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Context Biological quality of soil under rice-based cropping in Indo-Gangetic Plains of India is greatly influenced by different tillage and residue management practices. Aims The objectives of this study were to determine the effect of seasonal variation on enzyme activity and assessing biological soil quality (BSQ) under conservation agriculture (CA)-based rice–mustard cropping. Methods Soil samples were collected in the ninth year of a medium-term CA-based experiment in autumn, winter, spring and summer seasons from two soil depths (0–5 cm, 5–15 cm) and analysed for biological attributes (microbial biomass carbon, MBC; Walkley–Black carbon, WBC; total organic carbon, TOC), and enzyme activities (dehydrogenase, acid and alkaline phosphatase, and arylsulphatase). Key results A CA-based triple zero till (ZT) system with three crops residue treatments (ZT direct-seeded rice (DSR) with mungbean residue; ZT mustard (ZTM) with rice residue; and ZT summer mungbean (SMB) with mustard residue (∼ZTDSR–ZTM–ZTSMB (+R)) resulted in highest values of MBC, WBC and TOC at the 0–5 cm soil depth. Enzymes activities were highest during summer. Principal component analysis (PCA) and showed that arylsulphatase activity and TOC were sensitive indicators of BSQ. To validate soil quality indices (SQIs), regression analyses with rice equivalent yield (REY) of the rice–mustard system were done and better relationship observed with biological soil quality indices (BSQI) BSQIGMean (0.69–0.71) than BSQIPCA (0.65–0.66) based method. Conclusions Treatment with ZTDSR–ZTM–ZTSMB (+R) had the highest values of BSQI using GMean and PCA. Implications This CA-based triple ZT with residue practice [ZTDSR–ZTM–ZTSMB (+R)] is recommended for rice–mustard cropping for maintaining higher biological quality of soil in this region of India.

Global soils are under extreme pressure from various threats due to population expansion, economic development, and climate change. Mapping of land degradation vulnerability (LDV) using geospatial techniques play a significant role and has great importance, especially in semi-arid climates for the management of natural resources in a sustainable manner. The present study was conducted to assess the spatial distribution of land degradation hotspots based on some important parameters such as land use/land cover (LULC), Normalized Difference Vegetation Index (NDVI), terrain characteristics (Topographic Wetness Index and Multi-Resolution Index of Valley Bottom Flatness), climatic parameters (land surface temperature and mean annual rainfall), and pedological attributes (soil texture and soil organic carbon) by using Analytical Hierarchical Process (AHP) and GIS techniques in the semi-arid region of the Bundi district, Rajasthan, India. Land surface temperature (LST) and NDVI products were derived from time-series Moderate-Resolution Imaging Spectroradiometer (MODIS) datasets, rainfall data products from Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), terrain characteristics from Shuttle Radar Topography Mission (SRTM), LULC from Landsat 9, and pedological variables from legacy soil datasets. Weights derived for thematic layers from the AHP in the studied area were as follows: LULC (0.38) > NDVI (0.23) > ST (0.15) > LST (0.08) > TWI (0.06) > MAR (0.05) > SOC (0.03) > MRVBF (0.02). The consistency ratio (CR) for all studied parameters was

Zinc (Zn) is the most deficient micronutrient globally resulting in malnutrition and requires improved mode of delivery for increased nutrient use efficiency. An innovative fertilizer formulation, ...

The present experiment was conducted during 2018-19 under the ongoing All India Coordinated Research Project on Long-term Fertilizer Experiment with soybean-wheat cropping sequence since 1972 at the Research Farm of Department of Soil Science and Agricultural Chemistry, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh, India. The microbial properties and nitrogen (N2) fixation of soil under different nutrient combinations were studied in a 46-year old long-term fertilizer experiment in a Vertisol. The experiment was conducted in a randomized block design comprising of 10 treatments viz., T1: 50% NPK, T2: 100% NPK, T3: 150% NPK, T4: 100% NPK + Hand weeding (100% NPK+HW), T5: 100% NPK + zinc (100% NPK + Zn), T6: 100% NP, T7: 100% N, T8: 100% NPK+ 5 t FYM ha-1 (100% NPK+FYM), T9: 100% NPK(–S) and T10: Control, each treatment being replicated four times in a randomized block design. Soil samples from all the treatments were collected from 0–15 cm depth and microbial properties and N2 fixation of soil were estimated. Significant increase in soil organic carbon, total N and available N were recorded with 100% NPK+FYM. Similarly, the maximum number of nodules and their biomass were also recorded in 100% NPK+FYM treatment at 30, 45 and 60 days after sowing. The bacteria, fungi and actinomycetes population counts in soil were 39.1×107, 42.7×104 and 39.1×105 cfu g-1 soil, respectively with the integrated application of inorganic fertilizer and organic manure (100% NPK+FYM) over control (11.7×107, 18.5×104 and 13.6×105 cfu g-1 soil, respectively). Further, the conjoint use of balance dose of fertilizers with FYM was also significantly superior in terms of soil microbial biomass carbon and microbial biomass N over other treatments even after 46 years of experimentation. The grain and straw yield of soybean and their N uptake were also significantly increased with graded dose of fertilizers and maximum yield and N uptake were noted in 100% NPK+FYM treatments over control plot.

