紫色土不同土体的土壤养分和酶活性特征

对紫色土未培肥和培肥的不同土体,在小麦生育期内土壤养分和酶活性的动态测定结果表明:未培肥土体的全氮、有效磷、蔗糖酶、碱性磷酸酶有明显变化。尤其是砂土在改变为不同质地的土体后,上述土壤养分和酶活性都有所提高。培肥土体的土壤有机质、全氮、有效钾明显增加,土壤酶活性增强。砂土培肥的效果最显著。所以改变土体质地,并加以培肥,有助于提高土壤肥力,防治紫色土退化。

CHARACTERISTICS OF NUTRIENTS AND ENZYME ACTIVITY IN DIFFERENT PEDONS OF PURPLE SOILS

After wheat is planted, soil nutrients and enzyme activity of pedons of different textual solums and different fertilized solums of purple soils have been determined during different wheat growing periods. These results showed as follows:1.In the pedons of unfertilized and different textural solums, soil total nitrogen contents were higher in wheat harvest time than in wheat seeding period, soil total phosphorus and total potasium contents changed slightly, but available phosphorus contents reached the highest level in stooling stage. The sucroase activity in wheat harvest time and alkaline phosphatase activity in stooling stage were the highest. The changes of activities of hydrogen peroxidase and urease weren't obvious. Soil nutrient contents and enzyme activity varied significantly among different pedons. Soil organic matter, total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, available potassium and sucroase had the tendency: loam soil>soil with the constitution of solum of loam in upper layer and sand in lower layer>soil with the constitution of solum of sand in upper layer and loam in lower layer>soil with whole solum of sand.2.Soil nutrient contents of different fertilized solums reached the highest level except potassium in stooling stage. The activities of hydrogen peroxidase and alkaline phosphatase were the highest in stooling stage among soil enzymes,the activities of sucroase and urease were the highest in harvest time. The contents of soil organic matter and total nitrogen and available potassium increased significantly after sandy soils and loam soils were fertilized. At the same time, soil enzyme activities increased, especially, alkaline phosphatase. The fertilization promoted the soil enzyme activities in sandy soils more greatly than in loam soils. These results above indicate that the measures of altering textural solums and fertilizing can improve soil fertility and prevent soils form degradation.