Nutrient retention after crop harvest in a typic hapludults amended with biochar types under no-tillage system.

The utilization of biochar's as soil amendments for enhancing nutrient retention in subsoils present potential limitations. To address this issue, we conducted a greenhouse experiment to assess the effects of various biochar's derived from animal manures (swine manure, poultry litter, cattle manure) and plant residues (rice straw, soybean straw, corn straw) when applied to surface of an acidic soil. Our study focused on wheat crops under a no-tillage system, with a subsequent evaluation of the residual impacts on soybeans. The experimental design involved the application of biochar's at different rates i.e. 10 and 20 Mg ha-1, followed by the assessment of their influence on NPK levels, pH, and exchangeable Al in stratified soil layers (0-5, 5-10, 10-15, and 15-25 cm). Furthermore, we investigated the interplay between biochar doses and the application of nitrogen (N) in the top 5 cm of soil, specifically examining NO 3 - , NH 4 + , P and K levels. Our findings revealed that in the top 5 cm of soil, biochar doses and N application significantly affected NO 3 - , NH 4 + , P and K concentrations. However, in deeper soil layers, no significant differences were observed among biochar doses with or without N application. Interestingly, K levels were impacted throughout all soil depths, regardless of the presence or absence of N application. Moreover, biochar application up to a 5 cm depth induced favorable changes in soil pH and reduced exchangeable Al. In contrast, deeper layers experienced a decrease in soil pH and an increase in exchangeable Al following biochar treatment. In conclusion, our study demonstrates that biochar's can effectively retain NPK nutrients, enhance soil pH, and decrease exchangeable Al, independent of the type and dosage of application under a no-tillage system. Nonetheless, the efficacy of biochar amendments may vary with soil depth and type of nutrient, warranting careful consideration for maximizing their benefits in sustainable agricultural practices.

Characterization and carbon mineralization of biochars produced from different animal manures and plant residues.

Renewing carbon and re-establishing it again in the soil is one of the valuable means to cope with climate change. There are many technologies for carbon apprehension and storage, but the most important one gaining attention is biochar technology. So, to carbonize and return different biological materials back to the farmland, a comprehensive study was proposed to characterize and evaluate the carbon (C) mineralization of biochars produced from different animal manures and crop straws. Six types of biochars were prepared from animal manures (poultry litter, swine and cattle manures) and crop straws (rice, soybean, and corn straws). The biochars were analyzed for chemical characteristics (elemental variables, thermal decomposition, cation exchange capacity, pH, electrical conductivity, specific surface area, and surface functional groups) and an incubation experiment was conducted to evaluate C mineralization from soil biochar mixture. Biochars produced from crop straws resulted to have more C as compared to the biochars produced from animal manures. Concentration of nitrogen was low, while P, K, Ca, and Mg were found reasonably higher in all biochars except swine manure biochar. The plant-derived biochars presented lower CO2 emissions when incorporated to soil at 1 and 2% of C. Varying but all the biochars prepared represented an alkaline pH. Biochars prepared from the crop straws resulted to have more C, alkaline in nature, high CEC, low CO2 emissions, can sequester C and more suitable to enhance the soil fertility in comparison to biochars produced from other sources.