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Maintaining soil carbon is vital under changing climate. Conservation agriculture (CA) is reported to have potential to store soil organic carbon (SOC). The impact of carbon inputs on SOC dynamics and mineralization kinetics, and the priming effect of residue addition under long-term CA in subtropical regions, however, are not clear or adequately evaluated. Therefore, we studied these under a 12-year-old CA-based pigeon pea-wheat cropping system with permanent broad bed with residue (CA-PBB), permanent flatbed with residue (CA-PFB), permanent narrow bed with residue (CA-PNB), and conventional till (CT) treatments. Also, an incubation study was undertaken to understand better the processes involved. Results showed that CA treatments significantly enhanced the total SOC compared to CT practice, and, among them, the CA-PFB exhibited highest total SOC with 36.6% and 35.8% higher values at 0-5 and 5-15 cm depths, respectively. The CA-PFB followed by CA-PBB and CA-PNB had significantly higher carbon management index and carbon retention efficiency than CT. The CA-PFB also showed higher carbon sequestration rates of 68.4 and 188.8 kg ha -1 year -1 , surpassing values of 8.4 and 52.9 kg ha -1 year -1 under CT at 0-5 and 5-15 cm depth, respectively. Furthermore, soil incubation study revealed that the CA systems had higher cumulative mineralization values at 0-5 cm soil layer but lower at 5-15 cm soil compared to CT, indicating a considerable improvement in SOC at 5-15 cm soil depth. On the contrary, the SOC decay rate was higher under CA than CT, and at 35 °C than at 15 °C. A positive priming effect was also observed, depending on the substrate type, pigeon pea residue exhibiting higher priming effect than wheat residue. Thus, these studies show that residue input increases cumulative mineralization and SOC decay rate vis-à-vis helps to sequester carbon in the recalcitrant fraction, leading to higher stable carbon in soil., Competing Interests: Declaration of competing interest The authors declare that there is no potential conflict of interest associated with this article entitled “The interplay between external residue addition, and soil organic carbon dynamics and mineralization kinetics: experiences from a 12-year old conservation agriculture”. We 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.)

India's mango productivity is hindered by many factors but more importantly due to limited understanding of the genomic complexities behind regular bearing habit. This study is the first to quantify carbohydrate fractions, protein content, and macro and micronutrient storage pools, their transportation, and contributions to regular 'Totapuri' and alternate bearer 'Bombay Green' mango varieties during the 'off' year. Deep RNA sequencing was used to assess gene expression dynamics between buds and flowers of these varieties. Differential pathway analysis showed the greatest number of differentially expressed genes in metabolic processes (1377), followed by oxido-reductase (879), hormone (80), oxidative stress (77), starvation (39), alternate bearing (8), flowering (3), meristem (3), and cellular component (2) pathways. In silico analysis showed that among 15 genes, twelve genes up-regulated in Totapuri and three in Bombay Green, confirmed by qRT-PCR. Additionally, 202 SNPs were identified in 32 alternate bearing-related genes. The study confirmed the reproductive bud's strong ability to import sugars, protein, and starch in the regular bearer variety, enhancing flowering and fruiting during off years. The mineral nutrients and biochemical constituent of the bud and leaf tissue in contrasting genotypes, showed the potential role for regular bearing in mango., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: The continuous cultivation of rice-wheat in the same field is a key element of double-cropping systems in the Indo-Gangetic plains. Yields of such cropping systems are increasingly challenged as climate change drives increases in temperature, terminal stress and uneven rainfall, delaying rice harvesting and subsequently delaying sowing of wheat. In this paper, we evaluate the optimum sowing dates to achieve high grain yield and quality of wheat cultivars in northwest India. Three cultivars of wheat, HD-2967, HD-3086 and PBW-723, were sown on three different dates at the research farm of ICAR-IARI, New Delhi, to generate different weather conditions at different phenological stages. Different biophysical attributes, photosynthetic rate, stomatal conductance and transpiration rate, were measured at different phenological stages. Yield and grain quality parameters such as protein, starch, amylopectin, amylose and gluten were measured in different cultivars sown on different dates., Results: Biophysical parameters were found to be higher in timely sown crops followed by late-sown and very late-sown crops. Further, the different sowing dates had a significant (P < 0.05) impact on the grain quality parameters such as protein, starch, amylopectin, amylose and gluten content. Percentage increases in the value of starch and amylose content under timely sown were ~7% and 11.6%, ~5% and 8.4%, compared to the very late-sown treatment. In contrast, protein and amylopectin contents were found to increase by ~9.7% and 7.5%, ~13.8% and 16.6% under very late-sown treatment., Conclusion: High-temperature stress during the grain-filling periods significantly decreased the grain yield. Reduction in the grain yield was associated with a reduction in starch and amylose content in the grains. The protein content in the grains is less affected by terminal heat stress. Cultivar HD-3086 had higher growth, yield as well as quality parameters, compared to HD-2967 and PBW-723 in all treatments, hence could be adopted by farmers in northwest India. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

