【作者】 金洁；

【导师】 杨京平；

【作者基本信息】 浙江大学 ， 生态学， 2005， 硕士

【摘要】 氮素是维持作物高产和获得较高经济效益的主要因素,同时也易对环境产生污染危害。本论文主要通过独立排灌系统的田间试验研究了水稻田面氮素、磷素的动态特征,同时借助自行设计的渗漏计研究在控水灌溉条件下大田模式和网室盆栽模式下不同氮肥处理的氮素淋失的动态规律,以利于发现氮素在稻田水体的流失规律,为合理施肥、控制氮素流失、保护水体生态环境提供借鉴。本论文研究结果表明: （1）分次施肥后的次日,田面水中氨氮、总氮浓度明显升高,随着时间推移,氮素浓度下降很快。特别是第一次施氮后第9天,各处理铵氮浓度分别为施后第l天浓度的1.19%～2.70%,全氮则变为6.03%～18.74%（无氮肥处理N-I除外）。铵态氮/全氮比值也呈类似趋势。 （2）相比较而言,田面水体中的硝态氮含量要远远低于铵氮,最大值为2.07mg/L。同时还表现出不同的趋势,其峰值在第3天出现。另外,不同的施氮量的作用下,等量的磷肥所产生的田面效应表现不同,且大体表现为施氮量多者,田面水磷含量也相应多的现象。从环境污染角度考虑,控制氮素、磷素田面流失主要时期为施肥后9天内。 （3）大田渗漏水中铵态氮,硝态氮保持较低的浓度,均小于1mg/L,但对硝态氮而言,仍是氮素淋失的主要类型。从总的趋势来看,渗漏水中氮素浓度随着施肥量的增加而增加。每次施肥后,不同处理渗漏水中的NO₃-N 浓度均表现为短期内迅速上升、后期逐渐下降的趋势,其中NH₄⁺-N浓度与NO₃^--N 的消长规律相似,但表现出峰值超前的特征。 （4）大田渗漏计中NH₄⁺-N、NO₃^--N 及TN累积渗漏量与施肥量之间存在显著相关性,R² 分别达到0.933^*,0.984^**和0.982^**。另外从环境和经济角度考虑,建议在土壤质地粘重、基础肥力较高的水稻土施肥量控制在75～150kg/hm² 为宜,控制氮素淋失主要时期为施肥后一周内,特别在基肥施后尤为关键。 （5）网室盆栽渗漏水中,处理间反映了随着施氮水平增加,渗漏水中氮素浓度也增加,其中N-I（无氮肥处理）和N-III处理（施氮量300kg/hm²）的氮素均达到显著差异。同比例的施肥量在网室盆栽模拟中表现出来的铵态氮浓度要低于大田试验。各处理硝态氮的平均浓度均大于大田相应的硝态氮浓度。分次施氮更多还原

【Abstract】 Nitrogen is a major factor for maintaining crop yield, getting better economic return. It also produces some severe environmental pollution problem when it was over and unreasonable used. The paper studies the dynamic characteristics of nitrogen （N） and phosphorus （P） in surface water of paddy field under different N supply levels in 2003. The dynamic variation of N leaching and its amount loss in paddy field under 5 different N treatments in 2003 and the simulation experiment in the pots in 2004 using a self-designed lysimeter with independent irrigation system were arranged in the paddy field located in Yuhang and Hangzhou. It was studied and analyzed in order to find the rules of the N loss in the water-body. A reference for Appling urea reasonable, controlling N loss in the paddy field and protecting water ecology and environment is provided. The research results through the experiment indicated:（ 1 ） Split N fertilizer application with 4 times greatly increased the concentration of ammonia nitrogen （NH₄⁺-N） and total nitrogen （TN） in surface water in the field initially, then both declined subsequently as the time passed. After the first N application, The ninth day’s concentrations of NH₄⁺-N and TN in 6 different treatments was separately 1.19%².70% and 6.03%¹8.74% （except CK） separately as comparing the first day’s one. The rate of NH₄⁺-N/TN had the similar trend as TN, NH₄⁺-N.（2） The concentration of nitrate nitrogen （NO₃^--N） was lower than the one of NH₄⁺-N and the maximum concentration was 2.07 mg/L in the surface water. It also showed different trends from TN and NH₄⁺-N and the peak concentration value appeared after urea employed 3 days later each time. The same amount of P application in different N fertilizer application treatments showed different results that P concentration varied in the surface water. The P concentration in surface water of paddy had some relationships to N fertilizer application amounts. More N fertilizer application amount produced more P content in surface water of paddy field. In terms of the environment consideration, the period within 9 days after the fertilizer application was a critical time to control N, P loss and leaching from flooded paddyfield.（3） NH/-N and NCV-N concentration of the leakage water remained at a very low level during the whole growing period of rice, which were lower than lmg/L. The main leaching form in the leakage water was dominated by NCV-N. N loss from leaching in this experiment increased gradually with fertilizer applications increase. After the application of fertilizer for each time, the concentration of NCV-N in different treatments increased rapidly during a short period and then decreased gradually. The concentration dynamic patterns of NH4+-N had the similar trends and regularity as NCV-N, but it showed the peak concentration value of NH4+-N exceeded that of NO3’-N.（4） There were significant correlation between N fertilizer applied and the accumulative amount of NH4+-N, NCV-N and TN of the leakage water in the lysimeter of different treatments in the field and the coefficient is 0.933*,0.984**,0.982** respectively. Based on the point of economy and environment consideration, it is suggested that 75-150 kg/hm2 in Paddy field with sticky soil texture and higher fertility could be reasonable for better yield and reduce the N leaching. The period within a week after the N fertilizer application was critical time to control N leaching from paddy field, especially for the first N fertilizer application in paddy field.（5） The concentration of the leakage water in different treatments of the pots in the net room increased gradually with fertilizer applications increase. The differences of N concentration between treatment N-I （no N fertilizer application treatment） and treatment N-III （N fertilizer application 300kg/hm2） were significant .The NH4+-N concentration of the pots in the net room was lower than that in the paddy field for the same proportion N fertilizer application. The NO3’-N concentration was quite the contrary. Quantitative models with best coefficient for TN and NCV-N concentrations in the leaching water of the pots after N fertilizer application were cubic and quadratic.（6） The leakage amount of N was increased with fertilizer applications increase, but there is no significant difference among the treatments of the pots. The leakageamount of NCV-N and NH/-N are about 35% and 10% of that of total nitrogen amount, respectively. Paddy yields based on leaching cost of showed the pollution cost increased with the amount of N fertilizer application increase with producing lton paddy yield.（7） On the basis of the net room leakage amount of N, the relation between the leakage amount and the N fertilizer application was showed by the math expression. NH/-N: y=-7X10"V+0.0008x+0.0547 （R2=0.948**） NO3"-N:: y=3.4X10V+0.0003x+0.388 （R2=0.988**） TN: y=1.7X10-5x2-0.0014x+1.095 （R2=0.985**）（y express "leakage amount", x press "nitrogen application", unit "kg/hm2" ）更多还原