覆砂条件下保水剂对土壤水分蒸发影响的研究

Effects of water retaining agent application on evaporation from soils covered with gravel

覆砂条件下,保水剂具有更明显的抑制蒸发和提高土壤保水能力的作用。本文采用室外蒸发桶模拟实验,研究了在覆砂与不覆砂条件下,三种浓度保水剂对砂壤土水分蒸发的影响。结果表明:在无覆砂条件下,浓度为0.1%、0.2%、0.5%保水剂的累积蒸发量较裸土分别减少5.70%、20.20%、25.65%,说明加入保水剂后可明显减少土壤水分蒸发,浓度越大抑制蒸发效果越明显;在覆砂条件下,未加保水剂的土壤累积蒸发量较裸土减少了87.08%,当分别加入保水剂浓度为0.1%、0.2%和0.5%时,土壤水分累积蒸发量较裸土分别减少了90.47%、96.20%、96.32%,在覆砂条件下,保水剂浓度由0.2%增加到0.5%时,抑制水分蒸发的效果增加不明显,得出保水剂浓度为0.2%时,在三种保水剂浓度之间最为经济合理,说明"覆砂+保水剂"模式具有良好的节水效果,且累积蒸发量与时间的关系符合对数关系,该研究结果为西北旱区生态农业的可持续发展提供理论指导。

Water retaining agent is significant in inhibiting evaporation and enhancing soil water retention. This study aimed to investigate the impact of soil water retaining agent on evaporation from soils covered with gravel by using outdoor evaporation simulation experiments. For this purpose, treatments with three different concentrations （0.1%, 0.2%, and 0.5%） of water retaining agent and two soil covers （gravel and no gravel） were applied. The results showed that accumulated soil evaporation decreased by 5.70%, 20.20%, and 25.65%, respectively, for treatments with water retaining agent concentrations of 0. 1%, 0.2%, and 0.5% compared with no gravel cover treatment. This indicated that water retaining agent decreased evaporation and this effect was stronger for higher concentration of water retaining agent. In the gravel-mulched field without soil water retention agent, cumulative evaporation decreased by 87.08% compared with bare soil. When water retaining agent was added at the concentration of 0.1%, 0.2%, and 0.5%, the cumulative evaporation were reduced by 90.47%, 96.32%, and 96.20%, respectively, compared with bare soil. Because the effect of inhibiting evaporation did not change when the concentration of water retention agent increased from 0.2% and 0.5%, the suitable concentration of water retaining agent concentration could be 0.2%. This study indicated that ＂sand ＋ water retaining agent＂ model has a good water-saving effect, the relationship between the cumulative evaporation and time could be fitted well by the logarithmic function. This experiment provided theoretical foundation for sustainable development of gravel-sand mulched ecological agriculture in north-western arid area.