Search

Biochar application to soil has been projected as an approach to improve soil quality, which can also influence soil microbial activities. In this experiment, we have utilized four dissimilar feedstocks derived biochar amendments. The highest microbial biomass carbon was found in Lantana camara (LC) biochar followed by pine needle (PN), maize stalk (MS) and lowest in black gram (BG) biochar. The dehydrogenase activity in different biochar treatment increased significantly along with control with increase in incubation days except pine biochar where dehydrogenase decreased. Biochar application in soil increased acid phosphatase compared to control. The highest alkaline phosphatase was found in MS and it was 20.56, 31.27, 42.52, 57.62 and 69.56 at 1, 7, 30, 60 and 90 days of incubation, respectively. The highest urease was found in LC followed by BG, MS and lowest in PN among the biochar at both the biochar application rate. The biochar application augmented the protease enzyme activity in soil, which might be due to augmenting the accessibility of inorganic nitrogen. The highest fluorescein diacetate was found in LC and it was 10.12, 17.62, 24.62, 32.86 and 37.56 at 1, 7, 30, 60 and 90 days of incubation, respectively. The increased biological indicator was more at 2.5 t/ha biochar application rate than 5.0 t/ha i.e. lower concentration of biochar enhanced more than higher concentration. This laboratory study demonstrated that biochar application can profit incubated acid soils by improving microbial biomass carbon up-lift while increasing potential soil enzyme activity.

Management of the by-products generated during bioenergy conversion technologies is essential for technology sustainability and due to strict adherence to waste minimisation legislation. We investigated the potential of four types of bioenergy by-products (BEBPs), i.e. char from rice husk and digestates from 3 types of feedstocks: (i) Ipomoea carnea:cow dung (ICD), (ii) rice straw:green gram:cow dung (RGC) and (iii) cow dung (CD) as nutrient input for Zea mays L. Digestates were applied in four application phases, i.e., whole, solid, liquid and ash from solid digestates. BEBPs provoked significant changes in soil pH, electrical conductivity, available NPK, organic carbon and micronutrients depending upon both feedstock and phase. Digestates in solid and whole phases were found better as an organic amendment, whereas RGC and ICD digestates were superior in maintaining higher soil available P and K, respectively. BEBP showed satisfactory performance compared to BEBP-untreated control in terms of crop growth and yield, but chemical treatment resulted in the highest yield. N preservation against volatilization loss may be required through appropriate timing and method of application in case of high-ammonia-N-containing ICD digestates. Outcomes of this investigation are expected to be useful to undertake selective utilization practices of BEBPs for better handling and management.

International audience; The choice of cultivation system in arable agriculture exerts a strong influence not only on soil health and crop productivity but also on the wider environment. Conservation tillage using non-inversion methods conserves soil carbon, reduces erosion risk and enhances soil quality. In addition, conservation tillage has been shown to sequester more carbon within the soil than inversion tillage, reducing carbon dioxide losses to the atmosphere. Stable, well structured topsoils that develop following long-term conservation tillage lead to more energy efficient systems due to the reduced power requirements for cultivation. Long-term experiments, e.g. more than 20 years, that confirm the impact of conservation tillage over an extended period are not common. Here we evaluate the impact of different tillage methods and winter wheat straw management, either incorporated or removed, on organic matter turnover and soil quality indicators. No-till, chisel and mouldboard ploughing was carried out for 23 years on a silty clay loam soil in South West England that was not considered suitable for non-inversion tillage due to weak soil structure. In order to assess the effect of contrasting cultivation and straw disposal method on soil carbon dynamics, a range of assays were conducted, including water extractable organic carbon, hot water extractable carbohydrate, microbial biomass carbon, activity of β-glucosidase and acid phosphatase enzymes, C sequestration and the natural abundance of 13 C. Our results show that the soil organic carbon concentration in the topsoil was greater under no-till than mouldboard ploughing, while a reverse trend was observed in the lower depths. A 14-17% increase in soil organic carbon was observed in the topsoil for chisel plough and no-till treatments compared to mouldboard ploughing. Water extractable organic carbon was found to constitute only 1-7% of the microbial biomass carbon. Hot water extractable carbohydrate was one of the most sensitive indicators of soil quality and had a significant a negative correlation with bulk density and positive correlation with soil organic carbon microbial biomass carbon β-glucosidase and acid phosphatase. The choice of cultivation method exerted a major control on microbial and carbon dynamics. No-till and chisel ploughing maintained carbon in the soil surface horizons, which will benefit the stability of this weakly structured soil, but mouldboard ploughing distributed carbon more uniformly throughout the soil profile, particularly when straw was incorporated, hence leading to the retention of more carbon in the soil profile.

To achieve higher yields and better soil quality under rice–legume–rice (RLR) rotation in a rainfed production system, we formulated integrated nutrient management (INM) comprised of Azospirillum (Azo), Rhizobium (Rh), and phosphate-solubilizing bacteria (PSB) with phosphate rock (PR), compost, and muriate of potash (MOP). Performance of bacterial bioinoculants was evaluated by determining grain yield, nitrogenase activity, uptake and balance of N, P, and Zn, changes in water stability and distribution of soil aggregates, soil organic C and pH, fungal/bacterial biomass C ratio, casting activities of earthworms, and bacterial community composition using denaturing gradient gel electrophoresis (DGGE) fingerprinting. The performance comparison was made against the prevailing farmers’ nutrient management practices [N/P2O5/K2O at 40:20:20 kg ha−1 for rice and 20:30:20 kg ha−1 for legume as urea/single super-phosphate/MOP (urea/SSP/MOP)]. Cumulative grain yields of crops increased by 7–16% per RLR rotation and removal of N and P by six crops of 2 years rotation increased significantly (P