根系产生的有机酸对根际土壤养分活化的影响

本试验以采自中国东北3个地点的4种土壤,即棕色针叶林土、暗棕壤、黑土与黑钙土为材料,对根系分泌的两种有机酸及水在活化根际矿质养分方面的作用进行了模拟与比较。结果表明:有机酸能够活化养分,其程度主要取决于有机酸的数量和类型以及供试土壤的理化和生物化学性质;对于所有土壤类型,柠檬酸对Fe, Mn, Cu和Zn的活化效率明显高于苹果酸,而对于P, K, Ca 和Mg的活化效率并不是很高,有时甚至较苹果酸为低;所有元素的溶液浓度均随所加柠檬酸数量的增加而增加。图2表3参9。

Effect of root derived organic acids on the activation of nutrients in the rhizosphere soil

Four types of soils, including brown coniferous forest soil, dark brown soil, black soil, and black calic soil, sampled from three different places in northeast China were used in this test. The functions of two root-derived organic acids and water were simulated and compared in the activation of mineral nutrients from the rhizosphere soil. The results showed that the organic acids could activate the nutrients and the activated degree of the nutrient elements highly depended on the amount and types of the organic acid excreted and on the physiochemical and biochemical properties of the soil tested. The activation effect of the citric acid was obviously higher than that of malic acid in extracting Fe, Mn, Cu, and Zn for all the tested soil types. However, the activation efficiencies of P, K, Ca, and Mg extracting by the citric acid were not much higher, sometimes even lower, than those by malic acid. The solution concentration of all elements increased with increase of amount of the citric acid added.