Nav Raten Panwar | Central Electronics Engineering Research Institute (original) (raw)

Papers by Nav Raten Panwar

International Nano Letters

The Indian Journal of Agricultural Sciences

The bioactive compounds, total antioxidant activity and minerals in white, pink and red flesh gua... more The bioactive compounds, total antioxidant activity and minerals in white, pink and red flesh guava (Psidium guajava L.) varieties were assessed and quantified at three different stages of maturity in arid conditions. Changes in pectin content followed similar trend as fruit firmness and it gradually decreased till ripe stage. Total soluble solids and total sugars increased till full ripe stage but reverse was case for acidity. Ascorbic acid in white flesh guava varieties increased till colour turning stage and then after it decreased, while in coloured varieties it showed decreasing trend till ripe stage. White flesh varieties contains negligible quantity of anthocyanin, lycopene and total carotenoid while pink flesh (Lalit) had highest concentration of these compound followed by red flesh (Red flesh). Total phenols and total antioxidant activities of guava fruits were comparatively low during green mature stage and it increased progressively in later stages. Flesh colour did not s...

Inorganic and Nano-Metal Chemistry, Jan 7, 2022

Extreme Environments, 2021

Archives of Agronomy and Soil Science, 2021

Plants and microorganisms sense and respond to biotic and abiotic signals in the environment to c... more Plants and microorganisms sense and respond to biotic and abiotic signals in the environment to competitively optimize their fitness. These specific adjustments which are pertinent to prevailing en...

Agronomy, 2021

Protected vegetable cultivation is a fast-growing sector in which grafting plays a crucial role f... more Protected vegetable cultivation is a fast-growing sector in which grafting plays a crucial role for success. Cucumber is predominantly grown under protected conditions. The popular slicing (mini) cucumber comprises two segments, single- and cluster-fruit-bearing. In the present study, the performance of select fruit-bearing hybrids grafted as scions onto commercial Cucurbita hybrid rootstock ‘NS-55’ was evaluated under three different low-cost protected structures in arid regions. With respect to type of protected structure, cucumber performance was superior under a naturally ventilated polyhouse (NVP) than an insect net house (INH) or a shade net house (SNH). Micro-climate parameters inside NVP (air temperature, RH and PAR) were more congenial for cucumber than those in net houses, thereby facilitating improved physiology (chlorophyll fluorescence, chlorophyll and plant water potential) and leaf mineral status. Grafting invariably improved growth and yield parameters under all prot...

Journal of Soil Science and Plant Nutrition, 2021

Increasing fertilizer demands and dwindling mineral reserves warrant sustainable alternatives for... more Increasing fertilizer demands and dwindling mineral reserves warrant sustainable alternatives for plant fertilization. Organo-mineral fertilizers (OMFs) based on indigenous materials which are unutilized commercially are a possible option. The study describes the effect of novel OMF of phosphorus (OMF-P) and potassium (OMF-K), developed respectively from insoluble low-grade rock phosphate and feldspar on plant growth. The experiment was conducted in a glass chamber partitioned into two blocks, one with soil and the other with soil supplemented with 1% OMF-P or 1% OMF-K. Pearl millet plants were grown in the chambers for 45 days and the roots and soil from different chamber blocks were separated and analyzed. Root volume, fresh and dry weights, average root length, diameter and number of root tips were significantly increased with OMF-P/OMF-K and plants showed improved growth and plant height. The release and availability of P/K in soil was confirmed with isolations of P- and K-solubilizing fungi from the blocks with OMF along with significantly higher values of available P (0.006 mg g−1) and K (0.01 mg g−1) recorded from these blocks compared to control chambers. Moreover, the OMF prills did not exhibit any adverse effects on the plants and on soil microflora. The release of soluble P and K from the OMF is attributed to the presence of P and K solubilizers in soil, since conditions favourable for their selective enrichment are created. The OMF prills developed could address issues of deteriorating mineral reserves and associated environmental degradation, besides providing a sustainable management option.

