水氮调控对设施土壤有机氮组分、全氮和矿质氮的影响

Effects of Water and Nitrogen Regulation on Soil Organic Nitrogen Fractions,Total Nitrogen and Mineral Nitrogen in Greenhouse Soil

为探讨水氮调控对设施土壤有机氮组分、全氮和矿质氮的影响,通过膜下滴灌设施番茄田间定位试验,采用灌水下限(W_1、W_2、W_3)和施氮量(N_1、N_2、N_3)的两因素三水平随机区组设计,研究水氮调控对休耕期0—30cm土层土壤有机氮组分、全氮和矿质氮的影响。结果表明,不同水氮调控下,设施土壤有机氮主要是以酸解态氮为主,总体表现酸解态氮大于非酸解态氮含量。土壤有机氮组分在酸解态氮和非酸解态氮中分配比例差异明显。土壤有机氮各组分含量及占全氮比例的大小顺序为氨基酸氮/氨态氮>未知氮>氨基糖氮。除氨基糖氮,其余酸解态氮各组分和酸解总氮含量及其占全氮比例均随着土层深度的增加而降低,不同土层含量差异显著(P<0.05)。土壤全氮、矿质氮和总有机氮含量随土层深度的增加也呈降低趋势,且含量差异达到极显著水平(P<0.01)。除氨基糖氮,全氮与其他有机氮各组分、酸解总氮间均达到极显著正相关(P<0.01);矿质氮仅与酸解氨态氮及酸解总氮的影响达到极显著(P<0.01)和显著正相关(P<0.05)。灌水下限、施氮量及水氮交互对设施土壤全氮、矿质氮和总有机氮及有机氮组分影响均达到极显著水平(P<0.01)。因此,设施土壤氮素含量的变化与水氮管理模式紧密相关。氨态氮和氨基酸氮是设施土壤中最主要的有机氮形态,是土壤活性氮中的主要组分,亦是土壤供氮潜力的表征。考虑土壤供氮潜力,灌水下限35kPa、施氮量300kg/hm^2为该设施生产下最优的水氮管理措施。

To study the effects of water and nitrogen regulation on soil organic nitrogen fractions,total nitrogen（TN）and mineral nitrogen（MN）of greenhouse soil（0-30 cm）in fallow period,a tomato field experiment with mulched drip irrigation was conducted with different irrigation lower limits（W1,W2,W3）and nitrogen application rates（N1,N2,N3）.The results indicated that greenhouse soil organic nitrogen was mainly in the form of acid-hydrolyzable nitrogen（AHN）,and in general,the AHN content was greater than that of non-hydrolyzable nitrogen（NHN）.The distributions of soil organic nitrogen fractions under different treatments were significantly different in AHN and NHN.Generally,the order of the contents and distribution proportions of soil organic nitrogen fractions to total N was：Amino acid nitrogen（AAN）/ammonia nitrogen（AN）unknown nitrogen（UN）amino sugar nitrogen（ASN）.Except for the ASN,both the contents and distribution proportions of AHN fractions decreased significantly with the increase of soil depth（P〈0.05）.Similarly,the contents of TN,MN and total soil organic nitrogen（TSON）also decreased significantly with the increasing soil depth（P〈0.01）.Under different treatments,the differences among TN and soil organic nitrogen fractions besides ASN reached a very significant level（P〈0.01）.Only AN and AHN had the significant positive correlation with MN（P〈0.05）.The results from two-way ANOVAs showed that all the effects of irrigation,nitrogen fertilization and their interaction on TN,MN and TSON reached very significant levels（P〈0.01）.Therefore,the change of greenhouse soil nitrogen content was closely related to the regulationof water and nitrogen.AN and AAN were the main forms of soil organic nitrogen,the main components of soil available nitrogen,and also the indicators of nitrogen supply potential in greenhouse soil.Considering the soil nitrogen supply potential,the most reasonable pattern of water and nitrogen application was W2 N2 in greenhouse soil.