摘要：

This study was conducted to evaluate the trace elemental nutritive values of soil and forages collected from southwestern part of the province of Punjab, Pakistan. Soil and forage samples were collected fortnightly for two seasons. The concentrations of some trace minerals varied greatly among seasons and sampling periods. Seasonal effects were found in all soil micro-minerals except zinc, while forage iron, zinc, and selenium were affected by seasonal changes. Sampling periods effects were observed in all soil minerals and in forage copper, iron, zinc, and manganese only. All soil mineral levels except cobalt and selenium were sufficiently high to meet the requirements of plants for normal growth during both seasons. In contrast, soil Co and Se levels were severely deficient during both seasons and considered inadequate for plant growth. Soil Fe, Zn, Co, and Se levels were higher, and Cu and Mn lower during winter than those during summer. Forage Zn levels during summer were at marginal deficient levels, and in contrast, all other forage micro-minerals were within the required range for ruminants during both seasons. Although forage mico-minerals were within the range required by the ruminants, they were not sufficiently high to prevent the predisposition to various diseases caused by nutrient deficiency. Consequently, grazing animals at this location need continued mineral supplementation of these elements with a mixtures of high bio-availability rather than of high micro-mineral contents to support optimum ruminant productivity.

展开