International Journal of Current Microbiology and Applied Sciences, 2017

Environmental Chemistry Letters, 2017

Copper nanoparticles have improved properties compared to the bulk copper material. Copper nanopa... more Copper nanoparticles have improved properties compared to the bulk copper material. Copper nanoparticles indeed find applications in gas sensors, heat transfer fluids, catalysis, solar energy and batteries. Antibacterial and antifungal activities of copper nanoparticles find applications in the agriculture and healthcare sectors. Nonetheless, careless use of copper nanoparticles may cause environmental pollution and health effects. Here we review the biosynthesis of copper nanoparticles using plant materials, named phytosynthesis, and microorganisms. We also discuss the effect of copper nanoparticles on crops and pathogenic microorganisms. Copper nanoparticles varying in sizes from 5 to 295 nm have been synthesized using leaf extracts and latex from plants, and using bacteria and fungi. Biosynthesized copper nanoparticles show good antimicrobial activity inhibiting the growth of pathogenic bacteria and pathogenic fungi. Copper nanoparticles enhance the germination and growth of some plants at lower concentrations, whereas high concentrations result in retarded growth.

Agronomy, 2022

Red-fleshed dragon fruit offers an array of bioactive compounds. Its cultivation is gaining momen... more Red-fleshed dragon fruit offers an array of bioactive compounds. Its cultivation is gaining momentum in India, including in arid and semi-arid conditions. Among various factors, the fruit developmental stages and climatic conditions of locations greatly influence the biosynthesis and actual contents of different bioactive compounds and mineral contents of the fruit. The changes in physical attributes, and bioactive and mineral content in red-fleshed dragon fruit grown in semi-arid conditions in India were assessed and quantified at six developmental stages. Significant changes occurred in the physical attributes of the fruit and the bioactive compounds and mineral content during the fruit maturation stages of the red-fleshed dragon fruit. The fruit physical characteristics, such as fruit size, fruit and pulp weight gain, peel thickness, and fruit firmness, along with eating quality parameters, such as soluble solids, sugars, acidity and soluble proteins, were observed at optimum at ...

Current Science, 2014

Regular use of compost prepared from municipal solid waste is associated with the entry of heavy ... more Regular use of compost prepared from municipal solid waste is associated with the entry of heavy metals into the soil, which poses considerable risks to different components of the environment. Total metal content does not generally reflect the availability of metals for the expression of environmental risk because of rapid and strong interactions of the metals with different constituents of the soil. Hence, the present study was conducted to determine screening levels of Cd, Cr, Cu, Ni, Pb and Zn for a susceptible soil by following a widely recommended soil test procedure involving the extraction of these heavy metals with a dilute calcium chloride solution. Separate sets of pot-culture experiments were carried out for each of these heavy metals in graded dose levels (Cd at 0.02-20 mg kg -1 , Cr at 0.4-200 mg kg -1 , Cu at 1.6-800 mg kg -1 , Ni at 0.5- 250 mg kg -1 , Pb at 0.4 -1 50 mg kg -1 and Zn at 4.6- 1000 mg kg -1 ) added to an acidic, light-textured alluvial soil. Soil test ...

Waste Management, 2010

A study was conducted to investigate physico-chemical properties, fertilizing potential and heavy... more A study was conducted to investigate physico-chemical properties, fertilizing potential and heavy metal polluting potentials of municipal solid waste composts produced in 29 cities of the country. Results indicated that except a very few samples, all other samples have normal pH and EC. Organic matter as well as major nutrients N and P contents in MSW composts are generally low

Organic matter status of cultivated lands in most of the agroecological regions of India is low d... more Organic matter status of cultivated lands in most of the agroecological regions of India is low due to rapid mineralization loss of C input into the soil from different sources. This, in conjunction with low fertilizer input, has resulted in continuous decline in agricultural productivity. Long-term fertilizer experiments as well as manurial trials in various parts of the country have conclusively shown that integrated nutrient management (INM) involving various types of organic manure can sustain or augment agricultural productivity. Rural compost prepared mainly from cattle shed litters and agricultural wastes remained major source organic matter in the INM in Indian agri-horticulture. However, availability of rural compost is very low (on average, little over 2 t/ha) and is declining continuously due to decreased dependency on animals in crop husbandry. On the other hand, India generates about 70 million tonne (MT) of municipal solid wastes annually, which has the potential of pr...

