Interaction between water retaining agent and nitrogen fertilizers and the effect of water and fertilizer conservation | 保水剂与氮肥的相互影响及节水保肥效果

Chinese. 目的研究保水剂在吸水的同时，对不同氮肥的吸持作用以及不同氮肥对保水剂吸水性能的影响；保水剂和不同氮肥配合施用下的节水保肥效果。方法采用茶袋法测定保水剂在尿素、碳酸氢铵、硫酸铵、氯化铵溶液中的吸水倍率，差减法计算保水剂对氮素养分的吸持量；盆栽条件下以玉米为供试作物，研究保水剂与这些氮肥配合施用的节水保肥效果。结果保水剂在不同氮肥溶液中的吸水倍率随肥料浓度的增加而下降；不同氮肥对保水剂吸水倍率的影响按尿素、碳酸氢铵、硫酸铵、氯化铵的顺序递增；保水剂在大量吸水的同时，也对溶于水中的尿素分子或者NH4+有吸持作用，吸持量均随肥料浓度的增加而增加；除尿素外，保水剂对氮素的吸持率随肥料浓度的增加而呈降低趋势。保水剂和尿素、碳酸氢铵配合施用能显著地提高玉米生物学产量、根系干重和水肥利用效率，增加叶片净光合速率、蒸腾速率和气孔导度。结论保水剂在吸水的同时，还能吸持溶解在水中氮素养分，氮肥能显著降低保水剂的吸水倍率；尿素对保水剂吸水性能影响最小，保水剂与尿素配合施用，水肥调控效果最好。

English. Objective The objective of the experiment is to study the effects of different nitrogen fertilizers on water absorbent characteristics of water retaining agent (WRA), nutrients adsorption by WRA, and the effect of water and fertilizer-conservation when WRA and different nitrogen fertilizers are applied in combination. Method Water absorbency rates in different solution of urea, ammonium bicarbonate, ammonium sulfate and ammonium chloride were determined by tea bag method. N adsorption capacity was determined by the difference of N amount in the solution before and after adsorption occurred. Maize was used as the tested crop in a pot experiment to study the effect of water and fertilizer conservation when WRA and different nitrogen fertilizers are applied in combination. Result The results showed that the water absorbent rate of the WRA decreased obviously along with the increase of concentrations of various N fertilizers. The influence of nitrogen fertilizers on water absorbent rate of the WRA was in the order of urea＜ammonium bicarbonate＜ammonium sulfate＜ammonium chloride. While WRA absorbed water, it could absorb the molecules of urea or NH4+ of the fertilizers dissolved in water. The N amounts of absorbed fertilizers increased with the increase of concentrations of fertilizers. However, the rate of N absorbed showed a decrease trend along with the increase of concentrations of fertilizers except urea.WRA and urea or ammonium bicarbonate applied in combination could obviously increase the bioyield, root dry weight, N use efficiency and WUE, as well as net photosynthetic, transpiration rate and stomatal conductance. Conclusion While WRA absorbed water, it could absorb N nutrient dissolved in water. N fertilizer strongly decreased water absorbent rate of WRA, however, urea was the weakest. WRA and urea applied in combination had the best effect of water and fertilizer control.