The concentration of lignin in plant tissue is a major factor controlling organic matter degradation rates in forest ecosystems. Microbial biomass and lignin and cellulose decomposition were measured for six weeks in forest soil microcosms in order to determine the influence of pH, moisture, and temperature on organic matter decomposition. Microbial biomass was determined by chloroform fumigation: lignin and cellulose decomposition were measured radiometrically. The experiment was designed as a Latin square with soils of pH of 4.5. 5.5, and 6.5 adjusted to 20, 40, or 60% moisture content, and incubated at temperatures of 4, 12, or 24 degrees C. Microbial biomass and lignin and cellulose decomposition were not significantly affected by soil acidity. Microbial biomass was greater at higher soil moisture contents. Lignin and cellulose decomposition significantly increased at higher soil temperatures and moisture contents. Soil moisture was more important in affecting microbial biomass than either soil temperature or soil pH.

Over an 11-month sampling period, there were no significant differences in biomass between (Eucalyptus) woodland, mallee and heath habitats. Mean dry biomass in the surficial layer of soil (per 5000 cu cm) averaged 46 mg in woodland, 28 mg in mallee and 23 mg in heathland: termite biomass peaked in September, with 141 mg, 83 mg and 47 mg respectively. Soil moisture and termite activity near the surface were positively correlated.

The effect of experimental soil compaction represented by the bulk density in the development of aerial and terrestrial biomass of red clover and ryegrass were studied. The superficial layers of the Metrenco, Fresia and Malihue soils were used in five grades of compactness. The crops were carried out in pots in natural conditions and with irrigation during four months. After harvesting the aerial biomass and the root length and orientation development were taken. The aerial biomass of the clover decrease with the compactness, specially in the Malihue soil. The decrease of growth of the ryegrass began after the intermediate states of compactness. The depth reached by the clover roots was smaller with a greater bulk density. In ryegrass it was not possible to find any relations. An orientation of the clover roots in Melihue soil was not observed. In the Fresia and Metrenco soils dominated a horizontal pattern with the increase of the bulk density. This pattern was found only in the high levels of soil compactness

The effect of various spray programmes used in winter wheat and orchards on celluloytic activity and microbial biomass in the soil was investigated. In some instances pesticide combinations at low dosage caused stimulation whereas higher dosage were inhibitive. The same effects were observed when spray programmes were applied. It is suggested that for the prediction of pesticide side-effects in the field beside single compound studies pesticide combinations and spray programmes should be included