保水缓释氮肥在砖红土壤中的应用效果研究

摘要

Objective] A new-type water-absorbent slow release nitrogen fertilizer (WASRNF) was produced through polymerization reaction. Its physicochemical prop-erty and application effect in latosol were studied. Feasibility of using WASRNF to improve the serious problems of latosol in rubber planting area in Hainan Island in-cluding vulnerable nutrient, free-running fertilizer and water was studied. [Result] The results showed that raw materials of WASRNF, urea and water-retention material formed co-polymer through hydrogen-bond interaction that the WASRNF contained many hydrophilic groups. The pH value of WASRNF is near neutral and its water absorbent rate in tap water could reach 167.17 g·g-1. The water absorbent rates in latosol leach liquors with water/soil ratios of 1:5, 1:10 and 1:20 were 104.66, 122.93 and 145.38 g·g -1, respectively. The maximum water holding ratio of latosol in-creased by 23.72%, 30.89% and 39.68% when 0.5%, 1% and 2% WASRNFs were added to latosol, and water evaporation rate of latosol decreased efficiently. Com-pared with common urea, WASRNF could slow down the leaching rate of nitrogen and the initial leaching amount was only 22.17% of the total amount. [Conclusion] The results indicated that WASRNF in latosol had strong water absorption and wa-ter-retention abilities in addition to the good slow release effect, and could efficiently decrease nutrient loss, increase utilization ratio of water and fertilizer and promote interaction between water and fertilizer.%通过化学聚合反应制备了一种新型保水缓释氮肥，研究了保水缓释氮肥的理化性质及其在砖红壤中的保水缓释效果，探讨了施用保水缓释氮肥改善海南岛橡胶种植区砖红壤养分易流失和肥、水不同步等问题的可行性。结果表明：保水缓释氮肥的原料氮肥尿素与保水材料之间通过氢键作用形成了共聚体，含有大量亲水性基团，酸碱度接近中性，在自来水中吸水倍率可达167.17 g/g，在水土比为1：5、1：10和1：20的砖红壤浸提液中吸水倍率分别为104.66、122.93和145.38 g/g。砖红壤中添加0.5%、1%和2%的保水缓释氮肥后砖红壤最大持水率可分别提高23.72%、30.89%和39.68%，且能有效降低砖红壤水分蒸发速率。与普通尿素相比，保水缓释氮肥可减缓氮素淋出速率，首次淋出量仅为施氮总量的22.17%。表明保水缓释氮肥在砖红壤中既具有良好的养分缓释效应又具有较强的吸水保水能力，可有效减少养分流失，提高水肥利用率，促进水肥耦合。