Impact of conservation agriculture on humic acid quality and clay humus complexation under maize (Zea mays)-wheat (Triticum aestivum) and pigeon pea (Cajanus cajan)-wheat cropping systems

An attempt was made to study the humic acid (HA) quality and clay humus complex in order to generate valuable information regarding soil carbon (C) and recalcitrant carbon variations under conservation agriculture (CA) practices. It is worthwhile to mention that CA has got wider acceptance among researchers and farmers nowadays. A field experiment was conducted in an Inceptisol with three treatments, namely conventional tillage (CT), zero tillage (ZT) without residue and zero tillage with residue (ZT+R) in a maize (Zea mays L.)-wheat (Triticum aestivum L.) (M-W) and pigeon pea (Cajanus cajan L.)-wheat (P-W) cropping system at ICAR-Indian Agricultural Research Institute, New Delhi, with a view to characterize the HA by E4/E6 ratio and total acidity, and to specify the functional groups of clay humus complex. In ZT+R based treatments, lower E4/E6 ratio and total acidity of extracted HA showed higher degree of humification and stability of humic acid carbon (HA-C). The FTIR spectroscopy of the clay-humus complex (as extracted from soil) displayed the presence of a large number of functional groups in ZT+R treatment followed by ZT and CT. It was also observed that the yield of crops was also significantly higher in ZT+R than CT in both the cropping systems except in wheat crops in the M-W system. Therefore, it can be concluded that ZT+R has the potential to enrich the organic carbon (C) quality in soil and increase the aromaticity of HA, leading to carbon stabilization in soils

Transgenic Bt-cotton affects enzyme activity and nutrient availability in a sub-tropical inceptisol

We investigated the dynamics of N and P availability in the rhizosphere of Bt and non-Bt cotton crops during their growth. In a net-house pot culture experiment at the Indian Agricultural Research Institute, New Delhi, Bt-cotton (cv. MRC-6301Bt) and its non-transgenic near-isoline (MRC-6301) were grown on a sandy loam soil until maturity. A control (no-crop) treatment was also included. Rhizosphere soil and root samples were collected at 60, 90, and 120 days after sowing (DAS). Soil samples were analysed for dehydrogenase activity, soil respiration, mineral-N and Olsen-P. Results have revealed a significant reduction in dehydrogenase activity (-17 %) and soil respiration (-3.5 %) in the rhizosphere of Bt-cotton over non-Bt isoline. Total mineral-N (NH 4+-N + -N) in soil was reduced by 14 %, whereas Olsen-P was increased by 8 % because of Bt-cotton. Root biomass yields were not different (P > 0.05), but root volume was significantly higher in Bt than non-Bt isoline. Time of sampling strongly (P < 0.05) affected the above parameters, showing their highest values at 60 or 90 DAS. A significant interactive effect of sampling time and treatments was also indicated. Our results suggest that Bt-cotton may constrain the availability of N, but enhances P-availability in these soils

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Not AvailableA field experiment was conducted at the research farm of Indian Agricultural Research Institute, New Delhi on a sandy clay-loam soil (Typic Ustochrept) starting from Kharif- 2003 under organic amendments to rice-wheat cropping system. The experiment was laid out in a randomized block design with three replications and six treatments in a set. The treatments consisted of control (T1 ), farmyard manure (FYM) (T2 ); green manure (GM) (T3 ); GM+biofertilizers (B) (T4 ); GM+FYM (T5 ); and GM+FYM+B (T6 ). In this study, the effect of organic amendments were evaluated on some physical soil properties and yield of the respective system by sampling the soil from three depths (0-15, 15-30 and 30-60 cm) at the end of Rabi 2011-2012. The results of the study revealed that the plots where, farm yard manure (FYM) was incorporated along with green manure (GM) and biofertilizer (B), the yield of rice and wheat had substantially improved. The combination of B with GM+FYM had not only led to better soil bulk density but even prove superior to FYM alone or GM alone. Soil aggregation was significantly affected by organic amendments; particularly mean weight diameter (MWD) and geometric mean diameter (GMD) were increased to a tune of 73.5% and 34.6% over control in 0-15 cm soil layer. The water stable macroaggregate (WSMA)>0.25mm ranged from 54.60% under control to 71.27% under T6 in the surface soil (0-15 cm). The combined applications of FYM along with GM and B showed the highest contents of available N, P, K and S in soil. It is thus certain that the cumulative effect of GM+FYM+B proved to be the one that leads to increased productivity as well as increased soil physical properties.Not Availabl

