The phosphorus contents of living aboveground parts, standing-dead materials plus surface litter and underground parts in several pasture species in the Fujinita experimental pasture were determined during a period of 6 months. The contents of phosphorus in the soil microbial biomass, soil NaHCO3 extractable P (OLSEN-P) fraction, and soil NH4F-HCl extractable P (BRAY-P) fraction were also measured to evaluate the effect of the soil microbial biomass in a grazing pasture ecosystem. The amount of soil phosphorus transferred to the OLSEN-P fraction was 11kg/ha/155 days. The calculated amount of the OLSEN-P fraction through the soil biomass was 4.3kg/ha/155 days. About 39% of the phosphorus transferred to the OLSEN-P fraction originated from the soil biomass. These results suggest that biomass P could make a significant contribution to plant P nutrition in grasslands

The paper attempts to show that the changes in the humus content are usually associated with the changes in the number and biomass of soil fauna. The disturbance in the functioning of the ecosystem, cultivation of the primeval area, clear-cut, swamp drainage, is followed by permanent, or at least temporary, decrease in the content of organic matter and the number of animals in soil. Moreover, the highest rate of humus decrement is associated with the minimum number of soil fauna. The decrease of the amount of organic matter in the ecosystem involves not only a reduction of animal biomass, but also deep changes in the structure of animal communities. Presented data indicate that fauna biomass and humus content are closely interrelated. However, they do not determine how the soil fauna affects the latter. The results of the experiment described prove that, if the decomposition of organic matter takes place under similar habitat conditions, then more humus is formed in the site rich in biomass of soil fauna. From the information obtained it may be concluded that agricultural treatments which pauperize the soil fauna, at the same time cause a decrease in the organic matter content in soil. Hence they adversely affect one of the crucial factors of soil fertility

A ridge-spacing experiment was conducted for 5 year's 11987-1?83) at Mekele and Quiha on an improved variety of wheat to determine the effect of different spacing's on soil moisture grain and above-ground biomass yields. Spacing's of 20 cm 40 cm and 80 cm between tied ridges were used. The flat control was included for comparison. There was highly significant difference between ridge spacing's. The 80-cm spacing gave the highest grain yield and the best soil moisture values on the black soil at Mekele. The 40-cm spacing gave the highest grain yield and soil moisture on the red soil of Quiha. The above-ground biomass was greatest for 40-cm spacing at both locations.

Soil microbial biomass, which generally comprises about 2-3% of the total organic carbon in soil. has been rccognized as an important source of nutrients because of its fast turnover (Jenkinson and Ladd, 1981). The C. N, P and S contents of biomass have been measured by fumigation procedures (Jenkinson and Powlson, ,1976); however, knowledge of other mineral nutrients in biomass is scarce (Sparling and Berrow. 1985). Our aim was to determine the quantities of available plant nutrients (N. P. K. Ca. Mg and Na) after the death of microorganisms by CH,CI fumigation. | Peer reviewed

The response of northern red oak (Quercus rubra L.) seedlings to varying levels of soil Al was examined in a 16-wk greenhouse study. Forest soil samples representing three soil series were used as growth media: Captina (Fragiudult, Missouri), Lexington (Paleudalf, Mississippi) and Becket (Fragiorthod, New York). Soil from two horizons from each series was separately amended in four treatments to create a wide range of soil Al availability: (i) control, (ii) limed [Ca(OH)2], (iii) acidified (HCl), (iv) acidified with supplemental calcium added (+HCl and CaSO4). Treatments significantly (p less than 0.05) altered soil pH (range 3.65 to 5.48), base saturation, and 0.01 M SrCl2-extractable Al (range 0.6-37.2 mg kg-1). Compared to controls, both acidification treatments resulted in significant reductions in fine root and foliar biomass production or in fine root branching, in all horizons except the highly organic Bhs of the Fragiorthod. In the remaining five horizons, fine root branching and biomass production were highly and negatively correlated (R2 = 0.70 and 0.50, respectively) with 0.01 M SrCl2-extractable Al. Although fine root tissue concentrations of Al correlated highly with 0.01 M SrCl2- extractable Al levels, root tissue Al predicted root branching and biomass only moderately well (R2 = 0.30 and 0.21, respectively). Fine root branching was more sensitive to treatment effects than either root biomass production or root elongation. Reductions in foliar biomas appeared to be secondary responses to direct effects on root systems. Present soil Al levels and acidic deposition rates appear to pose no threat to northern red oak in the southern portion of its range, whereas the possibility of Al toxicity in northeastern Spodosols deserves further study.