By Gerrit Bezuidenhout
Foliar feeding is particularly beneficial during periods of plant stress, such as drought, cold weather, and hail events, as well as after grazing or after hay has been cut, according to Lourens van Rensburg, sales manager of Elim Fertilizer.
Lourens assisted Gert Kriek with plantings for trials on his farm, Palmietfontein, near Balfour. This was part of the Balfour Farmers’ Association’s program to educate farmers about precision hay production.
“When we consider fertilisation, it’s not only soil fertilisation that matters but also a practice where soil fertilisation is enhanced by foliar feeding,” Lourens remarked.
Soil fertilisation, during which nutrients such as nitrogen, potassium, and phosphate are applied, serves its purpose because these elements cannot be absorbed through the leaves. When plants shed their hair roots and nutrients cannot be absorbed as effectively in stressful times, foliar feeding can help promote growth.
The fine hair roots of a plant are among the most crucial aspects to consider. When a plant experiences stress, its first response is to shed its hair roots and reduce energy output. Therefore, feeding is essential to provide the plants with the necessary elements to prevent the growth process from stopping.
Secondly, the chemical element and foliar feeding choice must align. “Remember, a farmer doesn’t spray foliar feeding and then add chemicals; he sprays chemicals and incorporates foliar feeding. Therefore, the product choice must be correct and suitable for your practice.”
The chemicals and products used for foliar feeding must provide a better yield, whether for maize, soybeans, or pasture; otherwise, they are ineffective.
Balance is key
All applied elements must be balanced to ensure that plants produce optimally.
“When examining the Mulder Chart, elements cannot be applied randomly. For instance, nitrogen, boron, potassium, and calcium depend on one another, and if excessive calcium is used, the plant will have difficulty absorbing other elements.”
“A similar relationship exists between iron and phosphate, so leaf analysis is essential to understand what you’re dealing with. Elim provides a complimentary leaf analysis service for farmers, ensuring that soil samples and leaf analyses collaborate to prevent imbalances.”
Less energy, less production
When a plant reaches its reproductive stage, its available energy declines. Providing foliar feedings stimulates the plant to absorb elements again and continue growing efficiently.
“We are temporarily addressing a shortage and creating the illusion of abundant nutrition on the leaves, which enhances uptake.”
This is where foliar feeding can play an important role. If foliar feeding is not applied, the plant may determine its energy is running low, causing it to shut down and stop growing. Foliar feeding can assist, but the element must be made available to the plant in its simplest form. In the case of phosphates, a plant can only utilise orthophosphate.
“When fertilising with phosphates, a polyphosphate is typically applied to the soil. It must first break down into an orthophosphate to be usable by the plant. With a lower pH, as seen here in Palmietfontein, approximately 3.9, it will take 100 days to convert 50% of the phosphate. Foliar feeding can help bridge this period.”
Elim investigated stress conditions on four pasture test plots at Howick, Warden, Makwassie, and Rysmierbult, where farmers applied foliar feedings before or after cattle grazed the plots. “In the four trials, which have been ongoing at Howick for almost six years, there was an increase of nearly 19% in the dry matter yield.”
“It pays for the input over and over. It serves as proof again of the importance of foliar feedings to stimulate plants to reach that next stage.”
* This information comes from a talk by Lourens van Rensburg of Elim.
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• Fertiliser is expensive – don’t waste it!
