Row Spacing and Nitrogen Rate in Wheat, How Wide Can We Go?.

A wider spacing between crop rows provides producers with the opportunity to seed more land per day with the same horsepower, the potential to seed between the previous years crop rows to improve the seed bed and allow for taller standing stubble; however, the potential draw backs to a wider row spacing are reduced yield and damage to germinating seeds as the fertilizer mass in the sideband increases as the row widens. The objectives of the study were to study the interaction between row spacing and N rate in common spring wheat (Triticum aestivum L.) on plant establishment and development, biomass production, grain quality, and grain yield under a no-till production system. Four row spacing (25, 30, 35, and 40 cm) and five rates of Nitrogen (N) fertilizer were investigated for 4 years.   Plant density was not affected by N rate and there was no N rate by row spacing interaction. There was a 20% decrease in plant population going from 25 to 40 cm with some years showing no differences.   Grain yield was consistently low at 40 cm; however, the beginning of the decreased in grain yield varied among the three other row spacings, 25, 30, and 35 cm.  As expected the grain yield increased as the N rate increase and this was independent of the row spacing. Grain quality was not affected by spacing other than for a small increase in thin seed and seed weight at wider spacing. Grain N and P concentrations were not affected by row spacing. The results support the feasibility of wide row spacing up to 35 cm combined with placing all fertilizer requirements in a side-banded position. To use a 35 cm row spacing with wheat, producers must be will to tolerate a small potential decrease in grain yield.