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Not AvailableLong-term sustainability and a declining trend in productivity of rice–wheat rotation in the Indo-Gangetic plain, often direct towards the changes in soil quality parameters. Soil quality is decided through few sensitive soil physical, chemical and biological indicators as it cannot be measured directly. The present investigation was carried out to develop a valid soil quality index through some chosen indicators under long-term influences of tillage, water and nutrient-management practices in a rice–wheat cropping system. The experiment consisted of two tillage treatments, three irrigation treatments, and nine nutrient management treatments for both rice and wheat, was continued for 8 years. The index was developed using expert-opinion based conceptual framework model. After harvest of rice, the CFSQI-P (productivity) was higher under puddled situation, whereas CFSQI-EP (environmental protection) was more under non-puddled condition and 3-days of drainage was found promising for all the indices. No-tillage practice always showed higher soil quality index. The treatments either receiving full organics (100 % N) or 25 % substitution of fertilizer N with organics showed higher soil quality indices. Puddling, irrigation after 3 days of drainage and substitution of 25 % recommended fertilizer N dose with FYM in rice could be practiced for maintaining or enhancing soil quality. No-tillage, two irrigations, and domestic sewage sludge in wheat can safely be recommended for achieving higher soil quality.Not Availabl

Effect of deashing on physico-chemical properties of wheat and rice straw biochars and potential sorption of pyrazosulfuron-ethyl

Wheat (WBC) and rice straw biochars (RBC) prepared at 400 and 600 C and their deashed counterparts were characterized for their physico-chemical properties using CHN analysis, Brunauer–Emmett–Teller (BET), X-ray fluorescence (XRF), scanning electron microscopy (SEM), 13C-nuclear magnetic resonance (NMR), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) techniques. Pyrazosulfuron-ethyl sorption data on normal and deashed biochars could be well fitted to the Freundlich model. The characteristics of biochars and their adsorption capacities for pyrazosulfuron-ethyl were affected by the pyrolysis temperature and nature of feedstock. Rice biochars had higher sorption capacities than the wheat biochars. Deashing of biochars further enhanced their herbicide adsorption potential by a factor of 2–3. Sorption of herbicide on both normal and deashed biochars was concentration dependent (1/n < 1) and decreased with increase in the herbicide concentration in solution, indicating a saturation of sorption sites. The nonlinearity of the isotherms increased with increasing pyrolysis temperature and deashing. Furthermore, adsorption of pyrazosulfuron-ethyl was affected by the pH, surface area and pore volume of biochars. Results of this study suggested that the mineral fraction of biochars significantly affected pyrazosulfuron-ethyl sorption

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Not AvailableSoil available nutrients are very sensitive to change in response to management practices, and are considered to be chemical indicators of soil quality. The present investigation was conducted using two tillage managements for rice (puddled and nonpuddled) and wheat (conventional tillage and no-tillage), three water managements and nine nutrient managements. After eight cropping cycles, puddling significantly increased soil organic carbon (SOC)(9.6 g kg-1) and available N (159.5 mg kg-1) compared to non-puddled soil. The continuous submergence increased the SOC, available Fe, Cu, Mn contents in soil following rice growth, whereas significantly decreased the available N, P and Zn ones. On the contrary, less frequent irrigation improved the SOC, available N and micronutrient contents after wheat cultivation. No-tillage significantly enhanced SOC, available N and Mn. Application of sewage sludge enhanced the soil available Zn (2.98 and 2.09 mg kg-1) and Cu (2.95 and 2.06 mg kg-1) following harvest of both crops. Organic sources like crop residues, green manure, sewage sludge and combination of organic sources were more effective in improving soil quality indicators.Not Availabl

Biochar aided priming of carbon and nutrient availability in three soil orders of India

Abstract In recent years biochar (BC) has gained importance for its huge carbon (C) sequestration potential and positive effects on various soil functions. However, there is a paucity of information on the long-term impact of BC on the priming effect and nutrient availability in soil with different properties. This study investigates the effects of BC prepared from rice husk (RBC4, RBC6), sugarcane bagasse (SBC4, SBC6) and mustard stalk (MBC4, MBC6) at 400 and 600 °C on soil C priming and nitrogen (N), phosphorus (P), and potassium (K) availability in an Alfisol, Inceptisol, and Mollisol. BC properties were analyzed, and its decomposition in three soil orders was studied for 290 days in an incubation experiment. Post-incubation, available N, P, and K in soil were estimated. CO2 evolution from BC and soil alone was also studied to determine the direction of priming effect on native soil C. Increasing pyrolysis temperature enhanced pH and EC of most of the BC. The pyrolysis temperature did not show clear trend with respect to priming effect and nutrient availability across feedstock and soil type. MBC6 increased C mineralization in all the soil orders while RBC6 in Alfisol and SBC6 in both Inceptisol and Mollisol demonstrated high negative priming, making them potential amendments for preserving native soil C. Most of the BC showed negative priming of native SOC in long run (290 days) but all these BC enhanced the available N, P, and K in soil. SBC4 enhanced N availability in Alfisol and Inceptisol, RBC4 improved N and P availability in Mollisol and P in Alfisol and MBC6 increased K availability in all the soils. Thus, based on management goals, tailored BC or blending different BC can efficiently improve C sequestration and boost soil fertility

