SynopsisMeasurements of potential evapotranspiration indicate that mean temperature cannot be relied upon for general use in estimating evapotranspiration during short-periods. Mean temperature methods can be used with limited success for long-period (growing season, and annual) estimates of potential evapotranspiration, but energy balance methods are preferable if radiation data are available.

All new potato varieties and a large number of advanced generation experimental lines from many sources have been tested for disease resistance and adaptability to California growing conditions. A true breeding program with the production and evaluation of large numbers of F1—first generation hybrid—seedlings was initiated in the spring of 1958.

The research concerned the effect of drying out of soil on the yield of a number of vegetables and the practical use of irrigation.From the extensive literature published in various countries on this aspect of irrigation research, a series of soil moisture conditions for vegetables (early potatoes, carrots, broad beans, beet root, endive, lettuce, cauliflower, dwarf beans, Scottish kale, Savoy cabbage, spinach and strawberries) was achieved on a trial plot of rather drought-susceptible soil by preventing natural precipitation by removable glass-covers and by irrigation with mobile sprinkler booms. These conditions varied in the limit of drying measured as percentage soil moisture on a weight basis and expressed as average moisture tension (pF), either constant for the entire growing period or varied at different stages of crop development (sensitive period experiments). In other experiments drying of the soil was slowed down by small daily irrigations based on estimated evaporation in the previous 24 hours or at a fixed amount.The yield and crop quality was strongly correlated with the average pF, however sometimes as optimum curve for parts of the growing period.

The research concerned the effect of drying out of soil on the yield of a number of vegetables and the practical use of irrigation.From the extensive literature published in various countries on this aspect of irrigation research, a series of soil moisture conditions for vegetables (early potatoes, carrots, broad beans, beet root, endive, lettuce, cauliflower, dwarf beans, Scottish kale, Savoy cabbage, spinach and strawberries) was achieved on a trial plot of rather drought-susceptible soil by preventing natural precipitation by removable glass-covers and by irrigation with mobile sprinkler booms. These conditions varied in the limit of drying measured as percentage soil moisture on a weight basis and expressed as average moisture tension (pF), either constant for the entire growing period or varied at different stages of crop development (sensitive period experiments). In other experiments drying of the soil was slowed down by small daily irrigations based on estimated evaporation in the previous 24 hours or at a fixed amount.The yield and crop quality was strongly correlated with the average pF, however sometimes as optimum curve for parts of the growing period.

Experimental and commercial plantings of greenhouse tomatoes received supplemental fertilizers in the form of KH₂PO₄, (NH₄)₂HPO₄, KNO₃ and NH₄NO₃ in quantities greater than normally applied. Monthly changes in soil nutrient levels and soluble salt contents were determined and crop behavior observed. A total of 2,922 pounds of nitrogen, 3,054 pounds of P₂O₅, and 4,662 pounds of K₂O per acre were applied during two growing seasons in experimental plantings at the Michigan State University. Soil tests near the end of the growing season for the second year showed 10 pounds of nitrate-N, 188 pounds of P, and 402 pounds of K per acre by the Spurway “active” method. The soluble salt reading for a 1:2 soil/water mixture was 28 × 10⁻⁵ mho. Yields up to 100 tons of fruit per acre were harvested resulting in total crop removal of 350, 105, and 580 pounds per acre of nitrogen, phosphorus, and potassium, respectively. Cooperative studies were conducted with seven commercial growers. The fertilizer program followed closely that used at the University. Results of soil tests and soluble salt readings were similar to those obtained at the University greenhouse.

A rapid polarographic method for the determination of extractable zinc in mineral soils is described. Zinc is extracted by shaking the sample with 0.1N HCl for 2 minutes. After the soil extract is made to a known volume and filtered, an aliquot is diluted with electrolyte solution, and the polarogram is recorded. Significant correlations were obtained between extractable zinc in the soil and total zinc in leaves of tung trees growing in the soil.

Electron microscopical studies were made of changes in cotton fiber microstructure on samples from cultures of the bacterium Cellvibrio fulvus and the fungus Myrothecium verrucaria. Bacterial colonies, growing in the folds of the primary wall, caused diagonal or longitudinal splitting of the fiber surface. Degradation by the fungus was charac terized by transverse cracks in the fiber wall. Other changes in fiber microstructure during microbial growth were similar for both organisms. In areas of intense attack, surface replicas showed single fibrils detached from the underlying structure; on mer cerized fibers, hydrocellulose-like particles on the surface at times obscured the surface structure. Fragmentation patterns indicated a continued breaking down of the fibrillar structure into small fragments and particles. The final degradation products, seen in electron micrographs, resembled particles produced by a limited, heterogeneous acid hydrolysis, but positive identification with hydrocellulose particles has not been made. Cottons modified to produce a more expanded microstructure with higher amorphous cellulose content showed large decreases in resistance to microbial attack. Attack by growing microorganisms was more intense and rapid than degradation by growth filtrates obtained from cultures of cellulolytic fungi, but the mode of degradation was similar.

The study seeks to achieve three basic objectives: (1) to bring together information from both Canada and the United States in a more systematic and comparable form that has been attempted in readily available publications; (2) to utilize more fully the growing accumulation of postwar work in the field of raw material projections; and (3) to apply improved projection techniques....The study has an introductory analysis of background conditions and influences and a discussion of underlying assumptions. Past and future demand and supply conditions for individual commodities are then analyzed.

Millet was grown with and without added phosphorus at one temperature and moisture level on samples of two soils which had been incubated for 74 days at 23°, 2.7°, and −20.5° C. and at moistures of 40, 60 to 70 and 100 percent of field capacity. The higher the soil temperature prior to cropping, the greater was the yield of dry matter and phosphorus uptake. Soil moisture contents prior to cropping did not affect yield and phosphorus uptake. Millet was also grown at three soil moisture levels and at two soil temperatures. The effect depended on the accompanying temperature. The soil moisture level did not affect the yield and phosphorus uptake at a soil temperature of 16° C. but did affect it at a soil temperature of 21° to 33° C. during the cropping period. Response to phosphate in field trials with wheat was related to both temperature and rainfall during the growing season.