Drainage, Bearing Capacity and Yield (Losses) on Low Moor Peat Pasture Soils in the Netherlands

摘要

In the Netherlands dairy farming has highly intensified during the last two decades and put ever heavier requirements on the bearing capacity of grassland soils. It was found that bearing capacity is adequate for grazing cattle and field traffic at a penetration resistance of the turf of at least 0.6 MPa (cone: top angle 60 deg and base of 5 sq cm). Bulk density and soil water pressure head are main factors influencing bearing strength of peat soils. Compaction occurring under normal use by grazing cattle, field traffic or rolling improves bearing capacity considerably. Also drainage appears to be very effective to this end. Drainage reduces the frequency of wet top soil conditions and causes a light shrinkage and thereby an increase in bulk density of the peaty top layer. This effect can be ascribed to a higher N-mineralization induced by a better soil aeration due to improved drainage. At higher nitrogen applications the differences in dry matter yield between shallowly and deeply drained peat soils become smaller because nitrogen can substitute for drainage. From controlled trampling experiments with the usual cattle density it appears, however, that more than 50% of the amount of consumable grass is lost due to grazing at penetration resistances below 0.5 MPa.