Search

Developing successful mitigation strategies for greenhouse gases (GHGs) from crop residue returned to the soil can be difficult due to an incomplete understanding of factors controlling their magnitude and direction. Therefore, this study investigates the effects of varying levels of wheat residue (WR) and nutrient management on GHGs emissions (CO2, N2O, and CH4) across three soil types: Alfisol, Vertisol, and Inceptisol. A combination of laboratory-based measurements and a variety of data analysis techniques was used to assess the GHG responses under four levels of WR inputs (0, 5, 10, and 15 Mg/ha; WR0, WR5, WR10, and WR15) and three levels of nutrient (NP0: no nutrient, NP1: nutrients (N and P) were added to balance the residue C/nutrient stoichiometry of C/N/P= 100: 8.3: 2.0 to achieve 30% stabilization of added residue C input at 5 Mg/ha (R5), and NP2: 3 × NP1). The results of this study clearly showed that averaged across residue and nutrient input, Inceptisol showed negative N2O flux, suggesting consumption which was supported by its high legacy phosphorus (19.7 mg kg⁻1), elevated pH (8.49), and lower clay content (13%), which reduced microbial activity, as indicated by lower microbial biomass carbon (MBC) and alkaline phosphatase (Alk-P) levels. N2O emissions were more responsive to nutrient inputs, particularly in Vertisol under high WR (15 Mg/ha) input, while CH4 fluxes were significantly reduced under high residue inputs, especially in Vertisol and Inceptisol. Alfisol exhibited the highest total carbon mineralization and GWP, with cumulative GWP being 1.2 times higher than Vertisol and 1.4 times higher than Inceptisol across residue and nutrient input. The partial least square (PLS) regression revealed that anthropogenic factors significantly influenced CO2 and N2O fluxes more than CH4. The anthropogenic drivers contributed 62% and 44% of the variance explained for N2O and CH4 responses. Our study proves that different biogeochemical mechanisms operate simultaneously depending on the stoichiometry of residue C and nutrients influencing soil GHG responses. Our findings provide insight into the relative contribution of anthropogenic and natural drivers to agricultural GHG emissions, which are relevant for developing process-based models and addressing the broader challenge of climate change mitigation through crop residue management. [ABSTRACT FROM AUTHOR]

Optimum soil moisture and high crop residue return (RR) can increase the active pool of soil organic carbon and nitrogen, thus modulating the magnitude of greenhouse gas (GHG) fluxes. To determine the effect of soil moisture on the threshold level of RR for the wheat production system, we analyzed the relationship between GHG fluxes and RR at four levels, namely 0, 5, 10, and 15 Mg ha−1 (R0, R5, R10, and R15) under two soil moisture content (80% FC and 100% FC) and three levels of nutrient management (NS0: no nutrient; NS1, NS2= 3x NS1). Nutrient input (N and P) in NS1 balanced the residue C/nutrient stoichiometry to achieve 30% stabilization of the residue C input in RR (R5). All RR treatments (cf. R0) were found to significantly reduce N2O emission in moderate soil moisture content (80% FC) by 22–56% across nutrient management due to enhanced soil C mineralization, microbial biomass carbon, and N immobilization. However, averaged across nutrient management, a linear increase in N2O emission was observed with increasing RR under 100% FC soil moisture. A significant decrease in CH4 emission by ca. 46% in most RR treatments was observed in 100% FC compared with the R0. The N2O emission was negatively correlated (p = <0.001) with nutrient stoichiometry. Partial least square (PLS) regression indicated that GHG emissions were more responsive (values > 0.8) to management variables (RR rate, nitrogen (N) input rate, soil moisture, and nutrient stoichiometry of C: N) and post-incubation soil properties (SMBC and NO3-N) in Alfisols. This study demonstrated that the mechanisms responsible for RR effects on soil N2O, CH4 fluxes, and carbon mineralization depend on soil moisture and nutrient management, shifting the nutrient stoichiometry of residue C: N: P. [ABSTRACT FROM AUTHOR]

