【作者】 胡晓航；

【导师】 陈立新；

【作者基本信息】 东北林业大学 ， 森林培育， 2015， 博士

【摘要】 黑土是东北地区糖料作物甜菜(Beta vulgaris L.)的主栽土壤类型,其最显著的特点是有机质含量高且土层深厚,但目前东北黑土区已经出现水土流失、黑土退化等问题,其退化最突出的表现之一就是土壤氮素养分的调控能力减退,最终导致氮肥利用率和土壤供氮能力下降。因此,如何根据土壤供氮特征,有效进行氮素调控,达到甜菜高产、高糖、优质的效应是目前急需解决的问题。本文以甜菜主产区黑土为研究对象,在2010～2014年利用田间及室内试验研究了黑土有机氮构成及供氮特征,甜菜生长季内土壤不同形态氮素的迁移和转化动态变化,通过室内试验研究了温度和水分对有机氮矿化和迁移转化的影响,同时利用15N示踪技术分析了肥料氮在土壤有机氮库中的迁移和转化及对环境因子变化的响应,通过盆栽试验探索了甜菜生长季内不同形态氮对甜菜碳代谢影响,本项研究对于合理施肥、提高土壤氮供氮能力、通过生理调控改善甜菜产质量,丰富甜菜氮素营养理论具有重要意义。主要研究结果如下：1、土壤有机氮的矿化特征甜菜主产区黑土有机氮组分中的主体是酸解有机氮,其中各组分含量及比例的顺序为氨基酸态氮>氨态氮>未知态氮>氨基糖态氮。施氮肥处理(NPK)土壤酸解有机氮组分含量及比例有所增加,其中以氨基酸态氮和氨基糖态氮含量增加的幅度最高。甜菜生长季内土壤矿化氮以硝态氮为主,土壤累积矿化氮量呈指数函数增加,施氮肥提高了土壤供氮能力。两阶段一级反应动力学方程( Two pool模型)能够很好地描述甜菜黑土有机氮矿化过程。施用氮肥既可以土增加壤氮素矿化势(No),同时有利于易矿化有机氮(N1)的形成,可以改善甜菜黑土有机氮的品质。土壤氮矿化势(N0)与土壤有机氮各组分均关系密切,其中氨基酸态氮是土壤矿化势的主要贡献者。温度和水分是影响土壤有机氮矿化的重要因子。温度与水分对土壤氮矿化速率的单一作用大于二者的交互作用,温度为30℃,水分在30%是甜菜黑土有机氮矿化的适宜温度和水分水平。2、土壤不同形态氮的时空分布特征甜菜幼苗期施氮肥处理(NPK)可以增加0-30cm土壤铵态氮含量,促进块根糖分增长期(7月)0-70cm土壤硝态氮的吸收。在甜菜生长季内,施氮肥(NPK)可以提高0-30cm土壤氨态氮和氨基酸态氮的含量,同时非酸解态氮在甜菜生长后期(7-9月)出现深层残留。除氨基糖态氮和氨基酸态氮外,土壤有机氮其他组分含量随甜菜生育时间变化规律遵循三次曲线方程的分布规律。甜菜生长过程中,土壤有机氮组分中氨态氮和氨基酸态氮对无机氮贡献较大。在甜菜幼苗期,施入化肥氮主要残留在0-50cm土层中,并以氨态氮、氨基酸态氮和酸解未知态氮为主要方式结合到土壤有机氮库中,在50-70cm土层以酸解未知态氮和非酸解态氮方式结合在土壤有机氮库中；到甜菜收获期(9月),0-50cm土层化肥氮的残留量明显下降,但仍有5.29%～33.92%的化肥氮残留在土壤中,造成了氮肥资源浪费的现象,并主要结合到氨态氮和酸解未知态氮有机氮库中,而50-90cm土层化肥氮固持到难以分解的非酸解态氮的有机氮库中。土壤各有机氮组分与化肥氮之间存在相互转化关系。氨态氮对化肥氮在土壤有机氮组分中的转化直接贡献最大,其次是酸解未知态氮。当土壤氮供应不足时,化肥氮固持在氨基酸态氮和氨基糖态氮可以通过矿化作用转化为植物可吸收的氮。化肥氮在土壤有机氮组分中酸解未知态氮和非酸解态氮的转化间接通过氨态氮起到暂时积累作用。在收获期,植物吸收氮-15N与非酸解态氮-15N和氨基酸态氮-’5N关系密切,因此氨基酸态氮作为甜菜可吸收的有机氮源具有重要作用。3、土壤不同形态氮的迁移和转化对温度和水分变化的响应不施肥(CK)处理0-90cm土层之间NH4+-N、NO3--N含量随温度和水分变化差异不显著,施肥(NPK)后,NH4+-N在土柱内的迁移距离主要发生在0-15cm土层内,NO3--N迁移距离主要发生在0-50cm土层内,对温度和水分变化响应显著。不施肥(CK)处理0-30cm土层转化速率(矿化速率、硝化速率和氨化速率)随温度的增加而增加,矿化速率和硝化速率随水分的增加而降低,而在30-90cm土层以20℃为转折点,土壤转化速率随温度增加显著上升,硝化速率随水分的增加变化显著;施肥(NPK)处理0-30cm土层土壤矿化速率、硝化速率和氨化速率显著高于不施肥(CK)处理。在高水分条件下,土壤转化速率随温度的升高而升高。30-50cm土层在低含水量时矿化速率、氨化速率对温度变化的响应显著,在设定温度范围内,硝化速率随水分的增加而增加,50-90cm土层矿化速率、硝化速率与氨化速率在高含水量时,随着温度的升高先升高后降低,在5-20℃范围内,矿化速率、氨化速率和硝化速率随水分的增加而增加,氨化速率受水分变化的响应不显著。在不同的温度和水分条件下,不施肥和施肥土壤不同土层氮素转化速率存在显著差异,各因子之间具有不同程度的交互作用。4、土壤氮素形态与甜菜碳代谢的关系无机氮配施一定比例有机态氮可以促进甜菜生长,增加甜菜地上和地下的干物质积累；增加全生育期内甜菜叶片的叶绿素含量,提高光合能力；在糖分增长期之后,无机氮配施高比例有机氮(占总施氮量67%)处理甜菜块根和叶片氮积累量最大,说明氨基酸态氮也可以成为甜菜生长的良好氮源；可以提高甜菜叶片蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)活性和转化酶活力,维持块根营养生长所需的碳源和能源：块根中可溶性糖、蔗糖含量明显增加,还原糖含量降低,对块根蔗糖的积累有促进作用：有助于甜菜产量和产糖量的提高。更多还原

【Abstract】 Black soil is a main soil type for sugar beet(Beta vulgaris L.) cultivation in NE China, its most significant feature is high organic matter and deep soil layer. But now the black soil area in NE China is suffering from soil and water erosion, black soil degradation and other problems. One of the most prominent manifestations for its degradation is the decrease in the ability for black soil to regulate and control nitrogen nutrients, finally resulting in the decrease in nitrogen use efficiency and soil nitrogen supply ability. Therefore, how to efficiently regulate and control nitrogen in accordance with soil nitrogen supply features so as to achieve high yield, high sugar and good quality of sugar beet is the problem to need to be solved urgently at present. In this paper, organic nitrogen components and its supply features of black soil, dynamic changes in the migration and transformation of different forms of soil nitrogen in the growing season of sugar beet from 2010 to 2014 by field and laboratory experiments were studied in the main producing area of sugar beet. The effect of temperature and moisture on organic nitrogen mineralization, migration and transformation was explored through laboratory experiments. Meanwhile, fertilizer nitrogen’s migration and transformation in soil organic nitrogen pool by 15N tracer technique, their response to the changes in environmental factors were discussed. The influence of different types of nitrogen on carbon metabolism of sugar beet in growing season by pot experiment was analyzed. Therefore, this study was of great significance in rational fertilization, improvement of nitrogen supply ability and sugar