长期不同施肥模式下水田土壤可溶性有机氮动态及其迁移规律

发布时间：2018-08-18 19:12

【摘要】：可溶性有机氮(Soluble Organic Nitrogen,SON)对农田生态系统氮循环起着至关重要的作用,在稻田生态系统中,随着不同形态氮素的大量投入,SON 及其易于淋失组分 DON(Dissolved Organic Nitrogen,DON)的迁移所致的环境效应值的关注,而至今关于稻田土壤SON和渗滤水DON的动态规律、迁移特征及其机理以及可能导致的生态风险尚不明晰。为此,本研究以长期不同施肥模式(不施肥(CK);单施氮磷钾化肥(NPK);氮磷钾+牛粪(NPKM);氮磷钾+全部稻草还田(NPKS))的红壤性水稻土为研究对象,采集水稻生育期土壤及其渗滤液进行原位分析,研究长期不同施肥模式下稻田土壤SON随水稻生长的动态变化以及渗滤液DON随深度的迁移特征,分析二者间的消长关系;结合土壤理化和生化性质探讨长期不同施肥模式下土壤SON含量动态变化及其迁移机理,为完善农田土壤氮素循环理论、评估农田SON淋失风险和加强田间水肥管理提供科学依据。研究结果表明:(Ⅰ)稻田土壤SON主要存在于表层,且具有向下迁移的趋势。水稻种植前长期不同施肥模式下供试土壤0-20 cm的SON含量分别比20-40 cm 和 40-60 cm 土层高 107.78%-220.65%和 269.39%-374.06%,20-40 cm 土层的SON比40-60 cm 土层的高47.84%-77.78%,说明同一处理不同深度间土壤SON含量表现为0-20 cm20-40 cm40-60 cm,且0-20 cm 土壤SON含量显著高于20-40 cm和40-60 cm的SON含量,而20-40 cm和40-60cm土层SON含量之间无明显差异,随着深度增加,SON向下迁移量减少。(Ⅱ)土壤理化与生化性质对SON含量具有显著影响。灰色斜率关联结果表明pH和容重对土壤SON的影响表现为负向影响,其余相关属性对土壤SON的影响均表现为正向影响,其中有机质对SON的影响最为显著,各相关属性对SON的影响程度大小表现为有机质微生物量氮(Microbial Biomass Nitrogen,MBN)全氮谷氨酰胺酶通气孔隙度蛋白酶pH容重。(Ⅲ)在水稻整个生育期内,各处理土壤SON动态呈现为"下降-升高-上下波动后下降-升高-下降"的变化趋势,不同处理间SON含量在水稻生长不同时期有所差异,不同处理间的差异表现为前期:NPKMNPKSNPKCK;中期:NPKMNPKNPKSCK;后期:NPKSNPKMNPKCK。(Ⅳ)水稻生育期内淹水层DON浓度受施肥的影响变化较大,水稻生育前期不同处理间淹水层DON浓度大小表现为NPKNPKMNPKSCK,后期淹水层DON浓度大小表现为NPKMNPKSNPKCK。在水稻整个生育期内,NPK、NPKM和NPKS的淹水层DON浓度显著高于CK处理,且变化趋势相对一致,均在2d-10d快速减少,15d时有所升高,至20d时出现一小峰值,之后缓慢下降并趋于稳定,说明施肥有助提高淹水层和渗滤液的DON浓度,同时DON容易流失并可能导致生态风险的时期主要处于施肥至水稻移栽后的前20d内,应注意该时段的田间水分管理。(V)水稻生育期内稻田渗滤液DON浓度随深度增加而逐渐降低,不同施肥措施下渗滤液DON浓度迁移主要出现在0-20cm 土层。生育期内长期不同施肥模式下DON的迁移随水稻生育期的变化表现为插秧后35d前变化明显,35d之后差异不显著。在35d之前,供试土壤0-20cm的 DON 浓度比 20-40 cm 高 58.12%-1084.79%,20-40 cm 土层的 SON 比40-60cm 土层的高3.87%-388.67%,可见在水稻生育期内渗滤液DON浓度大小表现为 0-20 cm20-40 cm40-60 cm。
[Abstract]:Soluble Organic Nitrogen (SON) plays an important role in nitrogen cycling in farmland ecosystems. With the increasing input of different forms of nitrogen, the environmental effects of SON and its easily leached component DON (Dissolved Organic Nitrogen, DON) migration in paddy ecosystems have attracted much attention. Soil SON and leachate DON dynamics, migration characteristics and possible ecological risks are still unclear. Therefore, the red soil paddy soils with different fertilization patterns (no fertilization (CK), single nitrogen, phosphorus and potassium fertilizer (NPK), nitrogen, phosphorus and potassium + cattle manure (NPKM), nitrogen, phosphorus and potassium + all straw returning (NPKS) were selected as the research objects to collect water. In-situ analysis of soil and its leachate during rice growth period was carried out to study the dynamic changes of SON with rice growth and the migration characteristics of DON with depth in paddy soil under long-term and different fertilization patterns, and to analyze the relationship between them. The results showed that: (1) SON mainly existed in the surface layer of paddy soil, and had a downward migration tendency. SON content of 0-20 cm in the tested soils under different fertilization patterns for a long time before rice planting. The SON