SynopsisYields of Sudangrass, Starr millet, and Sart sorghum and evapotransipiration rates increased as available soil moisture level increased. Sart sorghum produced highest yield at all three moisture regimes. In general, nitrogen and potassium concentrations in plant tissue decreased with increasing soil moisture, but total uptake was usually higher with irrigation.

SynopsisAfter-frost sampling of the aftermaths of forage sorghum and sudangrass from 3 summer cuts, 1 summer cut, and no summer cuts showed no significant change in dry matter yield or percent crude protein. A significant linear increase in percent crude fiber within managements was noted; concentrations of prussic acid decreased sharply. When stockpiled, mature forage sorghum resulted in lower percent crude fiber than immature stages and appreciably lower than comparable growth stages of sudangrass.

SynopsisForage yields of Sart sorghum were increased by either nitrogen fertilizer or irrigation, but a far greater increase was obtained wh,en both were used. Nitrogen content of the plants increased as soil moisture decreased and rate of nitrogen application increased. Closer row spacing increased both forage yield and nitrogen content. Water use increased as the amount of available soil moisture increased.

Rates of oxygen diffusion were measured in soil contained in 3-foot-cube lysimeters in field installations. Water tables were maintained by subsurface watering at 6- to 30-inch depths below the soil surface. Some lysimeters were sheltered from rain. Soybeans, cabbage, grain sorghum, sweet corn, and dwarf field corn were grown in these lysimeters. The highest yields were obtained at oxygen diffusion rates of approximately 15 g. X 10⁻⁸ per cm.² per minute. The maximum yields were high in comparison with yields obtained in most field experiments. Oxygen diffusion rates at 6-inch water table depths were below 5 g. X 10⁻⁸ per cm.² per minute. Under these conditions of extremely poor aeration, yields of grain sorghum, soybeans, cabbage, sweet corn, and dwarf field corn were reduced 25, 35, 40, 65, and 75%, respectively.

Field studies were conducted over a 2-year period on experimental plots at the Escuela Agricola Panamericana situated in the valley of the Rio Yeguare at El Zamorano, Honduras, to study the effect of lime on the availability of soil P. Yields of corn (Zea mays), sorghum (Sorghum vulgare), beans (Phaseolus vulgaris), and cowpea (Vigna sinensis) green manure were recorded. Highly significant yield increased were obtained when the acid soil (pH 5.5) was limed to raise the pH to 6.5. The highest yields were obtained on plots receiving both lime and P. The major portion of the potentially available P in Zamorano soils is in the organic fraction. Analysis of the final soil samples showed that liming liberated the P locked up in the organic form and increased the efficiency of applied P for crop use.

To study the transfer to material through grazing food chains in herbaceous vegetation, a "well" surrounding the lower stem was used to introduce the radionuclides Fe⁵ ⁹, Sr⁸ ⁵, and Zn⁶ ⁵ into the vascular tissue. In most cases after 1 week the radionuclides from the wells were distributed throughout the aboveground part of the plants. Iron—59 was uniformly distributed in the folige of Sorghum and Solidago. Strontium—85 was distributed uniformly in Sorghum but remained concentrated in the stem of Solidago and did not move into the leaves. Zinc—65 moved laterally into the leaves near the point of application but its distribution in the upper portions of the plants was spotty. In Rumex, however, zinc—65 moved to all portions of the plant above the "well." The same radionuclides applied as "spots" to the leaves did not move throughout the plant but remained concentrated at the points of application.

SynopsisGreenhouse experiments indicate that sorghum is a good crop for studying exchangeable sodium-fertility interrelationships. For the five crops studied, exchangeable sodium generally caused an increase in the absorption of sodium, nitrogen, and molybdenum, and a decrease in the absorption of calcium, potassium, sulfur, manganese, copper, zinc, boron, and chlorine.

SynopsisPresoaking increased emergence of RS610 grain sorghum slightly (maximum 26%) where the soil moisture tension exceeded Y$ atm. and salt concentrations did not exceed 10 mmhos./cm. Critical total, soil moisture stress for the variety studied was about 8 alms. Increasing moisture tension and/or soil salinity increased emergence time and decreased total emergence.