Potassium Fertilization Impact on the Potential Leaching of Potassium Under Potato Production.

Appropriate K fertilization is essential to optimize potato yield and quality. In coarse-textured soils, added K is susceptible to losses by leaching. This study evaluated the effect of K fertilization on the risk of K leaching assessed by the soil solution potassium (SSK) concentrations.

In 2013, two sites were established on coarse-textured soil series; Orléans (loamy sand) and Pont-Rouge (loamy sand) near Quebec City, Canada. The experiments comprised three replications and eight treatments. The K was applied at five rates (0, 70, 105, 140, 210 kg K ha^-1) as a combination of potassium chloride and Sul-Po-Mag; there were three doses of calcium (15, 125, 250 kg Ca ha^-1) applied as calcium sulphate. The SSK was sampled biweekly from planting to harvest (8-9 sampling periods per site) using suction lysimeters.

At both sites, no significant difference between treatments on SSK was observed unlike sampling periods. The K leaching pattern differed between sites. At Pont-Rouge, the highest SSK level was observed 16 days after planting (DAP).Thereafter (30, 44 and 57 DAP), there were no significant differences. From 72 DAP on, SSK declined till the end of the growing season. At Orléans, SSK slightly increased until 78 DAP, followed by a decline until 90 DAP. At the end of the growing season SSK slightly increased. Those results suggest that the pattern of K leaching is soil-specific.