黄土高原半干旱区尾菜高量埋压抑制土壤氮淋溶的研究

为明确尾菜高量埋压带来的土壤氮淋溶风险，本研究设计了不同尾菜埋压厚度和表层覆土厚度的组合试验，分析不同土层水分和无机氮（NH₄⁺-N和NO₃^--N）时空变化特征。结果表明：埋压尾菜厚度0.2~0.6 m、表层覆土厚度0.1~0.3 m时，试验前10 d，表层土壤水分快速增加，较对照提高了40%~110%，尾菜向深层土壤补水深度最大为1.6 m；试验开始土壤无机氮以NH₄⁺-N增加为主，下移深度仅为0.6 m，试验第83天时，NO₃^--N快速积累，最大下移深度为0.8 m，土壤无机氮主要集中于耕作层，尾菜层上、下0.1 m土壤无机氮含量是当地高产玉米农田的1.0~3.5倍。当尾菜埋压厚度达到3.0 m、表层覆0.4 m黄土时，尾菜向深层土壤补水深度为5.0 m，NH₄⁺-N下移深度为1.5 m，试验第194天时NO₃^--N增加不显著，与对照无显著差异，尾菜层上、下0.1 m土壤无机氮含量是高产玉米农田的3.5~4.2倍。研究表明在黄土高原半干旱地区，采用覆土埋压法将尾菜高量还田可以显著增加土壤水分和无机氮固存量，尾菜厚度、表面覆土厚度与土壤水分、土壤无机氮累积量和NH₄⁺-N含量呈正相关，与土壤NO₃^--N含量呈负相关，无机氮并未随土壤水分向深层土壤淋溶。

Investigation on nitrogen leaching control in the semi-arid area of Loess Plateau restrained by surface soil covering and massive burying of vegetable waste

In order to ascertain the probability of nitrogen leaching ensuing in a field, subsequent to the incorporation of massive vegetable waste, a test design incorporating both the parameter for thicknesses of the buried vegetable waste and surface-soil covering was constructed to analyze the temporal variation characteristics of soil moisture and inorganic nitrogen (NH₄⁺-N and NO₃^--N) at different soil depths. When the thickness of the buried vegetable waste and surface-soil covering was 0.2-0.6 m and 0.1-0.3 m, respectively, the moisture of the soil surface increased rapidly in the first 10 days, which was 40%-110% higher than the control. The maximum depth at which the buried vegetable waste improved the soil moisture was found to be 1.6 m. At the beginning of the test, the soil inorganic nitrogen was mainly increased by NH₄⁺-N, and the downward movement depth was only 0.6 m. On the 83rd day after the test, rapid accumulation of NO₃^--N was observed, with a maximum downward movement depth of 0.8 m. The soil inorganic nitrogen was mainly distributed within the tillage depth, and its content level was 1.0-3.5 times higher than that of a high-yield maize field. When the thickness of the buried vegetable waste reached 3.0 m and the surface layer was covered with 0.4 m thick loess, the vegetable waste replenished water in the soil to 5.0 m depth, and NH₄⁺-N moved down to a depth of 1.5 m. Furthermore, the increase of NO₃^--N was insignificant when compared with that of the control on the 194th day after the test. The fertilizer efficiency level of soil inorganic nitrogen was 3.5-4.2 times that of a high-yield maize farmland. In the semi-arid Loess Plateau, the incorporation of massive vegetable waste in the field by surface-soil covering and buried pressure method can significantly increase the content of soil moisture and inorganic nitrogen. The thickness of vegetable waste and surface-soil covering are positively correlated with soil moisture, soil inorganic nitrogen accumulation, and NH₄⁺-N content, while negatively correlated with NO₃^--N. The inorganic nitrogen does not leach into the deep soil with infiltrating soil water.