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

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.