Evaluation of nitrogen utilizsation by means of the concept of primary production balance

Summary

Primary production balance (PPB) indicates the ratio (*) between harvested nutrients and nutrients put into crop production from outside the system (=primary nutrients). The PPB is independent of the final output (crop vs. animal products) and can be used to evaluate different systems (farms). The utilization of nitrogen(N) was evaluated by means of the PPB on nine organic farms, stockless and mixed ones, in eastern Finland.
The mixed farms were able to reach a remarkably higher primary production balance (1.0 – 1.2) compared with the stockless ones (0.5). Values higher than 1.0 indicate recirculation of nutrients. Other components of the high PPB were legumes as nitrogen source and optimum livestock density.