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Organic fertilizer: do you choose stable or dynamic?
Due to increasingly strict usage standards, it is a challenge every year to achieve a balanced organic matter balance. It often happens that organic fertilizer is used as a closing item in the autumn to fill the space that is still available within the standards. However, it is wise to think about supplying organic matter when drawing up the fertilization plan at the beginning of the year.
When supplying organic matter, it is important to take into account the soil conditions of the plot on which the organic fertilizer is to be applied. This can be done by taking a soil sample. In this analysis, an appreciation can be found for the microbial activity and for the relationship between fungi and bacteria. Recent analyzes also indicate an appreciation for the quality of the organic matter present in the soil.
The quality of organic matter is expressed in how stable or dynamic the organic matter is. Stable organic matter is organic matter that digests less easily and contributes to building structure in the soil. Especially when periods of extreme precipitation and extreme drought occur more often, stable organic matter contributes to improving the moisture balance in the soil. In extreme situations it is extra important to have the soil in order as a basis. Organic matter plays a key role in this.
In addition to its influence on the structure and moisture balance, organic matter also plays an important role as nutrition for soil life. Dynamic organic matter in particular is consumed by soil life and processed into minerals that can be absorbed by crops.
Points to consider when making your choice
When you supply organic fertilizer, there are a number of points that must be taken into account.
First, it is important to check which crop is planned for the plots next year. It is not wise to apply organic fertilizer, especially on plots where crops are planned that are sensitive to the bean fly. The bean fly is attracted to the smell of digesting organic material. This increases the risk of damage by the bean fly.
Furthermore, the quality of the organic matter already present in the soil is important when choosing which plots organic fertilizer can still be applied. If the assessment of the soil sample is already far from stable organic matter, an additional dose of organic fertilizer in the autumn will strengthen this. Take this into account by choosing another plot, or by at least planning a fertilizer application with more dynamic organic matter, such as liquid manure, on such a plot next spring.
It is also important when incorporating organic fertilizers that no oxygen-free conditions arise. Work the organic substances in carefully and superficially, preferably without turning.
Finally, in the autumn it is best to choose organic fertilizer with relatively low levels of mineral nitrogen. This prevents loss of nitrogen due to leaching.
Exemption for phosphate
From January 2023, there will be an exemption whereby only 75% of the phosphate in straw-rich manure and mushroom post needs to be counted towards the use standards. This may mean that some extra organic fertilizer can be spread compared to the original plan. Try to use this space to get the soil in optimal condition for the coming year.
Do you have questions about organic fertilizers? Please contact Ardon Verschoor (06-51789569, verschoor@iperen.com) or your arable farming advisor.
