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Improved nitrogen (N) use is key to future food security and environmental sustainability. While many regions still experience N shortages, agriculture is the leading global emitter of N2O due to losses exacerbated by N surpluses in other regions. In order to sustainably maintain or increase food production, farmers and their advisors need a comprehensive and actionable understanding of how nutrient management affects both yield and N2O emissions, particularly in tropical and subtropical agroecosystems. We performed a meta‐analysis to determine the effect of N management and other factors on N2O emissions, plant N uptake, and yield. Our analysis demonstrates that performance indicators—partial N balance and partial factor productivity—predicted N2O emissions as well as or better than N rate. While we observed consistent production and environmental benefits with enhanced‐efficiency fertilizers, we noted potential trade‐offs between yield and N2O emissions for fertilizer placement. Furthermore, we observed confounding effects due to management dynamics that co‐vary with nutrient application practices, thus challenging the interpretation of the effect of specific practices such as fertilization frequency. Therefore, rather than providing universally prescriptive management for N2O emission reduction, our evidence supports mitigation strategies based upon tailored nutrient management approaches that keep N balances within safe limits, so as to minimize N2O emissions while still achieving high crop yields. The limited evidence available suggests that these relationships hold for temperate, tropical, and subtropical regions, but given the potential for expansion of N use in crop production, further N2O data collection should be prioritized in under‐represented regions such as Sub‐Saharan Africa. [ABSTRACT FROM AUTHOR]

Reduction of excess nutrient application and balanced fertilizer use are the key mitigation options in agriculture. We evaluated Nutrient Expert (NE) tool-based site-specific nutrient management (SSNM) in rice and wheat crops by establishing 1594 side-by-side comparison trials with farmers' fertilization practices (FFP) across the Indo-Gangetic Plains (IGP) of India. We found that NE-based fertilizer management can lower global warming potential (GWP) by about 2.5% in rice, and between 12 and 20% in wheat over FFP. More than 80% of the participating farmers increased their crop yield and farm income by applying the NE-based fertilizer recommendation. We also observed that increased crop yield and reduced fertilizer consumption and associated greenhouse gas (GHG) emissions by using NE was significantly influenced by the crop type, agro-ecology, soil properties and farmers' current level of fertilization. Adoption of NE-based fertilizer recommendation practice in all rice and wheat acreage in India would translate into 13.92 million tonnes (Mt) more rice and wheat production with 1.44 Mt less N fertilizer use, and a reduction in GHG of 5.34 Mt CO2e per year over farmers' current practice. Our study establishes the utility of NE to help implement SSNM in smallholder production systems for increasing crop yields and farmers' income while reducing GHG emissions. [ABSTRACT FROM AUTHOR]

This study assesses the factors affecting the adoption of laser land leveling (LLL) and its impact on crop yields and net returns. It uses household survey data collected from 621 randomly selected farmers in Karnal District of Haryana, India, and applies endogenous switching regression models. Unbiased model results show that the adoption of LLL has significant positive impacts on yields (rice +549 kg ha−1; wheat +471 kg ha−1) and net returns (an aggregate increase of US$230/ha) in the rice‐wheat production system, thereby raising farmers' income substantially. Our results show that LLL adoption at the farm level is influenced by land size and quality, tenure system, availability of farm machinery (tractor), access to finance and farm cooperatives, gender of household head, level of education and training and access to extension services. Therefore, LLL scaling strategies need to consider these bio‐physical and socio‐economic parameters to reach adoption at scale and generate large social, economic, and environmental benefits. [ABSTRACT FROM AUTHOR]

