不同前作对磷肥后效的影响

The Residual Effect of Phosphate Fertilizer of Different Crops in Calcareous Soil

在小麦、毛苕、豌豆施用磷肥的土壤上,接连种植玉米和小麦,研究前3种作物施磷的后效。结果表明,不同前作施磷均有明显后效,其大小既和前作增产效果、由肥料中吸收的磷素多少有关,也和磷肥用量有关。前作增产效果大,吸磷多,肥料利用率高,后效减少;磷肥用量低而前作利用率较高时,后作利用率显著下降,反之亦然。尽管第二、三料作物的吸磷量和肥料的利用率因前作而异,但三料作物的总利用率却大致接近,以亩施4.5kg P_2O_5者最高。经过三料作物吸收,磷肥用量高者仍有明显后效,但用Olsen法测定,不同处理有效磷含量却无明显差别。

In a calcareous soil with different rates of phosphate fertilizer adding, wheat, Vicia and pea were planted as first crops, and then maize and wheat were followed in succession in order to investigate the residual effect of phosphate fertilizer following different crops. The results show that the residual effects were very significant after all the 3 previous crops. The magnitude of the effects was not only related with the yield increase of the previous crops and P uptake by plants from fertilizer, but also with application rates. When the yield increase, P uptake, and the P recovery from fertilizer in the previous crops were high, the residual effect was definitely low. Otherwise, the residual effect would be high. Also, the fertilizer recovery was low when the application rates were low but the recovery was high for the first crops. However, the reverse was true for high application rates with low recovery in the previous crops. Despite the difference of the P uptake and fertilizer recovery existed in the first and second crops due to the different previous crops, the total recovery of each sequence of the 3 crops in rotation was almost approximate. The highst recovery of the total was found in the application of 4.5 kg P2O5 per mu. Through P uptake by 3 crops in succession, the residual effect was still significant in the yield increases, but the available P in soil determined by Olsen's method was no significant difference.