An attempt has been made to assess the geoavailability of heavy metals in polluted soils using short sequential fractionation schemes. For this purpose, 25 composite soil samples were collected fro...

The present investigation was aimed at distribution of nitrogen (N) fractions in a 44-year-old (1972–73 to 2016–17) long-term fertilizer experiment on soybean-wheat cropping system in a Vertisol. The experiment included eight treatments comprising of different doses of fertilizers viz. 50% NPK, 100% NPK, 150% NPK, 100% NP, 100% N, 100% NPK + 5 t FYM, 100% NPK(−S) and control and replicated four times in a randomized block design. The applications of 100% recommended dose of fertilizers (NPK) with organic manure (5 t FYM ha−1) led to significant increases in organic carbon, total N, hydrolyzable-N (i.e., amino acid-N, hydrolyzable NH4+-N, hexose-amine-N) and non-hydrolyzable-N in both soil depths (0–15 and 1530 cm) as compared to control plot and their concentration was decreased with increasing soil depth. The result clearly indicates that both surface (0–15 cm) and sub-surface (15–30 cm) soil layers substantially contributed to the N requirement of soybean and wheat. The contents of various organic N fractions were higher in organic manure compared to untreated plots. The study revealed significant correlations of soil N mineralization with amino acid and hexose-amine-N fractions at 0–15 cm depth and hydrolyzable NH4+-N and amino acid-N fractions at 15–30 cm. Grain yields of soybean and wheat showed better correlations between amino acid-N in surface and hydrolyzable NH4+-N in the sub-surface soil layers with yields of soybean and wheat.

In view of scarcity of information, effectiveness of toxicity characteristics leaching procedure (TCLP) in assessing metal hazards of polluted soils was evaluated in relation to human health. Total...

Soil acidity, one of the causes of soil degradation, adversely affects phytoavailability of soil nutrients and crop growth in 50% of arable land of the world. There is a persistent need for...

Soil degradation due to elevated levels of metals is considered as a potent threat to soil quality and human health. Present investigation was carried out to develop a protocol for assessing degree of soil degradation in relation to metal accumulation due to long-term use of waste water and municipal solid-waste. For this purpose, surface soil samples having a long-history of receiving industrial-effluents, sewage, polluted river-water and municipal solid-waste were collected. Computation of conventional metal accumulation indices indicated metal-specific differential soil pollution at different sites. Multivariate analysis considering important physicochemical properties and ethylenediamine triacetic acid (EDTA)-extractable metal content of soil revealed more comprehensive status of soil-degradation due to metal accumulation. Results indicated that soils irrigated with cycle-factory effluent (soil quality index, SQI 0.42) were the most degraded and soils irrigated with polluted river-water (SQI 0.94) were the least degraded due to metal pollution. Hierarchical clustering suggests that quality of tube-well, river and sewage-effluent irrigated soils are almost similar, which differs significantly from other soils receiving industrial-effluents and solid-waste.

Fertilizer use in Indian agriculture is skewed towards nitrogen (N) and phosphorus (P), and farmers generally neglect potassium (K) input ignoring K requirement of crops. We, therefore, studied the long-term effect of imbalanced fertilization (i.e. without K) on K supplying capacity of a kaolinitic red soil (Typic Haplustalf) after 42 years of intensive cultivation. Soil samples (0–15 and 15–30 cm) were collected after the completion of 42 cropping cycles from an on-going long-term fertilizer experiment located at Birsa Agricultural University, Ranchi, India, from six treatments, viz. control (unfertilized), fertilizer N, NP, NPK, 150% NPK (1.5 times of NPK) and NPK + FYM (NPK + farmyard manure), along with adjacent uncultivated land. Soil K pools, clay minerals, quantity-intensity relationship and K release kinetics along with grain yield and K uptake of soybean and wheat were studied. Among the treatments, NP treated soils showed the lowest amounts of labile (KL) and non-exchangeable K (Knex). Equilibrium activity ratio (AReK) and non-specifically held K (−ΔK0) were also lowest under NP treatment. The gap between equilibrium exchangeable K (EK0) and minimum exchangeable K (EKmin) was minimum under NP. Cropping and fertilization-induced transformation in clay minerals was noticed wherein continuous neglect of K fertilizer led to a decrease in illite content with a concomitant increase in interstratified minerals. On the other hand, noticeably lower alteration in clay minerals and comparatively less depletion in overall K-supplying capacity of soil were recorded under K addition as compared to imbalanced fertilization (i.e. without K). Soybean showed a significant positive response to K application. The study thus underlined the necessity of adequate K input for the sustenance of soil health, inherent K-supplying capacity and crop productivity.

