麦稻轮作体系中磷素平衡的研究

Balance of Phosphorus in a Rotation System with Winter-Wheat and Rice

采用田间小区试验方法,研究了高肥力土壤施用磷肥对冬小麦/水稻轮作周期中作物产量、磷肥利用率和磷养分平衡等的影响。结果表明,施磷对当季作物有增产效果,而磷肥残效对后茬作物增产明显。1个轮作周期一次性施磷(P2O5)45kg·hm-2即可保持麦稻两季作物高产;磷肥施用在小麦季水稻利用其后效,小麦季磷肥利用率为7.6%～13.6%,水稻季磷肥利用率为7.3%～12.2%,累积利用率为14.9%～25.8%;磷肥施用在水稻季小麦利用其后效,水稻季磷肥利用率为7.9%～12.7%,小麦季磷肥利用率为7.8%～12.2%,累积利用率为15.7%～24.9%。1个轮作周期后还有74.2%～85.1%磷积累在土壤中。磷平衡计算结果进一步表明,经过3个轮作周期后,不施磷处理磷素亏缺144.73～145.22kg·hm-2,施磷(P2O5)45kg·hm-2亏缺磷素(P2O5)41.82～41.83kg·hm-2,施磷(P2O5)90kg·hm-2磷素盈余(P2O5)77.42～78.85kg·hm-2,施磷(P2O5)135kg·hm-2磷素盈余(P2O5)200.78～201.77kg·hm-2。随着施磷量的增加土壤速效磷呈明显递增趋势,小麦—水稻轮作高肥力土壤水稻季施用(P2O5)45kg·hm-2就可以维持土壤速效磷平衡。从磷素平衡角度来说,施入的磷肥量应大体上等于作物吸收带走的量,土壤施用磷肥(P2O5)45～90kg·hm-2之间就可以维持土壤-作物体系中磷素的收支平衡。

A field experiment from 1995 to 1999 was carried out at a field station of Handan in China with an aim at assessing effects of phosphorus application on grain yield, P recovery, p balance and dynamics of Olsen-P of soil in winter-wheat/rice rotation system. The experiment was conducted on a calcareous cultivated meadow cinnamon soil with pH 7.6,organic matter 42.3 g·kg-1, ALK.-N 112.0 mg·kg-1, Olsen-P 26.4 mg·kg-1, NH4OAC-K 168.5 mg·kg-1. Four P treatments (0, 45, 90, 135 P2O5 kg·hm-2) were randomly placed in 12plots as 3 blocks. Meanwhile, concentrated super nitrogen as N fertilizer was applied to the soil. After harvest, the grain yield and straw yield were calculated according to the weighed results from sampling plots. P recovery was calculated by method of difference. P balance between P input and P output was calculated according to both whole stage growth of winter wheat and rice. The results showed that with the increase of P fertilizer rates (0, 45, 90, 135 P2O5kg·hm-2) to rice or winter wheat, the Olsen-P content in the soil increased, and hada marked effect on the increase of grain yield in present rice season. P recovery of applying more P fertilizer to crop was in a rage of 7.3%～13.6%. The residual effects of phosphorus applied to the succeeding crop winter wheat were significant, and maintained the higher grain yield of succeeding crop, but available P decreased. Under high yield condition for the winter wheat-rice period of rotation, the phosphorus application of 135 kg·hm-2 for winter wheat or 90 kg·hm-2 for rice were suitable. P fertilizer at one time each year was able to meet the needs on growth and differentiation of rice or winter wheat. It may be concluded that supplying phosphorus in rice season could be decreased to 45kg·hm-2 that was able to maintain the higher grain yield of both rice and winter wheat. The research on P balance showed that P had deficit 144.73 kg·hm-2～145.22 kg·hm-2 and 41.82～41.83(P2O5)kg·hm-2 when P application rate was 0 kg·hm-2 and 45(P2O5)kg·hm-2, P had surplus 77.42～78.85(P2O5)kg·hm-2 and 200.78～201.77(P2O5)kg·hm-2 when P application rate was 90(P2O5)kg·hm-2 and 135(P2O5)kg·hm-2. When applied P fertilizer reached at 45～90 kg·hm-2,the balance of P was maintained.