聚天门冬氨酸钙盐对水稻田面水中三氮动态变化的影响

利用桶栽试验探究不同浓度水平的聚天门冬氨酸钙盐(PASP-Ca)对水稻田面水中铵态氮(NH_4~+)、硝态氮(NO_3~-)和总氮(TN)浓度动态变化的影响。结果表明,施氮后,田面水中TN、NH_4~+和NO_3~-分别于第1,3,9天达到最大值,随后逐渐降低。NO_3~-/TN多在0.1以下,(NH_4~++NO_3~-)/TN多在0.5以上。因此,可以将NH_4~+和TN作为农田水污染防治的主要监测指标,NO_3~-作为辅助指标。添加一定浓度的PASP—Ca能对田面水中氮素浓度的变化起到缓释作用,其中0.3%浓度水平的PASP—Ca效果相对较好,田面水中NH_4~+和TN的下降速率分别为3.452,4.806mg/(L·d),与单施氮肥(CK)相比,分别降低了11.68%和16.25%;同时,NH_4~+的平均浓度为6.999mg/L,较CK低了3.88%;NO_3~-的平均浓度为0.396mg/L,较CK低了24.83%;TN的平均浓度为20.077mg/L,较CK提升了3.10%。施氮后田面水中TN浓度随时间呈对数递减,而NH_4~+浓度在施氮后3天内随时间呈对数增加,之后随时间呈对数递减趋势。施氮后的9天内是防止稻田田面水中氮素流失的关键时期。

Effects of Polyaspartic Acid Calcium Salt on the Dynamic Changes of NH4+, NO3- and Total Nitrogen in Surface Water of Paddy Field

A barrels planted experiment was conducted to study the effects of PASP-Ca with different concentration levels on the dynamic changes of NH₄⁺, NO₃^- and total nitrogen (TN) concentrations in surface water of paddy field. The result showed that the concentrations of TN, NH₄⁺ and NO₃^- in the surface water of paddy field reached the maximum within 1 day, 3 days and 9 days respectively after nitrogen application. NO₃^-/TN was less than 0.1 and (NH₄⁺+NO₃^-)/TN was more than 0.5. Therefore, NH₄⁺ and TN could be used as the main monitoring indicators, and NO₃^- as an auxiliary indicator for the prevention and control of farmland water pollution. Adding a certain concentration of PASP-Ca had slow release effects for the changes of nitrogen concentrations in surface water of paddy field, while the effects of PASP-Ca at 0.3% concentration level was relatively better, the reduction rates of NH₄⁺ and TN in surface water of paddy field were 3.452 mg/(L·d) and 4.806 mg/(L·d) respectively. Compared with apply nitrogen only (CK), the reduction rates by 11.68% and 16.25%. Meanwhile, the average concentration of NH₄⁺ was 6.999 mg/L, which was 3.88% lower compared with CK. The average concentration of NO₃^- was 0.396 mg/L, which was 24.83% lower compared with CK. The average concentration of TN was 20.077 mg/L, which was 3.10% higher compared with CK. The dynamic changing trends of NH₄⁺ and TN concentrations with time could be expressed by logarithmic equations. After nitrogen application, the TN concentrations in paddy field decreased logarithmically with time, while the concentrations of NH₄⁺ increased logarithmically in 3 days, and then decreased logarithmically with time. 9 days after nitrogen application was the key stage to prevent nitrogen loss in surface water of paddy field.