Effects of Potassium and Magnesium Applied for Corn Grown on an Irrigated Sandy Soil1
- G. W. Rehm and
- R. C. Sorensen2
While the sandy soils of the Nebraska Sandhills and bordering areas are inherently low in N, P, and S, the levels of K and Mg in many soils are considered to be marginal. This study was conducted to evaluate the effects of repeated application of K and Mg on: (i) grain yield of corn, (ii) concentration of K and Mg in plant tissue, and (iii) soil test values for K and Mg. This study was conducted in north-central Nebraska from 1979 through 1982 at a site that was marginal with respect to K and Mg. The soil was classified as a Valentine loamy fine sand (Typic Ustipsamments, mixed, mesic). Twenty treatment combinations from a 92 complete factorial were selected to fit a central composite factorial design and replicated 3 times. Selected rates of K (0, 34, 67, 101, 134, 168, 202, 235, 269 kg ha−1) and Mg (0, 5.6, 11.2, 16.8, 22.4, 28.0, 33.6, 39.2, 44.8 kg ha−1) were broadcast and incorporated before planting. Whole corn plants were collected from each plot when plants were 40- to 60-cm tall and the leaf opposite and below the ear was sampled each year. These tissue samples as well as samples of grain were analyzed for K and Mg. Grain yields were measured each year. The application of both K and Mg had no significant effect on yield throughout the study. Although the concentrations of K and Mg were marginal as indicated by routine soil test procedures, this soil was apparently able to supply adequate K and Mg for corn production. Soil test values for K and Mg increased linearly with the rate applied. A yearly application of 33 kg K ha−1 was satisfactory for maintaining the initial level of soil test K. The K concentration in both whole plant and ear leaf tissue increased linearly with rate of K applied. In general, the K concentrations in the ear leaf tissue were in excess of the published critical level of 19 g kg−1. The Mg concentration in the plant tissue increased linearly with rate of applied Mg but decreased curvilinearly as the rate of K was increased. The Mg levels were substantially higher than published critical levels.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © .