穴施条件下肥料养分在土壤中迁移规律的初步研究

根区施肥是高效施肥的关键措施,确定根区施肥的最佳位置,需要了解肥料施用后肥料养分在土壤中的迁移规律。本研究通过室内模拟试验来研究尿素、聚磷酸铵和氯化钾复合肥穴施条件下,土壤水分、培养时间对两种土壤中氮磷钾养分迁移的影响效应。结果表明：随土壤水分由30%增加到42%,氮磷钾在土壤中的迁移距离都会显著增加,培养15d的姜堰和广德两种土壤中,铵态氮、速效磷和速效钾的迁移距离分别由9-11cm、4cm和9-10cm增加到12-14cm、5-6cm和11cm。土壤含水量增加使氮磷养分的迁移距离平均增加了约三分之一。随培养时间从15天延长到30天,30%土壤含水量条件下两种土壤中速效磷迁移距离无显著变化,而速效钾的迁移距离显著增加,铵态氮迁移距离在硝化作用弱些的广德水稻土中增加显著,而在硝化作用较强的姜堰水稻土中增加幅度较小。肥料穴施条件下铵态氮的硝化作用除受土壤水分、pH和时间因素影响外,还受肥际高浓度养分的强烈抑制作用,这种抑制作用延缓了铵态氮向硝态氮的转化,是根区一次施肥技术中氮肥持续高效供应的重要原因。总体而言,氮磷钾养分迁移距离表现为：硝态氮>铵态氮>钾>磷,肥料氮的迁移受硝化作用影响大,肥料磷的迁移受土壤水分影响较大,而肥料钾与铵态氮的迁移规律较为类似,都因土壤水分增加和时间的延长而逐渐增加。

Primary Study on Nutrient Migration Under Hole Fertilization in Soils

Root zone fertilization is a key measure for efficient fertilization. To determine the optimal location of root zone fertilization, it is necessary to understand the law of nutrient transfer in the soil after fertilization. The effects of soil moisture and incubation time on nitrogen, phosphorus, and potassium migration of point-applied compound fertilizer which composed of urea, ammonium polyphosphate and potassium chloride were studied with laboratory incubation experiment. The results showed that with the increase of soil moisture from 30% to 42%, the migration distances of nutrients increased significantly. After incubated for 15 d in soils of Jiangyan and Guangde, the migration distance of ammonium nitrogen, available phosphorus, and available potassium increased from 9-11 cm, 4 cm and 9-10 cm to 12-14 cm, 5-6 cm and 11 cm, respectively. With the increase of soil water content, the distance of N and P nutrient migration increased by about one third on average. With the increase of incubation time from 15 d to 30 d, there was no significant change in the migration distance of available phosphorus, but the migration distance of available potassium increased significantly. The migration distance of ammonium nitrogen increased significantly in Guangde paddy soil with weak nitrification, while it increased slightly in Jiangyan paddy soil with strong nitrification. The nitrification of ammonium nitrogen under fertilizer hole-application was not only affected by soil moisture, pH and time but also strongly inhibited by high concentration nutrients in the fertilizer field. The later factor delayed the transformation of ammonium to nitrate, which was an important mechanism account for the efficient nitrogen supply under root zone fertilization technology. In a whole, the nutrient migration distance of N, P and K is as follows: nitrate nitrogen > ammonium nitrogen > potassium> phosphorus. Nitrogen migration of fertilizer is easily affected by nitrification, while the phosphorus migration of fertilizer is greatly affected by soil moisture. The migration patterns of fertilizer potassium and ammonium nitrogen are similar, both of which increases gradually with the increased time and soil moisture.