干旱绿洲灌区大白菜施磷效应与磷肥投入阈值

针对磷肥施用量大且利用率不高的问题,通过2011-2013年在甘肃省农业科学院张掖绿洲灌区农业生态环境重点野外台站进行定位试验,研究了不同施磷量对露地大白菜产量、磷肥利用率以及磷素平衡的影响.结果表明:大白菜产量随施磷量的增加先增加后呈下降的趋势.在施磷量为 112.52 kg·hm^-2时产量达到最高(5489.1 kg·hm^-2),且显著高于其他处理,与不施磷处理相比,增产13.3%～23.8%,此时磷肥利用率为14.2%.土壤中土壤有效磷(Olsen-P)和可溶性总磷(CaCl₂-P)呈现较好的正相关性,土壤Olsen-P含量为24.22 mg·kg^-1时对应的施磷量为111.1 kg·hm^-2,表明当土壤中Olsen-P含量小于24.22 mg·kg^-1时,土壤中的磷素不发生盈余,对环境不造成污染.当施磷量为60.17 kg·hm^-2时,磷输入与输出达到平衡,即此施磷量水平能满足作物的需求.结合研究区的土壤肥力状况,综合产量、磷肥利用率及土壤有效磷含量,干旱绿洲灌区磷肥投入阈值在60.17～112.52 kg·hm^-2时,能保证露地大白菜高产,并且不会造成环境污染.

Phosphorus application effects and input threshold of Chinese cabbage in the oasis irrigation region.

To resolve the problem of higher application and lower use efficiency of phosphorus fertilizer of Chinese cabbage (Brassica pekinensis), the yield, use efficiency of phosphate fertilizer and soil phosphate balance were examined by a located field trial in Zhangye Observation and Experiment Station of the Agro-ecological Environment in oasis irrigation region from 2011 to 2013. The results showed that the yield increased with the increase of phosphorus fertilization rate from 0 to 112.52 kg P·hm^-2, beyond which there would be no further enhancement. The yield was 5489.1 kg·hm^-2 at 112.52 kg P·hm^-2 treatment. This treatment increased the yield by 13.3%-23.8%, under which the phosphorus use efficiency was 14.2%. Soil Olsen-P and CaCl₂-P were positively correlated. For 111.1 kg P·hm^-2 treatment, the content of soil Olsen-P was 24.22 mg·kg^-1, with no phosphorus leaching and no pollution. At the rate of 60.17 kg P·hm^-2, there was a balance between phosphorus input and output and the phosphate demand of Chinese cabbage being met. In conclusion, the optimal phosphorus threshold was 60.17-112.52 kg·hm^-2 for Chinese cabbage, the amount at which could reduce the risk of phosphorus pollution.