Impact of Integrated Management on Yield Sustainability in Relation to Soil Quality Under a Rice–Wheat Cropping System

This study concentrates on developing a soil quality index (SQI), linking productivity to soil quality indicators, and SQI using grain yield of rice and wheat grown in a sequence for 8 years in an integrated tillage-water-nutrient management system. Rice yield was significantly better under puddling, 3 days of drainage, and both 150 % NPK and 100 % NPK + FYM treatments, and the yields were positively correlated with bulk density (BD), available Fe and soil respiration. The wheat yield was significantly higher under conventional tillage, five lots of irrigation, and 150 % NPK, and was positively correlated with BD, water stable aggregates (WSA) and available N. However, it was negatively correlated with mean weight diameter, soil organic carbon and hydraulic conductivity. Stepwise regression identified available Fe, WSA and microbial biomass carbon as the most important indicators that explained 42 % variability in rice yield, which further correlated significantly with the PCA-based SQI (r = +0.44). Thus, crop yield emerged as an important indicator for maintaining soil quality to sustain high productivity under integrated management systems

Nitrification and urease inhibitors mitigate global warming potential and ammonia volatilization from urea in rice-wheat system in India : a field to lab experiment

The efficacy of alternative nitrogenous fertilizers for mitigating greenhouse gas and ammonia emissions from a rice-wheat cropping system in northern India was addressed in a laboratory incubation experiment using soil from a 10-year residue management field experiment (crop residue removal, CRR, vs. incorporation, CRI). Neem coated urea (NCU), standard urea (U), urea ammonium sulfate (UAS), and two alternative fertilizers, urea + urease inhibitor NBPT (UUI) and urea + urease inhibitor NBPT + nitrification inhibitor DMPSA (UUINI) were compared to non-fertilized controls for four weeks in incubation under anaerobic condition. Effects of fertilizers on global warming potential (GWP) and ammonia volatilization were dependent on residue treatment. Relative to standard urea, NCU reduced GWP by 11 % in CRI but not significantly in CRR; conversely, UAS reduced GWP by 12 % in CRR but not significantly in CRI. UUI and UUINI reduced GWP in both residue treatments and were more effective in CRI (21 % and 26 %) than CRR (15 % and 14 %). Relative to standard urea, NCU increased ammonia volatilization by 8 % in CRI but not significantly in CRR. Ammonia volatilization was reduced most strongly by UUI (40 % in CRI and 37 % in CRR); it was reduced 28–29 % by UUINI and 12–15 % by UAS. Overall, the urease inhibitor, alone and in combination with the nitrification inhibitor, was more effective in mitigating greenhouse gas and ammonia emissions than NCU. However, these products need to be tested in field settings to validate findings from the controlled laboratory experiment

Biological indicators of soil quality in a long-term rice-wheat system on the Indo-Gangetic plain: combined effect of tillage-water-nutrient management

The assessment of soil quality is essential to track changes in soils as a result of management practices. Although a range of soil physical and chemical properties have been used internationally to track change in soil quality, work to evaluate a range of soil biological indicators as a means of monitoring soil quality has been more limited. In order to identify key biological indicators of soil quality, a long-term field trial at the Indian Agricultural Research Institute, New Delhi, was conducted which included tillage (main plots), water (subplots) and nutrient (sub-subplots) treatments for both rice and wheat. Here the combined influence of tillage, water and nutrient management after eight cropping cycles of rice-wheat, on selected soil microbial properties, was assessed. Results showed that non-puddling significantly enhanced dehydrogenase activity (5%), microbial biomass carbon (3%) and potentially mineralizable nitrogen (5%) over puddling, whereas the latter treatment hugely benefited soil respiration (48%) and metabolic quotient (41%) in rice. No-tillage resulted in higher values of soil biological indicators under wheat cultivation. Partial substitution of fertilizer N by farmyard manure, sewage sludge and a combination of (FYM + biofertilizer + crop residues/green manure) increased indicators at higher magnitudes, like dehydrogenase activity (36%), microbial biomass carbon (33%) and potentially mineralizable nitrogen (57%), but reduced the metabolic quotient which implied an accumulation of stable organic C under organic nutrient management uniformly after both the crops. The drainage of irrigation water in rice also increased dehydrogenase activity and microbial biomass carbon. In contrast more frequent (five times and three times) irrigations in wheat significantly increased these indicators. Principal component analysis revealed that both microbial metabolic quotient and dehydrogenase activity were the most promising indicators of soil biological quality in the present experimental setup