Intensive tillage-based production systems coupled with inefficient fertilizer management practices have led to increased production costs, sub-optimal productivity, and significant environmental externalities. Conservation agriculture (CA) is being increasingly advocated as a management strategy to overcome these issues but precision nutrient management under the CA-based maize-wheat system is rarely studied. Two year's (2014–2015 and 2015–2016) research was conducted at the research farm of BISA, Pusa, Bihar, India to develop precision nutrient management practices for CA-based management in the maize-wheat system. Seven treatment combinations involving (i) tillage (conventional tillage; CT & permanent beds; PB) and (ii) nutrient management rates, application methods (farmers' fertilizer practices; FFP, state recommended dose of fertilizer; SR and precision nutrient management using Nutrient Expert tool; NE and GreenSeeker; (GS), applied using two methods; broadcasting (B) and drilling (D)) were investigated for multiple parameters. The results showed that NE, NE+GS, and SR-based nutrient management tactics with drilling improved crop yields, nutrient-use efficiency (NUE), and economic profitability relative to NE-broadcasting, SR broadcasting, and FFP broadcasting methods. Maize-wheat system productivity and net returns under NE+GS-drilling on PB were significantly higher by 31.2%, 49.7% compared to FFP-broadcasting method, respectively. Total global warming potential (GWP) was lower in the PB-based maize-wheat system coupled with precision nutrient management compared to CT-based maize-wheat system with FFP. Higher (15.2%) carbon sustainability index (CSI) was recorded with NE-drilling compared to FFP-broadcasting method. Results suggests that PB-based maize-wheat system together with precision nutrient management approaches (NE+GS+drilling) can significantly increase crop yields, NUE, and profitability while reducing the emission of greenhouse gases (GHGs) from maize-wheat systems in eastern Indo Gangetic Plains (IGP). [ABSTRACT FROM AUTHOR]

Yield-scaled nitrous oxide (N 2 O) emission (YSNE) has been recognized as a means for developing appropriate nitrogen (N) management strategies to balance food security and mitigating N 2 O emissions. To better understand and use the concept of YSNE, it is essential to be assessed under various field conditions. The main objectives of this study were to assess the relationship between N inputs and YSNE with published results and identify response patterns of YSNE to N inputs. We assessed the relationship between N inputs and YSNE using published results encompassing 1800 observations (published from 1980 to 2020) from maize, rice, and wheat crops worldwide. Background yield-scaled N 2 O emission (BYSNE; a YSNE in the condition of zero N input) was significantly different by crop type. Rice (90.8 ± 12.9 g N 2 O−N Mg−1) had lower BYSNE compared to maize (174.2 ± 30.1 g N 2 O−N Mg−1) and wheat (325.4 ± 41.8 g N 2 O−N Mg−1). BYSNE was positively correlated with annual mean temperature in maize, rice, and wheat fields. BYSNE was negatively correlated with soil total nitrogen contents in rice fields. Over 60% data set showed a positive relationship between N inputs and YSNE in all three crops studied. A small proportion of the dataset had an optimum N rate that minimized YSNE. The results suggest that in general, lower N input rates result in lower YSNE in crop production. YSNE can be reduced in three ways: increasing yields (Type 1), reducing N 2 O emissions (Type 2), and both increasing yields and reducing N 2 O emissions (Type 3). To identify appropriate measures, we suggest a N 2 O emission-yield curve combining responses of yields and N 2 O emissions to N inputs. In type 1, 2, and 3 measures, an N 2 O emission-yield curve is shifted to the right, down, and both right and down, respectively. Through identifying direction and magnitude of the shifting, the effects of applied measures on yields and N 2 O emission in N input levels can be easily compared and recognized. This study provided insights into the nature of YSNE and how YSNE responds to N inputs. It also suggested an N 2 O emission-yield curve, which can be useful to identify how certain measures affect both N 2 O emissions and crop yields. The information can be useful for scientific community and policymakers developing appropriate N management strategies to balance food security and the mitigation of N 2 O emissions. [Display omitted] • Background yield-scaled N 2 O emission (BYSNE) varied by crop type. • BYSNE was positively correlated with annual mean temperature. • Over 60% data sets showed consistently lower yield-scaled N 2 O emission as N input decreased. • N 2 O emission yield curve showed the effects of mitigation measures on both yields and N 2 O emission. [ABSTRACT FROM AUTHOR]

