Organic agriculture as system approach gains strength if it can produce its own nitrogen, more than what is now realized. This could be done by increased nitrogen fixation on both cattle farms and arable farms, combined with an increased nitrogen use efficiency. Because of these and other reasons, arable farmers can decide to reduce or stop the purchase of manure. Instead of this, cut-and-carry fertilizers could be used. Cut-and-carry fertilizers are alfalfa and grassclover, not sold but used on the farm as fertilizer.
This text reports on the design of an arable farm based on the use of alfalfa and grassclover as cut-and-carry fertilizer. This causes a shortage in the P-balance, which is compensated by the purchase of local available compost. The design is based on the arable farm of Joost van Strien, Ens, Noordoostpolder. The soil organic matter may not decline, and the yields may not be lower than what is realized now.
Based on these starting points, a crop rotation and fertilizer scheme is inserted in the nitrogen and organic matter model NDICEA. After this, an iterative process with the farmer, the farm advisor and the researcher led to a design accepted by the farmer.
It turns out to be possible to make a system based on farm-own nitrogen fixation and purchase of local compost with a net zero phosphate balance. The soil organic matter stays constant. Some fertilizer is left for crops which need more nitrogen.
The research will be continued in field experiments, testing the viability of the model calculations
