Lime for straw. Two goals in one treatment

Wapno na słomę. Dwa cele w jednym zabiegu

Applying lime to stubble immediately after harvest can accomplish two tasks at once.
Is applying lime to straw a good solution? How does lime work in such a situation?

Lime performs various tasks

Giving calcium is always highly recommended. In Polish conditions, most soils require an increase in pH. Not every situation requires the use of high doses of calcium fertilizers – sometimes smaller amounts are enough to maintain the appropriate pH level. However, this applies to soils where the reaction is already stabilized, which is why it is so important to know the richness of the site and select the appropriate dose. Applying lime after harvesting the crop is an even more attractive solution if it is applied to cut crop residues. Then we can achieve at least two goals – stabilizing (or increasing) the pH level and supporting the mineralization of straw.

Lime will improve the quality of the soil, which will positively affect mineralization

Research shows that lime itself – contrary to some popular opinions – does not directly accelerate straw mineralization. We must bear this in mind. We often say that we will add lime to make the straw decompose faster. Meanwhile, this is in a sense a mistake, because lime does not speed up this process, at least not directly. However, the mineralization itself has a very positive effect. But why? Well, it improves the quality of the soil, both its chemical and physical properties. But it also improves soil biology because it limits the development of fungi that thrive in acidic sites, which in turn will adversely affect mineralization. These are invisible things that we cannot assess visually. But the soil is a living organism that is constantly working and changing constantly.

However, it cannot be said that lime has no effect on the rate of straw mineralization, because this is not the case. It does, although not directly. The mere application of lime improves water and air conditions. These are factors that significantly improve the rate of decomposition of crop residues. In conditions where there is less oxygen in the soil, straw begins to decay instead of decomposing. At the same time, the application of lime makes it possible to create better conditions for the development of soil bacteria, which will bind, among others, nitrogen.

The difference between the application of nitrogen to straw and lime is, among other things, that nitrogen actually accelerates decomposition directly, while lime affects the speed of this process by improving the properties of the soil. Generally, after applying nitrogen, the mineralization itself may be faster, but this is not so beneficial for the soil, because the application of lime improves, among others, the structure of the earth and at the same time allows for the production of more humus compounds. Nitrogen increases the C:N ratio, but lime, in turn, allows for an increase in the amount of organic matter.

Lime is not the only solution for straw decomposition

However, it is difficult to choose a solution that will have a clear advantage over others in the context of mineralization of crop residues. Nitrogen and lime complement each other to some extent in the case of straw decomposition, as do products dedicated directly to straw mineralization (including bacterial preparations, fertilizers, etc.). Each of these solutions has a similar task, but performs it in a different way; at the same time, the final effect may differ in detail, and the indirect effects will differ from each other.