A model is proposed to determine the location of active urease in soil; that is, whether the urease was associated directly with soil microorganisms or free from microorganisms and adsorbed on the soil colloids. An indirect approach was used which consisted of making periodic measurements of urease activity during a period of time when the microbial population was undergoing change. Multiple regression analysis was applied to the data to determine the relationship between urease activity and microbial population. Under steady state conditions, 79–89% of the urease activity of the soil examined was due to urease adsorbed on soil colloids. An increase in microbial population reduced this percent temporarily until a new steady state was reached. Addition of a small amount of urea (13 ppm of urea-N) to the soil induced microorganisms to produce more urease.

Abstract: A 1966 Russian study described the effectiveness of microbial degradation in irradiated meat and its keeping quality during storage at room temperature. It was concluded that some proteolytic breakdown can occur if microorganisms remained in irradiated meat products.

The effects of single experimental exposures of plants, fish and microorganisms to members of a group of inorganic fluoride oxidizing agents have been summarized. The information obtained has enabled estimation of the damage to be expected as a result of single accidental exposures in the field. These agents--nitrogen trifluoride (NF₃), tetrafluorohydrazine (N₂F₄), oxygen difluoride (OF₂), chlorine trifluoride (ClF₃), bromine pentafluoride (BrF₅), and chlorine pentafluoride (ClF₅)--vary in chemical behavior and biological effects. NF₃ is relatively innocuous; OF₂ must be avoided absolutely by animals and plants, and both are quite stable chemically. The interhalogens react readily in contact with environmental constituents, and while destructive at the site of initial contact, they are self limiting in effect. N₂F₄ also reacts easily, but should cause only moderate damage. Plant injury in all cases would probably be limited to the currently growing crop, with little possibility of carry-over effects in soil.

The effect of adding urea as a supplemental nitrogen source for rumen microorganisms in a two-stage in vitro digestion technique was determined with shelled corn Zea mays L., corn fodder, sorghum fodder Sorghum bicolor (L.) Moench and alfalfa Medicago sativa L. as substrates. Digestibility in vitro of shelled corn and corn fodder was greatly increased by urea supplementation. Urea slightly increased digestion of sorghum fodder but had no effect on digestion of alfalfa. Some inhibition of sorghum digestion resulted with the highest level of urea supplementation (15 mg urea per 0.25 g substrate dry matter). The optimum amount of urea supplementation, an amount at which highest digestibility was obtained without inhibiting the digestion of any one crop, was 10 mg urea per 0.25 g substrate dry matter. The need for N supplementation to obtain maximum digestion in vitro of substrates containing large amounts of readily-available carbohydrates was clearly demonstrated.

Soil solutions from several areas of the US were analyzed by atomic absorption for total Mn and by resin exchange for percent Mn complexed. Values for the latter (84%–99%) in soil solution from the A horizon were intermediate to those previously reported for Zn and Cu. Soil solution from a New York forest soil at pH 7 contained 13 ppm Mn, of which 93% was complexed. Spectrophotometric and polarographic methods were developed to determine the oxidation state of Mn in this soil solution. Both methods indicated the Mn in solution was present in the +2 oxidation state. The presence of such large concentrations of Mn²⁺ in a soil solution of a neutral soil was still less than that predicted from measured values of the Eh of the soil solution and the Mn²⁺/MnO₂ half-cell potential. Soil microorganisms oxidized and precipitated Mn²⁺, presumably as MnO₂, but the presence of the neutral soil solution that contained 13 ppm Mn partially inhibited this precipitation.

Liquid propane (C₃H₈) was injected into the soil of plots for Zea mays (L.), Sorghum, bicolor (L.) Moench, and Glycine max (L.) Merr. with an anhydrous ammonia applicator at rates of from O to 376 liters/ha (O to 40 gal/A). Gaseous propane was injected into greenhouse and growth chamber pots of soybeans and sorghum at equivalent rates. Propane injections produced a small decrease in corn leaf nitrogen percent. No significant influence on corn yield was noted. Sorghum was not affected by propane injections. Soybean root nodulation was increased by propane injections. Propane had no effect on nodulation where nitrogen fertilizer was added and had no effect on soybean yields. Additional laboratory studies using a closed system showed that microbial activity and nitrogen immobiliaztion were directly related to the propane gas concentration in the soil. Propane may have been used as a source of energy by the microorganisms which then immobilized the soil inorganic nitrogen.

The following is substantially the authors' abstract. Conventional Warburg vessels were used in Illinois to obtain oxygen-uptake data from healthy larvae of Popillia japonica Newm. and larvae infected with the milky disease caused by Bacillus popilliae. The rate of oxygen uptake, expressed as the oxygen at standard temperature and pressure taken up per hour of living larva, was 0.392 ±0.047 for healthy third-instar larvae, 0.312±0.050 for diseased third-instar larvae, 0.156±0.048 for refrigerated third-instar larvae, and 0.332 ±0.058 for early pupae. Repeated determinations on single larvae over a 6-hr, period resulted in steadily decreasing values. No significant correlation existed between oxygen uptake and the dissolved oxygen content of the haemolymph. Injury to larvae caused by insertion of a polarograph needle for dissolved oxygen determination decreased the values obtained. After one day, the rate of oxygen uptake returned to the initial level. Regression analysis failed to establish a correlation between the concentration of microorganisms in diseased third-instar larvae and the rate of oxygen uptake.