Nitrogen Mineralization Rate And Its Influence Factors Research Under Maize Plastic Film Mulched In Danjingkou Reservoir Area,China

Soil nitrogen loss as the main way of agricultural non-point source pollution,soil nitrogen mineralization has an important influence on soil nitrogen loss.In order to understand the change characteristics of soil nitrogen mineralization rate at different growth stages and the influencing factors under different tillage methods,a field plot experiment was conducted to explore horizontal ridge mulching soil nitrogen mineralization rate and its influence factors under plastic film mulching ridge-furrow in Wulongchi small watershed,The comparison of four treatments,including flat film mulching,flat film without plastic film,horizontal ridge mulching,and flat ridge without covering film.The changing characteristics of nitrogen mineralization rate during the growth period of Maize under transverse ridge mulching were analyzed.The quantitative relationship between soil nitrogen mineralization rate and soil temperature,soil water content and soil total nitrogen content was established.The effects of soil temperature,soil water content and total nitrogen content on soil nitrogen mineralization rate were revealed.The major results as follows:(1)Effects of film mulching on soil temperature and soil water content.In maize growth period,ridge mulching can significantly increase soil temperature at early stage of seedling and jointing stage.However,at the late stage of jointing stage,heading stage and maturity stage,with the increase of corn growth and temperature,soil warming effect was not obvious under cross ridge mulching.The effect of horizontal ridge mulching on soil water content in seedling stage and early jointing stage was less,but it could increase the water content of the covered soil in the late jointing stage,heading stage and mature period,and increased by 43.05%compared with the earlier stage.(2)Effect of film mulching on total nitrogen content in soil.During the growth period of maize,the soil temperature of cross ridge mulching is higher than that of flat film mulching and Cross Ridge without mulching film at the seedling stage and jointing stage.At the late stage of jointing,the heading stage and the mature period,the horizontal ridge film mulching was only 1.32%and 1.66%,respectively,which showed that the warming effect was not obvious under the condition of film mulching.In the later stage of jointing stage,heading stage and maturity stage,the soil moisture content of cross ridge mulching was 8.26%and 23.42%higher than that of flat film mulching and cross ridge mulching.However,at the seedling stage and jointing stage,the soil moisture content of cross ridge mulching was 4.3%and 10.95%lower than that of flat film mulching and cross ridge mulching,respectively.(3)Effect of film mulching on nitrogen mineralization rate in soil.During the growth period,the nitrogen mineralization rate of the cross ridge mulching film was 6.36%lower than that of the transverse ridge without film mulching.The rate of soil nitrogen mineralization at the jointing stage was 25.11%and 119.19%higher than those of flat film mulching and cross ridge mulching.The rate of soil nitrogen mineralization at the heading stage was 9.38%and 94.92%higher than that of flat film mulching and no ridge mulching.In the mature stage,the rate of N mineralization in the ridge mulching film was 94.92%higher than that in the transverse ridge.(4)The relationship between soil nitrogen mineralization rate and soil temperature,soil water content and soil total nitrogen content at different growth stages in Maize at different growth stages were studied.There is a correlation and linear relationship between the rate of soil nitrogen mineralization and the influence factors.At the seedling stage,the total nitrogen content of soil just one factors into the optimal regression equation,the total nitrogen content is the main factor affecting the rate of soil nitrogen mineralization.Three factors of soil temperature,soil water content and total nitrogen content of soil all enter the optimal regression equation at jointing stage,show that soil temperature,water content and total nitrogen are the main factors affecting the nitrogen mineralization rate at jointing stage.Two factors of heading stage,soil water content and total nitrogen content of soil enter the optimal regression equation,showed that the soil water content and total nitrogen content were the main factors affecting the nitrogen mineralization rate in the heading stage.In the mature period,only one factors of soil water content enter the optimal regression equation,showed that soil water content was the main influence factor of nitrogen mineralization rate in mature soil.