保水剂用量对干旱区土壤水文生态特性的影响

Effects of Super Absorbent Polymers Dosages on Hydrologic-ecological Properties of Soil in Arid Area

针对塔里木盆地土地沙化、贫瘠、降水稀少、蒸发强烈、造林成活率低等问题,采用随机区组试验设计,以不施保水剂为对照,研究保水剂不同用量对荒漠土水文物理性质及养分含量的影响。结果表明:保水剂不同用量均能不同程度地改善荒漠土壤结构,增强土壤水文功能,提高土壤养分含量。与对照(CK)相比,保水剂用量≥0.30%各处理能明显降低土壤容重和改善土壤孔隙状况,显著提高粒径>0.25 mm大团聚体数量(P<0.05)。其中0.30%、0.40%处理土壤容重分别较CK降低5.63%、7.04%,总孔隙度、毛管孔隙度和>0.25 mm水稳性团聚体分别较CK增加了16.39%、9.83%、10.80%和21.96%、14.21%、10.72%。干旱炎热季节(6—9月),≥0.30%各处理显著提高土壤水分含量(P<0.05),其中0.30%、0.40%处理分别比CK提高21.97%、31.99%。同时,施用保水剂能有效提高荒漠土持水量、贮水量和水分入渗速率,增强土壤保持水土、涵养水源和旱季供应植物水分能力。其中0.30%、0.40%处理持水量、吸持贮水量、饱和贮水量及平均渗透速率显著高于CK(P<0.05),分别较CK提高24.04%、8.21%、16.60%、144.98%和28.45%、12.51%、22.01%、85.69%。施用保水剂能增加荒漠土有机质、碱解氮、有效磷和速效钾含量,保蓄土壤肥力。≥0.30%各处理保蓄土壤肥力效果较好,土壤有机质、碱解氮、有效磷与速效钾含量平均较CK提高36.33%、19.12%、11.76%和3.08%。综合考虑保水剂改土保水肥效果,极端干旱区荒漠土聚天冬氨酸保水剂最佳用量为0.30%。

Aiming at the obvious problems of the land desertification,scarce precipitation,intensive evaporation and high mortality of afforestation in Tarim Basin of Xinjiang,the field study was conducted with randomized block experiment design to investigate the effects of super absorbent polymers(SAP)dosages on the hydro-physical properties and nutrient contents of desert soil under drought condition with the treatment without SAP as the control(CK).The results showed that different dosages of SAP could improve soil structure,enhance soil hydrological function and increase nutrient content of desert soil.Compared with the control(CK),the treatments with SAP dosage≥0.30% could significantly reduce soil bulk density and improve soil porosity,and significantly increase the amounts of macroaggregates with particle size>0.25 mm(P<0.05).Especially,compared with CK,the soil bulk density under 0.30%and 0.40%treatments decreased by 5.63% and 7.04%,and the total porosity,capillary porosity and water-stable macroaggregates with particle size>0.25 mm increased by 16.39%,9.83%,10.80% and 21.96%,14.21%,10.72%,respectively.In the dry-hot season(from June to September),the treatments with≥0.30% dosage significantly increased soil moisture content(P<0.05),and the soil moisture content of 0.30% and 0.40%treatments were 21.97%,31.99% higher than CK,respectively.At the same time,SAP application could effectively improve the water-holding capacity,water storage capacity and water infiltration rate of desert soil,and enhance water-soil conservation,water supply capacity for plant in dry season.The water-holding capacity,water-holding capacity of capillary porosity and saturated water storage capacity,and average permeability rate of 0.30% and 0.40%treatments were 24.04%,8.21%,16.60%,144.98% and 28.45%,12.51%,22.01%,85.69% higher than that of CK(P<0.05),respectively.SAP application could increase the contents of organic matter,alkali-hydrolyzed nitrogen,available phosphorus and potassium in desert soil,and preserve soil fertility.The effect of 0.30% treatment on soil fertility storage was better,and the contents of organic matter,alkali-hydrolyzed nitrogen,available phosphorus and potassium in desert soil increased by 36.33%,19.12%,11.76%,3.08% under 0.30% treatments,compared with CK.Taking the effect of soil improvement,water storage and fertilizer preservation into consideration,the optimal dosage of SAP application for desert soil is 0.30% in extreme arid desert area.