Excessive pumping of groundwater over the years to meet the high irrigation water requirement of rice-wheat system has resulted in over exploitation of groundwater in the Indo-Gangetic plains (IGP) of India. Replacement of traditional rice with less water crops such as maize under conservation agriculture (CA) based management (tillage, crop establishment and residue management) practices are required to promote sustainable intensification. Furthermore, inefficient nutrient management practices are responsible for low crop yields and nutrient use efficiencies in MW system. A 3-year field experiment was conducted in farmer’s participatory strategic research mode at Taraori, Karnal, India to evaluate the effects of tillage and crop establishment (TCE) methods, residue management, mungbean integration, and nutrient management practices on crop yields, water productivity and profitability of MW system. The main plot treatments included four combinations of TCE, residue and mungbean integration [conventional tillage (CT), conventional tillage with mungbean (CT + MB), permanent bed (PB) and permanent bed with MB (PB + MB] with three nutrient management practices [farmer’s fertilizer practice (FFP), recommended dose of fertilize (RDF) and site specific nutrient management (SSNM)] using Nutrient Expert ® as sub plot treatments. System productivity, water use efficiency (WUE) and net returns under PB + MB were significantly increased by 28.2–30.7%, 27.8–31.0% and 36.8–40.5% compared to CT respectively, during three years of experimentation. Integration of MB in MW system contributed 24.9 and 27.6% increases in system productivity and net returns compared with no MB, respectively. SSNM based nutrient management increased the mean (averaged across 3 yrs) system productivity, WUE and net returns of MW system by 13.4%, 13.3% and 15.3% compared with FFP, respectively. Study showed that conservation agriculture based sustainable intensification (PB + MB) and SSNM approach provided opportunities for enhancing crop and water use efficiency, and profitability of MW system in North-West IGP of India. [ABSTRACT FROM AUTHOR]

Several resource use efficient technologies and practices have been developed and deployed to address the challenges related to natural resource degradation and climatic risks management in rice-wheat (RW) rotation of Indo-Gangetic Plains (IGP). However, the practices applied in isolation may not be effective as much as in combination due to changing input responses under varied weather abnormalities. Therefore, a multi-location farmer’s participatory strategic research was conducted to evaluate the effects of layering key technologies, practices and services in varied combinations and compared with business as usual (farmer’s practice) for productivity (crop, water and energy), profitability and global warming potential (GWP) in a RW system. Altogether, six scenarios were compared that includes; Farmer’s practice (FP); Improved FP (IFP) with low intensity of adaptive measures; IFP with high intensity of adaptive measures (IFP-AM); Climate smart agriculture (CSA) with low intensity of adaptive measures (CSA-L); CSA with medium intensity of adaptive measures (CSA-M); CSA with high intensity of adaptive measures (CSA-H). Results revealed that climate smart agricultural practice with high intensity of adaptive measures (CSA-H) recorded 7–9 and 19–26% higher system productivity and profitability, respectively compared to farmers’ practice in all the three years. CSAPs (mean of CSA-L, CSA-M and CSA-H) improved the system productivity and profitability by 6 and 19% (3 yrs’ mean) whereas, IFPs (mean of IFP and IFP-AM) by 2 and 5%, respectively compared to farmer’s practice (11.79 t ha −1 and USD 1833 ha −1 ). CSA with high (CSA-H) and medium (CSA-M) intensity of adaptive measures saved 17–30% of irrigation water and improved irrigation and total water productivity (WP I and WP I+R ) by 29–54 and 21–38%, respectively compared to FP in the study years. Across the years, CSA-H improved the energy-use-efficiency (EUE) and energy productivity (EP) by 43–61 and 44–56% respectively, compared to farmers’ practice. On 3 years mean basis, CSA-H lowered global warming potential (GWP) and greenhouse gas intensity by 40 and 44% respectively, compared to FP (7653 kg CO 2  eq ha −1  yr −1 and 0.64 kg kg −1  CO 2  eq ha −1  yr −1 ). On 3 years mean basis, our study revealed that CSA with high intensity of adaptive measures (CSA-H) increased 8% in system productivity, 23% in profitability, 31% in total water productivity and 53% in energy productivity with 24% less water while reducing the GWP by 40%. The improvement in yield, income as well as use efficiency of water and energy and reduction in GHGs was increasing with layering of portfolio of practices on farmers’ practice. This study helps in prioritizing the technological practices from the portfolio of CSAPs for maximizing crop productivity, profitability and input use efficiency while improving the adaptive capacity and reducing the environmental footprints. [ABSTRACT FROM AUTHOR]