EDAFOLOGÍA, Vol. 10 (3), pp. 131-137, 2003
ESTABILIDAD ESTRUCTURAL DE HORIZONTES SUPERFICIALES DE SUELOS DE PRADO Y CULTIVO DE LA PROVINCIA DE A CORUÑA (NO, ESPAÑA)
M.M. TABOADA CASTRO, M.T. TABOADA CASTRO
Facultad de Ciencias. Universidad de A Coruña. Campus de A Zapateira s/n. CP: 15071. E-Mail: [email protected].
The structural stability of surface horizons of agricultural soils (three of grassland and eight of crop) formed on schist and containing varying amounts of organic material (A Coruña, Spain) was analyzed. The aggregates were subjected to three treatments (fast wetting, mechanical breakdown, slow wetting) to simulate the behavior of the soil surface under different conditions, climatic, hydric and structural. The mean weight diameter (MWD) was determined for the three treatments and for each individual treatment. The average MWD ranged from 0.253 mm to 2.514 mm, corresponding to minimum and maximum levels of organic matter, respectively. A smaller MWD was observed after fast wetting than after slow wetting and mechanical breakdown, the latter showing the greatest diameter. The differences observed for the treatments reveal that the slaking produced from the effect of entrapped air is the principal aggregate-breakdown mechanism in these soils and that the mechanical action by raindrop impact contributes to a lower extent toward the reduction of mean diameter values.
Key words: aggregate stability, pasture and crop soils, fast and slow wetting, mechanical breakdown.