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Fluid Journal : Fluid Journal 1999-2001
2 Fluid Journal Summer 2000 The ability to direct flow and placement of a solution in the soil is viewed as an advantage in achieving separation between seed and fertilizer in a fluid system. Positioning In fields direct-seeded for a number of years, especially zero-till, a thatch or duff layer builds up on the soil surface. On the prairies, thatch can be as thick as one to two inches after 20 years. To minimize losses and assure good crop- use efficiency, fertilizers should be placed below the thatch into the mineral soil. Otherwise, nitrogen forms will volatilize when thatch is moist and urease enzyme activity is high. Immobile nutrients like P and K may be "hung up" in the surface and not accessible to roots, especially in dry years. Or, nutrients may be tied up by microorganisms as they decompose residue. It is not surprising, then, that placement of fertilizer in bands or nests at seeding depth or below has particularly benefited direct seeding systems in Western Canada. New opener designs and configurations have greatly expanded the number of precision placement options. A common approach is placement of the fertilizer about one inch to the side and one inch below the seed row. Such banding encourages root proliferation deeper in the soil. More recently, another fertilizer placement option for direct seeding termed "mid-row" has become available. In mid-row banding, fluids are applied in a band between the seed rows using a separate knife or coulter opener. Another approach unique for fluids is the use of point or spoke injectors that nest liquid nutrients with a minimum of soil disturbance. Delivery Transport of solution fertilizer to the field by the dealer reduces additional labor requirements or time lost off equipment by operators. With some grain farms in Western Canada approaching 5,000 acres or more and a narrow window for timely completion of seeding, maximum efficiency in seeding and fertilizing is a high priority. Dr. Schoenau is a senior research scientist and adjunct professor in the Department of Soil Science, University of Saskatchewan.
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