Soil and water

Soil health, micronutrients and macronutrients. (Part 2) – Ohio Ag Net


By Dusty Sonnenberg, CCA, Ohio Field Leader, An Ohio Soybean Council and Soybean Control Project.

Macronutrients can impact micronutrients. Carbon is a key macronutrient.

“Carbon is probably the most limiting element in our soils,” Hoorman said. “It takes 100 pounds of carbon every day to produce a corn crop of 200 bushels per acre. This carbon used by plants comes from both the atmosphere and the soil. The carbon cycle occurs both in the plant and in the soil. During photosynthesis, plants absorb CO2 from the atmosphere into the leaves and release O2. The roots take up O2 from the soil and release CO2 into the soil. When soils are plowed in the fall, there is a loss of soil carbon in the form of CO2. This is washed away and is not available for growing crops.

Jim Hoorman, Hoorman Soil Health Services

Another important macronutrient is nitrogen (N).

“Every 1% of organic matter contains 1,000 pounds of nitrogen,” Hoorman said. “We are only between 30% and 50% effective at keeping nitrogen in the soil. Due to denitrification due to poor soil structure, we can lose up to 60% N. We can lose 20-30% N through leaching. The same goes for phosphorus (P). Poor soil structure makes us only 10 to 50% efficient with phosphorus. About 50 to 70% of the P is bound to organic matter. About 90% can run off during the most intense rainy events. Of this loss of P, about 30% is lost due to surface erosion, and the remaining 70% is leached by water from the tiles. This is lost due to the poor structure of the soil and the water that is not retained in the soils.

Some of the soil structure problems are due to soil compaction.

Some soils have problems with potassium (K). In these soils K is applied, but test results show that K levels decrease.

“There is a concept called potassium induction that occurs under saturated soil conditions and the K is taken up in clay soil particles,” Hoorman said. “Farmers diffuse the K on their fields, then use vertical tillage to incorporate it lightly, but if the soil moisture conditions are not good, a hard layer of soil compaction occurs at around 1 in. 2 inches and with the wet falls we had, K is strapping in.

Nutrient deficiencies in plants can be confused with each other as well as with other growing season issues in the plant.

“A white midrib on a corn husk can be an example of zinc deficiency,” Hoorman said. Field Leader Explores Ag Equipment Innovations RoGator C Series Sprayer“We have seen a lot of zinc deficiency for two reasons this year. We had a relatively dry fall, winter and spring. Most micronutrients are available when we have reducing conditions and the soil is moist. Another thing that binds zinc is glyphosate. Along with zinc, glyphosate binds, manganese and iron. One way to lessen the impact of glyphosate use on micronutrients is to plant oats. Oats are a cover crop that can help counter the impact of glyphosate.

Increasing soil organic matter is also very important to improve the availability of micronutrients for plants.

“Organic matter buffers the pH and renders nutrients in a form that is available to plants. This increases the soil’s water and nutrient retention capacity, ”said Hoorman. “Organic matter is one of the chelators of micronutrients to put them in a form usable by plants. We need the nutrients to be reduced so that plants can use them and function by removing oxygen. Magnesium, manganese, calcium, copper, iron and zinc are helped by organic matter to be kept in a form available to plants.