三峡库区酸性紫色土磷淋溶特征研究

【摘要】三峡库区紫色土约30%为酸性.土壤酸性赋予其与中性或碱性土壤不同的理化性质,进而导致土壤磷淋溶特征不同.为研究三峡库区酸性紫色土磷淋溶特征,本研究利用温室盆栽试验,设置了不同过磷酸钙用量(0,1.006,2.515,4.527,6.036g/盆)对酸性紫色土磷淋溶及玉米生物量、磷素吸收和利用的影响.结果表明:酸性紫色土(旱地)自身磷淋溶量较高,达164.6μg/盆,施入少量磷肥,各形态磷淋溶量显著增加,但当施磷量达到2.515g/盆(即农户普遍磷用量87kg/km2)以上时,磷淋溶量不再随施磷量的增加而增加,呈下降—升高—稳定趋势.土壤总磷淋溶峰出现在玉米拔节期和灌浆期;玉米7~8叶期是溶解性磷和正磷酸盐淋溶高峰期,之后随玉米的生长总体上呈下降趋势.颗粒态磷是土壤磷淋溶的主要形态;溶解性有机磷是溶解态磷淋溶最主要的形态.本研究中,当地农民普遍施磷水平I2(2.515g/盆)为磷淋溶最低处理,但磷肥利用率仍然很低,仅为14.7%.

【英文摘要】Purple soil is the main kind of soils in the Three Gorges Reservoir area ,of which 30% is acid . Compared with neutral or alkaline soils of the same group ,acid soils have different physical and chemical properties ,w hich results in different characteristics of phosphorus leaching .In order to understand the leaching characteristics of phosphorus in acid purple soils of the Three Gorges Reservoir area ,pot experi‐ments in the greenhouse with corn were conducted under different phosphorus levels ,i.e. 0 ,1.006 , 2.515 ,4.527 or 6.036 g/pot .The results showed that the leaching amount of phosphorus in acid purple soil itself was already as high as 164.6 ug/pot ,and it significantly increased after applying a small amount of phosphate fertilizer ,but when phosphoric fertilizer application amount was greater than 2.515 g/pot , phosphorus leaching stopped increasing ,and presented a“falling‐rising‐stability” trend instead .Two peaks of total phosphorus leaching occurred in acid purple soil at the jointing stage and the milking stage of the corn plants ,w hile the peak of dissolved phosphorus and orthophosphate leaching appeared in the 7-8 leaf stage ,although the latter two patterns of phosphorus leaching presented a decline overall .Particulate phosphorus was the major form of phosphorus leaching ,while soluble organic phosphorus was the main form of dissolved phosphorus leaching in acid purple soil .Treatment I2 (2.515 g/pot) ,namely ,the local farmers’ phosphate fertilizer application level ,had the lowest phosphorus leaching in this study ,but its phosphate fertilizer utilization rate remained quite low (14.7% ) .