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The crop nitrogen (N) use efficiency has been recognized as a useful indicator to measure the overall progress of the country towards achieving the sustainable development goal. Moreover, national level N use efficiency indicators are essential for improved estimate of global N budget and environmental impact assessment. We made an attempt to calculate the indicators of N use efficiency for rice at national and regional level in India. We utilized the data from research papers (23 no) published in reputed scientific journals and theses (83 no) submitted to different state agricultural universities over a period of 46 years (between 1972 and 2018). The partial factor productivity of N for rice in India ranged from 39.8 to 68.0 kg kg−1 with a national average value of 52.8 kg kg−1. The national average agronomic N use efficiency and nitrogen recovery efficiency (REN) were 18 kg kg−1 and 42.6%, respectively. Conducive agro-climatic condition coupled with improved crop management resulted in higher REN (>50%) in northern zone states of India. Whereas, rain-fed eastern and central zone states have REN<40%. The partial N balance (PNB) in rice ranged from 0.72–1.42 in India. The states with lower PNB need to reconcile their N addition with crop N uptake by adopting N responsive varieties and advanced fertilizer management to prevent environment degradation and economic loss. The findings of this study have significant implications for N budget estimation and policy decisions on hunger, food security and environment at national and global level. [ABSTRACT FROM AUTHOR]

A field study was conducted from 2021 to 2023 in a rice–wheat cropping system in the Terai agro-ecological zone of West Bengal, India, using different management practices, i.e., tillage (conventional tillage, CT, and zero tillage, ZT), crop residue (R), and plant growth-promoting bacteria (B). This study was a part of long-term research on resource conservation technology (conservation agriculture, CA), undertaken on a research farm in Uttar Banga Krishi Viswavidyalaya, Pundibari (Cooch Behar), West Bengal. The project was established in 2006 in acidic alluvial soil. The aim of this study was to evaluate rice–wheat productivity, nutrient uptake, soil quality, and profitability after the 16th and 17th crop cycles under the above-mentioned management practices. The results revealed that the pooled yield of rice grain and straw was significantly higher under the CT + R + B treatment than under the other treatments (ZT, ZT + B, ZT + R, ZT + R + B, CT, CT + B, and CT + R). However, the wheat grain and straw yields were significantly greater under the ZT + R + B treatment than under other treatments. The system's grain yield and straw yield were significantly higher under the CT + R + B treatment, on par with ZT + R + B, compared to the other treatments. Nutrient uptake (nitrogen, N; phosphorus, P; and potassium, K) was increased by retaining R and inoculating B compared to the sample without R and without B. Soil properties, including organic carbon, available N, available P, and available K, were improved in all the treatments compared to the initial values, but the impact was greater in the treatments with R and B than in those without R and without B. In the 5–10-cm soil layer, the above-mentioned soil properties were also improved over the initial (2006) values by 37, 126, 65 and 60%, respectively, by applying the best treatment (ZT + R + B). In economic terms, the benefit–cost ratio was significantly higher under the CT + R + B treatment for rice crops (2.99) and ZT + R + B for wheat crops (3.37). Therefore, we can conclude that, after 17 years of cultivation, for rice, CT-based treatments performs better than ZT-based treatments; meanwhile, for wheat cultivation, ZT-based treatments produces greater yields than CT-based treatments in the Terai agro-ecological zone of West Bengal, India. [ABSTRACT FROM AUTHOR]

Silchar City and its surrounding areas have witnessed massive population growth in the last few decades due to local and migrated peoples, which led to the rapid transformation of its land use/land cover (LU/LC) pattern. The spatio‐temporal very high‐resolution satellite data (VHRS) and on‐screen visual interpretation techniques were used for detailed large‐scale LU/LC analysis. The LU/LC classification of the City has been prepared for 2005, 2011, and 2018 with five primary and a further 17 sub‐classes. In the present study use was made of the Census of India reports from 1991 to 2011, and the geometrical increase method was used to evaluate the ward‐level population, population density, and land requirements for residential purposes; these have been predicted from 2021 to 2051 with every 10 years interval. The ity's wards have been classified into five zones, and the Shannon entropy model has been applied to analyze the degree of randomness and trends of urban built‐up growth. The obtained results indicate that Silchar City is compact near the center, which follows the infill built‐up growth trend. However, as the distance increased from its center, the scattering with an infill growth pattern was observed. The accuracy assessment techniques are used to validate the results of the classification. The results of this study can provide detailed information for land‐use planners, researchers, policy‐decision makers, and municipal authorities. [ABSTRACT FROM AUTHOR]

