不同水分条件下表层施磷对小麦吸收下层土壤养分的影响

UPTAKE OF NUTRIENTS FROM SUBSOIL BY WHEAT AS AFFECTED P SUPPLY UNDER DIFFERENT SOIL MOISTURES

采用分层隔水盆栽试验,研究了不同土壤状况下,土壤表层(0-15cm)施磷对冬小麦吸收利用下层土壤(15-35cm)中氮磷钾养分影响。结果表明,土壤干旱降低了土壤磷、钾的有效性,严重抑制植株生长。不施磷肥时,小麦根系下扎量高于施磷处理,能从富含水分和养分的下层土壤吸收水分和养分,从而改善其营养状况,增加生物量。在土壤湿润的情况下,小麦对上层土壤养分的吸收量增加,同时由于扎入下层土壤中的根系量增多,因而也能利用一部分下层土壤中的氮磷钾养分。

In order to investigate the effects of P application rate on uptake of N, P and K under different soil moistures, a pot experiment was conducted in the greenhouse. Two kinds of pots were used. The tall pots consist of an upper soil layer of 15cm high and a lower soil layer of 20cm high, with a 2cm layer of coarse sand between them for protecting water and nutrients in the subsoil moving into the up soil. The short pots have the same height as the upper layer of the tall pots. Both the short pot and the upper soil layer of tall pot were supplied with P fertilizer at three levels each under two soil moisture regimes. The subsoil of the tall pots was supplied with sufficient water and N, P and K fertilizers. Winter wheat was grown for 60 days then harvested. The results showed that wheat growth was decreased greatly by lower soil moisture. Under lower soil moisture, the root growth into subsoil was found to be better at treatment without P supply than other P supply treatments, and took up more nutrients from subsoil and made great contribution to the total nutrient uptake of the plant although the absolute amount of nutrient uptake was lower than other treatments. When soil was supplied with sufficient water, the plants took up their major part of nutrients from the up soil.