content in 20-40 cm soil layer was 47.84% - 77.78% higher than that in 40-60 cm soil layer, indicating that the SON content in 0-20 cm 20-40 cm 40-60 cm soil layer was significantly higher than that in 20-40 cm and 40-60 cm soil layer, and the SON content in 0-20 cm soil was significantly higher than that in 20-40 cm and 40-60 cm soil layer. There was no significant difference in SON content between 40-60 cm soil layer and 40-60 cm soil layer. With the increase of soil depth, SON migration decreased. (II) Soil physicochemical and biochemical properties had a significant impact on SON content. Among them, organic matter had the most significant effect on SON, and the degree of influence of related properties on SON was as follows: the pH bulk density of total nitrogen glutaminase ventilating porosity proteinase (MBN). (III) During the whole growth period of rice, the SON dynamics of soil treated with various treatments showed "descend-rise-up-down wave" The variation trend of SON content in different treatments was different at different stages of rice growth. The differences among different treatments were as follows: NPKMNPKSNPKCK in the early stage; NPKMNPKNPKNPKSCK in the middle stage; and NPKSNPKMNPKCK in the late stage. (IV) The concentration of DON in submerged layer changed greatly during rice growth period, and was different at the early stage of rice growth. The concentration of DON in the flooded layer between treatments was NPKNPKMNPKSCK, and that in the late flooded layer was NPKMNPKSNPKCK. During the whole growth period of rice, the concentration of DON in the flooded layer of NPK, NPKM and NPKS was significantly higher than that in CK, and the variation trend was relatively consistent. The concentration of DON in the flooded layer of NPKM NPKMNPKSNPKCK decreased rapidly from 2 days to 10 days, increased slightly at 15 days, and reached a small peak at 20 days. The results showed that fertilization could increase the DON concentration in the flooded layer and leachate, and the period of DON loss was mainly within the first 20 days after fertilization and rice transplantation, so the field water management should be paid attention to. The migration of DON concentration in leachate mainly occurred in 0-20 cm soil layer under different fertilization treatments. The migration of DON in the long-term and different fertilization patterns during the growth period changed significantly before 35 days after transplanting, but not significantly after 35 days. Before 35 days, the concentration of DON in 0-20 cm soil was 58.12% - 108% higher than that in 20-40 cm soil. SON in the soil layer of 4.79% and 20-40 cm is 3.87% - 388.67% higher than that in the soil layer of 40-60 cm. It can be seen that the concentration of DON in the leachate of rice during the growth period is 0-20 cm 20-40 cm 40-60 cm.
【学位授予单位】：福建农林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S158

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