(土娄)土磷素淋移的形态研究

利用设在(?)土上的两个长期肥料定位试验所形成的不同土壤磷素水平试验小区的土壤,用原状土柱模拟灌溉(降水)进行了磷的淋失研究。结果表明,(?)土中磷淋移的主要形态为可溶性磷,平均占淋失全磷量的82.5%,颗粒磷占17.9%;在可溶性磷中,以钼酸盐反应磷居多,平均占全磷量的77.1%,可溶性有机磷只占全磷的13.8%;淋失到20cm以下的全磷浓度最高可达3.95 mg L-1,可溶性全磷最高达3.57 mg L-1; 在历时60d,相当于357mm(约为年灌溉降雨总和的36%)的灌溉量时,最大淋失总磷量达到1082 g hm-2;13次淋滤实验结果显示,渗滤液中钼酸盐反应磷、可溶性全磷和全磷浓度与土壤耕层Llsen-P呈显著正相关。

FORMS OF PHOSPHORUS LEACHING IN LOESSIAL SOIL

Based on the soil phosphorus gradient obtained from two long-term stationary fertilizer experiments on loessial soil,an intact soil cores (20 cm in depth) experiment was conducted to study forms of phosphorus in leachate. The results show that phosphorus leached from loessial soil mainly in dissolved form (TOP), which accounted for 82.5 percent of the total P (TP) in the leachate, and particulate phosphorus (PP) for only 17.9% . Molybdate reactive phosphorus (MRP) .being a chief component of the dissolved phosphorus, constituted on average 77. 1 % of the total P in the leachate, whilst dissolved organic phosphorus (DOP) did 13.8%. The maximum TP concentration of the leachate reached to 3.95 mg L-1 and TDP 3 .57 mg L-1 , during the 60-day experiment with a sum irrigation rate of 357 mm in total, approximately equal to 36% of the total annual precipitation and irrigation. The maximum phosphorus loss by leaching was observed reaching to 1082 g hm-2. The results also indicated that MRP,TDP and TP concentrations of the leachate were significantly correlated with Olsen-P content of the plough layers.