Assessment on organic farming benchmark trials in Denmark

Faerge,-J; Magid,-J
Department of Plant Nutrition, Soil Fertility Laboratory, Royal Veterinary
and Agricultural University, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark.

Abstract
At the request of the Danish Environmental Protection Agency, a scenario discussion about the possibilities of 100% organic conversion of Danish agriculture was published in spring 1999.

In the scenario, it was concluded that the most limiting factor regarding such a conversion, was a requirement of potassium (K) import to Denmark, necessary to obtain reasonable yields in clover leys which are also the principal nitrogen source in the scenario. At the time of the scenario review, there were no Danish data available on organic agriculture independent of nutrients imported through conventionally produced feed, manure and straw. However, since the scenario development, organic farming benchmark experiments have been established. A review of these experiments revealed that the manure applied was conventionally produced and not originated from within the experiments. At the same time the K content in the produced crops was reduced by 20-40% compared to Danish standard values.

Therefore, using conventionally produced manure based on conventional fodder indicated that considerably more K was allocated than available if experimentally produced fodder was the basis for the manure. Thus, important system feedbacks were missing. Hence, to gain knowledge about soil fertility in Danish organic agriculture, not dependent on industrial fertilizers, a few but important changes in the benchmark experiments could be considered.

First and foremost, the manure used at an individual experimental plot must reflect the harvested crops from the self-same plot, i.e. separate feeding procedures and collection of manure, corresponding to the individual plots may have to be carried out, or at the very least an assessment of maximum permissible nutrient content in added manure should be considered.

 

Source
Acta Agriculturae Scandinavica Section-B, Soil and Plant Science. 2003; 53(2): 64-68

en français

Posted February 2008