不同剂型聚丙烯酰胺对冷沙黄泥土壤持水性能的影响

为筛选用于提高沙质土壤保水能力的最佳保水剂型，以重庆市分布面积较大的冷沙黄泥为研究对象，采用模拟试验，研究了不同水解度和不同相对分子质量的聚丙烯酰胺（PAM）对沙质土壤的持水效应。结果表明，不同剂型的PAM均能在一定程度上抑制沙质土壤水分的蒸发，提高土壤的保水能力。施用质量分数为0.02%，相同相对分子质量 （800万），不同水解度（10%、20%、30%、40%）PAM的处理，冷沙黄泥累计蒸发量分别较对照减小7.76%～20.17%，平均含水率分别较对照增加2.65%～5.96%，以水解度为40%（高水解度）的PAM持水效果最好。相同水解度（40%），不同相对分子质量（400万、600万、800万、1 000万）PAM的处理，冷沙黄泥累计蒸发量分别较对照减小14.37%～ 20.74%，平均含水率分别较对照增加4.85%～6.11%，以相对分子质量为1 000万的PAM持水效果最好。可见施用质量分数为0.02%，水解度为40%，相对分子质量为1 000万的PAM对冷沙黄泥持水效果最好, 是有效提高冷沙黄泥吸水和保水能力最佳PAM剂型。

Effects of polyacrylamides with different hydrolysis degrees and molecular weights on water holding capacity of sandy yellow soil

A simulation experiment was carried out to identify the optimal polyacrylamide (PAM) formulations (hydrolyis degree, HD; molecular weight, MW) for increasing the water holding capacity of sandy yellow soil distributing widely in Chongqing City. The results indicated that different formulations of PAM could maintain the soil moisture and reduce soil water evaporation rate to some extent. Compared with the control, the treatments amended by PAMs having a MW of 8 million but with different HDs of 10%, 20%, 30%, and 40% reduced the cumulative evaporation rate from sandy yellow soil by a range of 7.76% to 20.17%, while increased the mean soil moisture by a range of 2.65% to 5.96%, with the PAM having a HD of 40% showing the maximum water holding capacity. On the other hand, the treatments amended by PAMs having a HD of 40% but with different MWs of 4, 6, 8, 10 million reduced the cumulative evaporation rate from sandy soils by 14.37% to 20.74%, but increased the mean soil moisture by 4.85% to 6.11% when compared to the control, with the PAM of 10 million MW showing the maximum capacity to hold soil water. Therefore, with the dosage of 0.02% the PAM product with a HD of 40% and a MW of 10 million can be recommended as the optimal formulation for increasing water retention in sandy yellow soil.