不同施肥处理对碱性设施土壤酸化的影响

Effects of Different Fertilizations on Acidification of A Greenhouse Alkaline Soil

为深入了解设施栽培中几种常见的施肥处理对碱性土壤酸化的影响，开展了长期定点试验。三茬试验结束后，各处理pHw（去二氧化碳水浸提测定）、pHCa（0.01 mol/l CaCl2浸提测定）均显著降低，土壤发生酸化。U（底肥为尿素、过磷酸钙和硫酸钾，追肥为尿素）与CF（底肥为硝基复合肥（15-15-15）、尿素和硫酸钾，追肥为尿素）处理（两处理施入氮磷钾量相等）氮吸收量与超量阳离子吸收量总体无差异，使得U与CF处理两者间的pH（pHw与pHCa）总体无差异。有机肥添加可促进作物氮与超量阳离子吸收，使得10 - 20 cm土壤pH下降幅度显著增大，加强土壤酸化。由于土壤为碱性，酸化有助于改良土壤，目前无需采取措施抑制土壤酸化。

To get insights into the effects of some common fertilization treatments on acidification of an alkaline soil in greenhouse system, long-term fixed-plot experiments were conducted. The pHw （determining in suspension of soil in water without CO2） and pHCa （determing in 0.01 mol/l CaCl2） of all the treatments decreased significantly after three consecutive crops, indicating that fertilizations caused soil acidification. There were no differences in the amounts of nitrogen and excess cations absorbed by crops between the U （urea, single superphosphate and potassium sulfate were used as base fertilizer, and urea was also used as topdressing） and CF （nitro-compound fertilizer, urea and potassium sulfate were used as base fertilizer, and urea was also used as topdressing） treatments. The same amount of nitrogen was applied for the two treatments. Therefore, there are no differences in soil pH values between U and CF treatments. Application of organic fertilizer increased the total amounts of nitrogen and excess cations absorbed by crops, leading to the significant decrease in soil pH of 10-20 cm layer. Hence, the organic fertilizer promoted the acidification of the alkaline soil. However,the acidification of alkaline soils is beneficial to crop growth and its negative effects can be ignored.