Greenhouse gas emissions from agricultural production systems are a major area of concern in mitigating climate change. Therefore, a study was conducted to investigate the effects of crop residue, nutrient management, and soil moisture on methane (CH4) emissions from maize, rice, soybean, and wheat production systems. In this study, incubation experiments were conducted with four residue types (maize, rice, soybean, wheat), seven nutrient management treatments {N0P0K0 (no nutrients), N0PK, N100PK, N150PK, N100PK + manure@ 5 Mg ha−1, N100PK + biochar@ 5 Mg ha−1, N150PK+ biochar@ 5 Mg ha−1}, and two soil moisture levels (80% FC, and 60% FC). The results of this study indicated that interactive effects of residue type, nutrient management, and soil moisture significantly affected methane (CH4) fluxes. After 87 days of incubation, the treatment receiving rice residue with N100PK at 60% FC had the highest cumulative CH4 mitigation of −19.4 µg C kg−1 soil, and the highest emission of CH4 was observed in wheat residue application with N0PK at 80% FC (+12.93 µg C kg−1 soil). Nutrient management had mixed effects on CH4 emissions across residue and soil moisture levels in the following order: N150PK > N0PK > N150PK + biochar > N0P0K0 > N100PK + manure > N100PK + biochar > N100PK. Decreasing soil moisture from 80% FC to 60% FC reduced methane emissions across all residue types and nutrient treatments. Wheat and maize residues exhibited the highest carbon mineralization rates, followed by rice and soybean residues. Nutrient inputs generally decreased residue carbon mineralization. The regression analysis indicated that soil moisture and residue C mineralization were the two dominant predictor variables that estimated 31% of soil methane fluxes in Vertisols. The results of this study show the complexity of methane dynamics and emphasize the importance of integrated crop, nutrient, and soil moisture (irrigation) management strategies that need to be developed to minimize methane emissions from agricultural production systems to mitigate climate change. [ABSTRACT FROM AUTHOR]

This study was undertaken to address how near-surface soil water content (SWC) patterns have varied across diverse agroecological regions (AERs) of mainland India from 1979 to 2022 (44 years) and how these variations relate to environmental factors. Grid-wise trend analysis using the Mann–Kendall (MK) trend test and Sen's slope was conducted to determine the trends and their magnitudes. Additionally, we used Spearman's rank correlation (ρ) to explore the relationships of ESA CCI's near-surface SWC data with key environmental variables, including rainfall, temperature, actual evapotranspiration, and the normalized difference vegetation index (NDVI). The results revealed significant variations in SWC patterns and trends across different AERs and months. The MK trend test indicated that 17.96% of the area exhibited a significantly increasing trend (p < 0.1), while7.6% showed a significantly decreasing trend, with an average annual Sen's slope of 0.9 × 10−4 m3 m−3 year−1 for mainland India. Areas with the highest decreasing trends were AER-16 (warm per-humid with brown and red hill soils), AER-15 (hot subhumid to humid with alluvium-derived soils), and AER-17 (warm per-humid with red and lateritic soils). In contrast, increasing trends were the most prominent in AER-5 (hot semi-arid with medium and deep black soils), AER-6 (hot semi-arid with shallow and medium black soils), and AER-19 (hot humid per-humid with red, lateritic, and alluvium-derived soils). Significant increasing trends were more prevalent during monsoon and post-monsoon months while decreasing trends were noted in pre-monsoon months. Correlation analysis showed strong positive correlations of SWC with rainfall (ρ = 0.70), actual evapotranspiration (ρ = 0.74), and NDVI (ρ = 0.65), but weak or negative correlations with temperature (ρ = 0.12). This study provides valuable insights for policymakers to delineate areas based on soil moisture availability patterns across seasons, aiding in agricultural and water resource planning under changing climatic conditions. [ABSTRACT FROM AUTHOR]