Microbial communities provide useful information about any chemical and physical changes in the environment and play an essential role in maintaining soil fertility. Biolog® eco-plates method was used to study the functional diversity of microbial communities, and their correlation with soil organic carbon (OC), microbial biomass and activities, under three different soil conditions of Sukinda chromite mining area of Odisha, India during August 2016. The OC, available nitrogen, available phosphorus and available potash were significantly (p < 0.05) lower in in situ and overburden soils as compared to forest soil. The average development rate of average well color development values decreased with incubation time in all soil conditions. The utilization of six categories of carbon sources by soil microbes decreased with the increase in chromium load and biplot analysis suggested that carbohydrate, polymer and amino acid utilizing microbes were dominant in mining soils. The ecotoxicological status of chromite mine soil would be useful for formulating strategies of possible bioremediation program. [ABSTRACT FROM AUTHOR]

A new concept to estimate the passenger car unit (PCU) of different types of vehicles under mixed traffic conditions is presented. It utilizes the area, as opposed to only the length, and speed of a vehicle. Data were collected at ten sections of two-lane roads in different parts of India. The width of carriageway (this term is commonly used in India for the total width of the paved surface of a road excluding its shoulders) ranged from 5.5 to 8.8 m. All vehicles were divided into nine different categories and their PCU’s were estimated at each road section. It was found that the PCU for a vehicle type increases linearly with the width of carriageway. This is attributed to the greater freedom of movement on wider roads and therefore a greater speed differential between a car and a vehicle type. The capacity of a two-lane road also increases with total width of the carriageway and the relationship between the two follows a second-degree curve. This relationship is used to derive the adjustment factors for substandard lane widths and the results are compared with literature. [ABSTRACT FROM AUTHOR]

Grassland is a highly dynamic land use system and it provides vital ecosystem services, mainly consisting of carbon storage in the tropics and subtropics. The objective of this study was to delineate grassland in India according to soil characteristics and carbon pools in comparison to native forestland, and to discuss management strategies for improving soil carbon (SC) storage in grassland. A total of 675 paired datasets from studies on grassland and forestland in India generated during the period of 1990–2019 were used for meta-analysis study. The analysis shows that soil pH and bulk density (BD) in grasslands were greater by 1.1% and 1.0% compared to forestlands while soil organic carbon (SOC) declined by 36.3% (p < 0.05). Among carbon pools, labile carbon (LC), non-labile carbon (NLC), and microbial biomass carbon (MBC) were 35.5%, 35.3% and 29.5% lower, respectively, in the grassland compared to the forestland. Total carbon (TC) was 35.0% lower in the grassland than the forestland (p < 0.05). Soil carbon stocks (SCS) were 32.8% lower in the grassland compared to the forestland. In the grassland, MBC/SOC (%) from the surface layer and subsurface layer were lower by 2.4% and 8.5%, respectively compared to forestland. The percentage effect size was found to have decreased from surface soil to subsurface soil. Relative SCS loss and carbon dioxide equivalent emission from the grassland compared to forestland were 15.2% and 33.3 Mg ha−1, respectively (p < 0.05). Proper management strategies like agroforestry, legume introduction, silvipastoral system, fertilization, irrigation, and quality grass species could improve SC storage and reduce SCS loss in grassland. Overall, this study gives an idea that conversion of native forestland into grassland in India has declined the SC content and hence it is necessary to adapt proper strategies to manage the soil-atmosphere carbon balance. [ABSTRACT FROM AUTHOR]

