Wide Row Spacing and Living Mulch: New Strategies for Producing High Protein Grains in Organic Cereal Production

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Abstract
Low levels of available nitrogen often reduce the protein content and baking quality of wheat produced on organic farms. Wide row spacing was suggested as a solution for improving crop production under limited nutrient conditions. In field experiments spring and winter wheats were cropped in wide spaced rows (22 and 75 cm, single and paired) at several positions in the crop rotation of an organic farm. Grain protein content was significantly increased by 0.5 to 1.2% above the 9.0–10.7% in normal seeded stands. Sedimentation volumes of flour in sodium dodecyl sulfate solution, another indicator of baking quality, were closely related to grain protein up to 11.5%, where they reached their maximum value. Yields were lower at row spacing of 75 cm compared with full stands. Nevertheless single rows at a distance of 75 cm yielded 3 t ha−1 and double rows 3.7 t ha−1. Competition by companion plants seeded between wheat rows not more than one month earlier than wheat affected yield but not grain protein. Strong interference, both in yield and grain protein, was effected by established non-legume living mulch. Competition by legumes resulted in moderate yield losses but additionally improved grain protein.