LA CROSSE, Ind. — Having the correct balance of nutrients is something farmers think about often. Without proper nutrients, row crops suffer in quality and yield. “Our philosophy is the buildup, maintenance approach,” said Jim Camberato, Purdue Extension soil fertility specialist. “The other approach is sufficiency, where you’re just adding enough this year to make profit and not worrying about subsequent years.” But with grain prices dropping, farmers also will have to decide how much money to spend on fertilizer. Camberato discussed this topic at a recent crop planning meeting in La Crosse. “Crop prices are low — some people may not want to or be able to afford 140 pounds of (potash) per acre. To maximize yield in this coming season, at a 50 ppm soil sample, you probably need about 100 pounds of potash per acre. There’s a lot that we’re recommending to build soil tests up so you can maintain moderate test levels,” he said. The closer you can put it into planting time, the better. But applying in fall or winter won’t reduce nutrient efficiency by much, Camberato said.
Many farmers ask: Since new varieties produce larger yields, do we need to add more nutrients?
The answer, Camberato said, is yes and no. “We need more because we are removing more (nutrients)” he said. “But research has shown that these higher-yielding hybrids and varieties have a lower concentration (of nutrients) in grain, so they are more efficient in using what they pick up. “But they also have bigger root systems and bigger above-ground plants. Nutrients like potassium and phosphorus are only taken from a little bit of soil right around the root. It’s about the concentration of the soil, not the absolute quantity.”
Camberato shared advice on how to manage manganese deficiency, as well.
Manganese deficiency can easily be confused for other deficiencies, like magnesium, he said. Conditions favoring manganese deficiency include high soil pH, muck or peat soils, or soils that are cold, dry or sandy. “What happens in those wet, sandy soils during the winter is whatever manganese that is there leeches out through the tile,” Camberato said. “It ends up leaving the field.” According to Camberato, the symptoms include: * Interveinal chlorosis, a condition in which the plant cannot produce enough chlorophyll, with veins remaining green. The chlorosis often is described as olive green or mustard yellow. * Necrotic brown spots develop in soybean plants as deficiency worsens. * Tissue sufficiency is 20 to 100 ppm.
The recommended correction for manganese deficiency is a foliar application of one to two pounds manganese per acre. Often, multiple applications are needed.