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Fluid Journal : Fluid Journal 2002-2004
1 Fluid Journal Late Spring 2003 K In NP Starters Helps Bump Corn Yields by Dr. Barney Gordon Three-year study shows that adding potassium can supply extra punch to push yields higher, even though soils already test high in P and K. Summary: In this three-year experiment, starters containing K as well as adequate amounts of N and P consistently increased early-season plant growth, nutrient content, and yield of ridge-till corn compared to starters containing only N and P. This occurred even though soil P and K levels were high. The NPK combination (30 lbs/A of N, 30 lbs/A of P205, and 5 lbs/A of K20) yielded 12 bu/ A more than the same N and P rates without K added. The results indicate that on some soils, K deficiency can be corrected with a small amount of K added to the starter. The use of conservation-till, including ridge-till, has increased in recent years because of its effectiveness in conserving soil and water. Potassium (K) deficiency can be a problem on soils that have been managed with reduced-till practices. The large amount of residue left on the soil surface can depress soil temperature, as well as interfere with plant root growth, nutrient availability, and crop uptake. Liquid starter fertilizer applications have proven effective in enhancing K uptake, even on soils that are not low in available nutrients. K is essential to many plant functions. A deficiency in K affects such processes as respiration, photosynthesis, chlorophyll development, and water content of leaves. K also influences crop maturity. The appearance of K deficiency symptoms in fields managed with ridge- till has thus become a concern for producers. K uptake in corn is greatest early in the season and decreases after 40 to 50 days of growth. Cool spring temperatures can limit early-season root growth and nutrient uptake. Early- season K deficiency can adversely affect corn grain yields. The objective of this three-year study was to determine if K deficiencies could be corrected and corn yields improved with a small amount of K applied in a starter at planting. Twelve Bu/A Bump The experimental area had been in ridge-till since 1984 and managed with an annual rotation of corn and soybeans. K deficiencies had been observed in this field prior to initiation of this study. Ear leaf K concentrations had been below the sufficiency range (1.5 to 1.7%). Dry matter. The 30-30-5 starter treatment increased corn 6-leaf stage dry matter by 65 lbs/A compared to the 30-30-0 treatment. Figure 1. Starter fertilizer composition effects on corn grain yield, 2000-2002, Scandia, KS. Yield - Bu/A Yield K Content K Content Check 30-15-0 15-30-5 30-30-0 30-30-5 16 14 12 10 8 6 4 2 0 205 200 195 190 185 180 175 170 165 160
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