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Fluid Journal : Fluid Journal 1993-1995
2 Fluid Journal Fall 1993 for the 50/50 treatments and lower (significant) than the preplant inject to the extent of 0.5 percent in 1991. A grain moisture response to N placement was not significant for the three-year average. Lodging problems occurred only in 1991 and over the three years were not affected by fertilizer placement. PK treatments Phosphorus and potassium applications did not significantly affect any plant Yield - bu/A N Preplant - Inject 50% Weed & Feed, 50% Sidedress 100% Weed & Feed 140 130 120 110 100 No Starter Starter Figure 2. Effect of starters and nitrogen placement on cor n yields, ridge-till (without check plots, three-year average). Yield - bu/A PK - Strip, Fall PK - Inject, Spring NPK 140 130 120 110 100 No Starter Starter parameter, except lodging in 1991 and plant height in 1989, and then only slightly. Yields were statistically the same for all PK treatments, including check plots with N, but without PK. Soils with these PK levels generally do not respond to surface or shallow PK placement, unless compaction was a problem. Leaf tissue analysis Leaf tissue analysis found a few treatments, usually the check, deficient in NPK. DRIS analysis found N, K and Zn to be the most limiting nutrients in 1989, 1990, and 1991. Depending on the plot, other nutrients, including S, Mn, and P were occasionally deficient. Calcium and Mg levels were usually high. Nutrient concentrations in full-rate plots were usually above the critical plant nutrient values found in the Illinois Agronomy Handbook. Only boron and zinc were below critical levels some years. Mainz is an agronomist/superintendent at the University of Illinois, Northwestern Illinois Agricultural Research and Demonstration Center, Monmouth, Illinois. ! Figure 3. Effect of starter and PK placement on cor n yields, ridge-till (without check plots, three-year average)
Fluid Journal 1996-1998