培养条件下微纳米增氧水添加对新疆砂壤土硝化作用的影响

为了提升氮素利用效率和生产能力，采用室内培养试验方法，研究不同土壤含水率（田间持水量的30%、60%、100%及175%）条件下增氧水处理对土壤硝化作用的影响，并分别利用硝化动力学方程和硝化作用强度定量评价NH4+-N和NO3--N含量的动态变化特征，比较NH4+-N初始消耗速率、NH4+-N最大消耗速率、达到最大消耗速率所用时间以及NO3--N平均生成速率的变化。结果表明：粉质砂壤土氮素转化以硝化作用为主；随着含水率的升高，土壤硝化作用强度呈现先增加后降低的趋势，并在田间持水量条件下达到最大。在不同含水率条件下增氧水处理对土壤硝化作用的影响具有显著差异（P<0.05）。与常规水处理相比，在田间持水量的60%条件下，增氧水处理对土壤硝化过程的促进作用更为明显，NH4+-N最大消耗速率提高了8.9%，最大消耗速率出现时间提前，NO3--N平均生成速率增加，硝化作用更强；而在田间持水量条件下，增氧水处理的土壤NH4+-N消耗没有显著差异，仅NO3--N平均生成速率增加；田间持水量的175%条件下，增氧水处理土壤NH4+-N最大消耗速率降低了21.5%，最大消耗速率出现时间滞后，但NO3--N平均生成速率没有显著变化。该研究提出了增氧水处理促进氮素转化作用的最适水分条件，为发展农业高效水肥利用技术提供了理论依据。

Effects of micro-nano oxygenated water addition on nitrification of Xinjiang sandy loam soil under controlled conditions

Abstract: Water shortage and excessive application of nitrogen fertilizer are two prominent problems in the agricultural production system globally. Finding new ways to improve the efficiency of water and nitrogen fertilizer use is of great significance to the realization of sustainable agricultural development. Oxygenated water is an efficient and non-pollution irrigation water treatment technology. The application of oxygenated water in the irrigation in agricultural production can improve the soil environmental conditions and promote crop growth. In this study, the objective was to investigate the effect of oxygenated water on soil nitrification under different water contents. The oxygenated water was produced by a rapid generation device of micro-nano bubbles, and the dissolved oxygen concentration in water was monitored to reach 20 mg/L. Silt sandy loam soil sampled from the Xinjiang cotton production area was incubated with ammonium sulfate as additional substrate under controlled conditions in the laboratory. Either ordinary water or oxygenated water was added into soil to obtain different soil moisture conditions (30%, 60%, 100% and 175% of Water Holding Capacity, WHC). During the incubation, soil samples were taken and NH4+-N and NO3--N contents were analyzed on day 0, 1, 2, 4, 6, 8, 12, 16 and 20. The nitrification kinetic equation and nitrification intensity were used to quantitatively evaluate the dynamic change characteristics of NH4+-N and NO3--N content over time. The initial consumption rate of NH4+-N, the maximum consumption rate of NH4+-N, the time to reach maximum consumption rate and the average production rate of NO3--N from each treatment were analyzed and compared. The results showed that the nitrogen transformation of the studied silt sandy loam was dominated by nitrification. During incubation, the NH4+-N added into soil was consumed, and almost depleted in all treatments except the ones with 30%WHC; The NO3--N was produced simultaneously. For both the ordinary water and the oxygenated water treatments, with the increase of moisture content, the soil nitrification intensity first increased to the maximum at 100%WHC, and then decreased. Under different soil moisture conditions, oxygenated water treatment affected the soil nitrification intensity to varying degrees. Compared with ordinary water treatment, oxygenated water promoted nitrification most significantly under the condition of 60%WHC, the maximum consumption rate of soil NH4+-N increased by 8.9%; the peak occurrence time was earlier, and the average generation rate of NO3--N increased. Under the condition of 100%WHC, no significant difference was found in the consumption of NH4+-N in the oxygenated water treatments, and only the average generation rate of NO3--N increases by 1.58 times. Under the condition of 175%WHC, the maximum consumption rate of NH4+-N in the soil decreased by 21.5% and the peak occurrence time lagged; and the average generation rate of NO3--N did not change obviously. This research proposes the most suitable water condition for the promotion of soil nitrogen transformation by oxygenated water, which provides an important theoretical basis for the development of agricultural efficient water and fertilizer utilization technology.