A greenhouse pot experiment was conducted with seven different levels of sludge (0, 5, 10, 20, 40, 80, 160 g kg -1 ) to assess the potential impact of sludge application on soybean (Glycine max (L.) Merr.) productivity, metal accumulation and translocation, and physico-chemical changes in acid and alkaline soils. The outcomes revealed that the application of sludge @ 5.0 to 160 g kg -1 resulted in a significant (p < 0.05) increase in seed and straw yield in both acid and alkaline soils compared to control. All the assessed heavy metals in soybean were within permissible ranges and did not exceed the phytotoxic limit, except for Fe, Zn, and Cu in the roots from the application of sewage sludge. The values of bioaccumulation factor (BF root/soil ) and translocation factor i.e., TF straw/root and TF seed/straw were < 1.0 for Ni, Pb and Cr. Overall, for all the sludge application doses the soil pH was observed to increase in the acid soil and decline in alkaline soil when compared to the control. All the investigated heavy metals (Fe, Mn, Zn, Cu, Ni, Cd, Pb, and Cr) in the different plant tissues (root, straw and seed) of soybean were correlated with the soil variables. The study finds that sludge can be a potential organic fertilizer and function as an eco-friendly technique for the recycling of nutrients in the soil while keeping a check on the heavy metals' availability to plants., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Most of the popular scion varieties of mango possess alternate/irregular bearing. There are many external and internal factors assigned, among them carbohydrate reserves, and nutrient content plays important roles in the floral induction process in many crop species. In addition to that rootstock can alter the carbohydrate reserve and nutrient acquisition of scion varieties in fruit crops. The present investigation was carried out to understand the effect of rootstocks on the physiochemical traits of leaf, and bud and nutrient content in regular and alternate bearing varieties of mango. The rootstock "Kurukkan" promoted starch content in leaves of both alternate bearing varieties 'Dashehari' (5.62 mg/g) and regular 'Amrapali' (5.49 mg/g) and encouraged higher protein content (6.71 mg/g) and C/N ratio (37.94) in buds of alternate bearing 'Dashehari'. While Olour rootstock upregulated the reducing sugar in leaves of 'Amrapali' (43.56 mg/g) and promoted K (1.34%) and B (78.58 ppm) content in reproductive buds of 'Dashehari'. Stomatal density in 'Dashehari' scion variety was found higher on Olour rootstock (700.40/mm 2), while the rootstock fails to modify stomatal density in the scion variety regular bearer 'Amrapali'. Further, a total of 30 carbohydrate metabolism-specific primers were designed and validated in 15 scion/rootstock combinations. A total of 33 alleles were amplified among carbohydrate metabolism-specific markers, which varied from 2 to 3 alleles with a mean of 2.53 per locus. Maximum and minimum PIC value was found for NMSPS10, and NMTPS9 primers (0.58). Cluster analysis revealed that scion grafted on Kurukkan rootstock clustered together except 'Pusa Arunima' on Olour rootstock. Our analysis revealed that Fe is the key component that is commonly expressed in both leaf and bud. Although Stomatal density (SD) and Intercellular CO2 Concentration (Ci) are more specific to leaf and Fe, B, and total sugar (TS) are abundant in buds. Based on the results it can be inferred that the physiochemical and nutrient responses of mango scion varieties are manipulated by the rootstock, hence, the scion-rootstock combination can be an important