Effects of zinc application on Timothy (Phleum pratense L.) grasslands in the Konsen district.

摘要

The effects of zinc application on timothy grass grown on grasslands in Andisols, low in zinc, in the Konsen district were examined. The application of zinc did not increase dry-matter yield, although its concentration in timothy (Phleum pratense) in the untreated grasslands was much lower than that required for dairy cattle. Timothy in the early growth stages contained almost sufficient zinc to meet dairy cattle needs without zinc application even in the deficient grasslands. Zinc content in whiteclover (Trifolium repens) was higher than that in timothy. Zinc application increased zinc content in timothy shoots. Younger timothy leaves receiving zinc fertilizers contained higher amounts of zinc. However, only 1% of applied zinc was available fortimothy, and it is suggested that zinc application might cause soil pollution. Therefore, it is not recommended to use fertilizer on grasslands to improve the zinc content in the forage when this element is in sufficient supply for the growth of timothy.Timothy should be harvested in the early growth stage, and the legume ratio should be improved in order to insure adequate zinc for dairy cattle on grasslands deficient in zinc.