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

Abstract

Increases 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.

Nutritional quality and safety of organic food. A review

“…for bread-making) and that optimized fertilization practices can maintain reasonably high protein levels. Moreover, a 25-30% increase in lysine has been reported in organic wheat (Wolfson and Shearer, 1981;Brandt et al, 2000). Comparative studies performed on hen eggs (Kouba, 2002) and raw cow's milk (Toledo et al, 2002) did not show any noticeable difference in protein levels.…”

The myth of organic agriculture

“…"It is considered that such higher-protein corn is superior feed-stuff." The results for maize, reported by Lockeretz et al (1981) and by Wolfson and Shearer (1981), showed that the crude protein concentration in a conventionally grown crop was significantly higher than that in the organically grown crop. One study has actually shown processed organic products to be less healthy than their conventionally produced equivalents.…”

The use of infrared spectrometers to predict quality parameters of cornmeal (corn grits) and differentiate between organic and conventional practices

“…This wavenumber can be associated to the C]O's side chain in aspartic acid and glutamic acid (Barth, 2000). Both aspartic acid and glutamic acid are shown to be present in higher amounts in conventionally grown corn versus organically grown corn (Wolfson and Shearer, 1981). The nitrogen that is present in the fertilizer used to grow conventional crops causes increased concentration and yield of proteins (Wolfson and Shearer, 1981).…”