consideration in mango for selecting suitable rootstock for alternate/irregular bearer varieties., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Vittal et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Heavy metals in soil pose a serious threat through their toxic effect on the human food chain. Phytoremediation is a clean and green potentially cost-effective technology in remediating the heavy metal-contaminated soil. However, the efficiency of phytoextraction is very often limited by low phytoavailability of heavy metals in soil, slow growth, and small biomass production of hyper-accumulator plants. To solve these issues, accumulator plant(s) with high biomass production and amendment(s) which can solubilize metals in soil is required for better phytoextraction. A pot experiment was conducted to assess the efficiency of phytoextraction of sunflower, marigold, and spinach as affected by the incorporation of Sesbania (solubilizer) and addition of gypsum (solubilizer) in nickel (Ni)-, lead (Pb)-, and chromium (Cr)-contaminated soil. A fractionation study was conducted to study the bioavailability of the heavy metals in contaminated soil after growing the accumulator plants and as affected by using soil amendments (Sesbania and gypsum). Results showed that marigold was the most efficient among the three accumulator plants in phytoextraction of the heavy metals in the contaminated soil. Both sunflower and marigold were able to reduce the bioavailability of the heavy metals in the post-harvest soil, which was reflected in their (heavy metals) lower concentration in subsequently grown paddy crop (straw). The fractionation study revealed that carbonate and organically bound fractions of the heavy metals control the bioavailability of the heavy metals in the experimental soil. Both Sesbania and gypsum were not effective in solubilizing the heavy metals in the experimental soil. Therefore, the possibility of using Sesbania and gypsum for solubilizing heavy metals in contaminated soil is ruled out., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Pearl millet (PM) is a nutri-cereal rich in various macro and micronutrients required for a balanced diet. Its grains have a unique phenolic and micronutrient composition; however, the lower bioaccessibility of nutrients and rancidity of flour during storage are the major constraints in its consumption and wide popularity. Here, to explore the effect of different thermal processing methods, i.e. , hydrothermal (HT), microwave (MW), and infrared (IR) treatments, on the digestion of starch, phenolics, and microelements (Fe and Zn), an in vitro digestion model consisting of oral, gastric and intestinal digestion was applied to PM rotis. The hydrothermally treated PM roti was promising as it showed lower inherent glycemic potential (60.4%) than the untreated sample (72.4%) and less enzymatic activities associated with rancidity in PM flour. FTIR revealed an increased ratio of 1047/1022 cm -1 in the hydrothermally treated sample, reflecting the enhancement of the structurally ordered degree and compactness of starch compared to other thermal treatments. A tighter and more compact microstructure with an agglomeration of starch in the hydrothermally treated PM flour was observed by SEM. These structural changes could provide a better understanding of the lower starch digestion rate in the hydrothermally treated flour. However, HT treatment significantly ( P < 0.05) reduced the bioaccessibility of phenolics (10.6%) compared to native PM rotis and slightly reduced the Fe (2%) and Zn (3.2%) bioaccessibility present in PM rotis.

