Interactions of Nitrogen Source and Rate and Weed Removal Timing Relative to Nitrogen Content in Corn and Weeds and Corn Grain Yield.

Alexandra M Knight,T Jot Smyth,David L Jordan,Wesley J Everman,Ronnie W Heiniger

doi:10.1155/2017/8961367

Alexandra M Knight, T Jot Smyth + Show 3 more

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https://doi.org/10.1155/2017/8961367

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Abstract

Adequate fertility combined with effective weed management is important in maximizing corn (Zea mays L.) grain yield. Corn uptake of nitrogen (N) is dependent upon many factors including weed species and density and the rate and formulation of applied N fertilizer. Understanding interactions among corn, applied N, and weeds is important in developing management strategies. Field studies were conducted in North Carolina to compare corn and weed responses to urea ammonium nitrate (UAN), sulfur-coated urea (SCU), and composted poultry litter (CPL) when a mixture of Palmer amaranth (Amaranthus palmeri S. Wats.) and large crabgrass (Digitaria sanguinalis L.) was removed with herbicides at heights of 8 or 16 cm. These respective removal timings corresponded with 22 and 28 days after corn planting or V2 and V3 stages of growth, respectively. Differences in N content in above-ground biomass of corn were noted early in the season due to weed interference but did not translate into differences in corn grain yield. Interactions of N source and N rate were noted for corn grain yield but these factors did not interact with timing of weed control. These results underscore that timely implementation of control tactics regardless of N fertility management is important to protect corn grain yield.

Highlights

Fertility and weed management are often considered two of the most critical management factors impacting corn yield [1, 2]
No difference in weed density was noted during 2012 at Clayton when urea ammonium nitrate (UAN) was applied, a decrease in weed population was observed when timing of weed removal was delayed for both sulfurcoated urea (SCU) and composted poultry litter (CPL)
Higher densities at the 8 cm timing of weed removal were noted following SCU and CPL compared with UAN

Summary

Introduction

Fertility and weed management are often considered two of the most critical management factors impacting corn yield [1, 2]. Nitrogen (N) uptake efficiency can be influenced by tillage, soil properties, interactions among crops and weeds, and the rate and source of N applied. Nitrogen uptake efficiency is defined as total plant N per unit of soil N [4] and has been shown to have a strong positive correlation with photosynthesis, biomass production, kernel number, and grain yield of corn [5]. Competition for N between crops and weeds can result in reduced available N for uptake and utilization by the crop, impacting crop yield [7,8,9]

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