Increasing the efficiency of plant nutrient recycling within the agricultural system as a way of reducing the load to the environment — experience from Sweden and Finland

Annual loads of nitrogen and phosphorus from the Baltic drainage area to the Baltic Sea in 1995 are estimated at 761 000 and 37 500 Mg, respectively. In Sweden it has been estimated that human activities account for 54% of the annual input of nitrogen and 55% of the annual input of phosphorus to the Baltic Sea. Agreements to halve the quantity of nutrients reaching the marine environment by 1995 were made within the Helsinki Commission (base year 1987) and at the North Sea Conference/Paris Commission (base year 1985). This goal has not been achieved. Agriculture has contributed substantially to an increase in nutrient leaching. From 1950 to 1980, the inputs of nitrogen, phosphorus and potassium in the form of inorganic fertilizer increased strongly in relation to their outputs in the form of agriculturally produced foodstuffs such as milk, meat and bread grain in Sweden and Finland. After 1980 the surplus of nitrogen remained at the same level. Based on the results of these studies it was concluded that the local and regional specialization of farms is one important reason for the high losses of plant nutrients: one type of farm specializes in crop production based on the use of artificial fertilizers, while the other specializes in animal production with high inputs of purchased fodder and a surplus of plant nutrients in the form of ineffectively utilized manure from the animals. To minimize the high surplus and losses of plant nutrients from the agricultural system the input of nutrients to the system needs to be reduced. This can be solved by increasing recycling within the system. In this paper, examples are presented showing that it is possible to conserve and minimize the losses of nitrogen and other plant nutrients through careful recycling within the agro-ecosystem trough integration of crop and animal production. However, to achieve high levels of production and recycling efficiency, there needs to be a good balance between the intensity of animal production and crop production hectarage at the local, regional, and national levels. Assuming that these principles are followed, animal production needs to be decreased in the southern regions in Sweden, while a corresponding increase is required in central Sweden. By applying these agricultural principles throughout the Baltic region it should be possible to halve nitrogen losses and minimize losses of phosphorus, thereby meeting the goals set by the states of the region. © 2000 Elsevier Science B.V. All rights reserved.