For remediating polluted soils, phytoextraction of metals received considerable attention in recent years, although slow removal of metals remained a major constraint in this approach. We, therefore, studied the effect of selected organic and inorganic amendments on the solubility of zinc (Zn), cadmium (Cd), and lead (Pb) in polluted soil and enhancing the efficacy of phytoextraction of these metals by Indian mustard (Brassica juncea cv. Pusa Vijay). For this purpose, a greenhouse experiment was conducted using a metal-polluted soil to evaluate the effect of amendments, viz. green manure (T2), EDTA (T3), sulfur (S)+S oxidizing bacteria (Thiobacillus spp.) (T4), metal-solubilizing bacteria (Pseudomonas spp.) (T5), and green manure + metal-solubilizing bacteria (T6), on solubility and bioavailability of Zn, Cd, and Pb. Distribution of metals in different soil fractions revealed that Cd content in water soluble + exchangeable fraction increased to the extent of 34.1, 523, 133, 123, and 75.8% in T2, T3, T4, T5, and T6 treatments, respectively, over control (T1). Cadmium concentrations in soil solution as extracted by Rhizon sampler were recorded as 3.78, 88.1, 11.2, 6.29, and 4.27 μg L−1in T2, T3, T4, T5, and T6, respectively, whereas soil solution concentration of Cd in T1 was 0.99 μg L−1. Activities of Cd (pCd2+) in Baker soil extract were 12.2, 10.9, 6.72, 7.74, 7.67, and 7.05 for T1, T2, T3, T4, T5, and T6, respectively. Cadmium contents in shoot were recorded as 2.74, 3.12, 4.03, 4.55, 4.68, and 4.63 mg kg−1 in T1, T2, T3, T4, T5, and T6 treatments, respectively. Similar trend in Zn and Pb content with different magnitude was also observed across the different amendments. Cadmium uptake by shoot of mustard was enhanced to the extent of 125, 62.5, 175, 175, and 212% grown on T2-, T3-, T4-, T5-, and T6-treated soil, respectively, over T1. By and large, free ion activity of metals as measured by Baker soil test proved to be the most effective index for predicting Zn, Cd, and Pb content in shoot of mustard, followed by EDTA and DTPA. Among the metal fractions, only water soluble + exchangeable metal contributed positively towards plant uptake, which explained the variation in shoot Zn, Cd, and Pb content to the extent of 74, 81, and 87%, respectively, along with other soil metal fractions. Risk to human health for intake of metals through the consumption of leafy vegetable (mustard) grown on polluted soil in terms of hazard quotient (HQ) ranged from 0.64 to 1.10 for Cd and 0.11 to 0.34 for Pb, thus rendering mustard unfit for the human consumption. Novelty of the study mainly consisted of the use of natural means and microorganisms for enhancing solubility of metals in soil with the ultimate aim of hastening the phytoremediation.

Wheat (Triticum aestivum L.) is one of most important rabi cereal crop of northern Madhya Pradesh in India. The availability of phosphorus in the soil for plant utilization is known to be affected not only by the inherent soil characteristics but also by the fertilizer use and management practices followed for crop production. Therefore, a study on the response of phosphorus on farmer field for improving wheat productivity was performed at Jabalpur, India. In between the technology intervention HRD components were also included to excel the farmers understanding and skill about the demonstrated technology on nutrient management aspects. The front line demonstration conducted at six farmer's field of village's viz. Luhari, Gathora, Ghatera, Kanthi and Gurda pipariya on wheat (variety GW-366) during Rabi 2015-16. The soil contained pH 6.5 to 7.2, EC 0.16 to 0.21 dSm-1, organic carbon 0.49 to 0.69%, available nitrogen 204 to 254 Kg ha-1, phosphorus 7.1 to 16.2 Kg ha-1 and potassium 411 to 470 Kg ha-1.The experiment included 5 treatments viz., T1 - 100% NPK + 5 t FYM ha-1, T2 - 100% NPK, T3 - 100% NK+ 50% K, T4 - 100% NPK – (S) and T5 – farmer's practice. The result indicated that the treatment T1-100% NPK+FYM produced the highest average yield of wheat. The lowest yield was recorded in T5-farmer's practice. The highest increase in yield (26%) was observed with 100% NPK + FYM over farmer's practice, followed by 13% increase in yield (100% NPK) of wheat over farmer's practice.

Soil physical degradation is one of the serious production constraints in the Indo-Gangetic Plain region. The present investigation was undertaken to study the effect of different nutrient manageme...

Potassium (K) demand by crops is almost as high as that of nitrogen (N) and plays a crucial role in many plant metabolic processes. Insufficient K application results in soil K mining, deficiency symptoms in crops, and decreased crop yields and quality. Crop K demands vary with crop types, growth patterns, nutrient needs at different physiological stages, and productivity. Science-based K application in crops needs to follow 4R Nutrient Stewardship to ensure high yield, improved farm income, and optimum nutrient use efficiency. Studies around the world report widespread K deficiency, ranging from tropical to temperate environments. Long-term experiments indicate significant yield responses to K application and negative K balances where K application is either omitted or applied suboptimally. Limited understanding of K supplementation dynamics from soil non-exchangeable K pools to the exchangeable and solution phases and over-reliance on native K supply to meet crop demand are major reasons for deficit of K supply to crops. Research on optimum timing of K fertilizer application in diverse climate–soil–crop systems is scarce. The common one-time basal K management practice is often not suitable to supply adequate K to the crops during peak demand phases. Besides, changes in crop establishment practices, residue retention, or fertigation require new research in terms of rate, time, or source of K application. The current review assesses the synchrony of K supply from indigenous soil system and from external sources vis-à-vis plant demand under different crops and cropping systems for achieving high yield and nutrient use efficiency.

The efficient (site-specific) management of soil nutrients is possible by understanding the spatial variability in distribution of phyto-available nutrients (here after called available nutrients) and identifying the soil management zones (MZs) of agricultural landscapes. There is need for delineating soil MZs of agricultural landscapes of the world for efficient management of soil nutrients in order to obtain sustainability in crop yield. The present study was, therefore, undertaken to understand the spatial distribution pattern of available micronutrients (zinc (Zn), boron (B), iron (Fe), manganese (Mn) and copper (Cu)), available sulphur (S), and soil properties (soil acidity (pH), electrical conductivity (EC) and organic carbon (SOC) content) in soils of intensively cultivated Indo-Gangetic Plain (IGP) of India and to delineate soil MZs for efficient management of soil nutrients. Totally, 55101 soil samples from 0-15 cm depth were obtained from 167 districts of IGP during 2014 to 2017 and were analysed for different soil parameters. Soil pH, EC and SOC content varied from 4.44 to 9.80, 0.02 to 2.13 dS m-1 and 0.10 to 1.99%, respectively. The concentration of available Zn, B, Fe, Mn, Cu and S varied from 0.01 to 3.27, 0.01 to 3.51, 0.19 to 55.7, 0.05 to 49.0, 0.01 to 5.29 and 1.01 to 108 mg kg-1, respectively. Geostatistical analysis resulted in varied distribution pattern of studied soil parameters with moderate to strong spatial dependence. The extent (% area) of nutrient deficiencies in IGP followed the order: S > Zn > B > Mn > Cu > Fe. Principal component analysis and fuzzy c-means clustering produced six distinctly different soil MZs of IGP for implementation of zone-specific soil nutrient management strategies for attaining sustainability in crop yield. The developed MZ maps could also be utilized for prioritization and rationalization of nutrients supply in IGP of India.

Series of chitosan grafted zinc containing nanoclay polymer bio-composites (CZNCPBCs) with variable percentage (8%, 10% and 12%) of clay and nanoclay were synthesized by a novel method. Clays as well as CZNCPBCs were characterized through X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Release study of Zn2+ from CZNCPBCs in Zn deficient soils revealed that combination having 12% nanoclay showed slowest release rate. Olsen-P content was found maximum in 8% clay containing composite. However, combination containing 8% clay recorded highest equilibrium water absorbency as well as moisture content at a particular tension. Inoculation with fungal species revealed that Aspergillus spp. was more effective as compared with Trichoderma spp. in evolution of cumulative CO2-C, indirectly indicating biodegradability. CZNCPBCs were found to be promising as controlled release (CR) Zn2+ fertilizer formulation.

Limited information is available on long-term fertilization impacts on soil organic carbon (SOC) sequestration in deep soils and C pools within bulk soils and aggregates. Hence, the major objectives of this study were to evaluate long-term (44 years) fertilization impacts on: (i) soil aggregation, labile and recalcitrant C pools within bulk soils and aggregates and (ii) deep soil C accumulation versus sequestration. Treatments were: no mineral fertilizer or manure (control), 100% recommended dose of nitrogen (N), N and phosphorus (NP), N, P and potassium (NPK), 150% recommended NPK (150% NPK), and NPK + farmyard manure (FYM) (NPK + FYM). Labile C, recalcitrant C, total SOC and glomalin in bulk soils and their aggregates were determined in the 0–15 and 15–30 cm soil layers. In addition, total SOC, labile and recalcitrant C contents were measured in the 30–60 and 60–90 cm soil layers. Results revealed that C accumulation and sequestration in NPK + FYM over control plots were 0.74 and 0.22 Mg C ha−1 yr−1, respectively, in 0–90 cm soil layer with >50% of the accumulated C in deep soil layers (30–90 cm). In 0–15 cm layer, despite NPK + FYM and NPK plots had similar amounts of soil macroaggregates, microaggregates were 27% higher with NPK + FYM than NPK, causing higher aggregate stability. Plots with NPK and NPK + FYM had more labile: recalcitrant C ratios in bulk soils than control, NP and N plots. The NPK + FYM plots also had highest recalcitrant C pools within macro- and microaggregates. Glomalin was generally positively correlated with all labile C pools in both soil layers. Additionally, mean weight diameter (MWD) was positively correlated with aggregate-associated C and glomalin within bulk soils. Overall, NPK + FYM management practice not only had higher C accumulation and sequestration in surface and deep soils, but also had better aggregation and ∼26% greater carbon management index than NPK in soil surface and hence should be adopted.

The aim of this study was to understand impacts of long-term (43 years) fertilization on soil aggregation, N accumulation rates and δ15N in surface and deep layers in an Alfisol. Soil samples from ...

Novel zincated nanoclay polymer composites (ZNCPCs) with variable percentage of commercial bentonite and nanobentonite (8%, 10% and 12% of monomer for each case) were synthesized. Polyacrylic acid-...

Use of wastewater for irrigating agricultural crops is on the rise, particularly in the developing countries. The present study was undertaken to assess the long-term effect of irrigation w...

Despite removal of potassium (K) by crops in large quantities, often exceeding that of nitrogen (N), K fertilization has long been neglected compared with N and phosphorus (P) in Indian agriculture leading to mining of soil K. We, therefore, studied the effect of long-term fertilization (with or without K) on K supplying ability of two major soil orders of India, viz. Inceptisol and Vertisol after more than four decades of cultivation. Soil samples (0–15 and 15–30 cm) were collected after the completion of 43 (Inceptisol) or 42 (Vertisol) cropping cycles from on-going long-term experiments located at New Delhi (Inceptisol) and Jabalpur (Vertisol), India, from six treatments, viz. no-fertilization (control), recommended N (N), N and P (NP), N, P and K (NPK), 150% NPK and NPK + farmyard manure (NPK + FYM), along with adjacent uncultivated land. Ammonium acetate extractable K (Kex), non-exchangeable K (NEK), quantity-intensity relationship and K release kinetics along with grain yields and K uptake by crops were studied. The Kex and K-saturation of exchange complex in both soils and NEK in the Inceptisol were the lowest under NP followed by N. Cropping without K input resulted in lower quantity (non-specifically and specifically held K i.e. –ΔK0 and Ks) and intensity (equilibrium activity ratio i.e. AReK) of K in both soils. More negative values of standard free energy of exchange (ΔG0) under cultivation without K in both soils indicated increased affinity of soil solids for K+ owing to K omission. The gap between equilibrium exchangeable K (EK0) and minimum exchangeable K (EKmin) was significantly lower under cropping without K than with K in the Vertisol. Imbalanced fertilization (N or NP) also showed noticeably smaller cumulative K releases and slower rates of replenishment of solution K by solid phase K in both soils. Interestingly, even under cropping with K fertilization at either experimental site, several K supply parameters showed decline compared with adjacent uncultivated soil. Grain yields of wheat and total K uptake by all crops (maize and wheat in Inceptisol; soybean and wheat in Vertisol) showed significant and positive response to K application. The study showed variable effect of long-term intensive cropping with or without K input on the K supplying ability of an Inceptisol and a Vertisol. The findings underlined inadequacy of the existing K fertilizer recommendations, and the need for their refinement to minimize native K mining and sustain K supplying ability of soils.

The systematic research on the effect of medium-term conservation agriculture (CA) on soil quality, especially under the rice (Oryza sativa L.)-based cropping systems is limited. Hence, the specific objective of the study was to develop soil quality indices with key soil physical, chemical and biological indicators under the conservation and conventional tillage practices in a rice–mustard [Brassica juncea (L.) Czern.] cropping system. Eight treatment combinations including tillage and crop establishment, crop residue and cropping system intensification with inclusion of short duration summer mungbean [Vigna radiata (L.) Wilczek] were adopted in rice - mustard cropping system in hot semi-arid, sub-tropical north-western Indo-Gangetic Plains agro-ecoregion of India. Soil samples collected from topsoil (0−5 cm) and 5−15 cm soil layer were analyzed for 15 physical, chemical and biological properties to develop unified soil quality index (SQI) through principal component analysis (PCA). The highest SQI was obtained in the zero till direct seeded rice (ZTDSR) – zero till mustard (ZTM) –ZT summer mungbean (ZTSMB (+R) (mungbean residue in ZTDSR - rice residue in ZTM- mustard residue in ZTSMB) treatment followed by the ZTDSR + BM (brown manuring) – ZTM (+R) (mustard residue in ZTDSR with BM – rice residue in ZTM). The lowest SQI was obtained in transplanted puddled rice (TPR) - conventional till mustard (CTM) for both soil layers. The identified key indicators for SQI in this Inceptisol were saturated hydraulic conductivity (Ks), pH, total N, available P, and available K. Besides, the plots under ZTDSR – ZTM – ZTSMB (+R) resulted in 14 % higher total organic C in topsoil and 28 % higher aggregate stability than the TPR - CTM plots. This ZTDSR – ZTM -ZTSMB (+R) treatment had 65 % higher surface soil microbial biomass C than the TPR – CTM treatment. The ZTDSR – ZTM -ZTSMB (+R) treatment also led to higher Ks, which was in the order of triple ZT > double ZT > ZT > conventional tillage. Thus, the medium-term CA with triple or double zero tillage with crop residue retention could lead to maintain agricultural sustainability under rice-mustard system. Hence, it may be recommended to the farmers for adoption.

Agricultural land degradation due to nutrient deficiencies is a threat to agricultural sustainability. As nutrients availability is influenced by soil heterogeneity, climatic conditions and anthropogenic activities, hence, delineation of nutrient management zones (MZs) based on spatial variability could be an effective management option at regional scale. Thus, the present study was carried out to delineate MZs in Shiwalik Himalayan region (SHR) of India by capturing spatial variability of soil properties and secondary and micronutrients status because of the emerging nutrient deficiencies. For the study, a total of 2575 geo-referenced representative surface (0-15 cm depth) soil samples were collected from the study region covering an area of 53483 km2. The soils were analyzed for pH, electrical conductivity (EC), soil organic carbon (SOC), available sulfur (S) and micronutrients (zinc (Zn), iron (Fe), copper (Cu), manganese (Mn), boron (B) and molybdenum (Mo)) concentrations. There was wide variation in soil properties with coefficient of variation (CV) values of 14 (for pH) to 86% for available Mo. Geostatistical analysis revealed spherical, Gaussian, exponential, stable, circular and K-Bessel best-fit models for soil properties. Most of the soil properties were having moderate spatial dependency except soil pH and S (strong spatial dependency) and Zn (weak spatial dependency). About 49, 10, 2, 13, 11, 12 and 8% area of the study region were found to be deficient (including acute and marginal deficiency) in S, Zn, Fe, Cu, Mn, B and Mo, respectively. The principal component (PC) analysis and fuzzy-c- mean clustering was performed to develop the MZs. Four PCs with eigen values greater than 1 and accounting 65.4% of total variance were retained for further analysis. On the basis of fuzzy performance index (FPI) and normalized classification entropy (NCE), four potential MZs were identified. Analysis of variance confirmed the heterogeneity in most of the studied soil properties among the MZs. The study indicated that the methodology of delineating MZs can be effectively used in site-specific S and micronutrients management in SHR of India.

