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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。
A new type of water-retaining and slow-release nitrogen fertilizer was prepared by chemical polymerization. The physicochemical properties of water-retaining and slow-release nitrogen fertilizer and its water-holding and slow-release effect in the latosol were studied. The effects of applying water- Few nutrients are easily lost and water is not synchronized. The results showed that the intermolecular hydrogen bonds formed between nitrogenous urea and water-retaining material of water-retaining and slow-release nitrogen fertilizer formed hydrogen bonds and contained a large amount of hydrophilic groups with nearly neutral pH. The water absorption ratio in tap water was 167.17 g / g, The water absorption rates of brick red soil extracts with water-soil ratio of 1: 5, 1:10 and 1:20 were 104.66, 122.93 and 145.38 g / g, respectively. After adding 0.5%, 1% and 2% of water-retaining and slow-release nitrogen fertilizers to brick red soil, the maximum water holding capacity of brick-red soil could be increased by 23.72%, 30.89% and 39.68% respectively, and the water evaporation rate of brick red soil could be effectively reduced. Compared with common urea, the slow-release nitrogen fertilizer can slow down the rate of nitrogen leaching, the first leaching amount is only 22.17% of the total amount of nitrogen fertilizer. It shows that the water-retaining and slow-release nitrogen fertilizer has both good nutrient-releasing effect and water-absorbing and water-holding capacity in brick red soil, which can effectively reduce nutrient loss, increase water and fertilizer utilization rate, and promote water and fertilizer coupling.