Nutrient imbalances are often not noticed in organic farms. Howev-er, having a nutrient deficit can deplete the soil in a long-term per-spective and therefore reduces soil fertility.
Farm gate nutrient budgets are an easy and efficient tool to assess the main nutrient flows in and out of the farm. They can reveal whether there is a nutrient surplus or deficit.
The outcome is a farm gate nutrient budget for one or up to three years. Nutrient inputs can be adjusted to achieve a balanced nutrient budget.
• To calculate the farm gate nutrient budget, all nutrient inputs and outputs need to quantified. The difference be-tween them shows if there is an imbalance or not (Figure 1).
• The following groups are regarded as nutrient inputs: imported feed, fertilizer, soil amendments, seeds and N2-fixation by legumes. For all imported goods, the nutrients can be calculated by multiplying the amount with the given nutrient content. The N2-fixation is calculated based on yield of the legume. If yields are not available, typical N2-fixation values per hectare are given for different intensities.
• All sold products or by-products are regarded as nutrient outputs. The nutrients can also be calculated by multi-plying the amount with the given nutrient content.
• The excel-tool (Figure 2) is an easy way to calculate a nutrient budget. It provides data for nutrient contents of common inputs and outputs, and it calculates the N2-fixation. The user only needs to enter the farm specific data. The tool will then calculate the farm gate nutrient budget. The excel tool is available in English and German online (LINK) or through contacting email@example.com.