Dynamic of Amino Acid N in Different Grow Seasons of Maize in Different Management

Soil amino acids are important for plant nutrition and act as both sink and source of nitrogen.In order to probe into the dynamics of soil amino acids and their availability in agricultural ecosystem,a field experiment was conducted on the two treatments included N fertilizer applications with and without crop stalk return.The contents of amino acids were determined at different growing stages of maize(Zea mays L.).During the silking and filling stages when the N uptake of the crop was intense,the contents of soil amino acids,especially in 10-20 cm depth,declined significantly to partly compensate the N demand.At the stage of harvest,the contents of soil amino acids rebounded although the magnitude in 10-20 cm was still lower than original value in N fertilization.The return of crop stalk enhanced the accumulation of soil amino acids and improved the capability of soil for the sustainable N application.