赤红壤在不同农作制中养分平衡的研究

A STUDY OF NUTRIENT BALANCE IN DIFFERENT CROPPING SYSTEMS ON A LATERITIC RED SOIL

在广州的赤红壤上进行六种农作制的五年试验表明,所有衣作制的氮平衡均盈余,其中水稻连作的农作制氮盈余较少,而含豆科作物者尤其是牧草大绿豆混播及双季稻冬种绿肥盈余最多,后者年亩增加氮素约10kg;各农作制氮盈余的原因是具有较高的氮肥效率和土壤全氮量显著增加。磷平衡在所有农作制中皆为亏损;磷肥效率低,多数衣作制投入的磷约有1/3移至耕层以下。钾平衡在含水稻的衣作制中亏损艮大,旱作者接近平衡或盈余;钾亏损的原因是含水稻的农作制钾的淋失量大,平均达投入的44％:土壤经种植五年后钾含量一般只能维持原有水平。养分平衡状况表明,供试六种衣作制中,油一茨和牧草混豆科作物两个农作制最有利于养分平衡,亏损较少,其次是油—稻和稻—肥两个农作制亦较有利于养分平衡。试验还说明稻秆和豆科作物基秆回田是维持农作制中氮平衡、钾平衡的重要手段。

The experiment in which six cropping systems was performed on a lateritic red soil were carried out from 1980 to 1984, on the campus of the South China Agricultural University, Results showed that the soil nitrogen, accumulated in all cropping systems, the ameunt of nitrogen increase in the doulle rice cropping system was low, whearas those systems includ-ing legumes, such as herbage mixed with murg bean and double cropped rice rosted with legume were the highest, the latter could increase about 150 kg/ha of nitrogen annually. Nitrogen accumulation in these systems was cue to higher efficiency of nitroyon fertilizer, and total soil nitrogen increased significantly.Phosphous balance of the soil showed deficit in all cropping systems, the effictercy of phosphorous fertilizer was low, about 1/3 of phosphorous fertilizer applied leaching to below the plow layer in most of the cropping systems.Patassium balance exhibited great deficit in the rice cropping systems. It was due to the considerable amount of K that leached tut under the sulmergeice cenditiers of rice culture the average amount reaching 44% of the potassium fertilizer applied. However, fer dryland cropping system, the potassium remained nearly in balance or showed increase, the soil potassium maintaining its original level after five years cultivation.It was demonstrated that the b(st way to maintain the N, K balance in the cropping systems was to incorporate rice straw and legume in the soil.