Constant removal of nutrients without replacing them through fertilization will lead to soil mining. This means there will be a depletion of nutrients, mainly potassium and phosphorus, affecting yields and long-term soil fertility. Omitting phosphorus and potassium application is a false economy; both nutrients need to be applied regularly in order to prevent reduced yields in the future.
Even if phosphorus and potassium fertilization increases yields only to a small extent on adequately supplied soils, it is still advisable to replenish these nutrients, which are removed by the harvest. By doing so this maintains soil fertility at a high level and requires only moderate amounts of P and K fertilization (offtake by the harvests).
Only a very small percentage of the total potassium and phosphorus in the soils are available for crop uptake. The majority of these nutrients become slowly available in the long-term. Fertilized P and K also slowly replenish these exchangeable and non-exchangeable pools. Therefore, a sufficient P and K supply in the soil solution is only secured when the soil stocks of these elements are adequately high. This is why the depletion of these elements has long-lasting consequences on yields and it is impossible to reach previous yield levels even with adequate fertilization once the P- and K-level in the soil is low.
Phosphorus and potassium fertilization is based on the off take of crops in a rotation and considers the following:
Fertilizers are essential for production, boosting both quantity and quality and making a major impact on farming revenue.