珠江三角洲土壤供钾能力的研究

珠江三角洲土壤钾素含量全钾平均1.68%,缓效性钾225ppm,速效性钾118ppm,在全省居中等水平.土壤有效钾含量不高.水平分布由三角洲前缘向顶部递减.水稻吸收缓效性钾越早,土壤供钾性能越差.水稻各生育期累积吸钾量变化呈开口向下的二次曲线,出现前轻、中重、后减弱规律.水稻中期吸钾越高,土壤供钾越好.土壤速效性钾变化呈开口向下的二次曲线,曲线变化越平缓,土壤供钾量越少.连续种植水稻吸钾总量占土壤有效钾贮量越多,供钾性能越差.粘质三角洲冲积潜育性水稻土,钾素的含量中上,土壤供钾性能好,早稻钾肥肥效不显著,晚稻极显著.粘质三角洲冲积沼泽性水稻土、粘质三角洲冲积盐溃强酸性水稻士钾素含量最高,但前者地下水位高,后者有酸害,影响水稻吸钾,钾肥肥效不显著.高度熟化粘质三角洲冲积潴育性水稻土等,土壤钾素含量,供钾性能较好,但生产性能高,需钾量大,钾肥肥效早晚稻极显著.沙质砖红壤性红壤潴育性水稻土,钾素含量和水稻吸钾量最少,供钾性能最差,钾肥肥效早晚稻十分显著.

POTASSIUM SUPPLY OF THE SOILS ON THE ZHUJIANG RIVER DELTA

Study on the soils of the Zhujiang River Delta showed that the average total K content was 1.68±0.33%, slowly available K 225±139 ppm and exchangeable K 118±52ppm. The potassium content of the soils in the region belongs to the medium level as compared with that of the soils in other reeions of Guandong Province. The slowly available K constituted 1.34% of the total K and the exchangeable K was only equal to 520% of the slowly available K. The content of exchangeable K was decreased from the fringe to the top of the delta.The slowly available K being absorbed earlier in growing stage indicates the less K supply ability of the soils, The curves of the accumulated content of K in various growing stages of rice shows that the content of K in rice plant in the middle growing stage is higher than that by the early and late growing stages. More K absorbed by rice in middle growing stage inticates the better K supply ability of the soil.