红壤旱地玉米施磷的示踪研究

红壤地区生物气候资源丰富，土壤风化强烈，盐基多被淋洗，土壤磷素容量小，供磷强度弱。本研究采用￣（３２）Ｐ核示踪技术，对玉米吸磷动态、磷素去向及磷肥的有效性进行了研究。结果表明，玉米吸收肥料磷以产量形成期为主，约占全生育期吸￣（３２）Ｐ总量的５８．０９％～７３．２７％，营养生长前期仅占２１．４８％～３２．５３％；籽实体是肥料磷素运积的主要蓄积库，约占全株吸￣（３２）Ｐ总量５４．７４％。浓度及积累容量均以籽实＞茎秆＞叶片＞叶鞘＞根。玉米部态布局的“上浓下稀”及阶段容量的“前少后多”的磷素时空流向，暴露了红壤旱地作物需磷与土壤供磷的不协调性，是当前磷肥利用率低的关键所在。优化施磷结构，能显著提高土壤─肥料─作物三者间的磷素循环水平，干物质积累及磷肥利用率趋以Ｎ￣（３２）ＰＫ＋ＰＭ＞Ｎ￣（３２）ＰＫ＞Ｎ￣（３２）Ｐ＞￣（３２）Ｐ，有机无机配施比化肥区磷肥利用率净增２３．６２％～３２．９９％，且有机肥供磷亦达７．２３％。

A Tracing Study on the Fate of Phosphorus in Maize in Arid Land of Red Earth

With the method of ￣(32)P tracing, the absorption dynamics,fate,and effect of phosphorusin maize was studied,The results showed that large proportion of P,up to 58. 09 through 73.27 percent,was absorbed in the yield-forming stage,while only 21.48 to 32. 53 percent in the earliy stage of vegetative growth。The seed was the main sink for phosphorus to accumulate in, containing 54.74 percent of its total uptake, Following the seed were , in descending order,the stem,leaf,leaf sheath, and root.The above results disclosed the disagreement between phosphorus uptake and supply,The accumulation of dry matter and the utilization rate of phosphorus were of the order NPK+PM>NPK>NP>P, The utilimtion rate uf phosphorus could be raised by 23. 62 through 32。99 percent when fertilizer and manure were applied mixedly,It was suggested that phosphorus be applied properly to improve its circulation in the soil-fertilizer-crop system。