Greenhouse experiments were conducted to determine the relative effect of various sources of nitrogen on the availability of the phosphorus in rock phosphate, waste pond phosphate, calcium metaphosphate, and superphosphate. The soils used were Cecil and Eutaw clays and Hartsells and Norfolk sandy loams. Various nitrogenous fertilizers were applied to unlimed and limed soils, and in other cases lime was mixed with the fertilizer before application to the soil. The results may be summarized as follows: 1. On unlimed and limed Cecil clay the use of ammonium sulfate or urea with rock and waste pond phosphate greatly increased the yield of sorghum and oats over that resulting from the use of sodium nitrate. When the lime was mixed with the fertilizer before application to the soil, these increases were not obtained. 2. Even though the yields of sorghum and oats were greatly increased by using acid-forming nitrogenous fertilizers with the more insoluble phosphates, the yields were still much lower than those obtained with superphosphate. 3. he use of ammonium sulfate or urea with the more insoluble phosphates increased the uptake of phosphorus and calcium by sorghum and oats grown on both unlimed and limed soils. 4. The Ca:P ratio in oats fertilized with ammonium sulfate or urea was about twice as high as the ratio in oats fertilized with sodium nitrate. Sodium nitrate decidedly reduced the total uptake of calcium by oats, but did not affect the uptake of phosphorus appreciably. 5. Superphosphate and calcium metaphosphate were the best phosphate fertilizers for oats and sorghum, fused rock phosphate was almost as good as the former two, and ordinary rock and waste pond phosphate were decidedly inferior.

The K response of seven different crops grown on a K-deficient high-lime soil of the Webster series was determined in the greenhouse, using two rates of K fertilization. The crops were analyzed for K, Ca Mg, and Na in order to determine if the variations in the K response of the different crops on high-lime soils might be explained by differences in their normal absorption of Ca, Mg, and Na in relation to K. Large responses to K fertilization were obtained with corn and sorghum, whereas only slight to moderate responses were obtained with flax, oats, and soybeans. Sweet clover gave no response and that of buckwheat was negative. Of the various crops studied, only flax and oats absorbed appreciable amounts of Na. It appears that these crops respond but little to K fertilization because the Na which they absorb substitutes for K in the plant and thereby lowers the crop demand for K. In the case of those crops which absorb only small amounts of Na, it was found that their K responsiveness on the high-lime soil studied varied with their normal contents of Ca and Mg in relation to K. Sweet clover and buckwheat, which gave no K response, are crops which ordinarily use large amounts of Ca and Mg in relation to K, whereas the highly responsive crops, corn and sorghum, normally use small amounts. Soybeans occupy an intermediate position as regards K response and contents of Ca and Mg. These results are explained on the basis that (a) K absorption by crops on high-lime soils is repressed by high concentrations of Ca and Mg in the soil solutions, and (b) that those crops which require considerable amounts of Ca and Mg for normal growth show low response to K fertilization because they lower the ratios of Ca and Mg to K in the soil solution sufficiently to reduce or remove the repressive effects of Ca and Mg on K absorption.

Iowa is a major crop- and seed-producing area. More acres of corn and oats are grown in Iowa than in any other state, and most of the seed of these crops for Iowa farmers is produced within the state. Furthermore, in 1943 over 95 percent of the corn acreage was planted with hybrid seed, and over 60 percent of the oat acreage was planted with seed of new rust-resistant varieties. Other seed crops of importance in Iowa are soybeans, bluegrass, timothy, wheat, flax, bromegrass, red clover, sweet clover, sudan grass, sweet corn, watermelon and sorghum. The yield and quality of a crop harvested each year is dependent in part on the quality of seed that is planted and the only way to know the quality factors of purity, vitality, weed seed content and sanitation is to test seed prior to planting. The purpose of this bulletin is to provide teachers and farmers with information about the need for clean seed and methods of testing seed with special emphasis on determination of pure seed, identification, of weed and crop seeds, germination tests and use of seed disinfectants for the control of molds that cause disease.

There is a limited demand for either imported or domestically produced starch possessing the peculiar characteristics of tapioca starch. Under current conditions the starch industry would be warranted in paying a premium, if necessary, for 50 to 75 million pounds of such starch annually, in comparison with the price of ordinary corn starch. The industry has found certain cereal crops, notably waxy corn and waxy sorghum, to be satisfactory domestic sources for the replacement of tapioca starch made from the imported cassava root. Waxy corn appears to be especially suitable for this purpose because it can be milled with the same equipment already extensively used for ordinary corn. Field performance tests have been made during 3 years, in eastern Nebraska, of several waxy corns having commercial possibilities in comparison with standard Corn Belt hybrids and an open-pollinated non-waxy variety. Of these, Iowax 1 (formerly known as Waxy Iowa 939) proved most productive and possessed superior vegetative characteristics during the 2 years tested, 1942-43. As an average, Iowax 1 was found to yield approximately 4% less than Iowa 939 and 15% less than U.S. 13 under prevailing conditions, a difference of 6% being required for statistical significance. It would seem advantageous to have Iowax 1 produced in territory where Iowa 939 is being extensively grown because of its special adaptation: Less price premium would need be paid there by the industry as a special inducement for its production than under conditions where a larger, later-maturing hybrid as U.S. 13 is superior. Because of the differences in characteristics and utilization of waxy and non-waxy starch, and the very limited specialized demand for the waxy-type starch, promiscuous production of waxy corn and its admixture with non-waxy corn should be avoided. This is best accomplished through strict contract production. With a loss of its waxy character when outcrossed, waxy corn fields should be reasonably isolated from other corn, the degree of isolation being specified by the contracting company. When grown in test plots subject to extensive outcrossing with unrelated pollen of both waxy and non-waxy corn, the outcrossed non-waxy kernels of Nebraska Waxy and Iowax 1 were 3.9 and 2.8% heavier, respectively, than the waxy kernels occurring on the same ears. No significant difference was found in the yield per acre from white and yellow waxy segregates. Comparable waxy and non-waxy segregates yielded essentially the same, and there was no significant difference in seedling emergence or vegetative habits. The observation that the waxy character may result in approximately 3% less translocation from the stalk to the grain suggests that two hybrids, identical in all genes except waxy, would differ about 3% in yield of grain per acre. This may account largely for the 4% lower yield of Iowax 1 compared with Iowa 939. Subjecting waxy corn plants to outcrossing by non-waxy pollen in varietal test plots may result in a maximum error of about 3% in the acre-yield determination, the amount depending upon the proportion of outcrossed kernels. Further tests of segregating populations confirm the earlier finds as to differential fertilization, there being a deficiency of about 1% in the total expected number of waxy kernels. Instead of 25% of the kernels on selfed segregating ears being homozygous for waxy, only 23.95% were so classified.