In view of the growing practice of testing crop plants for cold endurance under controlled conditions, the following studies with winter wheat at the Nebraska Agricultural Experiment Station may be of interest in connection with the technic of such investigation. These data were secured in connection with a wheat breeding project which has been reported elsewhere. The control equipment described by Peltier was available for the freezing of these plants. In part these tests correspond with those reported for alfalfa by Peltier and Tysdal.

Varieties of wheat and lowland rice were grown in complete nutrient solutions supplied with different chemical forms of nitrogen. Sodium nitrate, ammonium sulfate, and urea and combinations of sodium nitrate and ammonium sulfate to furnish nitric and ammoniacal nitrogen in the ratios of 1 to 3, 2 to 2, and 3 to 1 were used to supply chemically equivalent amounts of nitrogen. The plants were harvested in three growth stages and dry weight of plants and certain nitrogen fractions in the plants were determined. Both species of cereals assimilated all forms of nitrogen to a certain extent. On the whole, rice was more at home with ammonium sulfate than was wheat. Both kinds of plants assimilated nitrogen from ammonium sulfate better in the early stages than in the later stages of growth. The best growth of rice in all stages of growth was obtained with the 3 to 1 ratio of nitric and ammoniacal nitrogen and of wheat with the same ratio except that in the second stage urea gave the greatest weight. Toxicity of ammonium sulfate was more pronounced with wheat than with rice, and this toxicity increased with the age of the plant. The toxic effect rather closely paralleled the amount of ammoniacal nitrogen found in the plants. Rice exhibited a much higher iron requirement than did wheat.

Liming has proved an important factor in raising yields of all crops to paying levels in 16 years of field plat tests on Bedford silt loam. After liming, phosphorus was indicated as the principal plant food need of this soil for a number of years. Without manure or potash its effect is dropping rapidly in recent years. Nitrogen in spring and fall was effective on wheat. Increasing the spring application from 6 to 15 pounds per acre has produced a 5-bushel increase per acre. Potash in addition to phosphate showed little or no effects on wheat, soybeans, or clover. It was ineffective on corn in earlier years but has become increasingly important during the past 10 years where no manure has been used. Manure has produced fair increases on corn and only small increases on the other crops in the rotation unless supplemented by phosphate. A system of returning the manure produced, supplemented by 700 pounds of commercial fertilizer in the 4-year rotation on limed land has maintained yield levels of 31 bushels of corn, 9.5 bushels of soybeans, 14 bushels of wheat, and about a ton of clover hay per acre above the production levels of untreated Bedford silt loam over a 16-year period.

Daily measurements were made of the increase in the height of the plants at the tip of the spike and the ligule of the upper leaf during the heading period of 18 varieties of winter and spring wheat grown at Moscow, Idaho, during one or more of the 3 years, 1931 to 1933, inclusive. Wheat culms elongated rapidly during the heading stage, the rate of elongation increasing with the temperature. The maximum daily elongation during the heading period of varieties of common and club wheat ranged from 4.3 to 9.1 cm. The average increase in the height of the culm after the tip of the heads emerged above the ligule in the common and club wheats was 30.6% of the final height of the plants in 1931, 35.6% in 1932, and 39.4% in 1933. No significant varietal differences were observed except those clearly associated with the final height of the plant. The culm continued to elongate for 5 to 12 days after the tip of the head emerged above the ligule. No consistent relations were found between increase in height after heading, final height, exsertion of the head, or type of growth curve on the one hand and adaptation on the other. There were some indications that the amount of growth during the heading stage was less variable from season to season in the better adapted varieties, but this observation needs further verification. The time required for the spike to exsert its full length from the boot was 2 to 4 days in the common wheats, 1 to 3 days in the short-spiked club varieties, and nearly 4 days in White Polish wheat, which has very long spikes. Elongation of the wheat culm continued as long as blossoming continued and little or no growth occurred after blossoming was completed. The average blooming period for individual culms of the wheat varieties ranged from 1 to 3 days in 1932 and from 3 to 6 days in 1933.

It is the purpose of this paper to present some data showing the salt content which wheat land in the Great Plains may have and yet produce a profitable yield. A few other crops are also included, but for the most part data on these are rather limited. Data on the soluble and replaceable sodium and calcium for these solonchak soils, as well as for some solonetz soils, are presented.

Winter wheat seedlings in four 1-week interval stages of development from emergence to past tillering were compared for cold tolerance. Very young seedlings, presumably still dependent upon the endosperm to a considerable degree were found to excel all other more advanced stage of development groups in cold tolerance, whereas seedlings emerged from 7 to 12 days prior to controlled hardening and freezing, and probably on the verge of endosperm independence, were least cold tolerant. Hardening by exposure to a constant or an alternate (warm day and cold night) temperature near freezing revealed that actual cold resistance increased materially from exposure up to three weeks and none thereafter up to four weeks. The ranking of varieties was not affected by the duration of the hardening periods employed. Differences in varietal cold resistance relationships are indicated from (a) dissimilar growing temperatures or (b) dissimilar ages and stages of plant development at the time of initiating uniform hardening and freezing. These results, together with the seasonal effects reported in a previous paper (6), all point to the great importance of factors other than exposure to low temperatures and resultant high specific cold tolerance as determinators of the relative resistance of winter wheat varieties to cold.

The comparative maturity of corn was studied during an 8-year period on plats receiving various soil treatments. Phosphorus advanced maturity significantly. During 3 of the 8 years when the date on which plants silked in the various plats was determined, it was found that phosphorus had advanced silking about 2 days. The combination of manure and phosphorus advanced the silking date about 3 days during this period. Lime or potassium did not influence maturity consistently. Manure advanced maturity somewhat. During 3 consecutive years that date of silking was noted, the crop was definitely advanced on the manured plats. The differences during the other years were of a low order in the majority of cases. The correlation between yield rank and maturity rank was low. The increased maturity of the crop was not sufficient in degree to warrant, by itself, the application of phosphorus. However, the increased yield of corn, wheat, and oats, all of which was a credit to phosphorus since the application was made only once during a rotation period including these crops, was apparently sufficient to cover the cost of application. The enhanced maturity, therefore, essentially represented the margin of profit from the soil treatment.