秸秆与地膜覆盖对旱作土娄土碳氮组分的影响

为探明不同覆盖方式对土壤有机碳氮组分的影响及其机制,为旱作农田覆盖措施的选择提供理论和实践依据。在陕西关中土娄土地区冬小麦-夏玉米轮作体系下进行田间试验,设置秸秆覆盖(SM)、半膜覆盖(HFM)、全膜覆盖(FM)和不覆盖(NM)4种处理,研究不同覆盖措施对表层土壤有机碳(SOC)、全氮(TN)、微生物量碳氮(MBC、MBN)、可溶性有机碳氮(DOC、DON)以及0~200cm土壤剖面硝态氮和水分分布的影响。结果表明,与不覆盖处理相比,秸秆覆盖处理的土壤SOC、MBC、MBN、DOC质量分数提高3.9%、67.5%、56.2%和18.0%(P0.05),但土壤DON质量分数显著下降。全膜覆盖处理显著降低土壤DOC、DON质量分数及100~200cm土层水分储量(P0.05),但对MBC、MBN、SOC以及TN无显著影响。半膜覆盖显著降低SOC和DON的质量分数,对TN、MBN和DOC影响不显著,但显著提高MBC质量分数;半膜覆盖处理膜间的土壤MBC、MBN以及DOC质量分数均显著高于膜下,而膜间土壤DON质量分数及0~20cm、20~100cm、0~200cm土层硝态氮质量分数与累积量均低于膜下。秸秆覆盖处理与全膜覆盖处理均显著提高表层土壤(0~20cm)硝态氮质量分数和累积量,显著降低20~100cm和100~200cm土层硝态氮累积量。总体而言,秸秆覆盖提高SOC、MBC、MBN以及土壤表层硝态氮累积量,有利于提高土壤肥力,是西北土娄土区值得推广的覆盖栽培模式;薄膜覆盖降低硝态氮向深层土壤淋溶的风险,但对土壤肥力的长期影响尚不明确。

Effects of Straw and Plastic Film Mulching on Carbon and Nitrogen Components in Lou Soil of Dryland

The purpose of this study is to provide a theoretical and practical basis for mulching strategy selection, so as to ascertain the effects of different mulchings on soil organic carbon and nitrogen components and its mechanism. Effects of different straw and plastic film mulching, including straw mulching (SM), half plastic film mulching (HFM), full plastic mulching (FM), and no mulching(NM) under the rotation of winter wheat-summer maize system, on dryland of Eum-Orthric Anthrosols were studied in Guanzhong area of Shaanxi province. The results showed that, compared with no mulching, straw mulching increased SOC, MBC, MBN and DOC by 3.9%, 67.5%, 56.2% and 18.0%(P<0.05), respectively, whereas significantly decreased the soil DON mass fraction.Mulching treatment significantly decreased soil DOC and DON, and water storage of soil profile of 100-200 cm (P<0.05), however, it had no significant effect on soil MBC, MBN, SOC and TN. The mass fraction of SOC and DON were significantly decreased by the half plastic film mulching, however, the MBC mass fraction did not significantly increase,but the mass fraction of DOC significantly increased. The soil MBC, MBN and DOC between plastic films were significantly higher than those under plastic films in half plastic film mulching treatment, however, soil DON between plastic films and soil nitrate-nitrogen mass fraction and accumulation amount of 0-20 cm, 20-100 cm and 0-200 cm profile were lower than those under plastic films. The soil NO^-₃-N mass fraction and accumulation of 0-20 cm profile under straw mulching and full plastic film mulching were improved, however, the soil NO^-₃-N accumulation of 20-100 cm and 100-200 cm profile significantly decreased. Overall, straw mulching could increase the mass fraction of SOC, MBC, MBN and DOC, and accumulation of NO^-₃-N of topsoil, which was beneficial to improve the soil fertility, and was a worthy cultivation mode to be recommended on the Eum-Orthric Anthrosols area of Northwest China. Film mulching can reduce the leaching risk of NO^-₃-N, nevertheless, its long-term effects on soil fertility is not clear.