滴灌下酸性物质对石灰性土壤磷有效性及作物吸收的影响

Acidic Materials on Mobilization of Phosphorus in Calcareous Soil and Its Impact on Phosphorus Uptake of Drip-irrigated Cotton

大田滴灌条件下研究了少量多次施用硫酸和磷酸对石灰性土壤pH、磷有效性以及改善作物磷营养的效果。结果表明，施用磷酸和硫酸降低局部土壤pH，且随施用次数的增加，酸化效果趋于加强，在第5次施用酸化剂时下降到最大。水平方向上，滴灌带附近pH降低最大，随距离增加酸化效果减弱，pH最大降幅0．26个单位。垂直方向上，0～10cm酸化最为强烈，pH最大降幅0．29个单位。pH降低提高了土壤磷的有效性，0～20cm土层深度酸化剂处理有效磷含量均显著高于对照（P〈0．05），且硫酸与磷酸酸化效果接近。相同养分用量投入和管理水平下，酸化剂处理棉花吸磷量增加17．6％～23．4％，皮棉产量提高9．9％～11．4％。滴灌条件下施用酸化剂提高石灰性土壤养分有效性是一种可行的提高养分资源利用效率的方法。

The effects of acidic materials （phosphoric and sulfuric acid） applied to soil through drip irrigation at low dosage, high frequency on soil pH change and soil P availability, cotton plant growth and P uptake was studied. The results showed that adding acidic materials under drip irrigation decreased the regional soil pH, and acidification effect tended to strengthen with the increase of the acidulant application, in the fifth application the effect of acidification reached to the peak. In the horizontal direction, acidification decreased with increasing horizontal distance from the drip emitter, pH decreased 0.26 units at most, while at 0-10 cm layer, pH decreased 0.29 units. The decreased of soil pH increase soil available P content, at 0-20 cm layer, soil available P content were significantly higher in acidic materials treatment than that of control, sulfuric acid and phosphoric acid showed similar acidification effects. Under the uniform nutrient inputs and management level, plant P uptake of acidulant treatment increased by 17.6%-23.4%, and lint production of cotton increased by 9.9%-11.4%. Applying acidic material can improve nutrient availability in calcareous soil, and is an economically feasible way to improve the efficiency of nutrient in drip irrigation cultivation.