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India is an agricultural country and near about 500 MT of agricultural wastes are generated each year. India has huge reserves of low-grade iron ore fines. Therefore, considering the availability of these two, the present study mainly focuses on utilization of solid waste in iron and steel industry; also, biomass being carbon-neutral fuel, promotes mitigation of environmental issues. To carry out this study, agricultural wastes like groundnut shell and corn cob which contain more than 70% of volatile matter were considered. Hence, an attempt has been taken to utilize this volatiles as well as char (prepared at 350°C) of corn cob and groundnut shell as a reducing agent for reduction of iron ore pellets. Maximum reduction percentage was achieved at 1000°C and 75 min using corn cob as a reductant, i.e. 78.38% with its volatile and 92.01% using its char. Higher intensity of elemental iron is also reflected by X-ray Diffraction analysis of reduced pellets. Further, cost estimation of reduction of iron ore pellets was also done using both the reducing agents, which signifies that the reduction process using biomass volatiles is much more economical than biochar. The total cost of producing DRI from corn cob volatiles is 56% less than coal followed by groundnut shell volatiles 53.36% and minimum in the case of groundnut shell char 36.17%. Highlights Effects of biomass volatiles and char on iron ore pellets reduction @ 1000°C at different time interval of 15, 30, 45, 60 & 75 min. Comparative assessment of iron ore pellets reduction through XRD and FESEM analysis. Economic evaluation of iron ore reduction using volatiles and char of biomass. [ABSTRACT FROM AUTHOR]

Chrome tanning in India leads to severe contamination of soil and water. Due to the indiscriminate disposal of effluent from tanneries, several thousand hectares of agricultural lands have been degraded over several decades in Tamil Nadu. Several researchers were involved in developing remediation technologies for chromium contamination.Adsorption and desorption of Cr on soil determine the mobility of Cr and its environmental impact. There are several studies regarding the adsorption/desorption of Cr. A strategic study regarding the mechanism of adsorption/desorption of Cr to the context of remediation technologies is essential. A better understanding of the adsorption and desorption mechanism of Cr aids in developing a suitable remediation strategy. Therefore, in the present investigation, the adsorption Cr on soil and some critical factors affecting the adsorption were studied. The Cr adsorption on soil recorded maximum and was best illustrated by the Freundlich isotherm (R2 = 0.994) than the Langmuir isotherm (R2 = 0.841). Amongst the bio-amendments, biochar was found to enhance the adsorption of Cr on the soil. The co-contaminants such as cadmium and lead significantly reduced the adsorption of Cr. Further, a desorption study was carried out with different desorption agents such as NaOH, CH3COONH4and EDTA. It was found that NaOH exhibited higher desorption efficiency than the other agents. The results reveal that adsorption and desorption mechanisms aids in predicting the toxicity of Cr. This study also shows that the soil pH, bio-amendments, and co-contaminants in the contaminated soil may play a significant role in the remediation process. [ABSTRACT FROM AUTHOR]