beet quality by physiological regulation and control, and the enrichment of nitrogen nutrient theory for sugar beet. The main findings are as follows:1. Mineralization features of soil organic nitrogenThe main component of organic nitrogen in black soil in the main producing area is acid-hydrolysable nitrogen, and every component content and proportion was ranking in amino acid nitrogen>ammoniacal nitrogen>unknown nitrogen>amino sugar nitrogen. The content and proportion of soil acid-hydrolysable organic nitrogen increased after applying nitrogen treatment(NPK), the increased range in amino acid nitrogen and amino sugar nitrogen was highest among them.Nitrate nitrogen was dominated in soil mineralized nitrogen in the growing season of sugar beet, the cumulative mineralized nitrogen in the soil increased exponentially, the nitrogen supply ability of soil was enhanced after nitrogen fertilizers was applied. The first-order reaction kinetic equation (two pool model) during both stages could well describe the mineralization process of organic nitrogen in black soil.The application of nitrogen fertilizers can both increase soil nitrogen mineralization potential (No) and facilitate the formation of mineralized organic nitrogen (N1), and could improve the quality of organic nitrogen in black soil. Soil nitrogen mineralization potential (N0) was closely related to each component of organic nitrogen, amino acid nitrogen was a major contributor to soil mineralization potential. Temperature and moisture were important factors affecting soil organic nitrogen mineralization. The single effect of temperature or moisture on soil nitrogen mineralization rate was greater than their interactive effect. The temperature 30℃ and the moisture 30% were suitable for the mineralization of organic nitrogen in black soil.2. Temporal and spatial distribution features of different forms of soil nitrogenApplying Nitrogen fertilizer treatment(NPK) in the seedling stage of sugar beet can increase the content of ammonium nitrogen in 0-30 cm soil, and promote root’s absorption of nitrate nitrogen in 0-70cm soil in the sugar growth period (July). It can increase the content of ammonia nitrogen and amino acid nitrogen in 0-30cm soil in the growing season of sugar beet, in the meantime, the residual of non-acid hydrolysable nitrogen appears in deep soil layer in the late growth stage of sugar beet (July-September). Except amino sugar nitrogen and amino acid nitrogen, the change in the content of other constituents of soil organic nitrogen over time conformed to the distribution rule of cubic curve equation. In the growing process of sugar beet, ammonia nitrogen and amino acid nitrogen in the constituents of soil organic nitrogen contributed more to inorganic nitrogen.In the seedling stage of sugar beet, the residual chemical fertilizer nitrogen was mainly located in 0-50cm soil layer, mainly bonded to the soil organic nitrogen pool in the form of ammonia nitrogen, amino acid nitrogen and unknown acid hydrolysable nitrogen, but mainly in the form of unknown acid hydrolysable nitrogen and non-acid hydrolysable nitrogen in 50-70cm soil layer; In the harvest period of sugar beet (September), the residual chemical fertilizer nitrogen apparently decreased in 0-50cm soil layer, but 5.29%～33.92% residual amount of chemical fertilizer nitrogen was still in 0-50 cm soil layer, resulting in a waste of nitrogen fertilizer resources, they largely were combined in organic nitrogen pool in the form of ammonia nitrogen and unknown acid hydrolysable nitrogen, while immobilized in organic nitrogen pool in the forms of non-acid hydrolysable nitrogen in 50-90 cm soil layer.Each constituent of soil organic nitrogen can be mutually transformed with chemical fertilizer nitrogen. Ammonia nitrogen had the largest direct contribution to the transformation of chemical fertilizer nitrogen in the constituent of soil organic nitrogen, followed by unknown acid hydrolysable nitrogen. In the case of shortage of soil nitrogen supply, chemical fertilizer nitrogen