Soil Test Values for Phosphorus, Potassium, and Zinc as Affected by Rate Applied to Corn
1984
Rehm, G. W. | Sorensen, R. C. | Wiese, R. A.
The change in land use of the Nebraska Sandhills from native grassland to intensive production of irrigated corn (Zea mays L.) has provided a unique opportunity for the study of changes in nutrient levels of soils as affected by repeated fertilization. This study was initiated in northeast Nebraska in 1974 and continued through 1978 for the purpose of examining the effects of repeated application of P, K, and Zn on corn yield and changes in soil test values for these nutrients. Soil samples were collected prior to fertilization in 1974 for the purpose of site characterization. Soil samples (0–15 cm) were collected after each growing season where corn was harvested for grain and for silage. At the end of the 1978 growing season, samples were collected from each plot at depths of 0 to 15, 15 to 30, 30 to 60, 60 to 90, and 90 to 120 cm. Routine soil test procedures were used to analyze all samples for P, K, and Zn. Repeated application of fertilizer P and Zn produced rapid yearly increases in the soil test values for each nutrient. Repeated fertilization with K produced increases in soil test values for K but at a slower rate than changes in levels of P and Zn. Method of harvest appeared to have no influence on the soil test values for P and Zn. Average soil test values for K were lower when corn was repeatedly harvested for silage. Although relatively high rates were applied, there was no apparent movement of either P or Zn below the tillage zone. Repeated application of K produced increases in soil test values for K at depths as low as 120 cm.
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