Understanding temperature sensitivity of soil organic carbon (SOC) decomposition from bulk soils and aggregates of long-term fertilized plots is imperative to forecast soil C dynamics. We evaluated the impacts of 43 years of fertilization under a soybean ( Glycine max ) based cropping system on temperature sensitivity of SOC decomposition (Q 10 ) in an Alfisol. Treatments were: no mineral fertilizer or manure (control), 100% recommended dose of nitrogen (N), N and phosphorus (NP), N, P and potassium (NPK), NPK + lime at 0.4 Mg ha −1 (NPK + L), 150% recommended NPK (150% NPK), and NPK + farmyard manure (FYM) at 10 Mg ha −1 (NPK + FYM). Bulk soils as well as macro- and micro-aggregates were incubated for 24 days at 25 °C and 35 °C. Cumulative SOC mineralization (C t ) in the 0–15 cm soil layer of bulk soils with NPK + FYM and NPK treated plots were similar but significantly higher than unfertilized control plots. However, both C t and Q 10 values in the NPK + FYM plots were higher than NPK in the 15–30 cm soil layer. In the 0–15 cm soil layer, NPK + FYM plots had ∼10 and 26% greater Q 10 values of macro- and microaggregates than NPK. Activation energies required for bulk soils C mineralization was ∼2 and 3 times higher in NPK + FYM and NPK + L plots, respectively, compared with unfertilized control plots in that layer. Lime along with NPK application increased the activation energy of SOC decomposition. Thus, long-term NPK + FYM and NPK + L applications have great potential for less proportional SOC decomposition than NPK or unfertilized control plots under a temperature rise in these acid soils. However, NPK + FYM management practice is recommended as it has highest SOC accumulation and can have less SOC losses under a temperature rise.

Bioavailability and ecotoxicity of metals in contaminated soils depend largely on their solubility. The present investigation was carried out to predict the free ion activity of Zn2+, Cu2+, Ni2+, Pb2+ and Cd2+ in contaminated soils as a function of pH, organic carbon content and extractable metal concentration. Twenty-five composite soil samples were collected from various locations which had a history of receiving sewage sludge (Keshopur and IARI, Delhi), municipal solid waste (Kolkata, West Bengal), polluted river water (Madanpur, Delhi) and industrial effluents (Debari, Rajasthan and Sonepat, Haryana). Four composite soil samples were also collected from adjacent fields which had not received contaminated amendments. Free ion activities (-log10 values), viz. pZn2+, pCu2+, pNi2+, pPb2+ and pCd2+ as measured by the Baker soil test, were 10.1 ± 1.12, 13.4 ± 1.23, 12.9 ± 0.85, 11.6 ± 0.74 and 12.6 ± 2.26, respectively. Free metal ion activities were also determined using the geochemical speciation model WHAM-VII following extraction of soil solution with porous Rhizon samplers from the rhizosphere of growing plants. pH dependent Freundlich model based on soil properties could explain the variation in pZn2+, pCu2+, pNi2+, pPb2+ and pCd2+ to the extent of 84, 52, 73, 60 and 70%, respectively, in the case of data from Rhizon samplers coupled with speciation modelling. Whereas, C-Q model could explain 84, 57, 82, 72 and 74% variability in pZn2+, pCu2+, pNi2+, pPb2+ and pCd2+, respectively, based on soil properties and free metal ion activity as determined with integrated use of Rhizon-WHAM-VII. Modelling approach was superior compared to that based on the Baker soil test solution.