immobilized in amino nitrogen and amino sugar nitrogen can be transformed into absorbed nitrogen by plants through its mineralization. The transformation of chemical fertilizer nitrogen in the constituent of soil organic nitrogen between unknown acid hydrolysable nitrogen and non-acid hydrolysable ammonia nitrogen played a temporary accumulation role indirectly through ammonia nitrogen. In the harvest period, nitrogen-15N that can be absorbed by the plant was closely related to non-acid hydrolysable nitrogen-15N and amino acid nitrogen-15N, hence, as absorbable organic nitrogen source, amino acid nitrogen played an important role.3. Response of migration and transformation of different forms of soil nitrogen to changes in temperature and moistureFor no fertilizer application treatment(CK) soil, the content of NH4+-N and NO3--N in 0-90cm soil layer had insignificant difference with the changes in temperature and moisture, but for fertilizer application treatment (NPK), the migration distance of NH4+-N in the soil column mainly occurred within 0-15 cm soil layer and that of NO3--N mainly appeared in 0-50 cm soil layer with significant response to the changes in temperature and moisture.For no fertilizer application treatment(CK) soil, the transformation rate (mineralization rate, nitrification rate and ammonification rate) in 0-30 cm soil layer increased as temperature rose, while the mineralization rate and the nitrification rate decreased when the moisture increased. Significant increases in soil transformation rate in 30-90 cm soil layer occurred at the turning point of 20℃ as temperature rose. The nitrification rate changed significantly as moisture increased. For fertilizer application treatment(NPK) soil, the mineralization rate, nitrification rate and ammonification rate in 0-30 cm soil layer were significantly higher than those for no fertilizer application treatment(CK) soil. Under high moisture conditions, soil transformation rate increased as temperature rose. The mineralization rate and ammonification rate in 30-50 cm soil layer with low moisture had significant response to the change in temperature, and within the specified temperature range, the nitrification rate increased as moisture rose. The mineralization rate, nitrification rate and ammonification rate in 50-90 cm soil layer with high moisture first increased and then decreased as temperature rose. Within 5-20℃ range, the mineralization rate, nitrification rate and ammonification rate increased as moisture rose, the ammonification rate had an insignificant response to the change in moisture. Under different temperature and moisture conditions, the difference in the nitrogen transformation rate between fertilizer and no fertilizer application treatment (CK and NPK) soil was significant, and different degree of interactions occurred between various factors.4. Relationship between the form of soil nitrogen and carbon metabolism of sugar beetInorganic nitrogen application in the soil with a certain proportion of organic nitrogen can promoted the growth of sugar beet, can increase the dry matter accumulation of sugar beet above and below ground, and the chlorophyll content in the whole growth period, and can improve the photosynthetic capacity. After the growth period of sugar, if inorganic nitrogen with high proportion of organic nitrogen(67% of the total amount of nitrogen application) was applied in the soil, the beet root and leaf had the largest amount of accumulated nitrogen. This result indicated that amino acid nitrogen can also be a favorable nitrogen source for the growth of sugar beet. Amino acid nitrogen improved the activity of sucrose phosphate synthase (SPS), sucrose synthetase (SS), and the vitality of invertase of beet leaves, and maintained carbon and energy sources required by the growth of beet root. The content of soluble sugar and sucrose in the root increased significantly and that of reducing sugar decreased. These would promote the accumulation of sucrose in the root and increase the output of beet and sugar.更多还原