The Effects of Potassium Chloride to Counteract the Negative Effects of Side-banded Urea on Plant Establishment

The use of urea fertilizer as an N source has increased dramatically during the last 20 years, and its higher toxicity relative to ammonium nitrate [(NH₄)NO₃] requires careful management. The objective of this study was to determine if adding KCl (0, 15 and 30 lb K₂O/A) to a urea band (0, 60 and 120 lb N/A) placed either in a 1" x 1.5" (side and below) or 1" x 3" (side and below) configuration could potentially reduce the toxic effects of urea reflected in an increase in plant populations. Research has shown that adding KCl can reduce ammonia (NH₃), nitrous oxide (N₂O), and the pH as a result of the delay in urea hydrolysis. This concept was tested in flax and spring wheat on a clay loam and a sandy loam soil.

Adding KCl to the fertilizer band did increase the safety to the seedlings against the toxic effects of side banded urea, regardless of the separation between the seed and fertilizer. However, on both crops and soil types, seedling stand reductions were recorded. An interaction was recorded between urea-N and KCl in flax in 1999 such that the maximum yield of flax with N was obtained at a lower rate of N in the presence of KCl. This was only observed in 1999 on the sandy loam soil. In terms of separation between seed and fertilizer, the greater separation resulted in more soil disturbance and sometimes a decrease in plant numbers, but never a decrease in yield. In fact in 1999, for spring wheat, researchers observed an improvement in grain yield with the larger separation at all levels of N on both soil types, even with the check receiving no N. These results suggest that while addition of KCl to urea bands may minimize any negative impact on germinating seedlings, only when soil K levels were low was it reflected in any grain yield increases. SK-22F