太湖流域稻田对3种低污染水氮的消纳利用及化肥减量效果

摘要

A pot experiment was designed to study the potential capacity of paddy fields in reducing fertilizer application rates with the irrigation of 3 kinds of low⁃polluted wastewater: eutrophied river water ( RW) , tail water from a domestic sewage treatment plant ( DS) and biogas slurry ( BS) , as well as the effects on the growth and yield of Oryza sativa, N up⁃take, N loss in field runoff, ammonia volatilization, soil nutrients. Results show that 1) in Treatments BS, DS and RW, the plants all grew normally and yield of the crop was not affected with a higher N uptake efficiency. 2) Compared to Treat⁃ment SF ( irrigated with tap water) , Treatments BS, DS and RW were 21.6%-48.2% lower in concentration of total N in the overlaying surface water during the peiord before tillering. N concentration was more or less the same during the tille⁃ring period, and much higher during the panicle fertilization period and the milking period. 3) Treatments BS, DS and RW reduced the daily mean N volatilization during the basal and panicle fertilization periods, but increased the rate during the tillering and milking periods. However, the total ammonia volatilization of the whole growing season did not vary much between treatments and ranged from 41.58 to 45.45 kg·hm-2. 4) Soil available N, P, K and organic carbon after harves⁃ting was a bit higher in Treatments BS, DS and RW than in Treatment SF, especially in Treatment DS. 5) Throughout the whole rice growing season, the paddy field could accommodate 4 858-5 441 m3 ·hm-2 for low polluted water. Treatment DS, RW, and BS removed 107.1, 31.4 and 132.9 kg·hm-2 , respectively, and could reduce the use of chemical N fertil⁃izer by 44.41%, 12.83% and 55.11%, respectively. In terms of integrated yield and environmental benefits, Treatment DS significantly increased N fertilizer utilization rate and minimize the risk of N loss with runoff during the early rice growing season, and improved effectiveness of soil fertility of the paddy fields in the Tai Lake Region.%为探讨稻田对不同低污染水氮的消纳利用效果以及化肥减量潜力，选用生活污水处理尾水、沼液和富营养化河塘水3种来源的低污染水，采用盆栽试验研究稻田直接回用对水稻生长和产量、氮养分吸收、田面水氮径流风险、氨挥发和土壤养分的影响及对化肥减量的贡献。结果表明：（1）3种污染水回用均可保证水稻的正常生长，提高了氮肥利用率，对产量则无显著影响。（2）与清水灌溉相比，3种低污染水回用的田面水总氮浓度在基肥期降低21�6％～48�2％，蘖肥期基本持平，穗肥期及灌浆期则明显提高。（3）3种低污染水回用降低了基肥期和穗肥期的日均氨挥发量，增加了蘖肥期和灌浆期的日均氨挥发量，但稻季氨挥发总量（以N计）差异不明显，为41�58～45�45 kg·hm－2。（4）3种低污染水回用均增加了土壤碱解氮、总磷、有效磷和有机碳含量，以生活污水处理尾水回用最为明显。（5）整个生育期稻田可消纳生活污水处理尾水、富营养化河塘水和沼液4858～5441 m3·hm－2，回用的氮量分别为107�1、31�4和132�9 kg·hm－2，分别替代化肥用量44�41％、12�83％和55�11％。综合产量以及环境效益，生活污水尾水回用显著提高了氮肥利用率，降低了生育前期的径流损失风险，并具有提升土壤肥力的功效。