Influence of Moisture and Organic Matter on the Levels of Extractable Manganese in Soil

An investigation of the influence of soil moisture and organic matter on the levels of extractable manganese was conducted utilizing soil samples from residue management plots. Analysis of soil samples from the wheat-fallow plots at North Platte did not indicate significant differences in the ammonium acetate extractable manganese content of the soil due to treatment. This composition was significantly correlated with moisture content of the soil samples. Analysis of soil samples from the Agronomy Farm residue management-rotation plots for ammonium acetate extractable manganese was carried out at two moisture levels. The results indicated significant differences in the amount of manganese extracted from the samples due to the nature of the preceding crop and the moisture content of the samples. A series of incubation studies were conducted at 75◦F constant temperature to determine the effects of levels of organic matter, moisture, and manganese (Mn+2) on the amount of ammonium acetate extractable manganese formed in the soil over periods of 7 to 21 days. Results indicated that the rate of oxidation-reduction reactions in the soil was extremely rapid. The manganese ion status of the soil equilibrium was enhanced by increasing aeration and decreasing moisture content of the soil. The manganese ion content of the soil also tended to increase with increasing organic matter levels. This appeared to be related to the indirect effects of these factors on the soil microbial population Advisor: T. M. McCalla; Leon Chesni