C and N Mineralization of Newly Applied Crop Residues under Different Soil Fertilization History

摘要

A laboratory incubation study was conducted to determine C and N mineralization pattern of newlyadded maize and soybean residue under differently fertilized soil. The soil from three fertilization history weremixed thoroughly with residues and incubated in the dark at 25°C with 60% field capacity for 90 days. Thetreatments comprised up factorial combinations of three types of crop residue (viz., maize residue, soybeanresidue and maize + soybean residue) and three soil fertilization history (NPK fertilized, 1/2 (NPK + poultrymanure) fertilized and PM fertilized). The treatments were laid out in completely randomized design (CRD) withthree replications. CO evolution and inorganic N (NH and NH ) accumulation 2 4 3 were measured periodically+ -through out incubation period. The result showed that, cumulative CO2 evolution and N mineralization weresignificantly affected by crop residue type and soil fertilization history. The highest cumulative CO2 evolutionand N release was followed the sequence: soybean > maize + soybean > maize residues in all soils. Thecumulative CO2 evolution and N release was higher in PM fertilized soil compared to NPK fertilized and ? (NPK+ PM) fertilized soil. Nitrogen mineralization occurred with the soybean and maize +soybean residue throughoutthe study in all soil, whereas maize residues were characterized by N immobilization and mineralizationdepending on the fertilization history of the soil. Therfore, it can be concluded that decomposition and nutrientrelease of crop residue is a function of biochemical characteristics of the residue and nutrient status of the soilwhere added.