Thirteen field trials were conducted to test the effects of rates of N and K fertilizers and seeding dates differing by 2 weeks upon yield, percentage plump kernels, and protein content of malting barley. N fertilizer increased average grain yields on early‐seeded plots by 253, 410, and 534 kg/ha for 22.4, 44.8, and 67.2 kg N/ha, respectively. On late‐seeded plots, same rates of N increased average yields by 264, 303, and 389 kg/ha, respectively. Late seeding reduced average grain yields by 295 kg/ha. Rates of 14 and 28 kg K/ha increased average grain yields by 42 and 48 kg/ha, respectively, on early‐seeded plots and by 71 and 81 kg/ha, respectively on late‐seeded plots. N did not affect average percentage of plump kernels but 14 and 28 kg K/ha increased percentage plump barley by 1.3 and 1.7 percentage units on early‐seeded plots and by 1.8 and 2.7 percentage units on late‐seeded plots, respectively. Late seeding reduced the percentage of plump kernels by 9.8 percntage units. The average protein content of grain was 12.8, 13.1, 13.2, and 13.5% on early‐seeded plots and was 13.4, 13.6, 13.9, and 14.2%percent on late‐seeded plots for O, 22.4, 44.8, and 67.2 kg N/ha, respectively. Late seeding increased the average protein content by 0.7 percentage units. K reduced the average protein content by 0.1 percentage unit on both early and late‐seeded plots.

The relationship between yield response of spring wheat {Trlticum (aestivum L.)sp.) and barley (Hordeum vulgare L.) to fertilizer N and various soil and climatic factors was determined in a total of 66 field experiments over a 3-year period using simple and multiple correlation and regression.Measured variables included precipitation and air temperature from seeding to harvest; available soil moisture and NH 4 -N plus NOj-N at seeding to a depth of 152 cm; N extracted with alkaline permanganate and total N to 61 cm; organic matter to 30.5 cm; and NH 4 -N plus NO 3 -N accumulated during 2 weeks incubation at 35C from samples retained field moist, frozen, and air-dried before incubation, to 61 cm.The factors that showed significant relationships with yield response to nitrogen fertilizer were (i) stored available soil moisture at seeding to 122 cm or a dry zone, (ii) stored NO 3 -N to 61 cm at seeding, (iii) precipitation from seeding to 5 days before harvest and (iv) degree days above 21C from 5 to 60 days before harvest.Using stored NO 3 -N, stored available moisture, average growing-season precipitation and temperature, and a calculated value of 8.40 kg of fertilizer N/ha to produce a yield response of I quintal, predicted N fertilizer rates were within 11.2 kg/ha of actual amounts required in over 50% and within 22.4 kg in 89% of the experiments.