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Fluid Journal : Fluid Journal 1993-1995
4 Fluid Journal Spring 1993 and zinc, and compaction in the subsoil that restricts nutrient uptake. All of these problems contribute to poor fertil- izer efficiency when using conventional broadcast methods of applying fertilizer. The solution to most of these problems is liquid starter applied at planting time, positioned below the residue. In addi- tion, root zone banding of a complete fertilizer below the residue before or after planting will supply the balance of nutrients. This two-step fertilizer pro- gram can solve most of the problems of fertilizing a conservation tillage field. Many agronomists say, "Build P and K levels before switching to conserva- tion tillage." Do they realize how long it takes and how costly it is to build P and K levels by broadcasting and plowing? It is estimated that 16 pounds of P2O5 per acre (7 lbs P) are required to raise the soil test level by one part per million P. To raise the soil test level of 20 ppm P would thus require about 320 pounds of P2O5 per acre. During the time that they are trying to build these P and K levels, there is a tremendous loss of nu- trients taken by fixation of phosphorus, the possibility of soil erosion or the loss of yields because of poor water use effi- ciency. Five-year tests at Purdue show that you can build the soil fertility levels almost 50 percent faster by banding fer- tilizer than by broadcasting. Their tests showed that P test for broadcast applica- tion was 2l ppm while P test for surface banding was 31 ppm after only 5 years. Dr. Lohry is the agronomist for Nutra-Flo® Company in Sioux City, Iowa. !
Fluid Journal 1996-1998