Geo-referenced soil samples (0-15 cm) were collected from the farmers fields of Sehore (n = 120) ... more Geo-referenced soil samples (0-15 cm) were collected from the farmers fields of Sehore (n = 120) and Vidisha (n = 156) district representing AESR 10.1 to establish the relationship between oxidizable SOC and total SOC in Vertisols of Central India and also to study the distribution of different pools of SOC as well as their relationship with crop yield. Total SOC was apportioned into different pools by using 5, 10 and 20 ml of concentrated H 2 SO 4 that resulted in 3 acid-aqueous solution ratio of 0.5:1, 1:1 and 2:1. Also crop yields during the following winter season and rainy season from the geo-reference fields were recorded and were transformed to % relative yield. Oxidizable SOC (y) was related to total SOC (x) in the form of y = 0.825x – 0.086 (R 2 = 0.958, n = 276), indicating that oxidizable SOC comprised 82.5% of the total SOC. Therefore it was recommended that a correction factor of 1.21 should be used to convert oxidizable SOC values to get the estimate of total SOC. The mean crop productivity was better related to oxidizable SOC (r = 0.5275) as compared to total SOC(r = 0.4886). The threshold and optimum values of oxidizable SOC were 3.2 and 11.2 g C/kg, respectively, whereas the threshold and optimum values for total SOC were 3.87 and 14.1 g C/kg, respectively. Among the different pools, less labile C was highly correlated (r = 0.5871) with the crop productivity, the computed threshold and optimum value for less labile C were 1.53 and 5.2 g C/kg, respectively.

ABSTRACT Environmental pollutants, such as heavy metals, must be controlled because of their toxi... more ABSTRACT Environmental pollutants, such as heavy metals, must be controlled because of their toxicity to animals, plants and microorganisms. Although soils have considerable immobilizing capability, large-scale metal build-up can adversely affect different components of the environment. The current study was carried out to establish the limits of Cd, Cr, Cu, Ni, Pb, and Zn levels permissible in soil, which would help in protecting animals, plants, and microorganisms. Separate sets of pot experiments were carried out for each of these heavy metals in graded dose levels (Cd at 0.02–20 mg kg-1, Cr at 0.4–200 mg kg-1, Cu at 1.6–800 mg kg-1, Ni at 0.5–250 mg kg-1, Pb at 0.4–150 mg kg-1, and Zn at 4.6–1000 mg kg-1) added to an acidic, light-textured, alluvial soil. Spinach crop was grown for 50 days on these treated soils after a stabilization period of two months. Maximal protective concentration limits of these metals were determined in the soil through three different approaches, namely, ‘phytotoxicity’, ‘food contamination,’ and ‘soil microbial activity diminution’. Adverse effects of the heavy metals on microbial activity and contamination of the food chain were observed much before their adverse effects on plant growth became evident. The ED20 (ecological dose corresponding to a 20% decrease in soil microbial activity) values were found to be 392 mg kg-1 for Zn, 179 mg kg-1 for Cu, 9.5 mg kg-1 for Cd, 81 mg kg-1 for Pb, 51 mg kg-1 for Ni, and 31 mg kg-1 for Cr. Considering the lowest values of these maximal permissible soil concentrations of the heavy metals determined by three different approaches to be protective for all target organisms, these levels were found to be: 392 mg Zn kg-1, 179 mg Cu kg-1, 0.34 mg Cd kg-1, 81 mg Pb kg-1, 30.7 mg Ni kg-1 and 31 mg Cr kg-1.

