Soil acidity and liming to boost farmers yields  

11Aug 2020
The Guardian
Soil acidity and liming to boost farmers yields  

A TOTAL of 100 tonnes of rich agricultural lime will be distributed to 66,000 farmers in Mbeya, Songwe, Njombe, Iringa and Arusha regions to enable them increase soil fertility.

Soil acidity is the term used to express the quantity of hydrogen (H) and aluminum (Al) cations (positively charged ions) in soils. When levels of hydrogen or aluminum become too high—and the soil becomes too acid—the soil’s negatively charged cation exchange capacity (CEC) becomes “clogged” with the positively charged hydrogen and aluminum, and the nutrients needed for plant growth are pushed out. This is why root growth and plant development suffer when soils become too acid.

Over time, soils also become acidic because calcium and magnesium leach out, because hydrogen is added to soils by decomposition of plant residues and organic matter, or because nitrification of ammonium occurs when fertilizer (UAN solutions, urea, ammonium nitrate, ammonium sulfate, anhydrous ammonia), manure, or plant residues are added to the soil. Lime will neutralise this acidity by dissolving, whereupon it releases a base into the soil solution that reacts with the acidic components, hydrogen and aluminum.

One acre fund communication manager, Dorcas Tinga told The Guardian yesterday that the organisation is determined to support farmers in the coming farming season. She said through soil liming farmers will be able to increase their yields from 10 to 20 sacks per acre.

According to her, using lime makes the soil healthier. She said since lime is alkaline, it neutralizes the acidity of the soil and makes it more neutral.

The acidic increase in the soil is linked with frequent use of industrial fertilizers, said Tinga.

“The use of lime neutralises the acidity of the soil by adding minerals (calcium and magnesium). This product is already in the markets and will be used in the coming farming season. We encourage farmers whose lands are acidic to use lime to boost their harvests,” said Tinga.

She said the organization encourages farmers to form groups of between five and 16 people so that they are provided with agricultural input loans. She said the low interest loans are meant to facilitate access to the agricultural inputs.

Some interviewed farmers claimed that the soil is no longer fertile due to the use of industrial fertilizers as well as lack of professional advice from extension officers on how to enrich the soil. They said that poor soil fertility contributes to low yields.

One of the farmers, Joseph Martin expressed hopes that soil liming would result in increased productivity.