涌泉根灌肥液入渗水氮运移特性研究

为了提高涌泉根灌模式下水肥利用率,减少氮肥流失与深层渗漏,通过涌泉根灌肥液入渗田间试验,研究了不同肥液质量浓度涌泉根灌入渗湿润体及其水氮运移特性,揭示了涌泉根灌土壤入渗量和湿润锋运移距离随肥液质量浓度的变化关系;建立了不同肥液质量浓度涌泉根灌入渗量和湿润锋运移经验模型;分析了入渗湿润深度范围内肥液质量浓度分别对土壤NO-3-N和NH+4-N含量分布特性的影响。结果表明:肥液质量浓度增大,单位面积累计入渗量随入渗时间增加而增大,并且入渗量和湿润锋运移距离均与入渗时间呈极显著幂函数关系,决定系数分别达到0.98和0.96,均大于临界相关系数rα(0.605 5);入渗再分布阶段,肥液质量浓度41.7 g/L能更好地保证枣树根系水分的吸收,而不同肥液质量浓度对土壤氮素转化率影响有所不同,硝态氮转化率基本不明显,而肥液质量浓度为33.3 g/L时铵态氮转化率最高。

Transport Characteristics of Water and Nitrogen under Bubbled-root Irrigation with Fertilizer Solution

In order to improve the utilization rates of water and fertilizer and reduce the loss of nitrogen fertilizer and deep seepage under bubbled-root irrigation, the change features of soil wetted body as well as the water and nitrogen movement characteristics with different fertilizer solution concentrations were studied. The relation between the cumulative infiltration volume and transportation distance of wetting front with the change of solution concentration was presented. Besides, the empirical models for cumulative infiltration volume and wetting front transportation distance were established under bubbled-root irrigation; the impact of fertilizer solution concentration on the distribution laws of NO-3N and NH+4N content within the scope of infiltration depth was analyzed. The results of the experiment showed that when the liquid concentration was increased, the cumulative infiltration in unit area was increased with time, and both infiltration amount and wetting front transportation distance showed remarkable power function relationship with infiltration time. The determination coefficients were up to 0.98 and 0.96, respectively, which were greater than the critical correlation index (0.6055); in the redistribution of infiltration, the liquid concentration of 41.7g/L could guarantee better water absorption of jujube root, the influences of different concentrations of nitrogen on conversion rate of soil were different, the conversion rate of nitrate nitrogen was not significant, and the conversion rate of ammonium nitrogen of 33.3g/L was the highest.