Environmental Monitoring and Assessment, 2013

The present study compares the distribution and nature of heavy metals in composts from 12 cities... more The present study compares the distribution and nature of heavy metals in composts from 12 cities of India, prepared from different types of processed urban solid wastes, namely mixed wastes (MWC), partially segregated wastes (PSWC), and segregated bio-wastes (BWC). Compost samples were physically fractionated by wet sieving, followed by extraction of heavy metals by dilute HCl and NaOH. Bigger particles (>0.5 mm) constituted the major fraction in all three types of composts and had a relatively lower concentration of organic matter and heavy metals, the effect being more pronounced in MWC and PSWC in which a significant portion of the heavy metals was distributed in finer size fractions. Cd, Ni, Pb, and Zn were extracted to a greater extent by acid than by alkali, the difference being greater in MWC, which contained a higher amount of mineral matter. In contrast, Cu and Cr were extracted to a greater extent by dilute alkali, particularly from BWC containing a higher amount of organic matter. Water-soluble heavy metals were generally related to the water-soluble C or total C content as well as to pH, rather than to their total contents. This study concludes that wet sieving with dilute acid can effectively reduce heavy metal load in MWC and PSWC.

Environmental Monitoring and Assessment, 2009

In the peri-urban areas of central India, sewage water is a valuable resource for agricultural pr... more In the peri-urban areas of central India, sewage water is a valuable resource for agricultural production. In this study, impact of domestic sewage water irrigation for 5 years on Vertisol with no previous history of sewage irrigation was investigated in an ongoing field experiment at Bhopal (India) under subtropical monsoon type climate. The wheat (Triticum aestivum) crop was grown during post-rainy winter season with 30 cm of irrigation (groundwater or sewage water) and four nutrient treatments (T(1), 0; T(2), 100%; T(3), 50%; and T(4), 50% of general recommended doses of NPK + FYM at 10 Mg/ha). Results showed that sewage irrigation of about 150 cm over a period of 5 years resulted significant increases in salinity as well as available fractions of N, P, K, and micronutrients, viz., Zn, Fe, and Mn in soils. Carbon and phosphorus applied through sewage water were accumulated more in subsoil layer compared to topmost plough layer. Soil microbiological activity, as indicated by soil respiration, microbial biomass C, as well as dehydrogenase enzyme activity was higher in sewage water-irrigated soils. There was also significant increase in fungal and actinomycetes as well as total coliform population in such soils. Nutrients supplied through sewage water were not able to raise the productivity of wheat to the level that obtained through fertilizers at the recommended level which indicated that additional nutrients through fertilizers are required to obtain higher productivity of wheat under sewage farming. Protein and Zn content in wheat grains were more when the crop was grown with sewage irrigation. Overall results show that except for increase in coliform population, short duration (5 years) of municipal sewage water irrigation did not have any appreciable harmful effect on soil quality as well as crop productivity; rather, it proved beneficial in improving soil fertility, wheat productivity, and produce quality.

Environmental Monitoring and Assessment, 2009

Cadmium and lead are important environmental pollutants with high toxicity to animals and human. ... more Cadmium and lead are important environmental pollutants with high toxicity to animals and human. Soils, though have considerable metal immobilizing capability, can contaminate food chain via plants grown upon them when their built-up occurs to a large extent. Present experiment was carried out with the objective of quantifying the limits of Pb and Cd loading in soil for the purpose of preventing food chain contamination beyond background concentration levels. Two separate sets of pot experiment were carried out for these two heavy metals with graded levels of application doses of Pb at 0.4-150 mg/kg and Cd at 0.02-20 mg/kg to an acidic light textured alluvial soil. Spinach crop was grown for 50 days on these treated soils after a stabilization period of 2 months. Upper limit of background concentration levels (C(ul)) of these metals were calculated through statistical approach from the heavy metals concentration values in leaves of spinach crop grown in farmers' fields. Lead and Cd concentration limits in soil were calculated by dividing C(ul) with uptake response slope obtained from the pot experiment. Cumulative loading limits (concentration limits in soil minus contents in uncontaminated soil) for the experimental soil were estimated to be 170 kg Pb/ha and 0.8 kg Cd/ha. Based on certain assumptions on application rate and computed cumulative loading limit values, maximum permissible Pb and Cd concentration values in municipal solid waste (MSW) compost were proposed as 170 mg Pb/kg and 0.8 mg Cd/kg, respectively. In view of these limiting values, about 56% and 47% of the MSW compost samples from different cities are found to contain Pb and Cd in the safe range.

