增效复合肥减氮施用对稻田水氮素流失的影响

通过田间试验研究氨基酸、腐植酸和海藻酸增效复合肥减氮施用对稻田水氮素动态特征和损失的影响,旨在为增效复合肥环境效应评价提供依据。试验设7个处理:不施肥(CK)、不施氮(PK)、常规施肥(CF)、常规施肥减氮20%(CR)、腐植酸复合肥减氮20%(HR)、氨基酸复合肥减氮20%(AR)、海藻酸复合肥减氮20%(SR)。采集水稻生长期不同时间的田面水、径流水和田间渗漏水,分析了不同形态氮素浓度的动态特征和氮素损失。结果表明:增效复合肥减氮处理(AR、HR和SR)明显降低了田面水TN和NH_4~+-N浓度峰值,峰值分别维持在37.1～49.7 mg·L~(-1)和26.0～28.8 mg·L~(-1),以SR处理田面水TN和NH_4~+-N浓度峰值最低,较CR处理分别降低了38.4%和14.3%,其他减肥处理之间未见显著差异;施肥一周后,田面水TN与NH_4~+-N浓度逐渐降低至峰值的15%后趋于稳定;各施肥处理NO_3~--N浓度变幅较小,峰值未见明显差异。SR处理0～20 cm土层渗漏液TN浓度最低为16.5 mg·L~(-1),较CR、HR和AR处理分别降低了60.8%、50.1%和54.0%,氮素形态以NH_4~+-N为主,随土层深度增加,渗漏液TN和NH_4~+-N递减。施氮肥处理的氮素流失率大小顺序依次为CFCRHRARSR,SR处理氮素径流损失量最低为6.22 kg·hm~(-2),较CR处理降低了58.5%;增效复合肥氮素减施均明显降低氮素渗漏损失,施氮肥处理氮素淋失率大小顺序依次为ARCFCRHRSR,SR处理渗漏损失最低为7.70 kg·hm~(-2),较CR处理氮素淋失率降低了18.1%;稻田水氮素损失总量也以SR处理为最低,达13.9 kg·hm~(-2),较CR处理降低了22.8%。研究表明,增效复合肥减氮施用对稻田田面水、土壤渗漏液不同形态氮素浓度有明显影响,可减少稻田水氮素损失风险,以海藻酸增效复合肥减氮处理效果最佳。

Effects of synergistic compound fertilizer combined with nitrogen reducing application on loss of nitrogen in paddy water

To evaluate the environmental effects of synergistic compound fertilizer application in paddy fields, a field experiment was conducted to explore the effects of amino acid, humic acid, and alginic acid synergistic compound fertilizer combined with a nitrogen reducing application on the dynamic characteristics and loss of nitrogen in paddy water. Seven treatments were used:no fertilization(CK), no nitrogen application(PK), conventional fertilization(CF), conventional fertilization reducing nitrogen 20%(CR), humic acid synergistic compound fertilizer reducing nitrogen 20% (HR), amino acid synergistic compound fertilizer reducing nitrogen 20% (AR), and alginic acid synergistic compound fertilizer reducing nitrogen 20%(SR). The dynamic characteristics and loss of nitrogen in paddy water were analyzed by surface, runoff, and leakage water collected at different times during the rice-growing season. The results showed that:the peak values of the concentrations of TN and NH₄⁺-N in the surface water reduced significantly by the treatments of AR, HR, and SR. The peak values of TN and NH₄⁺-N concentrations were 37.1~49.7 mg·L^-1 and 26.0~28.8 mg·L^-1, respectively. Among four reducing nitrogen fertilization treatments, the peak values of TN and NH₄⁺-N concentrations of the SR treatment were the lowest, which decreased 38.4% and 14.3% compared with the values in the CR treatment, respectively. There were no obvious differences in the other three nitrogen reducing fertilization treatments. One week after fertilization, the concentrations of TN and NH₄⁺-N in the surface water gradually decreased to reach stability(approximately 15% of the maximum values). The concentrations of NO₃^--N in the surface water were generally low in each treatment and no obvious differences were observed. In soil depths of 0~20 cm, the lowest concentration of TN in the leakage water was observed in the SR treatment(16.5 mg·L^-1), which decreased 60.8%, 50.1% and 54.0% compared to that in CR, HR and AR treatments, respectively. The TN concentration in leakage water decreased with the increase of soil depth, in which NH₄⁺-N occupied a major proportion. The order of the loss rate was CF > CR > HR > AR > SR, in which the runoff of the SR treatment was the lowest(6.22 kg ·hm^-2)and its loss rate decreased 58.5% compared with that of the CR treatment. Moreover, the nitrogen leakage was significantly reduced in the three synergistic compound fertilizer treatments. The order of the leaching rate was AR > CF > CR > HR > SR, in which the leakage of the SR treatment was the lowest(7.70 kg·hm^-2); its leaching rate decreased 18.1% compared to that of the CR treatment. Furthermore, the total loss of nitrogen in the SR treatment was the lowest(13.9 kg·hm^-2)and its loss decreased by 22.8% compared to that of the CR treatment. In conclusion, these findings show that the concentrations of the different nitrogen forms in the surface and leakage water were significantly influenced by the treatments of synergistic compound fertilizer combined with a nitrogen reducing application, which can be an effective way to alleviate the risk of nitrogen loss through paddy water, especially by the treatment of an alginic acid synergistic compound fertilizer combined with a nitrogen reducing application.