Soil problems caused by low pH are most likely to develop in Kansas´ sandier soils. They´re common throughout the central corridor of the state, according to agronomists at Kansas State University.
Unfortunately, a factor that can exacerbate the situation is years of applying nitrogen fertilizer at high rates. So, farms can be especially vulnerable if they´re engaged in long-term, continuous wheat production in central and south central Kansas, said Dorivar Ruiz Diaz, a K-State Research and Extension soil nutrient management specialist.
For wheat producers, strongly acidic soils may present several problems, Ruiz Diaz said. These challenges include aluminum toxicity and, in some cases, manganese toxicity. Others are deficiencies of phosphorus, calcium, magnesium and molybdenum.
In general terms, he said, aluminum toxicity will reduce wheat´s yield potential when:
* Soil pH levels get below 5.2 to 5.5 and
* KCl-extractable (free aluminum) levels are greater than 25 parts per million (ppm).
When aluminum levels are not that high, pH levels in the 5.2 to 5.5 range aren´t as much of a problem for wheat, the agronomist said.
When soil pH is 5.0 or less, however, yields typically start dropping off rapidly.
"Fortunately, where acid soils are causing reductions in wheat production, liming and raising the soil´s pH to an optimum range can significantly improve plant growth and yield," Ruiz Diaz said.