Tillage and Fertility Placement Aspects of Root Zone Optimization for Corn (original) (raw)

Management decisions about root zone optimization should not be limited to corn hybrid selection, because even triple-stacked hybrids with corn rootworm resistance will not produce satisfactory yields if soil structure or chemical properties limit corn growth or nutrient uptake. Growing high yield corn is possible without intensive tillage systems, as numerous studies have shown no-till yielding equal to chisel or moldboard plowing for corn following soybean. Although maintaining soil-test P and K concentrations well above critical levels is important to achieving optimum corn yields, strip-till corn has not yielded consistently higher when P and K fertilizers were deep-banded versus broadcast applied. The relative yield benefits associated with broadcast versus deep-banded application of these nutrients seems to be related to soil moisture availability in the zones of nutrient placement during growing periods when plants take up the majority of their P and K requirements. Corn roots and plant populations suffer when corn rows are positioned too close to anhydrous ammonia or urea ammonium-nitrate N sources incorporated to shallow depths. Precision guidance is very beneficial for optimum corn row positioning at least 5 inches removed from the N fertilizer zone following spring preplant N application at high rates. The primary way to improve stress tolerance (e.g. tolerance to drought, high plant density, or delayed nutrient availability) in corn plants of a given hybrid is to achieve optimum root zones for unimpeded growth in a given soil and climate situation.

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