What do we see?
In the period between 2015 and 2019, the soil pH value was within the target zone for 33% of the cropland and 34% of the grassland. For soil organic carbon (SOC), this was the case for 39% and 31%, respectively. For phosphorus, it was 17% and 21%, for potassium 39% and 29%, for magnesium 28% and 25%, for sulphur 22% and 23% and for sodium 9% and 16%. Finally, the calcium value was within the target zone for 53% of both cropland and grassland.
The table below show an overview of the evolution of 5 of the 8 parameters. We do not have any data available for the evolution of calcium, sodium or sulphur. The most striking thing about these graphs is the high percentage of soil with a low SOC value and a high value for phosphorus, potassium and magnesium. The figures give an idea of the current condition of agricultural land in Belgium and the steps we need to take to optimise it. We can also use the figures to derive the needed recommendations around fertilisation. These are necessary to optimise the use of this input.
What’s the aim?
Soil quality determines whether a piece of land is suitable for production and what the yield will be. This quality is determined by a number of factors, including the physical structure, chemical balance and biological composition. If the land is badly managed, the quality of it can diminish and over time the soil can become infertile. Therefore, we need indicators to evaluate the chemical, physical and biological condition of the agricultural land in Flanders. This also gives us the chance to make recommendations regarding fertilisation so that we can get optimal use from this input. However, the health of the soil is about more than just the available nutrients, so we also need additional data like soil structure and the biodiversity of the soil. In collaboration with the ILVO (Flanders Research Institute for Agriculture, Fisheries and Food), the government is currently building up a monitoring network to have a structural way of checking up on the quality of the agricultural land in Flanders.
What does this indicator measure?
The Soil Service of Belgium (BDB) monitors the chemical and physical condition of the soil in Flanders. They report on 8 parameters that determine the fertility of cropland and grassland. Given that the values can vary significantly from year to year, the reporting period is 3-4 years.
The data discussed here relates to Belgium because there is no separate data available for Flanders. However, the data for Belgium is also representative of Flanders. The BDB reports on the percentage of the soil that is below, above or within the target range for each parameter. The target range for a given parameter is the optimal condition for growing the most crops (Tits et al., 2020). The target zones are individually determined for each sample depending on the texture and organic composition of the soil.