Elevated carbon dioxide (eCO 2), higher dose of recommended nitrogen (HDN), and water deficit stress (WDS) are three important factors which influence individually on diazotrophic community in paddy soil, thereby affecting crop yield and its nitrogen use efficiency. However, the combined effects of eCO 2 , HDN, and WDS on soil diazotrophic community remains inadequate particularly in rice. Hence, the present study was conducted in CO 2 -maintained open-top chamber to assess the diazotrophic community under combined influence of eCO 2 (550 ± 20 μmol mol−1 as compared to ambient CO 2 i.e. 400 ± 10 μmol mol−1) and HDN (120 kg N ha−1, 50% higher than recommended dose of N for rice i.e. 80 kg N ha−1, in sub-humid tropical region of eastern India) with and without WDS (−60 kPa) at two growth stages of rice (tillering, TI and panicle initiation, PI) and correlated with soil carbon (C) pools and enzyme activities. The results indicated that soil organic C, readily mineralizable C, microbial biomass C, acid and alkaline phosphatase activities were significantly (p < 0.05) increased under combined influence of eCO 2 and HDN at both TI and PI stages of rice without WDS. The results also showed that abundance of nifH varied from ambient CO 2 (aCO 2) to eCO 2 and found higher in aCO 2 under recommended dose of nitrogen (RDN) without WDS, whereas under eCO 2 , nifH copy number was found higher under HDN at both TI and PI stages of rice without WDS. Biplot analysis revealed that abundance of nifH and nitrifiers were highly correlated under aCO 2 coupled with RDN without WDS. Illumina MiSeq®-based targeted nifH metagenome showed that eCO 2 encouraged the relative abundance of Proteobacteria and Cyanobacteria, whereas suppressed the other diazotrophic phyla like Actinobacteria, Firmicutes, and Chlorobi, but the reverse trend was observed in HDN treatments. Heatmap analysis revealed a unique differentiation of Rhizobiales and Pseudomonadales under eCO 2 coupled with RDN without WDS. Moreover, three-way interactions of eCO 2 , HDN, and WDS also showed significant (p < 0.05) difference of soil C pools and enzymatic activities at both growth stages of rice. Overall, the present study showed that diazotrophic community in paddy soil was significantly (p < 0.05) altered by the additive effects of eCO 2 , HDN, and WDS. • Diazotrophs were analyzed under combined influence of eCO 2 , HDN, and water deficit paddy soil. • Abundance of nifH was significantly increased under combined effects of eCO 2 and HDN. • nifH- Illumina MiSeq® revealed that 35.6 to 66.2% of OTUs belonged to Bradyrhizobiaceae. • Rhizobiales and Pseudomonadales were predominant in eCO 2 and RDN without WDS. • eCO 2 and HDN significantly increased the soil carbon pools and enzyme activities in paddy soil. [ABSTRACT FROM AUTHOR]

• We studied the impact of 47-year long fertilization on mineralogical transformation. • Clay size mica loses crystallinity & becomes finer during intensive rice cultivation. • NP + FYM treatment recorded the highest total oxalate extractable Si, Al & Fe oxide. • P & K fixation is controlled by fertilization rather by short-range order minerals. • Carbon fractions had a positive correlation with short-range order minerals. The effect of long-term fertilizer and manure applications on short-range order (SRO) and crystalline mineral transformation was studied in a 47-year puddled rice-rice cropping system experiment in Odisha, India. The relationship of SRO minerals with phosphorus and potassium fixation capacity and soil carbon fractions was also evaluated. Soils from different treatment combinations of farmyard manure (FYM), nitrogen (N), phosphorus (P) and potassium (K) were separated in two ways: (i) removal of binding materials (ii) non-removal of binding materials (ultrasonic vibration), followed by fractionation of the contents into silt and clay. All crystalline minerals, SRO minerals, P and K fixation were measured in silt and clay. The X-ray diffractograms of clays (<2 μm) were recorded in Philips Diffractometer (model PW 1710). Selective dissolutions of SRO minerals were carried out by extraction with sodium hydroxide, acid ammonium oxalate, dithionite-citrate-bicarbonate and sodium pyrophosphate. The results showed that the soils were composed of kaolin (49.6–54.4%), mica (32.7–39.0%) and smectite (10.6–17.0%). The clay-size mica loses its crystallinity and becomes finer after the addition of fertilizers and manure during intensive rice cultivation. The content of amorphous ferri-aluminosilicate varied from 8.0 to 16.23 g 100 g−1 in clay and 1.49–3.38 g 100 g−1 in silt. The plots treated with NP + FYM had the highest total oxalate extractable oxide in both clay and silt. Application of FYM increased ferrihydrite in both clay and silt. Potassium fixation was higher in plots skipped with the long-term application of K. Formation of SRO minerals was positively affected by nutrient stress caused by the omission of one or more nutrients. SRO minerals in the rice soil did not have a major effect on the fixation of K and P; rather, it is controlled by the fertilizer and FYM application. However, carbon fractions had a significant positive correlation with SRO minerals. [ABSTRACT FROM AUTHOR]

