Investigations on the Nutrient Cycle and its Components of a Biodynamically-Managed Farm

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Abstract
Experimental analyses of the nutrient cycle and its components in organically managed farms have not yet been performed. This paper summarizes results of a three-year (1985 to 1987) research project aimed at balancing the overall nutrient cycle on a biodynamically managed farm (‘Boschheidehof’), located in the lower Rhine valley of Germany. The ‘Boschheidehof’ farm, with 29 ha of worked land and a stocking rate of 1.04 Livestock Units (LU) per ha, has been under biodynamic management since 1979. Fields are cropped with a seven-year rotational scheme, beginning with a two-year grass/clover ley. Fertilization is based on farmyard manure and green manures. There is no closed nutrient cycle on this farm. The phosphorus and magnesium balance amounted to a deficit of 2.9 kg phosphorus and 8.4 kg magnesium per ha per year, whereas the potassium balance had a deficit of 65 kg potassium per ha per year. The nitrogen balance could not be calculated exactly. A range from +16 to -38 kg nitrogen per ha per year was found, when subtracting the maximum farm output from the minimum farm input and vice versa, i.e. the maximum range for all variables used. Losses were caused by different factors for each nutrient and, therefore, different measures are required subsequently to balance the nutrient cycle as far as possible. 73% of the estimated annual phosphorus loss was due to sale of products, 23% was caused by deficits in the internal nutrient cycle and 4% by phosphorus leaching in the field. A calculated 14% of the overall potassium loss was caused by exporting products for sale and 78% was lost during the inner-farm nutrient cycling, whereas only 8% was due to leaching in the field. The farm lost 26% of its nitrogen through the sale of products, 38% through losses in the inner-farm cycle and 36% at the field level.