Although crop residue returns are extensively practiced in agriculture, large uncertainties remain about greenhouse gas (GHG) emissions and global warming potential (GWP) responses to residue return (RR) rates under different residue placements and nutrient supplements. We conducted a laboratory mesocosm experiment in Alfisol in central India to investigate the responses of soil GHG emissions (CO2, N2O, and CH4) and the global warming potential to four wheat RR rates (R0: no residue; R5: 5 Mg/ha; R10: 10 Mg/ha; R15: 15 Mg/ha) and two placements (surface [Rsur] and incorporated [Rinc]) under three nutrient supplement levels (NSLs) (NS0: no nutrients, NS1: nutrients (N and P) added to balance the stoichiometry of C:N:P to achieve 30% humification in RR at 5 t/ha, NS2: 3 × NS1). The results demonstrated a significant (p < 0.05) interaction effect of RR × NSL × residue placement on N2O emission. However, CH4 and GWP responses to the RR rate were independent of NSL. N2O fluxes ranged from −2.3 µg N2O-N kg−1 soil (R5 NS0 Rsur) to 43.8 µg N2O-N kg−1 soil (R10 NS2 Rinc). A non-linear quadratic model yielded the best fit for N2O emissions with RR rate (R2 ranging from 0.55 to 0.99) in all NSLs and residue placements. Co-applying wheat residue at 10 and 15 Mg/ha at NS1 reduced CH4 and N2O emissions (cf. R0 at NS1). However, increasing NSLs in NS2 reduced the nutrient stoichiometry to < 12:1 (C:N) and < 50:1 (C:P), which increased N2O emissions in all RR rates (cf. R0) across all residue placements. Averaged across nutrient levels and residue placements, the order of the effects of RR rates on CH4 emissions (µg C kg−1 soil) was R10 (5.5) > R5 (3.8) > R15 (2.6) > R0 (1.6). Our results demonstrated a significant linear response of total GWP to RR rates R15 > R10 > R5 > R0, ranging from 201.4 to 1563.6 mg CO2 eq kg−1 soil. In conclusion, quadratic/linear responses of GHGs to RR rates underscore the need to optimize RR rates with nutrient supplements and residue placement to reduce GHG emissions and GWP while ensuring optimal soil health and crop productivity. [ABSTRACT FROM AUTHOR]

Evaluating the impacts of high temperature-mediated changes in soil-plant systems is crucial in sustaining the productivity of heat-sensitive crops like chickpea (Cicer arietinum L.). Currently, the impact of a high temperature environment on soil processes and crop nutrition, particularly phosphorus (P), remains uncertain in tropical alkaline soils. Therefore, an open-top chamber-based experiment with ambient temperature [a(Temp)] and elevated temperature [e(Temp)] (+2 °C over ambient) aimed to investigate the impacts of high temperature environment on plant physiology, soilplant P dynamics, and yield of chickpea in a moderately-alkaline Vertisol of sub-tropical climate. The e(Temp) reduced Olsen-P (available-P) and NaHCO3-Pi at the flowering stage by 12% and 32%, respectively, as compared to a(Temp) treatment. The e(Temp) treatment markedly reduced KMnO4-oxidizable carbon (-25% to 42%), but did not alter water-soluble carbon. Alkaline phosphatase and ß-glucosidase activities were reduced under the e(Temp) treatment, while acid phosphatase activity remained unchanged. The elevated temperature had a significant impact on chlorophyll-b content (+18%), stomatal conductance (+5%), transpiration rate (+8%), and photosynthetic rate (-22%). The e(Temp) treatment did not alter total P uptake rather altered its distribution in grain (-16%) and stover (+17%) parts, resulting in a lower internal P use efficiency (-12%) and P harvest index (+15%). The e(Temp) treatment caused 12% yield loss compared to a(Temp) treatment. Therefore, this is concluded that retardation in P-mineralization along with terminal heat stress could impair P nutrition, physiological activity, and yield of chickpea. [ABSTRACT FROM AUTHOR]

This document is an editorial published in the journal Frontiers in Plant Science. It discusses the challenges of sustaining gains in crop productivity through CO2 fertilization under conditions of water and nutrient stress. The editorial highlights the potential benefits of increased atmospheric CO2 levels on plant growth and development, but also emphasizes the need to understand the combined effects of CO2 and temperature increases on plant responses, soil systems, and water and nutrient use efficiency. The document includes a summary of various studies that examine the effects of elevated CO2 on crop plants under different stress conditions, such as heat stress, drought stress, and nitrogen limitation. Overall, the editorial aims to provide insights and solutions for bridging the gap between the promise of CO2 fertilization and the reality of sustainable crop production in the face of climate change. [Extracted from the article]

