保水剂与磷肥的相互影响及节水保肥效果

采用茶袋法测定保水剂在磷酸一铵、过磷酸钙溶液中的吸水倍率，并以差减法计算保水剂对磷素养分的吸持量，研究不同磷肥对保水剂吸水性能以及保水剂对不同磷肥的吸持作用的影响；盆栽条件下以玉米为供试作物，研究保水剂和不同磷肥配合施用下的节水保肥效果。结果表明:保水剂在不同磷肥溶液中的吸水倍率随肥料浓度的增加而下降，过磷酸钙对保水剂吸水倍率的影响大于磷酸一铵；保水剂在大量吸水的同时，也对溶于水中的磷素养分有吸持作用，吸持量随肥料浓度的增加出现先增大后减小的规律；保水剂和磷肥配合施用能增加叶片净光合速率和气孔导度，提高玉米生物量和水肥利用效率，保水剂与磷酸一铵配合施用水肥调控效果较好。

Interaction Between Water Retaining Agent and Phosphorus Fertilizers and the Effect of Water and Fertilizer Conservation

Water absorbencies of water retaining agent (WRA) in different solution of ammonium phosphate and super phosphate were determined by tea bag method, and phosphorus adsorption capacities of WRA were determined by the difference of phosphorus amounts in the solution before and after adsorption occurred. The effects of different phosphorus fertilizers on water absorbent characteristics of WRA and nutrients adsorption by WRA were studied. Maize was used as the tested crop in a pot experiment to study the effect of water and fertilizer conservation when WRA and different phosphorus fertilizers were applied in combination. The results showed that the water absorbency of the WRA decreased obviously along with the increase of concentrations of various phosphorus fertilizers. Calcium super phosphate had much stronger influence on the water absorbeency of WRA. While WRA absorbed water, it could also absorb phosphate in the solution. With the increase of concentrations of fertilizers, phosphorus adsorption capacity increased at the first stage and then decreased at the second stage. WRA and phosphorus fertilizers applied in combination could obviously increase the net photosynthetic, stomatal conductance and bioyield, as well as phosphorus use efficiency and WUE. WRA and ammonium phosphate applied in combination had the best effect of water and fertilizer conservation.