Soybean Growth and Yield Responses to Starter Fertilizers1
- J. T. Touchton and
- D. H. Rickerl2
On highly fertile soils, increases in plant growth resulting from starter fertilizers, applications generally do not occur unless root growth is restricted or temperatures are cool. The use of some conservation-tillage systems may result in restricted root growth and cooler soils at planting. The purpose of this 3-yr field study was to determine if growth and yield of soybeans [Glycine max (L.) Merr.] planted in a conservation-tillage system would be increased by starter fertilizers, and if interactions occurred between residual fertility levels and starter fertilizers. Treatments included residual fertility levels (low P and K, low P and high K, high P and low K, and high P and K) and starter fertilizers (no starter, N, P, K, N-P, N-K, and N-P-K). The N, P, and K starter fertilizer rates were 16, 19, and 44 kg ha−1, respectively. Raising both residual P and K to the high soil test rating improved soybean yields 43%. The N-containing starter fertilizers, especially those also containing P, increased early season plant root and top weights, but the K starters did not. However, the P, K, N-K, and P-K starter fertilizers had the greatest effect on yields; when compared to the control, they increased yields 46% when residual P, K, or both were low, and 26% when the residual P and K were high. The N, N-P, and N-P-K starter fertilizers increased yields 21% when residual P was low, but had no effect on yields when P was high. Seed quality did not vary among residual fertility levels, but was improved by the starter fertilizers, especially those containing K. The P and K concentrations in the leaves just prior to pod set corresponded to differences in yields among residual fertility levels, but not to differences among starter fertilizers.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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