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With the increasing water scarcity and the demand for sustainable agriculture, precise estimation of crop evapotranspiration (ET) is crucial for effective irrigation management, crop yield assessment, and equitable water distribution, particularly in semi-arid regions. In this study, a large aperture scintillometer (LAS) was used to validate the remote sensing-based ET model SETMI (Spatial Evapotranspiration Modeling Interface) in an irrigated maize-wheat cropping system in a semi-arid region at the ICAR-Indian Agricultural Research Institute, New Delhi. Results obtained by the SETMI model depicted modeled surface energy fluxes compared well with LAS field data, showing a very high R2 (0.83–0.95) and NRMSE (8–29%). The SETMI model performed better in the case of the maize crop than the wheat crop in field experiments. Further, the SETMI model was employed at the regional level using high-resolution Sentinel-2 to estimate the regional water productivity of wheat crops over a semi-arid region in India. The estimated regional, seasonal wheat actual ET mainly ranged between 101 mm and 325 mm. The regional wheat water productivity varied from 0.9 kg m−3 to 2.20 kg m−3. Our research reveals that the SETMI model can give reliable estimates of regional wheat water productivity by examining its spatial and temporal fluctuations and facilitating the creation of regional benchmark values. [ABSTRACT FROM AUTHOR]

China and India are the two top consumers of fertilizer nitrogen (N) in the world not only to provide food security to 36% of the global population living in the two countries but also due to fertilizer-related government policies being followed during the last more than 50 years. Excessive fertilizer N use is now a cause of N-related environmental pollution as well as a concern for climate change. Nitrogen use efficiency (NUE) at farmers' fields dictates both production of food crops as well as loss of N to the environment including efforts to curb climate change due to N2O emission. We used a gridded database on N input and N output for wheat, rice, and maize in China and India from 1961 to 2013 to synthesize the dynamics of NUE (percentage of applied N used by the crop) and surplus N (difference between total N input and N output) and in the light of relevant literature interpreted it in terms of past and future fertilizer N management scenarios and fertilizer related policies in the two countries. From 1961 to 2013, the percentage of fertilizer N in total N input in cereal crop production increased from 8-10% to 71-75% in India and from 30-37% to 80-84% in China. In both India and China, NUE has been continuously declining and in 2013 it was in the range of 20-24% (except 32% for wheat in India) due to several-fold increases in fertilizer N use and imbalanced use of fertilizer nutrients (particularly in India)--a consequence of huge subsidies provided by the governments on different fertilizer products. Estimates of maximum N output in the form of crop yield at saturating N input regimes determined from trajectories of N output as a function of total N input for 1961-2013 and 2001-13 revealed that crop and fertilizer N management for rice, wheat, and maize in India and China did not improve significantly since the Green Revolution era. As a large number of studies in India and China show that NUE can be increased by the advancement of technology front in terms of crop and fertilizer management and by reducing the fertilizer N rate without a significant reduction in the yield of crops, recommendations have been given for governments (to frame suitable policies), farmers, extension agencies, and fertilizer dealers. [ABSTRACT FROM AUTHOR]

Salinity is one of the most significant constraints to crop production in dry parts of the world. This research emphasizes the beneficial effects of plant growth-promoting rhizo- bacterial isolates (PGPR) on the physiological responses of maize and wheat in a saline (NaCl) environment. Soil samples for the study were collected from a maize field in Baddi, Himachal Pradesh, India. Isolated bacterial strains were screened for salt (NaCl) toler- ance and plant growth-promoting characters (i.e., indole acetic acid (IAA) production, siderophore production, amino cyclopropane-1-carboxylic acid (ACC) deaminase activ- ity, hydrogen cyanide (HCN) production, and mineral phosphate solubilization). Screened bacterial isolates were further tested in pot experiments to examine their effects on wheat and maize growth. The treatments included five levels of bacterial inoculation (P0: control, P1: ACC deaminase positive + siderophore producer + NaCl tolerant bacteria, P2: mineral phosphate solubilizer + HCN producer + NaCl tolerant bacteria, P3: IAA producer + ACC deaminase positive + NaCl tolerant bacteria, P4: bacterial consortium, P5: Phosphomax commercial biofertilizer) and salt stress at 6 dS/m. Research findings found that exposure to a bacterial consortium led to the highest growth parameter in maize, including shoot length, root length, shoot and root dry weight followed by P2, P3, and P5 treatments at 6 dS/m salinity levels. However, P2 showed the best results for wheat at the same salinity levels, followed by P3, P4 and P5 treatments. P1 treatment did not show a significant result compared to control at 6dS/m salt level for both crops. The maximum proline content in maize and wheat was observed in P4 (23.28 μmol · g−1 ) and P2 (15.52 μmol · g−1 ) treatments, respectively, followed by P5 with Phosphomax biofertilizer. Therefore, the study proposed the application of growth-promoting bacterial isolates as efficient biofertilizers in the Baddi region of Himachal Pradesh, India. [ABSTRACT FROM AUTHOR]

Long-term effects of integrated application of organics and chemical fertilizers on transformation of copper (Cu) into various chemical pools and their availability under maize–wheat cropping system were investigated in the ongoing long-term fertilizer experiment initiated in 1972 at the research farm of Chaudhary Sarwan Kumar Himachal Pradesh Agricultural University on an acidic soil in the Western Himalayas of India. The continuous use of chemical fertilizers alone for 36 years brought about marked depletion in all forms of copper except organically bound Cu (Cu-III) compared to buffer plots. Integrated use of organics and chemical fertilizers gave higher content of Cu forms over chemically treated plots except Cu occluded by free oxides (Cu-IV). Residual Cu was the most dominant form of copper contributing about 62% of the total Cu. Organically bound Cu (Cu-III) was the most important fraction of copper contributing toward DTPA (diethylene triamine pentaacetic acid) extractable Cu. Content of DTPA-extractable Cu increased over control when chemical fertilizers were applied in conjunction with different organics, whereas DTPA-Cu content declined over control with application of chemical fertilizers alone for the last 36 years. [ABSTRACT FROM AUTHOR]

India is one of the largest landmasses under crop cultivation with staple consumption of food security crops. Post green revolution (since 1967), there has been a steady March towards self-sustainability in food production. Though the general trends speak of an increase in crop yields, the detailed study on decade wise trends and fast approaching state of stagnation in crop yields is largely missing. The present manuscript is the first study examining the crop yield trends of three major food crops—wheat, rice, and maize across Indian states. The four types of regression models were fitted on the annual yield data from all the 29 Indian states over the period 1967–2017. The best-fit statistical models were chosen using the Akaike information criterion. Our results suggest that (1) Wheat yields in 13 Indian states, rice yields in eleven Indian states, and maize yields in six Indian states are now not improving. (2) The yields in ~ 76% of wheat harvested area (~ 18.5 million hectares), ~ 47% of rice harvested area (~ 19.5 million hectares), and ~ 18% of maize harvested area (~ 1.2 million hectares) are not improving for the recent decade. The detailed mapping of current crop yield trends across Indian states is the first step towards achieving a bigger goal of identifying the responsible factors affecting current crop yield trends and then identifying and recommending appropriate mitigation strategies. [ABSTRACT FROM AUTHOR]

Abstract India is an agrarian country generating surplus amounts of paddy, wheat, and maize crop residues at large scale, which are not being managed properly. The anaerobic digestion is an efficient way of managing these residues in an environmentally friendly manner. It results in high calorific methane gas and fertile rich digestate. The current study focused on reviewing the availability, methane potential and technological developments to improve the methane production of crop residues. The methane potential from the anaerobic digestion of surplus paddy, wheat, and maize residues in India is estimated as 18,677 Mm3/year (632 × 109 MJ/year). The methane potential of crop residues could substitute 52 Mt/year of coal utilisation that evades 46 Mt/year of net CO 2 emissions from releasing into the atmosphere. Highlights • Technological developments in anaerobic digestion of crop residues are discussed. • Co-digestion of crop residues with nitrogen rich substrates improves the efficiency. • Pre-treatment methods and recirculation digestate improves the efficiency. • Anaerobic digestion of crop residues had net energy potential of 632 × 109 MJ/year. [ABSTRACT FROM AUTHOR]