From the story:
For successful results in strip-till, fertilizer needs to be placed in a zone where the roots and seedlings of corn can readily access plant-food nutrients.
But soil types, weather conditions and soil-sample results that affect the application timing and fertilizer placement and choice can all be major factors in that success.
For example, shallow placement of anhydrous ammonia in spring strip-tilled fields can burn the roots and kill germinating corn. And if strip-tillers apply anhydrous ammonia in the fall when the soil temperature is too warm — or if they strip-till into sandy soils — nitrogen can drop out of the seed zone.
Fertilizer programs and placement need to be just right, leaving an array of important choices for strip-tillers to make.
From the Mike Petersen interview:
“Plant roots don’t seek nutrition,” Petersen says. “They live in the presence of nutrition. Roots are pulled down by gravity and follow the warming of soil. If nutrition is in the same areas as the growing roots, they will be fed. But if the roots have to hunt for nutrition, the plant suffers and yields suffer.”
In the first 45 days of corn growth, the roots tend to grow in two triangles, one on top of the other, Petersen says. The corn roots in the top triangle represent the first shallow growth in that triangle, which is 6 inches tall and 13 inches across at the base.
The second stage of root growth is in a triangle that is 8 inches tall and 18 inches wide at the base, Petersen says. The top point of the second triangle starts 3½ inches below the surface of the soil, which is the top of the first triangle of root growth.
Roots in the top triangle represent the first 20 days of corn growth, while those in the bottom triangle are the next 25 days of growth.
“We must provide fertilizer for the plant so it’s healthy up to 45 days after emergence, which is when the corn plant determines yield,” he says. “At 45 days after emergence, the plant sets the number of rows around the cob.
“In the next 20 to 40 days — right up to pollination and shortly afterward — the corn plant sets the number of kernels running the length of the ear.”
Read the complete story here on the StriptillFarmer site.