Calcium alginate−biochar composite promotes nutrient retention, enzyme activity, and plant growth in lime soil
Qianwei Feng, Bing Wang, Miao Chen, Jian Zhang, Xueyang Zhang, Pan Wu
Abstract
Soil nutrients loss in karst area is an urgent eco-environmental problem. To control soil erosion and improve soil quality, calcium alginate−rice straw biochar composite (CA−MRB300) was prepared by embedding method. The retention mechanisms of soil nutrients onto CA-MRB300 were explored through batch adsorption experiments of soil nutrients, soil column leaching experiments combined with the analysis of physicochemical properties and soil enzyme activity. The effects of CA-MRB300 and its co-application with fertilizer on plant growth were investigated by a pot experiment. The results suggested that CA−MRB300 effectively retained PO43− and NO3− in lime soil mainly through surface precipitation and physical adsorption. The addition of CA-MRB300 increased the activities of alkaline phosphatase, urease, and sucrase in lime soil. Increased activity of urease accelerated the hydrolysis of urea to NH4+ in lime soil. Compared to a low proportion, a high proportion of CA-MRB30 was more likely to lead to the loss of K+. Moreover, the application of CA−MRB300 alone was more beneficial to the growth of soybean than the co−application of CA−MRB300 with fertilizer. This study indicates that CA-MRB300 has a great potential for application in retaining nutrients and promoting crop growth in lime soil.