The Effects of Potassium Chloride to Counteract the Negative Effects of Side-banded Urea on Plant Establishment
A series of experiments to determine if adding KCl to side-banded urea would increase the safety to the seedlings against the toxic effects of side banded urea, regardless of the separation between the seed and fertilizer. No significant effect was observed, although there was one site-year observed where addition of KCL with urea in the side-banded urea for flax was beneficial.
IPNI-1999-CAN-SK22
18 May 2001
2000
See attached photos from the trial site in 2000 showing the variable stand of flax due to band placement relative to the seed row (shallow band on the left).
Results and Reports:
The use of urea fertilizer as a nitrogen source has increased dramatically during the last 20 years and its higher toxicity relative to ammonium nitrate requires careful management. The objective of this study was to determine if adding potassium chloride (0, 15 and 30 kg-K2O/ha) to a urea band (0, 60 and 120 kg-N/ha) placed either in a 1"x1.5" (side and below) or 1"x3" (side and below) could potentially reduce the toxic effects of urea with an increase in plant populations. Research has shown that adding potassium chloride can reduce NH3, NO2 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.
Flax: Increasing the rate of nitrogen reduced plant populations. When the separation was varied, an interaction was observed such that the wider separation caused the reduction in plant numbers to be substantially lower as nitrogen rate was increased. In the absence of nitrogen, the narrower separation resulted in higher plant numbers probably as a result of less soil disturbance. Adding K to the urea band did not cause a further reduction in plant numbers due to the lack of a N-KCl interaction. There was a significant placement-KCl interaction for both soil types for plant numbers. Another year of data is required to ensure these interactions are agronomically important. There was a significant nitrogen-potassium interaction for grain yield. The presence of K resulted in maximizing grain yield at a lower rate of nitrogen.
Wheat: The wider separation resulted in slightly lower plant numbers due to more soil disturbance. However the yield was greater with the wider separation. This was observed on both soil types. Potassium caused a slight reduction in plant numbers on the sandy loam but not the clay loam soil. No effect of potassium chloride on yield was observed. There was a significant placement-KCl interaction for plant numbers. At the narrow separation, plant numbers increased with the addition of potassium chloride while at the wider separation, there was no difference. This is evidence that potassium chloride can alleviate the effects of urea in reducing plant numbers. As expected, increasing rates of nitrogen increased grain protein. On the sandy loam soil, a reduction in grain protein was observed with the use of KCl while on the clay loam, the effect was negligible. There was a nitrogen x placement interaction for grain protein on the sandy loam soil. The wider separation gave higher grain protein values at the high rate of nitrogen.
Overall, the study did not show any main effects due to potassium chloride except on plant numbers for spring wheat on the sandy loam site. A number of interactions were observed. For flax there was a nitrogen-KCl interaction for grain yield on the sandy loam site and a placement-KCl interaction for plant numbers for flax on both soil type. With spring wheat, only one interaction was observed. In this case it was the placement-KCl interaction for plant numbers on the clay loam soil. This supports the argument that potassium chloride can reduce the toxic effects of urea on plant numbers when placed together in a band.