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Interpretive Summaries:
2004 - Nutrient Management for High Yield Corn and Soybeans
2003 - Nutrient Management for High Yield Corn and Soybeans
2002 - Effects of Phosphorus and Potassium Fertilizer Placement in High Yield Corn Situations
2001 - Potassium and Phosphorus Placement Effects in High Yield Corn
Effects of Phosphorous and Potassium Fertilizer Placement in High Yield Corn Situations, 2002
The purpose of this project is to investigate the specific effects of depth of phosphorus (P) and potassium (K) placement on corn response in a high yield environment. Fertilizer rates and placement are important considerations for farmers hoping to raise high yielding corn. Because of the relative immobility of P and K in the soil, different techniques for placing these fertilizers have been studied. Although P and K fertilizers are most commonly broadcast applied, deeper placement of these nutrients may allow corn roots to better utilize the fertilizers applied. Corn yields might also increase if available P and exchangeable K were more uniformly distributed in the rooting zone.
Two studies were initiated in 2001 on dark prairie soils at the Agronomy Research Center near West Lafayette, Indiana. Year 1 (2001) was a fairly representative year for Indiana weather patterns. Conversely, the second year (2002) had an excessively wet spring, with almost 10 in. of rain in April and May. Planting of some of the plots was delayed as a result.
P and K analyses for all 2002 ear leaf, grain, and root samples will be completed in 2003. There was a tendency for broadcast application to increase leaf area at V-5, and for a consistent increase in leaf area at higher plant population. The only leaf area increase (at R1) observed with deep banding treatments was with Pioneer 34B24 at the higher plant population.
In study #1, Pioneer 34B24 yields were 10 to 17 bu/A higher with 12 in. or 6 in. plus 12 in. banding treatments than in the control treatment. A similar yield gain was noted with deep banding for Pioneer 34M95 at the lower population, but not with the higher population. In study #2, neither broadcast P and K together, nor banding of P alone, resulted in any increase in grain yields compared to the control.
Despite the late planting, grain yields were close to 200 bu/A, just slightly less than the yields in 2001. For Pioneer 34B24, higher yields were attained for the 42,000 plants per acre (ppa) population. Conversely, with Pioneer 34M95, most yields were higher with a population of 32,000 ppa. The 2001 yield data showed no significant fertility treatment differences, although there were similar yield responses to plant population.
For shoot weights, broadcast application had a consistent advantage over all other treatments. Chlorophyll readings in hybrid 34B24 tended to be highest in the deep plus shallow-band treatment (6 in. plus 12 in.). The banding advantage is associated with improved photosynthetic function during the grain fill period. Hybrid and population factors had much greater impacts on most root and shoot characteristics than fertility treatments. The broadcast treatment resulted in higher shoot weights than other treatments. This did not translate into a yield advantage.
At V10, banded P alone decreased root length and total root volume compared to both deep K alone and broadcast P plus K treatments. At these rates, deep-banded P and K did not enhance shoot weights, root weights, or root proliferation relative to broadcast P and K application. IN-18F
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