Microbial and Enzyme Properties in Response to Amelioration of an Acidic Ultisol by Industrial and Agricultural By-Products

Alkaline slag, rice chaff, and peanut straw were chosen to investigate the ameliorating effects of these industrial and agricultural by-products on soil microbial and enzyme properties in a field experiment on an acidic Ultisol. The alkaline slag was superior to rice chaff and peanut straw in correcting soil acidity and induced a larger increase in catalase activity, acid phosphatase activity, and the microbial quotient and thus depressed the metabolic quotient more, since soil acidity was an important stress factor for microbial and enzyme activities in the Ultisol. Incorporation of rice chaff and peanut straw markedly increased the soil microbial C, urease activity, and basal respiration and improved soil fertility to a greater extent, by more greatly enriching soil with organic C and the nutrients nitrogen, phosphorus, and potassium, which were also significant factors affecting microorganism properties. Consequently, the application of alkaline slag and rice chaff together was the most effective in enhancing the geometric mean of enzyme activities (an important index of soil quality), suggesting that the combined industrial and agricultural by-products together as an amendment was the better choice to improve soil quality in the Ultisol.