International Nano Letters

The Indian Journal of Agricultural Sciences

The bioactive compounds, total antioxidant activity and minerals in white, pink and red flesh gua... more The bioactive compounds, total antioxidant activity and minerals in white, pink and red flesh guava (Psidium guajava L.) varieties were assessed and quantified at three different stages of maturity in arid conditions. Changes in pectin content followed similar trend as fruit firmness and it gradually decreased till ripe stage. Total soluble solids and total sugars increased till full ripe stage but reverse was case for acidity. Ascorbic acid in white flesh guava varieties increased till colour turning stage and then after it decreased, while in coloured varieties it showed decreasing trend till ripe stage. White flesh varieties contains negligible quantity of anthocyanin, lycopene and total carotenoid while pink flesh (Lalit) had highest concentration of these compound followed by red flesh (Red flesh). Total phenols and total antioxidant activities of guava fruits were comparatively low during green mature stage and it increased progressively in later stages. Flesh colour did not s...

Inorganic and Nano-Metal Chemistry, Jan 7, 2022

Extreme Environments, 2021

Archives of Agronomy and Soil Science, 2021

Plants and microorganisms sense and respond to biotic and abiotic signals in the environment to c... more Plants and microorganisms sense and respond to biotic and abiotic signals in the environment to competitively optimize their fitness. These specific adjustments which are pertinent to prevailing en...

Agronomy, 2021

Protected vegetable cultivation is a fast-growing sector in which grafting plays a crucial role f... more Protected vegetable cultivation is a fast-growing sector in which grafting plays a crucial role for success. Cucumber is predominantly grown under protected conditions. The popular slicing (mini) cucumber comprises two segments, single- and cluster-fruit-bearing. In the present study, the performance of select fruit-bearing hybrids grafted as scions onto commercial Cucurbita hybrid rootstock ‘NS-55’ was evaluated under three different low-cost protected structures in arid regions. With respect to type of protected structure, cucumber performance was superior under a naturally ventilated polyhouse (NVP) than an insect net house (INH) or a shade net house (SNH). Micro-climate parameters inside NVP (air temperature, RH and PAR) were more congenial for cucumber than those in net houses, thereby facilitating improved physiology (chlorophyll fluorescence, chlorophyll and plant water potential) and leaf mineral status. Grafting invariably improved growth and yield parameters under all prot...

Journal of Soil Science and Plant Nutrition, 2021

Increasing fertilizer demands and dwindling mineral reserves warrant sustainable alternatives for... more Increasing fertilizer demands and dwindling mineral reserves warrant sustainable alternatives for plant fertilization. Organo-mineral fertilizers (OMFs) based on indigenous materials which are unutilized commercially are a possible option. The study describes the effect of novel OMF of phosphorus (OMF-P) and potassium (OMF-K), developed respectively from insoluble low-grade rock phosphate and feldspar on plant growth. The experiment was conducted in a glass chamber partitioned into two blocks, one with soil and the other with soil supplemented with 1% OMF-P or 1% OMF-K. Pearl millet plants were grown in the chambers for 45 days and the roots and soil from different chamber blocks were separated and analyzed. Root volume, fresh and dry weights, average root length, diameter and number of root tips were significantly increased with OMF-P/OMF-K and plants showed improved growth and plant height. The release and availability of P/K in soil was confirmed with isolations of P- and K-solubilizing fungi from the blocks with OMF along with significantly higher values of available P (0.006 mg g−1) and K (0.01 mg g−1) recorded from these blocks compared to control chambers. Moreover, the OMF prills did not exhibit any adverse effects on the plants and on soil microflora. The release of soluble P and K from the OMF is attributed to the presence of P and K solubilizers in soil, since conditions favourable for their selective enrichment are created. The OMF prills developed could address issues of deteriorating mineral reserves and associated environmental degradation, besides providing a sustainable management option.

