关中灌区小麦、玉米轮作田磷肥施用定位研究

PHOSPHORUS FERTILIZER RECOMMENDATION FOR WHEAT-MAIZE RATATION SYSTEM IN GUAZHOMG IRRIGTIOM AREA

１１年定位研究表明，在关中灌区土的小麦、玉米轮作制中，将磷肥施于小麦，每ｋｇＰ＿２Ｏ－５平均增产１４．９ｋｇ，后作玉米平均增产７．３ｋｇ，磷肥利用率达２５．６％，比等量磷肥施于玉米的增产效益高。施磷肥后，耕层上壤有效磷含量增多，耕层下土壤因得不到磷素补充，有效磷含量减少较多。年生产粮食１０．５～１２．０ｔ／ｈｍ￣２，年需增施磷肥（Ｐ＿２Ｏ＿５）１０５～１２０ｋｇ／ｈｍ￣２，可维持土壤磷素的平衡。

It was shown by the 11 years experiment that one kg P_2O_5 can increase 14.9kg wheat and7.1kg maize in wheat-maize rotation system in Guanzhong irrigation area.The phosphorus utilization effi-ciency is as high as 25.6%, It is more efficient in this system than in maize only.The available phos-phorus in cultivated soil layer is increased.But under this layer available phosphorus is more decreasedbecause no phosphorus added.In order to keep the equilibriun of phosphorus in soil it will be applied105～120 kg P_2O_5/hm￣2 to maintain a good further harvest.