The effects of different concentrations of urea (1 to 12%) sprayed at heading and blooming and after blooming on the components of yield, yield, crude and true protein, gluten, Ca, P, and niacin content of wheat, were studied over 3 years. Foliar application of urea caused an increase in the number of kernels per head and 1000-kernel weight. Concentrations beyond 3% eliminated mottling in grains altogether. Mottling was inversely related to die protein content. Concentrations from 1 to 6% increased the yield of grain irrespective of season and the yield response was linear when spray was given at heading, an increase of 52 pounds per acre (4% of that under check) having been recorded with each increase of 1% in concentration, the maximum increase being of the order 24%. Subsequent sprays were not beneficial. Urea sprays increased the proportion of grain in total dry matter produced. Spraying urea resulted in considerable increase in both crude and true protein contents, the response in protein to different concentrations being linear at all the three frequencies. Increase in total protein content was largely due to that in the true protein fraction. The range of increase in protein varied from 18 to 34%. Spraying after blooming was more efficient than at heading or at blooming for enhancing the rate of accumulation of protein in grain. Increases in protein yield per acre due to N sprays ranged from 24 to 60%. Increases in gluten followed the pattern of protein and were of the order of 53 to 70%. Gluten constituted 70% of crude protein and 80% of true protein in nonsprayed wheat and 82% of crude protein and 90% of true protein in N sprayed wheat. While ash and Ca contents remained unaffected P content increased on account of spraying urea. Foliar sprays of N increased the niacin content of grain.

In one experiment, on a brown colluvial clay loam derived from basalt and sandstone, wheat grown after three years of grazed lucerne and grass sheep pasture was compared with wheat grown after three years of summer (grain sorghum) or winter (grazing oats) animal cropping. In a second experiment, on a dark brown clay derived from basalt, an eight-year rotation of alternate wheat-grain sorghum was compared with four years of lucerne grown for hay followed by sorghum, wheat, oats, wheat. Wheat yields were increased by growing lucerne on the more fertile soil which had good moisture-holding capacity; lucerne did not increase wheat yields on the less fertile soil. Grain-protein content increased where wheat followed lucerne, particularly on the less fertile soil; flour quality also improved.

Sulfur deficiency must be considered in management of crop residues. With adequate N, P, and K, the decomposition rate of straw in soil low in sulfates depended on the S content of the straw. Incubation studies showed that unless S fertilizer is added, the S content of straw must exceed about 0.15% for a maximum rate of straw decomposition. Growth of winter wheat (Triticum aestivum L. ‘Wichita’), in the greenhouse, on a NPK-fertilized soil was governed by the S content of straw mixed in the soil. Straws with < 0.15% S added to soil depressed wheat growth, but straws with a higher S content increased yields compared to the no-straw treatment. When S was added along with N, P, and K, the S content of the straws had no effect on wheat growth.

Winter wheat, Triticum aestivum L. ‘Monon’, was grown for 3 years on Cisne silt loam soil at Newton, Illinois. Fertilizer variables were O, 20, 40, and 60 pounds of nitrogen per acre applied in the fall and in the spring in factorial combination. Multiple regression equations for the regression of yield on nitrogen were calculated from yearly yields for each of the 3 years and from yields for the 3-year average. The equation for 1961–63 is: Y = 2123 + 14.287 Nf + 21.487 Nₛ − 0.028 Nf² − 0.066 Nₛ² − 0.142 NfNₛ Y is yield of wheat in pounds per acre, and Nf and Nₛ are pounds per acre of nitrogen added in the fall and in the spring. The largest yield increases from added nitrogen were 56, 23, and 117% in 1961, 1962, and 1963, respectively. A pound of nitrogen applied in the spring increased yields more than a pound of nitrogen applied in the fall. The relative efficiency of fall-applied nitrogen, with respect to spring-applied nitrogen, ranged from 0.55 to 0.97 for individual years and nitrogen rates. The relative efficiency of fall-applied nitrogen increased as the rate of nitrogen increased in 1962 and in 1963. For the 3-year yield average, the relative efficiency of fall applied nitrogen was 0.67 at all nitrogen rates. Weather data offered only a limited explanation for the variation in relative efficiency of fall-applied nitrogen from year to year.

Four hard red winter wheat varieties differing in plant height were compared in a 4-year field study conducted at locations in Nebraska and Colorado. Yield, spike number, number of kernels per spike, kernel weight, and 11 other agronomic characteristics were studied. The short-statured varieties, ‘C.I. 13678’ and ‘C.I. 13677,’ were more productive on the average than the taller varieties, ‘Pawnee’ and ‘Cheyenne.’ C.I. 13678, which was highest-yielding, consistently produced more kernels per spike, but its kernel weight and spike number were less than the other varieties. C.I. 13677, the variety with the shortest straw, produced lighter-weight grain and fewer spikes than Pawnee and Cheyenne. The high number of kernels per spike of C.I. 13678 was associated with more spikelets per spike and more kernels per spikelet than were produced by the other varieties. C.I. 13677 had fewer spikelets but more kernels per spikelet than the taller varieties. Although their flag leaves were shorter than Pawnee, the greater leaf width of C.I. 13678 and C.I. 13677 produced total flag leaf area equal to, or greater than, Pawnee. Yield and yield component relationships among the varieties studied are discussed.