Phosphorus, Potassium and Sulfur on Malt Barley

Balancing high yield with acceptable grain protein levels is a challenge for malt barley growers in semi-arid regions. Research in Alberta has shown that many farmers under-fertilize their malt barley with nitrogen (N) to avoid high protein, leading to grain yield losses of 10 to 40%. The objective of this research is to evaluate the necessary balance between N, phosphorus (P), potassium (K), and sulfur (S) fertilizer rates to maximize yield and ensure optimum malt barley quality.

Phosphorus fertilizer additions provided an economic increase in barley yield at 29% of the sites in this study, fewer than past projects in the region. Hot, dry summer conditions in the study limited yield response of barley. A minimal response of both grain protein concentration and kernel size, two major factors in malt barley grading, can be attributed to the lack of P yield response at most sites. At a few of the sites, a negative response for kernel plumpness to P additions reflected on the early season soil water depletion by these crops, leading to fewer plump kernels. The small increases in grain yield from K application were found on soils with a soil test K of less than 180 lb K/A in the surface 6 in. Kernel size was not affected by K application. No responses to S were recorded, even though soil S levels were quite low. Subsoil S levels was sufficient to meet the malt barley requirements. AB-22