International Journal of Current Microbiology and Applied Sciences, 2017

Environmental Chemistry Letters, 2017

Copper nanoparticles have improved properties compared to the bulk copper material. Copper nanopa... more Copper nanoparticles have improved properties compared to the bulk copper material. Copper nanoparticles indeed find applications in gas sensors, heat transfer fluids, catalysis, solar energy and batteries. Antibacterial and antifungal activities of copper nanoparticles find applications in the agriculture and healthcare sectors. Nonetheless, careless use of copper nanoparticles may cause environmental pollution and health effects. Here we review the biosynthesis of copper nanoparticles using plant materials, named phytosynthesis, and microorganisms. We also discuss the effect of copper nanoparticles on crops and pathogenic microorganisms. Copper nanoparticles varying in sizes from 5 to 295 nm have been synthesized using leaf extracts and latex from plants, and using bacteria and fungi. Biosynthesized copper nanoparticles show good antimicrobial activity inhibiting the growth of pathogenic bacteria and pathogenic fungi. Copper nanoparticles enhance the germination and growth of some plants at lower concentrations, whereas high concentrations result in retarded growth.

Agronomy, 2022

Red-fleshed dragon fruit offers an array of bioactive compounds. Its cultivation is gaining momen... more Red-fleshed dragon fruit offers an array of bioactive compounds. Its cultivation is gaining momentum in India, including in arid and semi-arid conditions. Among various factors, the fruit developmental stages and climatic conditions of locations greatly influence the biosynthesis and actual contents of different bioactive compounds and mineral contents of the fruit. The changes in physical attributes, and bioactive and mineral content in red-fleshed dragon fruit grown in semi-arid conditions in India were assessed and quantified at six developmental stages. Significant changes occurred in the physical attributes of the fruit and the bioactive compounds and mineral content during the fruit maturation stages of the red-fleshed dragon fruit. The fruit physical characteristics, such as fruit size, fruit and pulp weight gain, peel thickness, and fruit firmness, along with eating quality parameters, such as soluble solids, sugars, acidity and soluble proteins, were observed at optimum at ...

Current Science, 2014

Regular use of compost prepared from municipal solid waste is associated with the entry of heavy ... more Regular use of compost prepared from municipal solid waste is associated with the entry of heavy metals into the soil, which poses considerable risks to different components of the environment. Total metal content does not generally reflect the availability of metals for the expression of environmental risk because of rapid and strong interactions of the metals with different constituents of the soil. Hence, the present study was conducted to determine screening levels of Cd, Cr, Cu, Ni, Pb and Zn for a susceptible soil by following a widely recommended soil test procedure involving the extraction of these heavy metals with a dilute calcium chloride solution. Separate sets of pot-culture experiments were carried out for each of these heavy metals in graded dose levels (Cd at 0.02-20 mg kg -1 , Cr at 0.4-200 mg kg -1 , Cu at 1.6-800 mg kg -1 , Ni at 0.5- 250 mg kg -1 , Pb at 0.4 -1 50 mg kg -1 and Zn at 4.6- 1000 mg kg -1 ) added to an acidic, light-textured alluvial soil. Soil test ...

Waste Management, 2010

A study was conducted to investigate physico-chemical properties, fertilizing potential and heavy... more A study was conducted to investigate physico-chemical properties, fertilizing potential and heavy metal polluting potentials of municipal solid waste composts produced in 29 cities of the country. Results indicated that except a very few samples, all other samples have normal pH and EC. Organic matter as well as major nutrients N and P contents in MSW composts are generally low

Organic matter status of cultivated lands in most of the agroecological regions of India is low d... more Organic matter status of cultivated lands in most of the agroecological regions of India is low due to rapid mineralization loss of C input into the soil from different sources. This, in conjunction with low fertilizer input, has resulted in continuous decline in agricultural productivity. Long-term fertilizer experiments as well as manurial trials in various parts of the country have conclusively shown that integrated nutrient management (INM) involving various types of organic manure can sustain or augment agricultural productivity. Rural compost prepared mainly from cattle shed litters and agricultural wastes remained major source organic matter in the INM in Indian agri-horticulture. However, availability of rural compost is very low (on average, little over 2 t/ha) and is declining continuously due to decreased dependency on animals in crop husbandry. On the other hand, India generates about 70 million tonne (MT) of municipal solid wastes annually, which has the potential of pr...

