Effects on nitrate leaching and yield potential of implementing newly developed sustainable land use systems for dairy farming on sandy soils in the Netherlands

摘要

The land use system of the De Marke experimental farm for sustainable dairy farming was standardized to allow extrapolation to other sandy soils by means of a simulation study. This standardization is a description of the land use system as a set ofdecision rules. Three parcel types were distinguished on the farm: permanent pastures and two different rotations with grass and silage maize. Land use of these three parcel types was thus described with decision rules for fertilization, grazing and cutting of grassland and supplementary irrigation. The effect of temporal variability due to weather conditions was taken into account by using a set of weather data over a period of 30 years for the simulations. The decision rules were applied to the actual fields and soils of De Marke for these 30 years as well as to five representative soils for major soil mapping units of the sandy areas of the 1:50 000 Soil Map of the Netherlands in order to explore the possible effects of introducing this land use atfarms in other areas with sandy soils. The profile descriptions of the representative soils were formed from all available soil survey information for the mapping units. The average simulated nitrate-N concentration at a depth of 1 m for the De Marke farm as a whole was 15.1 mg litre-1 and the probability of exceeding the European Community directive for drinking water (11.3 mg litre-1) at the same depth was 67%. The probabilities of exceeding this value ranged from 3 to 73% for the five major mappingunits. The average actual transpiration of the land use system was higher than at De Marke for all five soil map units, which implies a potential for higher crop yields. This means that it would be easier to meet both the environmental and agricultural goals of De Marke on most other sandy soils than those of De Marke itself. The three parcel types resulted in different levels of nitrate leaching, and it would therefore be worthwhile locating permanent pastures, which are used most intensively, on soilswhich show the least environmental risk, and vice versa.