In the quest of achieving sustainable crop productivity, improved soil health, and increased carbon (C) sequestration in the soil, conservation agriculture (CA) is increasingly being promoted and adopted in the Indian subcontinent. However, because some researchers from different regions of the world have reported reduced crop yield under CA relative to agriculture based on conventional tillage (CT), a meta-analysis has been conducted based on published research from India to evaluate the effects of CA on the yield of crops, accumulation of soil organic C as an index of soil health, and C sequestration in the soil in different regions and soil textural groups in the country. The meta-analysis is based on 544 paired observations under CA and CT from 35 publications from India was carried out using Meta Win 2.1 software. The results showed an overall significant (p < 0.05) reduction of 1.15% crop yield under CA compared to CT. Yearwise data showed a reduction of yields under CA from 2009 to 2016, but an increase from 2017 to 2020. Yield reduction was observed in the eastern, north-eastern, and southern regions of India but in western, northern, and north-western regions of the country, an increase was observed under CA rather than CT. Sandy loam and clayey soils exhibited higher crop yield under CA than under CT. Compared to CT, soil organic C content and soil C sequestration under CA increased by 8.9% and 7.3%, respectively. Also, in all the regions and soil textural groups both soil organic C accumulation and soil C sequestration were higher under CA than under CT. Factors such as rainfall, soil depth, available nitrogen (N), and total N significantly influenced the extent of yield increase/decrease and soil organic C accumulation under CA. Overall, results of the meta-analysis suggest that the promotion of CA in India will have to be location-specific taking into consideration the crops, soil attributes, and climatic conditions., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Crop residue management has become more challenging with intensive agricultural operations. Zero tillage and crop residue returns, along with the enhancement of in-situ residue decomposition through microbial intervention, are essential measures for preserving and enhancing soil quality. To address this problem in view of stubble burning, field experiments were conducted in rice-rice (variety Swarna) cropping systems under lowland conditions, wherein the following different residue management practices were adopted viz., conventional cultivation (CC), residue incorporation (RI @ 6 t paddy straw ha -1 ), residue retention (RR @6 t paddy straw ha -1 ), and zero tillage (ZT). In this experiment, two microbial products i.e. solid microbial consortium (SMC) at 2.0 kg ha -1 ) and capsule (10 numbers ha -1 ), were evaluated in both Rabi (dry) and Kharif (wet) seasons under different residue management practices. The results on soil microbial properties showed that application of either SMC or capsule based formulation could significantly improve the soil organic carbon (SOC) content in ZT (9.51 g/kg), followed by RI (9.36 g/kg), and RR (9.34 g/kg) as compared to CC (7.61 g/kg). There were significant differences in the soil functional properties (AcP, AkP, FDA, and DHA) with microbial interventions across all residue management practices. SOC was significantly positive correlated with cellulase (R 2  = 0.64, p < 0.001), β-glucosidase (R 2  = 0.61, p < 0.001), and laccase (R 2  = 0.66, p < 0.001) activity; however, the regression coefficients varied significantly with microbial intervention. Moreover, the availability of N, P, and K in soil was significantly (p < 0.05) improved under microbial treatments with either RR or RI practices. Among the different methods of residues management practices, RI with microbial intervention registered a consistent yield improvement (8.4-17.8%) compared to conventional practices with microbial intervention. The present findings prove that the application of decomposing microbial consortia for in-situ rice residue management under field conditions significantly enhances soil quality and crop yield compared to conventional practices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)