VARIABILITY OF SOIL CHEMICAL PROPERTIES IN TWO UNCULTIVATED BROWN EARTHS

The variability in pH, loss-on-ignition, exchangeable cations, extractable phosphate, and soil moisture, has been studied for the 0.15 cm horizon of uncultivated, unfertilized Brown Earths at two upland grassland sites in North Wales. The results show that there is a high degree of variability in samples taken at the same time on circles of 1 m radius at all sampling locations. For example, coefficients of variation for exchangeable cations (except sodium) average 33 per cent for twenty-two samples taken on the same occasion at three locations. This spatial variability prevented detection of any additional seasonal trends during a 22-week summer sampling period. It is essential to consider the importance of spatial variability in any pedological or ecological study.