控释氮肥对玉米秸秆腐解及潮土有机碳组分的影响

施肥影响秸秆还田效果,研究不同形态氮肥对秸秆腐解及土壤有机碳组分的影响可为秸秆还田下氮肥合理施用提供科学依据。以10年小麦-玉米轮作定位施肥试验为基础,采用尼龙网袋田间填埋法,研究了控释掺混尿素和普通尿素不同用量(纯氮120,240,360 kg/hm~2)对潮土中玉米秸秆腐解及土壤有机碳组分的影响。结果表明:与普通尿素相比,控释掺混尿素具有促进秸秆腐解的趋势;在秸秆腐解后期,控释掺混尿素处理较普通尿素显著促进了秸秆氮、磷的释放,而不同氮肥处理对秸秆中钾素的释放影响并不显著。在秸秆腐解后期,相同施氮量条件下,常规施氮量和增施氮量的控释掺混尿素处理较普通尿素显著增加土壤水溶性和热水溶性有机碳含量。在增加土壤微生物量碳、氮含量方面,在秸秆腐解的某些阶段控释掺混尿素处理的促进作用显著高于普通尿素处理。综合来看,与普通尿素相比,控释掺混尿素在秸秆腐解和增加土壤有机碳组分方面具有较好的促进作用。

Effects of Controlled-release Nitrogen Fertilizer on Decomposition of Maize Straw and Organic Carbon Fractions in Fluvo-aquic Soil

Fertilization affects the effect of straw returning to the field. To study the effects of different forms of nitrogen fertilizer on the decomposition of straw and the soil organic carbon fractions can provide scientific basis for the rational application of nitrogen fertilizer under straw returning. Based on the 10-year experiment of wheat-maize rotation and location fertilization, the effects of different amounts of controlled-release urea mixed and common urea(CRF)and common urea (CF) (120, 240 and 360 kg N/hm²) on the decomposition of maize straw and soil organic carbon fractions in fluvo-aquic soil were studied. The results showed that compared with the CF treatment, the CRF treatment had a tendency of promoting the decomposition of straw. At the late stage of straw decomposition, CRF treatment significantly promoted the release of nitrogen and phosphorus from straw compared with CF treatment, while different nitrogen fertilizer treatments had no significant effect on the release of potassium from straw. At the later stage of straw decomposition, under the same nitrogen application rates, CRF treatment with conventional nitrogen application and increased nitrogen application significantly increased the content of water-soluble and heat-soluble organic carbon in soil. In terms of increasing soil microbial biomass carbon and nitrogen contents, the promotion of CRF treatment was significantly higher than that of CF treatment at some stages of straw decomposition. In general, compared with CF treatment, CRF treatment has a better effect on promoting straw decomposition and increasing soil organic carbon fractions.