It’s no secret. Fertilizer marketing and sales procedures have changed dramatically.

Instead of basing fertilizer purchases for the coming year on the results of a recent soil test and planning for one or two years at a time, croop producers are now asked to order and pay for fertilizer for next year before this year’s crop is harvested. Short term planning in this new system is very difficult. So, decisions about fertilizer management have shifted to long term thinking. What can growers do? Are they at the mercy of fertilizer marketers? To respond to these questions, some suggestions are described in the paragraphs that follow.

USE NBMP’s: A series of Extension publications that describe Best Management Practices for nitrogen fertilizers was printed this year. These publications, each written for a specific area of the state, describe management practices for nitrogen fertilizers that will minimize loss without reducing or limiting yield. These publications are anailable on line (see an earlier blog for the URL’s) or at county and regional Extension offices.

Using the new Corn Belt concept for N guidelines is one important component of the NBMP’s. These new guidelines were verified in field trials conducted in fields of cooperating farmers in 2006 and 2007. They work if combined with NBMP’s. These N management practices can easily be used for the long term and should be used in long term planning.

BAND, NOT BROADCAST OF IMMOBILE NUTRIENTS: There’s no question about it. Rates of phosphate and potash can be halved if applied in a band near the seed when planting corn. This management practice has been promoteed for a number of years and has been verified by considerable research conducted throughout Minnesota.

We don’t have to be married to the old 2×2 starter placement concept. It is possible to place the band in a number of locations near the seed and still achieve optimum yields. Use of a band near the seed does not have to be a management practice good for only one year. Banded application of immobile nutrients can be used for several consecutive years. This is a long term mamagement practice. The long term use of the banded placement has been verified by trials conducted at the West-Central Research and Outreach Center, (Morris), the Southwest Reasearch and Outreach Center (Lamberton), and the Southern Research and Outreach Center (Waseca). These trials, conducted for five or six years, were on sites where the initial soil test for P was in the medium or low range.

There’s a general perception that soil test values will drop drastically if phosphate or potash fertilizer is banded year after year and no broadcast is used. Data collected from these multi-year trials lead to another conclusion. At the WCROC (Morris), the initial value for P in the fall of 1998 was 8.6 ppm (Olson) test). Following repeated use of the U of M suggested rate of phosphate in a band, the soil test P in the spring of 2003 was 8.5 ppm (Olson test). That was no change. When higher rates of phosphate were applied (crop removal concept), soil test P (Olson test) in the spring of 2003 was 11.3 ppm. However, the respective yields were 201 bu./acre (band application) and 205 bu./acre (crop removal concept). Statistically, that the same yield.

The conclusion was similar at the SROC (Waseca) where the soil is slightly acid. The initial soil test for P (Bray test) was 15.0 ppm. In 1999, yield from the control and U 0f M band guidelines were 179 and 180 bu./acre respectively. In the fall of 1999, soil test P values (Bray) were 15.5 and 13.3 ppm respectively. At the end of the 2003 growing season, the Bray P values from the same treatments were 12.0 and 18.5 ppm respectively. THe 2003 yields were 159 bu./acre (control) and 175 bu./acre (banded phosphate).

The results of this study conducted at sites with contrasting soil chemistry show that soil test values for P do not drop dramatically if banded application of phosphate fertilizer is used. Yields at these locations were not reduced by the use of this management practice. So, for long term planning, use of immobile nutrients (P,K,Zn) in a band is certainly a good management practice.

BANDING WITH RTK: The merger of the RTK concept with banded fertilizer, I believe, is the trend of the future. This merger will increase the efficient use of immobile nutrients. Repeated application of an immobile nutrient in a small zone in the soil is certainly a positive practice. Research with potash in the ridge-till system showed this to be true. Better yet, thanks to equipment currently on the market, the rate of nutrients applied in a band can be varied according to soil test values. So, two factors (banded placement, variable rate application) are combined to achieve ultimate efficiency in the use of immobile nutrients. This type of system should be a major consideration in any long range plans for fertilizer use.

THS ROLE OF SOIL TESTING: For many years, soil sampling has been used as a predictive management practice. Soil samples were collected and analyzed and fertilizer use was based on the results of this analysis. Soil testing will be much more important as long term planning replaces short term decisions. This management tool will be used to monitor the impact of long term decisions as well as a predictive tool for making those decisions. It will be more important than ever to use accuracy in collection of samples. The days of random collection of samples in a field are past.

Without question, the new strategies in fertilizer marketing will change plans for fertilizer use. Fortunately, there are management practices that can be effective in long range planning. There’s no doubt. Continued research will identify others.

SOURCE: George Rehm