Farmers Urged to Test Soil pH to Optimise Crop Production

Farmers across Jamaica are being encouraged to test soil pH as a critical step in improving crop productivity and getting better value from fertiliser use.

Testing determines if soil is too acidic or alkaline, which directly impacts nutrient availability and prevents over fertilisation.

Soil Fertility Specialist, Ministry of Agriculture, Fisheries and Mining, Dennis Joosse, tells JIS News that understanding soil pH can make the difference between struggling crops and thriving fields.

“Soil pH is a measure of the acidity or the alkalinity of soil. pH is a phenomenon that exists in water, soils, the food you drink, your blood, and that pH is important,” he points out.

On the pH scale, seven is considered neutral. Values above seven are alkaline, while those below seven are acidic. Many Jamaican soils are more acidic with pH levels often falling between four and five.

Mr. Joose, who is a volunteer with World University Services Canada (WUSC), currently placed in the Ministry’s Agricultural Land Management Division (ALMD), notes that plant nutrition is closely tied to soil pH.

“Plants rely on a whole lot of nutrients that they take out of the soil and their availability is inextricably linked to the pH of the soil. So, at a low pH, some nutrients are not available to the plant and at a high pH, some nutrients are not available to the plants. You could say that a neutral pH is kind of the Goldilocks zone for soils or an area where almost all nutrients are widely available to plants,” he says.

Acidic soils present a challenge for plants, limiting the availability of essential nutrients but also increasing the presence of aluminum, a naturally occurring element in soil that becomes highly available at low pH levels.

“That aluminum…is not a useful plant nutrient, it’s actually a toxin. So, you get two negative effects there; low availability of some nutrients and you get high availability of a toxin [resulting in] aluminum toxicity at low pH,” Mr. Joose points out.

He explains that soils derived from volcanic materials tend to be more acidic, while those formed from limestone or calcareous materials are typically more alkaline.

While natural processes such as weathering and the leaching of positive ions gradually acidify soils over time, agricultural practices can also contribute to acidity.

“In particular, nitrogen fertilisers tend to make them acidic as well. Loss of organic matter tends to reduce our soil’s ability to buffer against changes in pH,” Mr. Joose points out.

He is advising farmers to get their soil tested.

“The best thing you can do is really understand what your soil pH is. It is a really inexpensive, easy thing to do,” he says, noting that pH analysis is included in standard soil nutrient testing packages offered by the ALMD.

If soils are already neutral, no additional pH management may be necessary. However, where soils are alkaline, sulphur-based fertilisers can help reduce pH.

“Sulphate of ammonium, for example, is a really useful fertiliser. It provides sulphur, but it also provides a nitrogen source in the ammonium and almost all crops can benefit from having nitrogen available to them,” Mr. Joose says.

For acidic soils, he says that liming is the most effective corrective measure.

“We’re blessed in Jamaica. We have excellent sources of high-quality limestone that we can add to our soils. It’s really quite inexpensive to do, and we don’t often think of limestone as a fertiliser, but we really should start to think of it that way, because it can make many other nutrients more available,” he points out.

Stressing that soil testing is one of the best investments a farmer can make, he says it could reduce the money spent on fertilisers.

“We spend hundreds of dollars an acre on fertilisers for our soils. We can spend much less than that on a whole field to test our soils and fine-tune our use of fertilisers and other crop nutrients,” he says.

The ALMD provides soil testing services, with results typically available within two weeks.

Farmers receive detailed recommendations tailored to the specific crop they intend to grow and guidance on how to improve yields.

Understanding soil pH is not just for farmers, but for anyone involved in crop production including agronomists, fertiliser suppliers and agricultural consultants.

To access soil testing services, persons can contact the ALMD at 876-927-0441 for more information.