Geo-referenced soil samples (0-15 cm) were collected from the farmers fields of Sehore (n = 120) ... more Geo-referenced soil samples (0-15 cm) were collected from the farmers fields of Sehore (n = 120) and Vidisha (n = 156) district representing AESR 10.1 to establish the relationship between oxidizable SOC and total SOC in Vertisols of Central India and also to study the distribution of different pools of SOC as well as their relationship with crop yield. Total SOC was apportioned into different pools by using 5, 10 and 20 ml of concentrated H 2 SO 4 that resulted in 3 acid-aqueous solution ratio of 0.5:1, 1:1 and 2:1. Also crop yields during the following winter season and rainy season from the geo-reference fields were recorded and were transformed to % relative yield. Oxidizable SOC (y) was related to total SOC (x) in the form of y = 0.825x – 0.086 (R 2 = 0.958, n = 276), indicating that oxidizable SOC comprised 82.5% of the total SOC. Therefore it was recommended that a correction factor of 1.21 should be used to convert oxidizable SOC values to get the estimate of total SOC. The mean crop productivity was better related to oxidizable SOC (r = 0.5275) as compared to total SOC(r = 0.4886). The threshold and optimum values of oxidizable SOC were 3.2 and 11.2 g C/kg, respectively, whereas the threshold and optimum values for total SOC were 3.87 and 14.1 g C/kg, respectively. Among the different pools, less labile C was highly correlated (r = 0.5871) with the crop productivity, the computed threshold and optimum value for less labile C were 1.53 and 5.2 g C/kg, respectively.

ABSTRACT Environmental pollutants, such as heavy metals, must be controlled because of their toxi... more ABSTRACT Environmental pollutants, such as heavy metals, must be controlled because of their toxicity to animals, plants and microorganisms. Although soils have considerable immobilizing capability, large-scale metal build-up can adversely affect different components of the environment. The current study was carried out to establish the limits of Cd, Cr, Cu, Ni, Pb, and Zn levels permissible in soil, which would help in protecting animals, plants, and microorganisms. Separate sets of pot experiments were carried out for each of these heavy metals in graded dose levels (Cd at 0.02–20 mg kg-1, Cr at 0.4–200 mg kg-1, Cu at 1.6–800 mg kg-1, Ni at 0.5–250 mg kg-1, Pb at 0.4–150 mg kg-1, and Zn at 4.6–1000 mg kg-1) added to an acidic, light-textured, alluvial soil. Spinach crop was grown for 50 days on these treated soils after a stabilization period of two months. Maximal protective concentration limits of these metals were determined in the soil through three different approaches, namely, ‘phytotoxicity’, ‘food contamination,’ and ‘soil microbial activity diminution’. Adverse effects of the heavy metals on microbial activity and contamination of the food chain were observed much before their adverse effects on plant growth became evident. The ED20 (ecological dose corresponding to a 20% decrease in soil microbial activity) values were found to be 392 mg kg-1 for Zn, 179 mg kg-1 for Cu, 9.5 mg kg-1 for Cd, 81 mg kg-1 for Pb, 51 mg kg-1 for Ni, and 31 mg kg-1 for Cr. Considering the lowest values of these maximal permissible soil concentrations of the heavy metals determined by three different approaches to be protective for all target organisms, these levels were found to be: 392 mg Zn kg-1, 179 mg Cu kg-1, 0.34 mg Cd kg-1, 81 mg Pb kg-1, 30.7 mg Ni kg-1 and 31 mg Cr kg-1.

