Foliar Micronutrient Application for High-Yield Maize

Zachary P Stewart,Ellen T Paparozzi,Charles A Shapiro,Prakash Kumar Jha,Charles S Wortmann

doi:10.3390/agronomy10121946

Abstract

Nebraska soils are generally micronutrient sufficient. However, critical levels for current yields have not been validated. From 2013 to 2015, 26 on-farm paired comparison strip-trials were conducted across Nebraska to test the effect of foliar-applied micronutrients on maize (Zea mays L.) yield and foliar nutrient concentrations. Treatments were applied from V6 to V14 at sites with 10.9 to 16.4 Mg ha−1 yield. Soils ranged from silty clays to fine sands. Soil micronutrient availability and tissue concentrations were all above critical levels for deficiency. Significant grain yield increases were few. Micronutrient concentrations for leaf growth that occurred after foliar applications were increased 4 to 9 mg Zn kg−1 at 5 of 17 sites with application of 87 to 119 g Zn ha−1, 12 to 16 mg kg−1 Mn at 2 of 17 sites with application of 87 to 89 g Mn ha−1, and an average of 8.1 mg kg−1 Fe across 10 sites showing signs of Fe deficiency with application of 123 g foliar Fe ha−1. Foliar B concentration was not affected by B application. Increases in nutrient concentrations were not related to grain yield responses except for Mn (r = 0.54). The mean, significant grain yield response to 123 g foliar Fe ha−1 was 0.4 Mg ha−1 for the 10 sites with Fe deficiency symptoms. On average, maize yield response to foliar Fe application can be profitable if Fe deficiency symptoms are observed. Response to other foliar micronutrient applications is not likely to be profitable without solid evidence of a nutrient deficiency.

Highlights

Nebraska soils are generally micronutrient sufficient with few sites with soil and/or plant tissue samples below critical values for maize production
The objective of this study is to evaluate the effect of foliar-applied micronutrients on grain yield and plant tissue nutrient concentrations under current management practices using commercially available foliar micronutrient products as guided by soil and plant tissue testing
Greater yield response but this relationship did not occur (r = 0.03). The objective of these on-farm strip-trials was to evaluate the effect of foliar-applied micronutrients on grain yield and plant tissue nutrient status under current management practices using commercially available foliar micronutrients

Summary

Introduction

Nebraska soils are generally micronutrient sufficient with few sites with soil and/or plant tissue samples below critical values for maize production. Critical levels have not been validated for current yield levels. Production of 12.0 Mg ha−1 of maize grain requires 1.4 kg Fe, 0.5 kg Mn, 0.5 kg Zn, and 0.08 kg B ha−1 [1]. For most Nebraska soils, agronomic crops are most likely constrained from reaching their genetic and environmental potential by insufficient N and water availability [2] but other growth factors become more likely to be limiting as these factors are exceedingly met according to Julius von Liebig and Carl Sprengel’s “Law of the Minimum” [3]. The likelihood of a micronutrient deficiency being the yield limiting factor increases [4]. Especially when high yielding, has high rates of nutrient uptake during the V4 to VT stage during which demand may exceed supply

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Conclusion