Information on the fate of micronutrients in plant tissue and total uptake from soil upon exposure to elevated carbon dioxide (CO2) is meager. Hence, this field study was conducted in open top field chambers to investigate the effects of elevated CO2 and applied nitrogen (N) on partitioning and uptake of zinc (Zn), copper (Cu), iron (Fe), and manganese (Mn) in soybean crop under two CO2 and four N levels during 2016 and 2018 crop seasons. The two CO2 concentrations were ambient and elevated (∼550 µmol mol−1). Nitrogen treatments included application at 0, 50, 100, and 150% of the recommended dose. Significant effects of CO2 and N were observed on grain yield, biomass and uptake of the four micronutrients. Seed Fe concentration was significantly increased by 12% under CO2 enrichment. Tukey's post-hoc test revealed significantly higher grain yield, biomass and uptake of micronutrients in seed and straw under CO2 elevation and at higher N application. Uptake of Fe, Zn, Cu, and Mn increased by 53, 42, 36, and 41%, respectively, in seed and by 25, 26, 31, and 18% in straw under elevated CO2. Total uptake of Fe, Zn, Cu, and Mn increased by 39, 38, 34, and 29%, respectively. Nitrogen at 100% level enhanced uptake of Fe, Zn, Cu, and Mn by 25, 20, 32, and 28%. The study bears implications in micronutrient management for sustaining soil health under changing climate. [ABSTRACT FROM AUTHOR]

Conservation tillage has proven advantageous in improving soil health and productivity. However, the greenhouse gases (GHGs) emission and intensity from different conservation tillage and nutrient management systems under Indian conditions are less understood. Therefore, here, we compared the effect of tillage and nutrient management on GHGs emissions, net global warming potential (NGWP), and greenhouse gas intensity (GHGI) from a field experiment under five years in a soybean-wheat cropping system in the Vertisols. The tillage treatments comprised of reduced tillage (RT) and no tillage (NT). The three nutrient management treatments included application of 100% NPK (T1), 100% NPK + 1.0 Mg FYM-C ha-1 (T2), 100% NPK + 2.0 Mg FYM-C ha-1 (T3). The results showed significantly higher SOC sequestration under NT (1388 kg ha-1 yr-1) followed by RT (1134 kg ha-1 yr-1) with application of FYM (2.0 Mg C ha-1) (T3) every year. Across tillage, integrated nutrient management (T2 and T3) lowered NGWP and GHGI compared to NPK (T1). The GHGI of NT system was less by 33% compared to RT. The results suggest that GHGs mitigation and sustained food production in the soybean-wheat system can be achieved in NT and RT with integrated use of organic and inorganic fertilizer as the major component of nutrient management. [ABSTRACT FROM AUTHOR]

Studies on the effect of biochar on nitrate leaching are few. Hence, a laboratory column experiment was conducted using surface (0–20 cm) soil from three different land uses of a Vertisol, to investigate the effect of biochar amendment on leaching behaviour of nitrate and salts. The three selected land uses were: thick forest, agriculture land use with good soil fertility and good crop production history and agriculture land use with low soil fertility and poor crop production history. Biochar was added at 0, 0.5, 1.0 and 2.0% (w/w) to the soil in the upper half of the columns. The treatments were taken with three replications in a factorial completely randomized design. The PVC made columns (40 cm height and 11 cm internal diameter) filled with soil to a bulk density of 1.2 Mg m −3 were leached with deionized water once a week for 15 consecutive weeks. Nitrate in form of KNO 3 was added at the rate equivalent to 100 mg N kg −1 soil (220 kg ha −1 ) at each application in the 1st, 8th and 11th week. The forest soil showed significantly higher salt and NO 3 − -N leaching. Biochar amendment @ 0.5% or at higher level showed a significant reduction in NO 3 − -N leaching in the forest and good agriculture soil, whereas, in the poor agriculture soil, no significant effect was observed even at 2.0% biochar amendment level. With the highest level of biochar amendment (2%, w/w), reduction in NO 3 − -N leaching to the extent of 27% and 23% was observed in the forest and good agriculture soil, respectively. Biochar application significantly reduced salt leaching in the forest soil at 0.5% amendment level, and in the good agriculture soil at 1.0% level. At 2.0% biochar amendment, reduction in salt leaching to the extent of 18% and 16% was observed in the forest and good agriculture soil, respectively. [ABSTRACT FROM AUTHOR]

