AGRI-BRIEFS
  AGRONOMIC NEWS ITEMS
From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335

Spring 2002, No. 5

FEEDING CROPS UNDER REDUCED TILLAGE

The increased use of reduced tillage systems in the Midwest has changed the environment for crop growth and development and for the management of soil nutrients to meet the needs of the crop. As a result, crops are more likely to experience nutrient shortages early in the season. Stratification of nutrients is another side-effect of reduced tillage. But farmers and implement manufacturers are finding ways to provide the needed nutrients. For some, it is a resurgence of the use of starter fertilizer. Others are looking at different application methods that better fit their management system.

Back to starter. Using starter fertilizer is a sound management practice from an agronomic standpoint. While response to starter fertilizer cannot be guaranteed every year, it can be critical in years when it is needed. The cost to benefit relationship must be carefully evaluated. For many farmers, starter fertilizer provides good insurance. The basic concept behind starter fertilizer is to provide a concentrated source of nutrients to help meet the high demand for the young seedlings until the primary root system has had time to develop. The first two to three weeks are critical to corn plant development. Initial stages of ear formation occur before the plant is 12 inches tall. If nutrients are limiting due to slow root growth, the number of rows of kernels formed on the young ear may be reduced. Development of leaves may also be delayed, resulting in lower efficiency for trapping light and carbon dioxide during critical growth stages and less shading to control water loss from soil evaporation.

Earlier planting usually increases potential for starter response, but research also has shown an economic starter response for later planting dates. Starter helps accelerate growth and hasten maturity of late-planted, full-season hybrids, often increasing grain yield and reducing drying costs. It usually enhances early growth and helps build a higher yield potential. However, later stresses, such as water shortage or inadequate nitrogen during grain filling, can prevent that potential from being realized. Good nutrition is a season-long challenge. Lack of yield response to starter may be due to failure to complete the package.

Not a popular recommendation. Many farmers would prefer to skip starter fertilizer to trim expenses and time for planting their corn crop. Unfortunately, that choice may cause their crop to suffer nutrient shortages during the first few weeks of growth, and suffer lost yield potential. Using starter helps the crop tolerate stresses of cool, wet soils, herbicide injury, and compaction, that often occur during early growth.

Strip alternative. Strip-placement offers a variation on the starter concept, placing a narrow band of fertilizer with a knife or chisel point positioned just below the intended seed furrow. A narrow strip of tilled soil improves the seedbed conditions and places nutrients below the surface where they will be more readily absorbed by roots and less susceptible to erosion losses. There is still the advantage of a concentrated source, but these benefits may be realized a little later in the growing season than for starter. Sometimes referred to as zone-tillage, this system fits within the designation of “no-till” as defined by USDA-NRCS. Application is often done in the fall when there is less time pressure. Markers on the tillage unit guide the placement of rows. Then the planter follows the tillage tracks in the spring. Global positioning system (GPS)-based guidance systems can be used in the tillage and planting operations for more precise placement of both fertilizer and seed rows. This system may provide somewhat less of a starter effect, but rates can be higher, there is less impact on the planting schedule, and overall equipment costs may be less.


—HFR—

For more information, contact Dr. Harold F. Reetz, Jr., Midwest Director, PPI, 111 E. Washington Street, Monticello, IL 61856-1640. Phone: (217) 762-2074. E-mail: hreetz@ppi-far.org
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