The rice-wheat system (RWS), managed over 10.5 Mha in the Indo-Gangetic Plains of India suffers from production fatigue caused by declining soil organic matter, multi-nutrient deficiencies and diminishing factor productivity. We, therefore, conducted a long-term field experiment (1998&ndash, 1999 to 2017&ndash, 2018) in Modipuram, India to study the effect of continuous use of farmyard manure (FYM) as an organic fertilizer (OF), mineral fertilizers applied alone (RDF) and their combination (IPNS), as well as the inclusion of forage berseem (IPNS+B) or forage cowpea (IPNS+C) on crop yield, soil health and profits. The long-term yield trends were positive (p &lt, 0.05) in all treatments except the control (unfertilized) in rice, and the control and RDF in wheat. Although the yields of rice, wheat and RWS were highest under IPNS treatments (IPNS, IPNS+B, IPNS+C), the maximum annual yield increase in rice (9.2%) and wheat (13.7%) was obtained under OF. A linear regression fitted to the yield data under different IPNS options revealed a highly significant (p &lt, 0.001) annual yield increase in rice (5.1 to 6.6%) and wheat (6.8 to 7.7%) crops. Continuous rice-wheat cropping with RDF brought an increase in soil bulk density (Db) over the initial Db at different soil profile depths, more so at depths of 30&ndash, 45 cm, but inclusion of forage cowpea or berseem in every third year (IPNS+B or C) helped to decrease Db, not only in surface (0&ndash, 15 cm) but also in sub-surface (15&ndash, 30 and 30&ndash, 45 cm depth) soil. Whereas soil organic carbon (SOC) increased under OF, IPNS and IPNS + legume (B or C) treatments, it remained unaffected under RDF after 20 RW cycles. The inclusion of legumes along with IPNS not only helped to trap the NO3&ndash, N from soil layers below 45 cm but also increased its retention in the upper soil (0&ndash, 15 cm depth). On the other hand, RDF had a higher NO3&ndash, N content in the lower layers (beyond 45 cm depth), indicating downward NO3&ndash, N leaching beyond the root zone. A build-up of Olsen-P was noticed under RDF at different time intervals. The soil exchangeable K and available S contents were maximal under OF and IPNS options, whereas a decline in DTPA extractable-Zn was recorded under OF. Overall, RWS economics revealed that OF treatment involved the maximum cost of cultivation (US$1174 ha&minus, 1) with the least economic net return (US$1211 ha&minus, 1). Conversely, IPNS + legume (B or C) had lowest cost of cultivation (US$707 to 765 ha&minus, 1) and a significantly higher (p &lt, 0.05) net return (US$2233 to 2260 ha&minus, 1). The study, thus, underlines the superiority of IPNS over RDF or OF, the inclusion of legumes gives an added advantage in terms of production sustainability and soil health. Further studies involving IPNS ingredients other than FYM is needed to develop location-specific IPNS recommendations.

A case study was undertaken to assess the risk of sewage-irrigated soils in relation to the transfer of trace elements to rice and wheat grain. For this purpose, peri-urban agricultural lands under the Keshopur Effluent Irrigation Scheme (KEIS) of Delhi were selected. These agricultural lands have been receiving irrigation through sewage effluents since 1979. Sewage effluent, groundwater, soil, and plant (rice and wheat grain) samples were collected with GPS coordinates from this peri-urban area. Under wheat crop, sewage irrigation for four decades resulted into a significant buildup of zinc (141 %), copper (219 %), iron (514 %), nickel (75.0 %), and lead (28.1 %) in sewage-irrigated soils over adjacent tube well water-irrigated ones. Under rice crop, there was also a significant buildup of phosphorus (339 %), sulfur (130 %), zinc (287 %), copper (352 %), iron (457 %), nickel (258 %), lead (136 %), and cadmium (147 %) in sewage-irrigated soils as compared to that of tube well water-irrigated soils. The values of hazard quotient (HQ) for intake of trace toxic elements by humans through consumption of rice and wheat grain grown on these sewage-irrigated soils were well within the safe permissible limit. The variation in Zn, Ni, and Cd content in wheat grain could be explained by solubility-free ion activity model (FIAM) to the extent of 50.1, 56.8, and 37.2 %, respectively. Corresponding values for rice grain were 49.9, 41.2, and 42.7 %, respectively. As high as 36.4 % variation in As content in rice grain could be explained by solubility-FIAM model. Toxic limit of extractable Cd and As in soil for rice in relation to soil properties and human health hazard associated with consumption of rice grain by humans was established. A similar exercise was also done in respect of Cd for wheat. The conceptual framework of fixing the toxic limit of extractable metals and metalloid in soils with respect to soil properties and human health hazard under the modeling framework was established.

Rice-maize system (RMS) is emerging as dominant option for diversification of existing rice-wheat systems in Asia due to better suitability and higher yields of maize compared to wheat after long duration rice cultivars, and increasing demand of maize from poultry and fish industries. The conventional practice of cultivation of RMS is input intensive, deteriorates soil health and is less profitable. Conservation agriculture (CA) based management practices such as dry direct-seeded rice (DSR), zero tillage (ZT) and residue retention may hold potential to increase yields, reduce costs and increase farmers' profits in RMS. Therefore, replicated 5-year field study was conducted to evaluate the effects of six combinations of three tillage and crop establishment (TCE) techniques and two residue management options on soil physical properties, system productivity and economics of an irrigated RMS in north-west India. The TCE techniques consisted of transplanted puddled rice (TPR) followed by conventionally tilled maize (CTM); CTDSR followed by CTM; and ZTDSR followed by ZTM in main plots and two residue management options; removal of residues of both the crops (−R) and partial residue (5 t ha −1 ) either retained at soil surface on ZT plots or incorporated into the soil in CT plots (+R) for both rice and maize in sub-plots. Compared with TPR/CTM-R, soil physical parameters such as water-stable aggregates >0.2 mm were 89% higher, and bulk density, penetrometer resistance and infiltration rate showed significant ( P −1 in ZTDSR/ZTM (+R) over conventional practice. Grain yield of TPR was 5 –7% higher compared to CTDSR and ZTDSR, which was attributed to increased number of grains panicle −1 and grain weight. Maize yield under ZTDSR/ZTM was significantly higher by 4.0% and 14.2% compared to CTDSR/CTM and TPR/CTM, respectively, due to increase in number of cobs plant −1 and grain number cob −1 . Gradual improvement in soil physical health in ZTDSR/ZTM +R system resulted in higher and stable crop productivity (17.4–17.6 kg m −3 ) with higher profitability in different years over conventional system. Our study demonstrates that CA based management practices can be adopted for RMS on sandy loam or similar soils for sustaining soil and crop productivity in South Asia.

