#208Gypsum application to soil
208⸱AConcept
- Regulates soil pH
- Improves soil structure
- Fosters deeper root growth
- Improves the coffee plant’s tolerance to drought
- Improves plant nutrition
- Increases the coffee yield
The one-off application of a large quantity of gypsum (calcium sulfate) to the soil stimulates coffee roots to grow deeper, enabling them to access more moisture during dry seasons and prolonged periods of drought. It serves as a soil conditioner, mainly in the surface layers.
Gypsum (calcium sulfate, CaSO4) is an input used in coffee as a calcium and sulfur soil amendment, for acidity regulation (sodic soils only), aluminum toxicity treatment, and soil structure improvement to facilitate water infiltration. Therefore, in certain types of soil, especially oxisols and other soils that are sodic, highly acidic or suffering from high levels of aluminium, application of gypsum has been found to improve yields of coffee and many other crops.
Unlike applications of lime (calcium carbonate + varying quantities of calcium oxide, magnesium oxide and magnesium carbonate) which also have the effect to reduce soil acidity, gypsum is far more soluble than lime and can penetrate deeper into many soils. Once dissolved, gypsum is mobile in the soil, tending to aggregate soil particles together. This process tends to counteract soil crusting, allowing air, water and nutrients to penetrate deeper into the soil profile. Gypsum has been shown to counteract aluminum toxicity and to increase the availability of Ca2+ ions throughout the soil, both of which can affect coffee yields.
The above factors all make it easier for coffee roots to grow downwards and penetrate deeper into the soil where they tend to find increased moisture, especially in the dry season, and thereby better resist severe droughts.
208⸱BTo be considered
It is necessary to apply large amounts of gypsum, 8-12 tons per hectare, depending on the soil conditions. As Gypsum is a by-product of other industrial processes, it is often not expensive. However, transport costs for the required amounts must be taken into consideration.
The amount of gypsum required to neutralize the pH depends on several factors, among which are factors related to soil properties (pH, clay content, organic matter, texture, and others) and, on the other hand, those related to the quality of the amendment (fineness of the material = mesh degrees). Due to the diversity of these conditions, it is not easy to predict the response of plants to a single application of gypsum or to follow the recommendations of a soil analysis. Therefore, it is recommended to have technical support and the results of a soil analysis, to define the amount to be applied.
Applying high doses of gypsum can greatly increase calcium in the soil and consequently promote an imbalance of other nutrients, such as magnesium. Therefore, it may be necessary to supplement the soil with additional nutrients. A soil analysis helps to keep an eye on the soil’s nutrient balance. Annual leaf analyses might be recommended to observe the nutritional status of the coffee plants.
Due to the above-mentioned aspects, it is recommended to start with a small number of trees, observe the results, and scale according to budget availability if the results are positive.
In years of good rainfall, it might seem that there are no differences between fields with and without gypsum; the main effect will be expressed in years of drought. It is not advisable to apply gypsum on sandy soils and with a risk of high rainfall.
Timing:
Large amounts of gypsum should be applied just once. They are generally applied during the preparation for planting until the third year, when the plants’ root system is developing
Supplementary doses can be applied at any stage of the crop's development, but it is recommended to do so at the end of the dry season and beginning of the rainy season, so it can start working quickly.
208⸱CImplementation
Materials
For 0.1 ha
208⸱1Application
If preparing a fresh coffee field for the plantation of new seedlings:
The gypsum can be mixed with other fertilizers and organic matter.
208⸱2
If applying to existing coffee plants in a field:
Gypsum application to young coffee plants
It is recommended to perform a soil analysis at a depth of 0-20 cm annually, the first being 6 months after planting, to check the effect on the soil’s nutrient balance and to make the necessary corrections to avoid the crop’s nutritional imbalances.
Every two years, also carry out an analysis at a depth of 20-40 cm.
208⸱DEconomic benefits
Higher coffee yield
The effects of this tool can lead to a higher coffee yield and therefore a higher income.
208⸱EGreen benefits
Better soil life
This tool helps improve soil life (microbes, earthworms, etc.). This plays a vital role in plant nutrition and contributes to a healthy ecosystem.