不同保水剂对土壤水分和氮素保持的比较研究

Effect of different super absorbent polymers on soil moisture and soil nitrogen holding capacity

保水剂应用对土壤水肥利用效率具有重要影响。本文采用土柱模拟试验方法,以不施保水剂处理为对照,比较3种保水剂——聚丙烯酸盐类保水剂(A)、有机–无机复合保水剂(B)、腐植酸型多功能保水剂(C)对土壤水分和两种氮肥(尿素、硝酸铵)的保持效应,筛选保水剂与氮肥的合理施用配合。8次土壤淋溶结果表明:3种保水剂对土壤水分和两种氮肥都有保持作用,但差异明显。在保水方面,A、B保水剂土壤水分保持效果较好且保水效果相近,C保水剂相对较差;随浇水次数增加,3种保水剂的保水效果均有所降低。在保肥方面,C保水剂对两种氮素的保持效果显著优于对照,且对硝酸铵保持效果优于对尿素的保持效果;A保水剂对尿素的保持效果明显,但对硝酸铵的保持效果很小,淋溶8次后,甚至对氮素淋溶有促进作用;B保水剂对尿素的保持效果8次淋溶后与C保水剂相近,对硝酸铵的保持效果介于其他两种保水剂之间。此外,保水剂对土壤脲酶活性有一定影响,其变化与氮素转化有关;施用尿素的土壤中,保水剂对土壤脲酶活性的影响为B保水剂>C保水剂>A保水剂,而施用硝酸铵的土壤中为A保水剂>B保水剂>C保水剂。

Application of super absorbent polymer （SAP） is important for improving water and fertilizer use efficiency. In the present study, a soil column experiment was simulated to determine the effects of three SAPs [polyacrylate （SAP-A）, organic-inorganic multiple agent （SAP-B） and humic acid （SAP-C）] on soil moisture and urea/ammonium nitrate nitrogen conservation under eight rounds of watering. Soil nitrogen application without SAP was used as the control treatment. The analyses show that all the three SAPs enhance soil moisture and nitrogen holding capacity, but at different degrees. For soil moisture conservation, SAP-A and SAP-B exhibit similar and better effect, while SAP-C shows relatively less effect. With increasing rounds of watering, the conservation effect of the three SAPs on soil moisture decreases. For soil nitrogen holding capacity, the effect of SAP-C on the two sources of fertilizer is sig-nificantly higher than that of the control, while the effect for ammonium nitrate is higher than for urea. Though SAP-A has significant holding capacity for urea, its holding capacity for ammonium nitrate is lower, and it even shows increasing nitrogen lose effect after 8 rounds watering. The nitrogen holding capacity of SAP-B is similar to that of SAP-C after 8 rounds watering for urea, but it is moderate for ammonium nitrate. The SAPs have some form of influence on soil urease activity, which correlates with soil nitrogen transformation. The order of the effects of the three SAPs on urease activity is SAP-B 〉 SAP-C 〉 SAP-A with urea application, and is SAP-A 〉 SAP-B 〉 SAP-C with ammonium nitrate application.