The effects of induced soil aggregation on the occurrence of Azotobacter and Streptomyces.

Abstract

1. The effect of soil aggregation produced by synthetic soil conditioners on the occurrence ofAzotobacter andStreptomyces in a highly fertile Belgian loess soil was investigated by various methods. 2. Wide differences in levels of soil aggregation introduced technical problems which made impossible the obtaining of strictly comparable results. 3. In general increased soil aggregation tended to favour an augmentation ofAzotobacter andStreptomyces in the soil used and under the environmental conditions prevailing. 4. However, it seemed clear that in such investigations straight-line relationships cannot be obtained reliably because other soil micro-organisms also are favoured by such treatments and competitive effects may be emphazised from time to time. 5. No evidence was found of any inherent toxicity in the soil aggregating products used when they were employed within commercially practical limits.