Nitrogen-potassium concentrated complex fertilizers versus nitrogen-potassium blends: Effects on potassium uptake by perennial Ryegrass

It was hypothesized that supplying potassium (K) in concentrated complex fertilizer (CCF) form with nitrogen (N) (NK CCF) to all fertilizer microsites, rather than in NK-blended fertilizer form to a fraction of the total fertilizer microsites, should enhance the rate of K uptake by perennial ryegrass. Two complementary pot experiments were conducted to test this hypothesis. The results demonstrated that plants fertilized with an NK CCF absorbed K at faster rates than those fertilized with an NK blend and that use of K2SO4 in place of KCl as the K source lowered the rate of K uptake by plants regardless of fertilizer form. Form of fertilizer (i.e., CCF or blend), however, had no effect on NH4+ or NO3- uptake. Unfortunately, the positive effects of the CCF oil K absorption were only manifest during the second 2 weeks of regrowth and did not result in significant improvements ill dry matter production by the end of the 5-week regrowth periods.