Atmospheric carbon dioxide (CO 2) concentration, temperature and nitrogen (N) are the key regulators of productivity and water use of plants under the changing climate. However, field scale studies on the interactive effect of the three above critical inputs are limited. Hence, this field study was conducted with three climate treatments (ambient (AC), elevated CO 2 (eC, ~550 µmol mol−1) and co-elevation of both CO 2 and temperature (eCeT, ~550 µmol mol−1 and temperature ~2 °C above ambient)) and four N treatments (0%, 50%, 100% and 150% of recommended N dose of 120 kg N ha−1). The experiment was carried out in open top field chambers to study the effects of climate and N application on grain yield, evapotranspiration (ET) and water use efficiency (WUE) in wheat crop. Crop ET was estimated by field water balance method and WUE by taking the ratio of grain yield to crop ET. Elevation of CO 2 showed 9% yield gain over ambient (averaged across N levels), whereas, co-elevation of temperature reduced the yield gain to 4%. Further, N application significantly altered the level of CO 2 response. Under CO 2 enriched environment, the yield gain was 15% with N 100 as compared to 2% and 4% under N 0 and N 50 , respectively, indicating CO 2 enrichment benefits in grain yield was N dependent. The three years' pooled data showed significant effect of climate, N and their interaction on profile water storage, evapotranspiration and WUE. Elevation of CO 2 alone or with co-elevation of temperature resulted in significant decline in crop ET by 4–11 mm and significant increase in profile soil moisture and WUE. The WUE improved significantly, by 12% under eC and by 4% under eCeT, respectively, with the increase, more attributed to gain in grain yield. Quantitative derivation from the three years' field experimentation could establish that under elevated CO 2 scenario (550 µmol mol−1), an additional 1 °C rise in temperature would result in enhanced crop ET by 5 mm and yield loss of about 4%. This study thus revealed that limited N and increased temperature would potentially restrict the CO 2 mediated benefits in wheat yield and water use under the changing climate. • CO 2 fertilization effect is N dependent, drastically reduced with low N application. • Elevation of CO 2 showed 15% yield advantage with recommended N application. • Higher profile water storage (7%) and lower ET under CO 2 elevation. • Higher water use efficiency by 4–12% under sole elevation of CO 2 or with temperature. • Co-elevation of temperature reduced the yield gain but improved water use efficiency. [ABSTRACT FROM AUTHOR]

Effect of conservation tillage on crop performance and soil properties has been studied extensively under different agro-climatic situations. However, the impact of reversal from conservation tillage to conventional tillage on crop growth and soil nutrient release is rarely addressed. Thus, this study was conducted by converting half of the eight years old conservation tillage experiment to the conventional one with a similar level of residue return to compare the effect on soil nutrient availability and nutrient uptake in soybean crops in the Vertisols of Central India. The conservation tillage treatments included no-tillage (NT) and reduced tillage (RT) with 100% NPK (T1), 100% NPK + farmyard manure (FYM) at 1.0 Mg-carbon (C)/ha (T2), and 100% NPK + FYM at 2.0 Mg-C/ha (T3). After eight years of the experiment, the RT and NT treatments were subjected to conventional tillage, and thus the tillage treatments were RT-CT, RT, NT, and NT-CT. After tillage reversal for three growing seasons, soybean yield and nutrient uptake (N, P, K) got significantly influenced by the tillage and nutrient management. Averaged across nutrient treatments, NT showed highest soil organic carbon (SOC) content (8.4 g/kg) in the surface 0–5 cm layer. However, at 5–15 cm depth, the SOC was greater in the RT-CT treatment by 14% over RT and by 5% in the NT-CT treatment over NT. The soil nutrient availability (N and P) was not significantly (p > 0.05) affected by the interaction effect of tillage and nutrient on the surface soil layer (0–5 cm). Interaction effect of tillage and nutrient was significant on available P content at 5–15 cm soil depth. In contrast to N, soil available P relatively increased with reversal of tillage in both NT and RT. Tillage reversal (NT-CT, RT-CT) and RT had significantly higher available potassium than NT in 0–5 and 5–15 cm soil layers. Among the treatments, NT-CT-T3 showed significantly higher seed N (85.49 kg/ha), P (10.05 kg/ha), and K (24.51 kg/ha) uptake in soybean. The study indicates conventional tillage with residue returns and integrated nutrient management could be a feasible alternative to overcome the limitations of no-till farming in the deep black Vertisols of Central India. [ABSTRACT FROM AUTHOR]

