Applied Nitrogen and Phosporus

The maximum amount of nitrogen and phosphorous that may be applied by way of fertilizers used, averaged over the crop rotation, may not exceed the amount that would be produced by those animals which the farm could support by its own irrigated (if necessary) forage production.

Application of this Demeter International requirement is based on the concept of a “manure unit” (mu). A maximum of .56-mu/ acre is allowed. This is the equivalent of 40kg N/feddan and 35 kg. of applied P205. For cropping systems with high nutrient export in the form of harvested crops, and systems that are inherently nutrient-deficient from previous management or basic inherent geological and biological realities, a maximum of 65 kg N/feddan and 55kg. P/acre can be applied. The applicant must adequately demonstrate need via a calculated nutrient budget that demonstrates at a minimum 42 kg N/ feddan is exported via harvested crops. Green manure plough down crops will not be calculated as “applied fertility”. Calculation of N and P applications will be based on the analysis of the material applied. For example, a 5-5-3 fertilizer represents 5% total N and 5% available P205. If 450 Kg of this material/ acre are applied then it represents 22.5 kg each of applied N and available P205. Materials will be approached on a dry matter basis.

Total application of other crop macro and micronutrients needs to be monitored and evaluated on a case-by-case basis. Nutrients should not be applied in any manner that results in a disproportionate nutrient balance or a toxic situation. In addition, the application of nutrients for plants should be targeted for maximum efficiency to avoid leeching and run-off in order to protect ground and surface water.

Note: This is an excerpt of "Biodynamic Farm Standard (2010). Demeter Association Inc."