Amino Acid Composition of Grain Protein of Maize Grown with and without Pesticides and Standard Commercial Fertilizers1

Abstract

AbstractIncreases in the price of agricultural chemicals and uncertain supplies are likely to cause a reduction of pesticide and fertilizer use in the future. Therefore, it is of interest to compare yields and quality of crops grown under present conventional practice with those grown at the lower limit of chemical intensiveness. In this paper, we report measurements of the amino acid composition of protein from maize (Zea mays L.) grain raised on 14 pairs of fields which did (conventional) and which did not (organic) receive pesticides and standard commercial fertilizers. The pairs of fields were matched for location, cultivar, planting date, and soil type.When expressed as percent of grain protein, five amino acids were at significantly higher concentration in organic grain and three were at significantly higher concentration in conventional grain. However, because of the lower protein concentration in the organic maize grain, most of the amino acids in conventional grain had significantly higher concentrations, when expressed as percent of total grain weight. The latter fact is more important from the standpoint of livestock feeding.Differences in yield, protein concentration, and amino acid composition between organic and conventional maize were qualitatively similar to reported differences between N‐fertilized and non‐N‐fertilized maize. At least part of the difference between organic and conventional maize is consistent with a greater accumulation of zein in conventionally raised maize.Results presented in this paper suggest that organic maize yields could be increased by N application. Since the yield difference was small, the N limitation should be overcome by modest rates of application.