Farm406

farm406 42 When nitrogen fertilizer is applied to the field, the nitrogen is oxidized and turns to nitrate. at is what the plant generally takes up, but in the reaction, acid is produced. As the acid dissolves in the soil, it releases aluminum which is detrimental to the plants. In soils of pH 5 or less, aluminum becomes more soluble and is toxic to root tips. Finding a remedy to the acidity problem takes a review of the meaning of pH levels. Soil pH is the relative content of hydrogen (-H+) and hydroxyl (-OH) ions. Each pH unit change represents a ten-fold (10X) change in acidity. For example, a soil with pH 6 is ten times more acidotic than a soil with pH 7, and a hundred times more acidic than pH 8. Raising soil pH means decreasing the H concentration in the soil. is primarily takes carbonate, or the hydroxyl ion, but calcium plays an important role too. at is why Jones recommends an application of calcium carbonate, which is lime, to those areas with low pH. Manure can produce a benefit too because it is generally high pH. Lime can be purchased as agricultural lime or spent lime. At Western Sugar in Billings, Montana, lime is used in processing sugar beets to extract sugar and becomes a waste product to the company. is spent lime is free. Many farmers hire a trucking company to deliver the lime, and this can become expensive. Several companies in the state are geing set up to do this. As an example, Rocky Mountain Compost in Billings can now deliver both types of lime. "Although the expense of applying the lime can be high, the good news is liming will only need to be done every fieen or twenty years," said Jones. "e lime should be tilled into the soil on dryland farms since Montana normally doesn't get enough moisture to push the lime into the root zone where it is needed." Five years ago, both Duane Beirwagen from Big Sandy and Hardy O'Hara from Fort Benton found patches in wheat fields where the ground was either bare, the leaves of the plants were discolored, or the roots had a clubroot appearance. Both ran pH level tests on the fields and found acidity problems. "With the tractor pulling a probe that mapped the pH level every forty feet, we found that we had three zones in the field: calling for no lime, one ton of lime per acre, or two tons per acre," said O'Hara. Both Beirwagen and O'Hara had spent lime from Western Sugar in Billings delivered. "It takes a while for the lime to get into the soil, and because of the type of soil we have that easily blows aer tilling, we knew it was best to till in the lime during the spring," said Beirwagen. Beirwagen used a manure spreader to distribute the lime while O'Hara used a lime spreader with a variable rate applicator. "It is so noticeable that we can see in plant growth exactly where we stopped applying the lime," said O'Hara. "We are happy with the results. Even the yield maps are more even." Mitigate Yellow pea roots exhibited differences in nodule abundance between areas with lime (left) and without lime (right). June 19, 2019 Photo: Hardy O'Hara

• Cover