We investigated the effect of practically realizable doses of silicate on arsenic (As) uptake by differential-As-accumulating rice cultivars grown on geogenically As-polluted soil. The possible health risk from the dietary ingestion of As through rice was also assessed. In addition, a solution culture experiment was conducted to examine the role of root-secreted weak acids in differential As acquisition by rice cultivars. When grown without silicate, Badshabhog accumulated a much smaller amount of As in grain (0.11 mg kg -1 ) when compared to the other three varieties. Satabdi, IR-36, and Khitish accumulated As in grain beyond the permissible limit (0.2 mg kg -1 ) for human consumption. The application of silicate effectively reduced the As content in the grain, husk, and straw of all of the cultivars. The grain As content fell to 17.2 and 27.6% with the addition of sodium metasilicate at the rates of 250 and 500 mg kg -1 , respectively. In the case of Khitish, the grain As content was brought down within permissible limits by the applied silicate (500 mg kg -1 ). The integrated use of low-As-accumulating cultivars and silicate has great potential to reduce the public health risks associated with As. A positive correlation between root-secreted total weak acid and grain As content could explain the different rice cultivars' differential As acquisition capacity.

Safe levels of extractable pollutant elements in soil have not been universally established. Prediction of metal solubility in polluted soils and the subsequent transfer of these metals from soil pore water to the human food supply via crops are required for effective risk assessment from polluted soils. Thus an attempt has been made to develop a novel approach to protect human health from exposure to toxic metals through assessing risk from metal polluted soils utilised for agriculture. In this study, we assess the relative efficacy of various forms of 'free ion activity model' (FIAM) for predicting the concentration of cadmium (Cd), lead (Pb), nickel (Ni), zinc (Zn) and copper (Cu) in spinach and wheat as example crops, thereby providing an assessment of risk to human health from consumption of these crops. Free metal ion activity in soil solution was estimated using the Windermere Humic Aqueous Model VII (WHAM-VII) and the Baker soil test. Approximately 91, 81, 75, 94 and 70% of the variability in Cd, Pb, Ni, Zn and Cu content, respectively, of spinach could be described by a FIAM using an estimate of the free ion activity of the metals provided by WHAM-VII. Owing to the different concentration of ethylenediamine tetraacetic acid (EDTA) and diethylenetriamine pentaacetic acid (DTPA) used in the present experiment, higher prediction coefficients were obtained using EDTA (0.05 M), rather than DTPA (0.005 M), as the metal extractant in an integrated solubility-FIAM model. Out of three formulations, the FIAM, based on free ion activity of metals in soil pore water, determined from solution extracted with Rhizon samplers, was distinctly superior to the other formulations in predicting metal uptake by spinach and wheat. A safe level of extractable metal in soil was prescribed using a hazard quotient derived from predicted plant metal content and estimated dietary intake of wheat and spinach by a human population., Supplementary Information: The online version contains supplementary material available at 10.1007/s12665-021-09988-7., Competing Interests: Conflict of interestThe 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., (© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2021.)

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., Competing Interests: The authors have declared that no competing interests exist.

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 Zn 2+ , Cu 2+ , Ni 2+ , Pb 2+ and Cd 2+ 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 (-log 10 values), viz. pZn 2+ , pCu 2+ , pNi 2+ , pPb 2+ and pCd 2+ 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 pZn 2+ , pCu 2+ , pNi 2+ , pPb 2+ and pCd 2+ 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 pZn 2+ , pCu 2+ , pNi 2+ , pPb 2+ and pCd 2+ , 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., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Iron (Fe) and zinc (Zn) deficiencies are wide spread in South Asia and Africa. Biofortification of food crops is a viable means of addressing micronutrient deficiencies. Lentil is an important pulse crop that provides affordable source of proteins, minerals, fibre and carbohydrates for micronutrient deficient countries. An association mapping (AM) panel of 96 diverse lentil genotypes from India and Mediterranean region was evaluated for three seasons and genotyped using 80 polymorphic simple-sequence repeat (SSR) markers for identification of the markers associated with grain Fe and Zn concentrations. A Bayesian model based clustering identified five subpopulations, adequately explaining the genetic structure of the AM panel. The linkage disequilibrium (LD) analysis using mixed linear model (MLM) identified two SSR markers, GLLC106 and GLLC108, associated with grain Fe concentration explaining 17% and 6% phenotypic variation, respectively and three SSR markers (PBALC 364, PBALC 92 and GLLC592) associated with grain Zn concentration, explaining 6%, 8% and 13% phenotypic variation, respectively. The identified SSRs exhibited consistent performance across three seasons and have potential for utilization in lentil molecular breeding programme.

