DRYLAND CORN RESPONSE TO TILLAGE AND NITROGEN-FERTILIZATION .2. P, K, CA, MG

Nitrogen fertilization and tillage practices may influence the availability and uptake of essential plant nutrients other than N. This study was conducted t o assess the interactive effects of N rate and timing and tillage practices on uptake and concentration of P, K, Ca and Mg 1n corn grown under dryland conditions. Potassium accumulations in no till (NT) soils were greater than in conventional till (CT) near the surface and lower than CT in t h e subsoil. Phosphorus and Ca levels decreased with soil depth, while Mg tended to accumulate in t h e subsoil. Phosphorus uptake and concentration of 5-leaf stage corn was increased as tillage intensity decreased.Nitrogen rate at planting increased 5-leaf P uptake but reduced P concentration; however, by silking no effect of till age or N fertilization practice on ear leaf P concentration was obtained. Increases in 5-leaf corn K uptake and concentration as tillage intensity decreased may have reduced Mg and Ca concentrations via cation antagonism. Ear leaf Mg and Ca concentrations were increased by N rate, probably as a re - sult of solubilization of Ca and Mg and improved crop growth. Distribution of essential elements in the soil due to tillage in combination with varying N fertilization practices can influence temporal nutrient uptake, thereby altering plant nutrient diagnosis. © 1990, Taylor & Francis Group, LLC. All rights reserved.