Soil pH adjustments improve plant growth
PH is the measurement of the concentration of hydrogen ions in the soil. A higher concentration of hydrogen ions results in a more acidic soil. Most soils in the Ozarks are acidic, having a pH value ranging from zero to seven.
Johnny Gunsaulis, Benton County extension agent and staff chair, said that while pH varies throughout seasons, pasture and forage grasses still thrive within an optimal pH range.
“For grasses, for the most part, 5.5 to 6.5 is ideal,” Gunsaulis said. “If they want to have clover or other legumes out in their field, they’ll do better to maintain the pH above six.”
He further explained any value lower than these ranges threatens productivity. Most nutrients are pH dependent: as soil gets more acidic, nutrient availability decreases.
“It has to do with those other nutrients that get unlocked,” Gunsaulis said. “Nutrients get tied up as the soil pH gets lower.”
According to Gunsaulis, this link between soil pH and nutrient availability impacts both physical properties and growth patterns of the plant. Growing plants within their optimal pH range results in higher yield and healthier crops, which is the primary reason farmers seek to raise their soil pH.
Anyone can find out the pH of their soil through standard soil tests, which are available through land grant universities. If raising the pH is necessary to reach the optimal level, a lime requirement is recommended based on calcium levels in the soil.
“That calcium level will determine how much lime is needed to adjust that pH,” Gunsaulis said.
Liming materials contain calcium carbonates that neutralize the acidity in the soil, ultimately raising the pH. Gunsaulis said ag lime is one of the most common forms of liming material. This is generally the most budget-friendly option.
Pelletized lime is a viable second option. Pelletized lime is easier to apply than ag lime, but it is usually recommended at lower application rates due to it being much more expensive. Although not as common as ag lime, Gunsaulis said pelletized lime is beneficial for specific cases.
“Pelletized lime can help some folks in certain situations,” Gunsaulis said. “Like people that have a food plot that’s hard to get to or just have a small three acres.”
The biggest difference between ag lime and pelletized lime is the particle size. The particle size of ag lime is much larger than pelletized lime, so it takes longer to fully react.
“The coarser that particle, the longer it takes for it to break down,” Gunsaulis explained. “So, the ag lime will have an effect over a longer period of time.”
Other liming methods include liquid slurries, wood ash, gypsum, marl, slag or any other product used for correcting soil acidity. These methods work like ag and pelletized lime varieties, but Gunsaulis said the expenses may look different for different application methods.
“On those products, I would say just to compare the price of what they’re getting with the price of either the ag lime or the pelletized lime,” Gunsaulis suggested.
The effectiveness of the liming material depends on several factors, including fineness, the levels of calcium in the liming material and topography. Gunsaulis said the primary factor, however, is the type of crop the pH is being adjusted to accommodate.
“It’s all got to do with what exactly it is that you’re growing,” Gunsaulis said.
While adjusting the pH of the soil may seem daunting, in the end it is worthwhile.
“It’s a good investment,” Gunsaulis said. “That investment will help your forage production years into the future.”