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 -1 in T2, T3, T4, T5, and T6, respectively, whereas soil solution concentration of Cd in T1 was 0.99 μg L -1 . Activities of Cd (pCd 2+ ) 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.

Micronutrient malnutrition, especially deficiency of two mineral elements, iron [Fe] and zinc [Zn] in the developing world needs urgent attention. Pearl millet is one of the best crops with many nutritional properties and is accessible to the poor. We report findings of the first attempt to mine favorable alleles for grain iron and zinc content through association mapping in pearl millet. An association mapping panel of 130 diverse lines was evaluated at Delhi, Jodhpur and Dharwad, representing all the three pearl millet growing agro-climatic zones of India, during 2014 and 2015. Wide range of variation was observed for grain iron (32.3-111.9 ppm) and zinc (26.6-73.7 ppm) content. Genotyping with 114 representative polymorphic SSRs revealed 0.35 mean gene diversity. STRUCTURE analysis revealed presence of three sub-populations which was further supported by Neighbor-Joining method of clustering and principal coordinate analysis (PCoA). Marker-trait associations (MTAs) were analyzed with 267 markers (250 SSRs and 17 genic markers) in both general linear model (GLM) and mixed linear model (MLM), however, MTAs resulting from MLM were considered for more robustness of the associations. After appropriate Bonferroni correction, Xpsmp 2261 (13.34% R 2 -value), Xipes 0180 ( R 2 -value of 11.40%) and Xipes 0096 ( R 2 -value of 11.38%) were consistently associated with grain iron and zinc content for all the three locations. Favorable alleles and promising lines were identified for across and specific environments. PPMI 1102 had highest number (7) of favorable alleles, followed by four each for PPMFeZMP 199 and PPMI 708 for across the environment performance for both grain Fe and Zn content, while PPMI 1104 had alleles specific to Dharwad for grain Fe and Zn content. When compared with the reference genome Tift 23D 2 B 1 -P1-P5, Xpsmp 2261 amplicon was identified in intergenic region on pseudomolecule 5, while the other marker, Xipes 0810 was observed to be overlapping with aspartic proteinase ( Asp ) gene on pseudomolecule 3. Thus, this study can help in breeding new lines with enhanced micronutrient content using marker-assisted selection (MAS) in pearl millet leading to improved well-being especially for women and children.

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.

Limited information is available related to the effect of moisture and temperature on release of metals from sludge treated soils. In an incubation experiment, effect of ten levels of sludge (0, 1.12, 2.24, 4.48, 8.96, 17.9, 35.8, 71.6, 142, 285 g kg(-1)), two levels of moisture (field capacity and 2.5 cm standing water) and two levels of temperature (20 and 35 degrees C) on the release of zinc and cadmium was evaluated in acid and alkaline soils. The results indicated that application of sludge was more effective in enhancing EDTA extractable Zn and Cd in acid soil than in alkaline soil. On an average, maximum increase in release of EDTA extractable Zn and Cd were 32.0 and 5.2 fold in sludge treated soil over control. There was decrease in EDTA extractable Zn and Cd by 37.7% and 25.4%, respectively under submergence as compared to that under field capacity. On an average, the amount of EDTA extractable Zn and Cd increased by 22.6% and 43.6%, respectively at 35 degrees C than that at 20 degrees C.

