Micronutrients

Abstract

Applying molybdenum (Mo) to a large proportion of the acidic sandplain soils in Western Australia will correct a deficiency of Mo in wheat. Large variations exist between these soils in the time an application of Mo remains effective for maximum wheat production.

The leaching of Mo is unlikely to be a cause of this variation in effectiveness. Moreover, there is no marked variation between soils in their rate of decline in effectiveness of added Mo after the initial reaction. The variation in residual effectiveness between soils appears to be due to the large variation in the initial effectiveness of freshly added Mo for uptake by wheat plants. Variation among soils in the initial effectiveness of added Mo was closely correlated with differences in the adsorption of Mo.

Key words:

• Adsorption
• initial and residual effectiveness