覆膜与降雨类型对土壤水分及NO3--N淋失的影响

在丹江口库区青塘河五龙池小流域,以黄棕壤横垄种植玉米为例,设置覆膜与无覆膜两种处理,采用田间小区实验研究覆膜与降雨类型对0~30 cm土壤水分和NO-3-N淋失的影响.结果表明:两处理土壤含水量均随土层加深而增加,与无覆膜相比覆膜可降低0~10、10~20、20~30cm土层中的含水量.不同降雨类型对覆膜土壤含水量的影响有区别,小雨时3层土壤间差异显著,含水量随土层加深急剧增加;中雨时10~20cm比0~10 cm、20~30 cm比10~20 cm分别高50.80%、6.62%,0~10 cm土壤含水量显著低于10~20 cm和20~30 cm;暴雨时含水量随土层加深增幅变小;覆膜土壤土层越深土壤含水量受降雨的影响越小.覆膜可降低0~10、10~20 cm土层中的NO-3-N淋失量,分别降低40.74%、24.48%,但会增加20~30 cm的淋失;两处理土壤NO-3-N淋失量均随土层加深而增加.不同降雨类型对覆膜土壤NO-3-N淋失的影响也有区别,小雨时随土壤深度的增加淋失量增多;中雨时,0~10、20~30 cm NO-3-N淋失量分别为10~20 cm的1.75、8.41倍;暴雨时,0~10、20~30 cm分别比10~20 cm低18.97%和60.69%.土壤中NO-3-N淋失受土壤含水量的影响,且随土层加深含水量对NO-3-N淋失的影响减弱.

Effects of plastic filming and rainfall patterns on soil moisture and NO3--N leaching

To study the effect of plastic mulching and rainfall patterns on soil moisture and NO₃^--N leaching in 0~30 cm soil, the typical yellow brown soil at Wulong Pool watershed was selected in this study. Maize was planted on the horizontal ridge tillage with and without film mulching. Results showed that soil moisture content increased with the increase of soil depth in both treatments, but film mulching greatly decreased the moisture content in soil in the depth of 0~30 cm. Strength of rainfall had significant effects on soil moisture of mulched soil. Under light rain, soil moisture among the three layers increased significantly with the increase of depth; under moderate rain, the 0~10 cm soil moisture content was significantly lower than that of 10~20 and 20~30 cm; under heavy rain, the increase of soil moisture content with soil depth slowed down. Effects of rainfall on moisture content in mulched soil became weaker with the increase of depth. Plastic film mulching reduced the NO₃^--N leaching in 0~10 and 10~20 cm soil layers, by 40.74% and 24.48% respectively, but increased the leaching of 20~30 cm. NO₃^--N leaching increased with the increase of soil depth with or without film mulching. Strength of rainfall had significant effects on NO₃^--N leaching in mulched soil. Under light rain, NO₃^--N leaching increased with the increase of soil depth; under moderate rain, the amount of NO₃^--N leaching in the 0~10 cm and 20~30 cm was 1.75 and 8.41 times higher than that in 10~20 cm; under heavy rain, NO₃^--N leaching in the 0~10 cm and 20~30 cm were 18.97% and 60.69% lower than that of 10~20 cm, respectively. NO₃^--N leaching in soil was influenced by soil water content, which is weakened with the increase of soil depth.