Chronic hemoglobinopathies like thalassemia are associated with many osteopathies like osteoporosis. Methods. This observational study was carried out to compare the bone mineral density (BMD) in transfusion dependent thalassemics with that of healthy controls. Thirty-two thalassemia patients, aged 2-18 years, and 32 age and sex matched controls were studied. The bone mineral concentration (BMC) and BMD were assessed at lumbar spine, distal radius, and neck of femur. Biochemical parameters like serum calcium and vitamin D levels were also assessed. Results. The BMC of neck of femur was significantly low in cases in comparison to controls. We also observed significantly lower BMD at the lumbar spine in cases in comparison to controls. A significantly positive correlation was observed between serum calcium levels and BMD at neck of femur. Conclusion. Hence, low serum calcium may be used as a predictor of low BMD especially in populations where incidence of hypovitaminosis D is very high.

We attempted to develop a protocol for fixing the maximum permissible limit of sludge in agricultural lands based on transfer of metals from sludge-amended soils to human food chain. For this purpose, spinach was grown as a test crop on acid and alkaline soils with graded doses of sludge (0, 1.12, 2.24, 4.48, 8.96, 17.9, 35.8, 71.6, 142 and 285 g kg(-1) of soil) in a pot experiment. Biomass yield of spinach was increased due to sludge application in both acid and alkaline soils. Among the chemical extractants, EDTA extracted the highest amount of metals from sludge-amended soil followed by diethylenetriaminepentaacetic acid (DTPA) and CaCl2. Elevated levels of Zn, Cu, Fe, Mn, Ni, Cd and Pb in spinach were observed due to sludge application over control. Application of sludge was more effective in increasing metal content in spinach grown on acid soil than alkaline soil. Solubility-free ion activity model as a function of pH, organic carbon and extractable metal was far more effective in predicting metal uptake by spinach grown on sludge-amended soils as compared to that of chemical extractants. Risk in terms of hazard quotient (HQ) for intake of metals through consumption of spinach by humans grown on sludge-treated soils was computed for different metals separately. In a 90-day pot experiment, safe rates of sludge application were worked out as 4.48 and 71.6 g kg(-1) for acid and alkaline soils, respectively.

Risk assessment of metal-contaminated soil depends on how precisely one can predict the solubility of metals in soils. Responses of plants and soil organisms to metal toxicity are explained by the variation in free metal ion activity in soil pore water. This study was undertaken to predict the free ion activity of Zn, Cu, Ni, Cd, and Pb in metal-contaminated soil as a function of pH, soil organic carbon, and extractable metal content. For this purpose, 21 surface soil samples (0-15 cm) were collected from agricultural lands of various locations receiving sewage sludge and industrial effluents for a long period. One soil sample was also collected from agricultural land which has been under intensive cropping and receiving irrigation through tube well water. Soil samples were varied widely in respect of physicochemical properties including metal content. Total Zn, Cu, Ni, Cd, and Pb in experimental soils were 2,015 ± 3,373, 236 ± 286, 103 ± 192, 29.8 ± 6.04, and 141 ± 270 mg kg(-1), respectively. Free metal ion activity, viz., pZn(2+), pCu(2+), pNi(2+), pCd(2+), and pPb(2+), as estimated by the Baker soil test was 9.37 ± 1.89, 13.1 ± 1.96, 12.8 ± 1.89, 11.9 ± 2.00, and 11.6 ± 1.52, respectively. Free metal ion activity was predicted by pH-dependent Freundlich equation (solubility model) as a function of pH, organic carbon, and extractable metal. Results indicate that solubility model as a function of pH, Walkley-Black carbon (WBC), and ethylenediaminetetraacetic acid (EDTA)-extractable metals could explain the variation in pZn(2+), pCu(2+), pNi(2+), pCd(2+), and pPb(2+) to the extent of 59, 56, 46, 52, and 51%, respectively. Predictability of the solubility model based on pH, KMnO4-oxidizable carbon, and diethylenetriaminepentaacetic acid-extractable or CaCl2-extractable metal was inferior compared to that based on EDTA-extractable metals and WBC.