Crop alternation was compared with continuous cropping for sunflowers and soybeans and for grain sorghum and corn at Rosemount, Minnesota. No fertilizer was used in order that full effect of crop removal could be observed. Yields from crop alternations of corn-sorghum or sunflower-soybeans exceeded those from continuous cropping. Sunflower-soybean alternation was superior to continuous sunflower in sunflower disease control. Soybeans in a corn or sorghum sequence greatly increased yields of the feed grains. Differences between sunflowers and soybeans and between sorghum and corn in effect on soil pH and depletion of acid-soluble P and K were small and unimportant. Verticillium albo-atrum on sunflowers increased during the study and became the major factor affecting yield. The benefit of rotation in delaying the appearance of the disease was evident even though one might expect spread of inoculum from plot to plot by tillage practices. No other disease or insect problem was observed as a result of continuous cropping of plots to sunflowers, soybeans, grain sorghum, or corn.

Various degrees of compaction were carried out prior to and immediately after planting a summer crop of sorghum under conditions of dryland farming. Soil physical properties—bulk density, penetrability, air permeability and surface cracking—were affected appreciably only to a depth of 15 cm. Preplanting compaction significantly reduced seedling emergence and yields. Postplanting treatments increased sorghum stand density and yield significantly.

The effect of two irrigation schemes common to the High Plains and the effect of plastic film, asphalt film, and asphalt coated paper soil covers on grain sorghum (Sorghum vulgare Pers.) yield and soil moisture efficiency were examined. Early season results indicate that soil moisture losses are largely confined to soil evaporation and that these losses may predominate for approximately 3 weeks after planting. Conventional irrigation by physiological plant growth stages did not insure maximum yields. Maximum yields, maximum consumptive use, and minimum water use efficiency were obtained by maintaining the soil profile above 50% available moisture. With this high soil moisture condition, some consumptive use values for grain sorghum in the southern Great Plains exceeded 0.7 inch per day during mid-summer. Exceptionally good yields, minimum consumptive use, and maximum water use efficiency were obtained by eliminating soil surface evaporation with a complete plastic film soil cover applied at planting. Partial soil surface covers of plastic film, asphalt film, and asphalt coated paper proved equally effective in reducing surface evaporation and increasing water use efficiency. Reduced yields were obtained from plots where the grain sorghum plants were allowed to show visual signs of moisture stress.

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.

Combining ability analyses were computed on a diallel cross of eight inbred sorghum lines in the F₁ and F₂ generations. Five of the lines were standard combine height grain sorghums and three were widely diverse and relatively recent introductions differing for height and maturity genes. The objective of the study was to determine the usefulness of recent sorghum introductions in a hybrid sorghum breeding program and to determine the yield components responsible for any heterosis obtained. Heterosis was striking, but only if at least one of the parents was an introduction. General combining ability effects were high in the F₁ and F₂ but specific combining ability effects were high only in the F₁. The correlation between the yield of the midparent and the yield of the F₁ (r = .07) indicated that the superior parents could not have been selected phenotypically. Number of seeds per head was the most important component of yield in the F₁ generation. From the available data it could not be ascertained whether the outstanding performance of the three introductions as parents was due to genetic diversity of many genes or to hybrid vigor associated with a relatively few height and maturity genes.

Simultaneous evapotranspiration rates were determined biweekly for the crop combinations of alfalfa and barley, alfalfa and cotton, alfalfa and sorghum, wheat and oats, and cotton from meteorological data by the Bowen ratio method. The crops were grown under irrigated conditions in the hot, arid region of south-central Arizona. Calculated evapotranspiration rates ranged from 1.0 to 1.8 times net radiation, indicating that large amounts of energy were extracted from the air mass. Alfalfa prior to cutting tended to use more water than the other crops. Water use by cotton after canopy development approached that of alfalfa. Barley, wheat, and grain sorghum appeared to require the least water. The Bowen ratio method, as a survey technique or continuous sampling method, can be used to obtain short-period evapotranspiration rates under field conditions. It appears to be one of the few methods which will yield valid results when crops are subjected to frequent and heavy irrigation or where water tables are present.

A 3-year study was conducted on Austin clay at Temple, Texas, to determine the effect of mulches of straw, gravel, and soil treated with dioctadecyl dimethyl ammonium chloride (DDAC) on runoff, erosion, and evaporation. Mulches were applied to 0.01-acre plots on a 4% slope. Plots were fallowed 2 years and planted in grain sorghum (Sorghum vulgare) the third year. Runoff and erosion were greater from DDAC-treated soil than from bare-check soil. A surface cover of straw or gravel reduced runoff significantly and essentially eliminated erosion. Both the 2-inch straw mulch and the bare DDAC-treated soil reduced evaporation significantly from the 0- to 6-inch depth during a hot, rainless 10-day period. Straw, gravel, and DDAC-treated soil mulches were about equally effective in evaporation control over periods of a month or more. During high rainfall periods, straw and gravel mulches increased infiltration and movement of excess water below 54 inches. The effect of chemical treatments on runoff and erosion should be considered in addition to their ability to reduce evaporation of soil moisture.

A 2-year trial is described where locally produced rations, fed to Zebu (Nkedi)cattle as a supplement to normal grazing, were tested for their effects on milk yield and cattle condition. The rations used were a cooked mixture of eight parts of sorghum to two parts of cottonseed, cooked cassava and raw cassava, fed at the rate of 12 lb of wet matter per gallon of morning milk, and compared with an unsuplemented control group. No effects were found on milk yield, suckling calf growth rates of lactation length, but all rations maintained the milking cattle in better condition. Part of this condition effect appeared to be carried through to the following calving interval. A second trial is also described where a sorghum/ cottonseed cake ration was tested for its effects on growth rate in young stock. The response was again disappointing. It is concluded that moderately well managed local pastures are capable of supplying all the necessary nutrients for the local cattle to realize their present genetic milk potential of approximately one gallon a day.

Under greenhouse conditions, iron and manganese deficiencies in potato and sorghum test plants have been identified when grown in soils from Copic Bay. However, correction of these micronutrient deficiencies in the potato and enhancement of tuber yields have not been realized under field conditions. Cultural practices, frost damage, and severity of Rhizoctonia infection have minimized plant response to fertilizer treatments.