Recycling of sewage sludge as an organic amendment and source of macro- and micro-nutrient in agricultural fields can be a potential option for proper disposal of organic wastes. A field experiment was conducted at the experimental farm of Indian Agricultural Research Institute, New Delhi, to examine the short-term effect of municipal sewage sludge application on soil physical, chemical and biological properties of a sandy loam soil (typic haplustept) under cowpea-wheat cropping system. Control and four treatments adopted in this study were, 100%NPK (nitrogen, phosphorus and potassium), and three sludge applications i.e. equivalent to 5, 10, 15tha−1. The results showed a positive effect of sewage sludge on different parameters. Bulk density was decreased by about 21% in surface layer, increased the mean weight diameter (MWD), porosity, dehydrogenase activity and microbial biomass carbon. A higher amount of aggregate associated organic carbon was associated with soil macro-aggregate (>0.25mm) in comparison to micro-aggregate (

Developing suitable crop rotations and crop establishment practices is an important mechanism that can enhance factor productivity and sustainability of an agro-ecosystem. However, the impact of Conservation Agriculture (CA) on alternate crop rotation of the most-dominant but tillage- and input-intensive rice (Oryza sativa L.)-wheat (Triticum aestivum (L.) emend Fiori & Paol) rotation of the Indo-Gangetic Plains (IGP) of India is not elaborately studied. Hence, we evaluated the effect of CA on crop and water productivity, profitability, and soil carbon status in rice-mustard (Brassica juncea L.) rotation in the North-western IGP of India for five consecutive years. Eight treatments comprising of tillage, crop residue, brown manuring (BM) using Sesbania bispinosa, and summer mungbean [Vigna radiata (L.) Wilczek] (SMB) were adopted in rice - mustard cropping system. The conventional transplanted puddled rice (TPR) - conventional till mustard (CTM) (∼TPR-CTM) rotation resulted in significantly higher rice grain yield than zero till direct-seeded rice (ZTDSR) – ZT mustard (ZTM) system with or without crop residue in all five years. However, in this regard, the CA-based ZT rice – mustard - SMB with residue [ZTDSR-ZTM-ZTSMB (+R)] was comparable with it during first three years, but was inferior to it in 4th and 5th years. The ZTDSR-ZTM-ZTSMB (+R) had overall 10.9 % lower five-year mean rice yield than that in the TPR-CTM system. This CA-based system gave significantly higher mustard grain yield in all the years (except first year), and the five-year mean mustard yield was 30.3 % higher than in the TPR-CTM. Another CA-based double cropping system having ZTDSR + BM – ZTM (+R) was comparable with TPR-CTM in all the years and resulted in 27.6 % higher five-year mean mustard yield than the TPR–CTM practice. The ZTDSR-ZTM-ZTSMB (+R) practice gave 44 % (including SMB) and 8.1 % (excluding SMB) higher system productivity and significantly higher sustainable yield index of the rice-mustard system compared with the TPR-CTM practice. The ZTDSR-ZTM-ZTSMB (+R) practice encountered significantly lower weed density in mustard in all five years than TPR-CTM system. The cost-benefit analysis revealed that this CA practice fetched higher net returns by INR 53,000 and 21,400 ha−1 from the rice-mustard system with and without SMB, respectively over the TPR-CTM system. Again, this ZTDSR -ZTM- ZTSMB (+R) system led to an increase in irrigation water productivity by 27.8 % in rice and 35.1 % in mustard, and the total water (irrigation + rainfall) productivity by 35.7 % in mustard crop compared with the TPR-CTM system (P ≤ 0.05). This CA-based rice-mustard system resulted in significantly higher very labile (∼50.6 %) and labile (∼47.7 %) carbon concentration at 0–5 cm depth of soil compared to the conventional TPR-CTM system. The CA system being productive, profitable, and resource-efficient can be recommended for North-western IGP of India and in similar agro-ecologies of the tropics and sub-tropics. It can be adopted with suitable site-specific refinement in South-Asian countries, where decline in crop productivity and soil health is a consistent pervasive problem due to continuous cereal-cereal rotation.

Understanding impact of long-term fertilisation on soil aggregation, carbon (C) stabilisation and temperature sensitivity of soil organic C (SOC) mineralisation are necessary to foresee C dynamics. The present study was conducted in an Inceptisol under wheat (Triticum aestivum) based cropping system, with the objective to quantify the effect of 44 years of integrated nutrient management on soil aggregation, enzymatic activity, and temperature sensitivity (Q10) of SOC. Treatments were: unfertilised control (UC), 100% recommended dose of nitrogen (N), N and phosphorus (NP), N, P and potassium (NPK), integrated application of NPK and farmyard manure (FYM) (NPKF) and 150% recommended dose of N, P and K (1.5NPK). The observed data were analysed using analysis of variance for randomized block design and Tukey’s HSD test (P