丹江口库区覆膜土壤不同土层氮素矿化速率及其影响因素

以丹江口库区五龙池小流域玉米黄棕壤为例,利用原位土壤氮矿化试验,研究覆膜条件下0～10、10～20、20～30 cm土层土壤氮素矿化速率及其影响因素.结果表明: 玉米生长期内,土壤氨化速率随土层加深呈逐渐降低的趋势;土壤硝化速率在苗期、拔节期、抽穗期表现为10～20 cm＞0～10 cm＞20～30 cm,在成熟期随土层加深呈逐渐升高的趋势;土壤氮矿化速率在苗期、拔节期、抽穗期随土层加深呈逐渐降低的趋势,在成熟期随土层加深呈逐渐升高的趋势.与无覆膜相比,覆膜会加快0～10 cm土壤氨化过程,也会提高拔节期、抽穗期和成熟期0～10、10～20 cm土层土壤硝化速率和氮矿化速率,但苗期覆膜土壤硝化速率、氮矿化速率均低于无覆膜土壤.逐步回归分析显示,土壤含水量和全氮含量是0～10 cm土壤氮矿化速率的主要影响因子,土壤温度、含水量、全氮含量是10～20 cm土壤氮矿化速率的主要影响因子,土壤温度是20～30 cm土壤氮矿化速率的主要影响因子.

Nitrogen mineralization rate in different soil layers and its influence factors under plastic film mulched in Danjiangkou Reservoir area,China

The objective of this study was to investigate the rate of nitrogen mineralization in various soil layers (0-10, 10-20, and 20-30 cm) and its influencing factors under plastic film mulching ridge-furrow in a corn field of Wulongchi small watershed, Danjiangkou Reservoir Area. Results showed that the rate of soil ammonification decreased with soil depth during the entire maize growth period. The rate of nitrification in seedling, jointing, and heading stages decreased in the following order: 10-20 cm > 0-10 cm > 20-30 cm, while it increased with soil depth in maturation stage. The rate of soil nitrogen mineralization decreased with the increases in soil depth in the seedling, jointing and heading stages, whereas an opposite pattern was observed in maturation stage. Compared with non-filming, film mulching promoted the soil ammonification process in 0-10 cm and the soil nitrification and nitrogen mineralization processes in jointing, heading, and maturation stages in both 0-10 and 10-20 cm. However, the rates of soil nitrification and nitrogen mineralization under film mulching were much lower than those under non-filming in seedling stage. The stepwise regression analysis indicated that the main factors influencing soil nitrogen mineralization rate varied with soil depth. Soil moisture and total N content were the dominant controller for variation of soil nitrogen mineralization in 0-10 cm layer. Soil temperature, moisture, and total N content were dominant controller for that in 10-20 cm layer. Soil temperature drove the variation of soil nitrogen mineralization in 20-30 cm layer.