耕型红壤和红壤性水稻土铜的化学行为及施铜效应研究 Ⅱ.土壤中铜的化学形态及施铜效应

Studies on Chemical Behaviour of Cu and Effects of Cu Fertilization on Growth of Rice in Cultivated Red Earths and Red Earth Paddy Soils

应用选择溶解性的化学提取和幼苗试验等方法，研究了湖南省几种耕型红壤及其发育而成的水稻土铜的化学形态及其与土壤有效铜的关系，以及红壤旱地改水田后施铜对水稻吸铜和幼苗生长的影响．结果表明，供试土壤中的铜主要以有机态（１５．２％ ）、无定形铁态（１１．７％ ）、晶形铁态（１７．２％ ）和残留态（５６．０％ ）４ 种形态存在，其中红壤性水稻土有机态铜（１８．７％ ）和无定形铁态铜（１４．６％ ）明显高于耕型红壤（分别为８．０％ 和５．８％ ），而晶形铁态铜和残留态铜含量则是后者高于前者．红壤性水稻土有效铜含量显著高于耕型红壤．幼苗试验结果表明，耕型砂岩红壤施铜能明显促进水稻幼苗对铜的吸收，最佳施铜量为 ５～１０ ｍ ｇ／ｋｇ 土．

By adopting methods of sequential selective dissolution and pot experiment,studies were made on,(1)chemical fractions of Cu in several types of cultivated red earths and cultivated red earth paddy soil developing from cultivated red earth;(2)relation between available Cu and the chemical fractions of Cu in the tested soils;(3)effects of Cu fertilization on Cu uptaken by rice seedling and rice growth when dry land was turned into paddy field. Results obtained showed that the chemical fractions of Cu in tested soils were mainly organic bound Cu,amorphous Fe oxides bound Cu,Crystalline Fe oxide bound Cu and residual Cu,of which, the former two fractions in paddy soils were much higher than that in red earths, while the latter two fracions in paddy soils were lower than that in red earths.Also available Cu in paddy soils were higher than that in red earths,and available Cu in the two soils were higher than the critical level of Cu defficiency for rice plant. Pot experiment showed that there was a significant positive effect of Cu fertilization on Cu uptaken by rice seedlings in the sandstone red earth,and slightly positive effect of Cu fertilization on dry matter producion of rice seedlings at the rate of lower than 10 mg/kg soil only.