AGGREGATE STABILITY DYNAMICS AS AFFECTED BY SOIL-TEMPERATURE AND MOISTURE REGIMES

The relationships between aggregate stability dynamics and soil temper ature and moisture were studied at three sites in Israel under Mediter ranean and arid climatic conditions. Soil moisture and temperature wer e monitored and aggregate stability was measured during a two year per iod. The data were analysed in terms of the effect of soil temperature and moisture on bonding and breakdown agents and mechanisms such as c lay and organic matter content, microbial activity and polysaccharide release, and freeze/thaw cycles. The conclusions were: 1. Aggregate st ability decreases with increasing aridity. This trend reflects the inf luence of soil properties that have evolved over long period of time. 2. Soil temperature and moisture exert a strong control on aggregate s tability dynamics in the seasonal scale under both Mediterranean and a rid climatic conditions. The applicability of the conclusions to diffe rent environments was examined in the central Cordillera. While the ge neral relationships with temperature and moisture could not be applied , the effect of agricultural activity on aggregate stability could be explained.