Phosphorus, Potassium and Sulfur on Malt Barley
Determine the effect of phosphorus, potassium and sulfur on the yield and quality parameters of malt barley across the agro-ecological regions of Alberta.
IPNI-2003-CAN-AB22
17 Feb 2006
2005 Annual Interpretive Summary
Phosphorus, Potassium, and Sulfur on Malt Barley, 2005
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.
Field trials were conducted at 12 dryland sites and two irrigated sites over a 3-year period. At each site, five experiments were conducted with the following treatments: 1) N rate (0, 36, 72, 108, and 144 lb N/A), 2) P2O5 rate (0, 13, 26 and 39 lb/A), 3) K2O rate (0, 28, and 56 lb/A), 4) S rate (0, 9, and 18 lb/A), and 5) seeding date (three dates at 10-day intervals). Seven cultivars were included in the first experiment and two cultivars were included in the remainder of the experiments. Maximum grain yields were achieved when fertilizer + available soil N (estimated from unfertilized grain N yield) were 1.25 lb N/bu grain yield, whereas protein concentrations were usually acceptable if fertilizer + available soil N was between 1.15 to 1.25 lb N/bu. Higher N rates generally reduced kernel size. Unfertilized grain N yield was poorly correlated to pre-seeding soil NO3-N (0 to 24 in.). Cultivar differences in N response were negligible. Application of P, K, or S did not affect malt yield or quality. Seeding delays of approximtely 20 days reduced grain yields by an average of 20%, with relatively greater yield declines under drought-stressed conditions. Delayed seeding either did not affect or slightly increased grain protein concentration. Kernel size was both increased and decreased by delayed seeding. The most beneficial agronomic practices for malt barley production in southern Alberta were early seeding and application of N fertilizer at rates appropriate to the expected availability of moisture and soil N. AB-22