• Elevation of CO 2 (eC) and both CO 2 and temperature (eCeT) showed 32–47% yield advantage. • Stomatal conductance reduced by18-42% under eC and eCeT. • Significantly higher profile moisture storage and lower crop ET under eC and eCeT. • Water use efficiency increased by 37–50% under eC and eCeT treatments. • Reduction in soil evaporation due to higher leaf coverage explains lower water use. Rising concentration of atmospheric carbon dioxide (CO 2) is reported to cause fertilization effect resulting in enhanced crop biomass and yields and may alter the water use of plants. However, factors like air temperature and nitrogen (N) management could modify the feedbacks of CO 2 on crop water use. Hence, this field study was carried out in open top field chambers (OTC) for two crop seasons to investigate the interactive effects of climate and N on evapotranspiration, yield and water use efficiency in soybean (Glycine max L.). Soybean crop was grown under three climate conditions (ambient : AC, elevated CO 2 : eC, and co-elevation of both CO 2 and temperature : eCeT) and four N treatments during July to October 2016 and 2018. Elevation of CO 2 was done to the level of 535–540 μmol mol−1, and temperature was elevated by about 2 °C above ambient. The four N levels were N 0 , N 50 , N 100 and N 150 referring to 0, 50, 100 and 150% of recommended N dose (30 kg N ha−1). Crop evapotranspiration (ET) was computed by soil water balance method. The two years' field study indicated eC and eCeT showed significant yield advantage to the extent of 32-47% over ambient. Significant effect (P < 0.05) of climate was observed on crop ET, profile water storage and water use efficiency (WUE) during both the study years. The effect of N application on these three parameters was significant only in 2016 crop year. Averaged across N treatments, profile soil water storage at harvest was higher by about 5% in 2016 and by 9% in 2018 crop season under eC and eCeT treatments as compared to AC. The crop ET was significantly lower under eC and eCeT in both the years, with significantly higher WUE. The WUE varied from 2.99 to 4.48 kg ha−1 mm−1 in 2016 and from 4.62 to 6.42 kg ha−1 mm−1 in 2018 crop year. Stomatal conductance during major growth period reduced by 21–42% under eC and by 19–31% under eCeT, though it did not reflect in reduced transpiration. The study indicated significantly higher leaf area contributing to reduced soil water evaporation is the major mechanism explaining higher soil water profile under eC and eCeT. Over ambient, the WUE was higher by 48-50% in 2016 and by 37-39% in 2018 under eC and eCeT treatments, which was mostly attributed to higher grain yield. [ABSTRACT FROM AUTHOR]

Soil nutrient management is a key component contributing to the greenhouse gas (GHG) flux and mitigation potential of agricultural production systems. However, the effect of soil nutrient management practices on GHG flux and global warming potential (GWP) is less understood in agricultural soils of India. The present study was conducted to compare three nutrient management systems practiced for nine consecutive years in a soybean-wheat cropping system in the Vertisols of India, in terms of GHG flux and GWP. The treatments were composed of 100% organic (ONM), 100% inorganic (NPK), and integrated nutrient management (INM) with 50% organic + 50% inorganic inputs. The gas samples for GHGs (CO 2 , CH 4 , and N 2 O) were collected by static chamber method at about 15-day interval during 2012-13 growing season. The change in soil organic carbon (SOC) content was estimated in terms of the changes in SOC stock in the 0-15 cm soil over the 9-year period covering 2004 to 2013. There was a net uptake of CH 4 in all the treatments in both soybean and wheat crop seasons. The cumulative N 2 O and CO 2 emissions were in the order of INM > ONM > NPK with significant difference between treatments (p < 0.05) in both the crop seasons. The annual GWP, expressed in terms of CH 4 and N 2 O emission, also followed the same trend and was estimated to be 1126, 1002, and 896 kg CO 2 eq ha -1  year -1 under INM, ONM, and NPK treatments, respectively. However, the change in SOC stock was significantly higher under ONM (1250 kg ha -1  year -1 ) followed by INM (417 kg ha -1  year -1 ) and least under NPK (198 kg ha -1  year -1 ) treatment. The wheat equivalent yield was similar under ONM and INM treatments and was significantly lower under NPK treatment. Thus, the GWP per unit grain yield was lower under ONM followed by NPK and INM treatments and varied from 250, 261, and 307 kg CO 2 eq Mg -1 grain yield under ONM, NPK, and INM treatments, respectively.