Environmental Monitoring and Assessment, 2013

The present study compares the distribution and nature of heavy metals in composts from 12 cities... more The present study compares the distribution and nature of heavy metals in composts from 12 cities of India, prepared from different types of processed urban solid wastes, namely mixed wastes (MWC), partially segregated wastes (PSWC), and segregated bio-wastes (BWC). Compost samples were physically fractionated by wet sieving, followed by extraction of heavy metals by dilute HCl and NaOH. Bigger particles (>0.5 mm) constituted the major fraction in all three types of composts and had a relatively lower concentration of organic matter and heavy metals, the effect being more pronounced in MWC and PSWC in which a significant portion of the heavy metals was distributed in finer size fractions. Cd, Ni, Pb, and Zn were extracted to a greater extent by acid than by alkali, the difference being greater in MWC, which contained a higher amount of mineral matter. In contrast, Cu and Cr were extracted to a greater extent by dilute alkali, particularly from BWC containing a higher amount of organic matter. Water-soluble heavy metals were generally related to the water-soluble C or total C content as well as to pH, rather than to their total contents. This study concludes that wet sieving with dilute acid can effectively reduce heavy metal load in MWC and PSWC.

Environmental Monitoring and Assessment, 2009

In the peri-urban areas of central India, sewage water is a valuable resource for agricultural pr... more In the peri-urban areas of central India, sewage water is a valuable resource for agricultural production. In this study, impact of domestic sewage water irrigation for 5 years on Vertisol with no previous history of sewage irrigation was investigated in an ongoing field experiment at Bhopal (India) under subtropical monsoon type climate. The wheat (Triticum aestivum) crop was grown during post-rainy winter season with 30 cm of irrigation (groundwater or sewage water) and four nutrient treatments (T(1), 0; T(2), 100%; T(3), 50%; and T(4), 50% of general recommended doses of NPK + FYM at 10 Mg/ha). Results showed that sewage irrigation of about 150 cm over a period of 5 years resulted significant increases in salinity as well as available fractions of N, P, K, and micronutrients, viz., Zn, Fe, and Mn in soils. Carbon and phosphorus applied through sewage water were accumulated more in subsoil layer compared to topmost plough layer. Soil microbiological activity, as indicated by soil respiration, microbial biomass C, as well as dehydrogenase enzyme activity was higher in sewage water-irrigated soils. There was also significant increase in fungal and actinomycetes as well as total coliform population in such soils. Nutrients supplied through sewage water were not able to raise the productivity of wheat to the level that obtained through fertilizers at the recommended level which indicated that additional nutrients through fertilizers are required to obtain higher productivity of wheat under sewage farming. Protein and Zn content in wheat grains were more when the crop was grown with sewage irrigation. Overall results show that except for increase in coliform population, short duration (5 years) of municipal sewage water irrigation did not have any appreciable harmful effect on soil quality as well as crop productivity; rather, it proved beneficial in improving soil fertility, wheat productivity, and produce quality.

Environmental Monitoring and Assessment, 2009

Cadmium and lead are important environmental pollutants with high toxicity to animals and human. ... more Cadmium and lead are important environmental pollutants with high toxicity to animals and human. Soils, though have considerable metal immobilizing capability, can contaminate food chain via plants grown upon them when their built-up occurs to a large extent. Present experiment was carried out with the objective of quantifying the limits of Pb and Cd loading in soil for the purpose of preventing food chain contamination beyond background concentration levels. Two separate sets of pot experiment were carried out for these two heavy metals with graded levels of application doses of Pb at 0.4-150 mg/kg and Cd at 0.02-20 mg/kg to an acidic light textured alluvial soil. Spinach crop was grown for 50 days on these treated soils after a stabilization period of 2 months. Upper limit of background concentration levels (C(ul)) of these metals were calculated through statistical approach from the heavy metals concentration values in leaves of spinach crop grown in farmers' fields. Lead and Cd concentration limits in soil were calculated by dividing C(ul) with uptake response slope obtained from the pot experiment. Cumulative loading limits (concentration limits in soil minus contents in uncontaminated soil) for the experimental soil were estimated to be 170 kg Pb/ha and 0.8 kg Cd/ha. Based on certain assumptions on application rate and computed cumulative loading limit values, maximum permissible Pb and Cd concentration values in municipal solid waste (MSW) compost were proposed as 170 mg Pb/kg and 0.8 mg Cd/kg, respectively. In view of these limiting values, about 56% and 47% of the MSW compost samples from different cities are found to contain Pb and Cd in the safe range.