The PB-SSNM registered (44.1%) higher SOC content as compared to CT-unfertilized plots. Values for MBC, FDA and βGA declined in the order SSNM=Ad-hoc>FFP > Control. While, the DHA declined in the order SSNM>Ad-hoc=FFP > Control. Principal component analysis included MWD, SOC and available K in the minimum data set (MDS) as the soil quality indicators. Adoption of PB/ZT resulted ∼22.5% higher SQI compared with CT. The SSNM plots improved SQI by ∼19.3% and ∼5.3% over unfertilized and FFP. The SSNM based CA practices attained a significantly higher annual C sequestration rate than other treatments. Therefore, adoption of CA with SSNM and Ad-hoc nutrient management in intensive cereal based systems of NW-IGP is essential for improving nutrient cycling, soil quality, crop productivity and C-sequestration potential.

Given the increasing scarcity of production resources such as water, energy and labour coupled with growing climatic risks, maize-based production systems could be potential alternatives to intensive rice-wheat (RW) rotation in western Indo-Gangetic Plains (IGP). Conservation agriculture (CA) in maize systems has been widely promoted for minimizing soil degradation and ensuring sustainability under emerging climate change scenario. Such practices are also believed to provide mitigation co–benefits through reduced GHG emission and increased soil carbon sequestration. However, the combined effects of diversified crop rotations and CA-based management on GHG mitigation potential and other co-benefits are generally over looked and hence warrant greater attention. A field trial was conducted for 5–years to assess the changes in soil organic carbon fractions, mineral–N, N2O emission and global warming potential (GWP) of maize-based production systems under different tillage & crop establishment methods. Four diversified cropping systems i.e. maize–wheat–mungbean (MWMb), maize–chickpea–Sesbania (MCS), maize–mustard–mungbean (MMuMb) and maize–maize–Sesbania (MMS) were factorially combined with three tillage & crop establishment methods i.e. zero tilled permanent beds (PB), zero–tillage flat (ZT) and conventional tillage (CT) in a split–plot design. After 5–years of continued experimentation, we recorded that across the soil depths, SOC content, its pools and mineral-N fractions were greatly affected by tillage & crop establishment methods and cropping systems. ZT and PB increased SOC stock (0–30 cm depth) by 7.22–7.23 Mg C ha−1 whereas CT system increased it only by 0.88 Mg C ha−1as compared to initial value. Several researchers reported that SOC & mineral–N fraction contents in the top 30 cm soil depth are correlated with N2O–N emission. In our study, global warming potential (GWP) under CT system was higher by 18.1 and 17.4%, compared to CA-based ZT and PB, respectively. Among various maize systems, GWP of MMS were higher by 11.2, 6.7 and 6.6%, compared that of MWMb (1212 kg CO2–eq. ha−1), MCS (1274 kg CO2–eq. ha−1) and MMuMb (1275 kg CO2–eq. ha−1), respectively. The results of our study suggest that CA and diversified crop rotations should be promoted in north-western IGP and other similar agro-ecologies across the globe for ensuring food security, restoration of soil health and climate change mitigation, the key sustainable development goals (SDGs).

Increasing resource degradation (soil) and resource scarcity (water) in Indo Gangetic Planes (IGP) had popularized the concept of conservation agriculture (CA). CA practices can alter the soil hydraulic properties by improving soil physical environment and hence water productivity (WP). Since CA practices are highly site-specific in nature, its worthiness under different cropping systems, soil types and agro-climatic zones must be studied. In the context of above-mentioned scenario of crop management practices, Hydrus-2D model was used to evaluate most suitable CA-based practice for north western (NW) IGP to understand the process of water transport. The experiment had 3-tillage and crop establishment practices [ZT-zero tillage; PB-permanent raised bed and CT-conventional tillage] in main plot and 4-cropping systems [MWMb-maize-wheat-mungbean; MCS-maize-chickpea-Sesbania; MMuMb-maize-mustard-mungbean and MMS-maize-maize-Sesbania] in sub-plot. The validation of Hydrus-2D showed that nRMSE was observed between 0.19-0.25 and R2 value between 0.80-0.87 at P