Application of biochar as an amendment not only improves water retention in soil but also improves overall soil physical environment. To test this hypothesis, a field study was conducted for 2 years, i.e., 2019 and 2020, in an ongoing experiment on maize-based system at the Research Farm, Department of Soil Science, Punjab Agricultural University, Ludhiana, in a sandy loam soil. The parameters tested include soil water-holding capacity, moisture retention, water transmission characteristics, aggregate stability, bulk density, and penetration resistance of soil. Six biochar (B), farmyard manure (fym), and nitrogen (N) combinations were tested, which includes BN1 (biochar @ 7.5 t ha−1 + N @ 75 kg ha−1), BN2 (biochar @ 7.5 t ha−1 + N @ 150 kg ha−1), FN1 (fym @ 20 t ha−1 + N @ 75 kg ha−1), FN2 (fym @ 20 t ha−1 + N @ 150 kg ha−1), N1 (N @ 75 kg ha−1), and N2 (N @ 150 kg ha−1) in main plots and two irrigation regimes IW/CPE ratio 0.6 (I0.6) and 0.9 (I0.9) (irrigation water over cumulative open pan evaporation), i.e., deficit and full irrigation were in subplots. Moisture retention at 0.3 bar was significantly higher under biochar treatment BN1, i.e., 30.0%, while the lowest was recorded under N2, i.e., 25.5% at the end of spring 2020. Biochar and fym-amended soils decreased penetration resistance of soil by 22.57% and 20.85% at 10 cm soil depth as compared to unamended soil. BN1 showed increased mean weight diameter by 43.90% over N1 (control). Deficit irrigation, i.e., I0.6, resulted in 6.11% and 18.78% higher water productivity of both kharif and spring maize, respectively, over I0.9. It is also concluded that biochar as soil amendment may retain more water due to its porous nature and more surface area and also reduce the frequency of irrigation, hence sustaining and optimizing the limited water available for crop production in northwest India. [ABSTRACT FROM AUTHOR]

Conventional fertilizer nitrogen (N) recommendations for rainfed maize resulted in low N use efficiency (NUE) due to several reasons. This warrants application of fertilizer synchronous with plant requirements that could aid in improved productivity and NUE. In this backdrop, to optimize N rates for maize, a field experiment was conducted during 2014 to 2016 in Vertisols. Twelve treatments in combinations viz., N omission, skipping basal dose, multi-split topdressing at varying time either as broadcast or band placement, soil test crop response (STCR) based N with target yield 6.0 t ha−1 and biochar application were investigated in a randomized block design (RBD). Late application of N rates (120 kg ha−1) in 2 equal splits at knee high (V8) and tasseling (VT) stages with skipping of basal N, significantly increased grain yield, agronomy efficiency (AE), partial factor productivity (PFP), physiological efficiency (PE) and recovery efficiency (RE) to the tune of 16.3%, 45.1%, 15.3%, 14.0% and 37.9% than conventional recommendations, respectively. The higher yields and NUE with late application of N were ascribed due to positive significant linear relationship between yield and N availability. Factor analysis too revealed the one to one positive function of biomass with N uptake at V8 and VT. Principal component (PC) regression exhibited that PC1 acted as a major predictor for yield and dominated by leaf area index (LAI) and N uptake. Thus, we conclude that the multi-split N, to achieve higher yield and greater NUE, is strongly linked with late splits of N at V8 and VT. [ABSTRACT FROM AUTHOR]

A field experiment was conducted at Zonal Agricultural Research Station, Mandya to evaluate the effect of biochar, lime and fertilizer on soil acidity and microbiological properties in an acidic soil. The experiment was laid out in randomized complete block design with seven treatments and three replications. The results revealed that application of fertilizer based on the soil test value (STV) either in combination with biochar or lime influenced soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), dehydrogenase, urease and phosphatase activities significantly. Similarly, application of STV-based fertilizer along with biochar+FYM (Farm Yard Manure) + ZnSO4 significantly decreased exchangeable aluminum, exchangeable acidity and total acidity as compared with recommended dose of fertilizer (RDF) + FYM+ ZnSO4 treatment. The grain yield of rice was increased by 37.90% in STV + biochar + FYM + ZnSO4 and by 22.87% in STV + lime +FYM + ZnSO4 plots than RDF + FYM + ZnSO4 plot. Seed and haulm yield of cowpea increased by 33.57% and 18.53% in STV + biochar + FYM + ZnSO4 treatments as compared with RDF + FYM + ZnSO4 treatment. Exchangeable aluminum and exchangeable acidity were found to be negatively correlated with yield of rice (r = -0.179) and cowpea (r = -0.266). However, yield of rice and cowpea showed the significantly and positively correlated with microbiological properties. The exchangeable Al and exchangeable acidity were found to be negatively correlated with SMBC, SMBN, dehydrogenase activity, urease activity and phosphatase activity. [ABSTRACT FROM AUTHOR]