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Fluid Journal : Fluid Journal 1993-1995
1 Fluid Journal Spring 1994 n this final of a three-part series on the use of fluid starters in conservation tillage, we will take a look at their use on soybeans, canola, sorghum, potatoes, and sugar beets. The use of starters is advantageous, especially in reduced-till environments, because they perform well in cooler temperatures, offer precise placement and higher efficiency, plus reduce weed pressure, stratification, and nutrient tie- up. Regions covered in this report are Alabama, Kansas, Nebraska, North Carolina, Florida. Minnesota, and Canada. Soybeans Most studies in the Midwest have shown soybeans to be less responsive to starter than corn. The early-season inflow (uptake per unit of root length) requirements of soybeans are considerably lower than for corn and the physiological traits of soybean roots lessen their ability to use nutrients in a concentrated band. Unlike corn, soybeans are traditionally planted later when soil temperatures are more favorable for nutrient uptake. North Carolina. In 1989 North Carolina experiments at four sites by Kamprath, soybeans failed to respond to a PKS starter on Coastal Plain soils. Starter materials were concentrated superphosphate. KCI, and calcium sulfate. Rate of application for the PKS starter was 20 lbs/A. Soil test P and K both ranged from medium to high at all sites. Kamprath indicated that the lack of S response was likely due to adsorbed S in the B horizon of one of by Dr. PaulE. Fixen and Dr. Raun D.Lohry Mu lti-crop R Mu lti-crop R Multi-crop R Multi-crop R Multi-crop Responses T esponses T esponses T esponses T esponses To Star o Star o Star o Star o Starters V ters V ters V ters V ters Var ar ar ar a r yyyyy I Researchers report on yield responses to starters applied on soybeans, canola, sorghum, potatoes, and sugar beets the soils and high amounts of S in the Ap horizon of the other soil. Leaf concentrations of P, K, and S were all in the sufficiency range at flowering. Alabama. In a 1986 study on the effects of NPK starters on soybeans in the Coastal Plains of Alabama, Touchton and Rickerl concluded that the primary yield response was to K. The P, K, NK, and PK starters increased yields 46 percent when residual P, K, or both were low, and 26 percent when the residual P and K were high. The N, NP, and NPK relative importance of specific nutrients appears to vary with geography and cropping system, making summarizing starters resulted in less response. Applied rates were: N at 14 lbs/A, phosphate at 38 lbs/A, and potash at 47 lbs/A. The starter was placed in a vertical band, extending to a depth of six to eight inches immediately below the row in a subsoiler channel. The researchers suggest that poor performance of NP and NPK starters may have been due to damage from the diammonium phosphate source used in these treatments. In another study by Touchton (1984), application of starters on southern Coastal Plain soils testing high in P and K resulted in increased yields in two of three years. Placement was two to four inches to the side or eight to ten inches deep in the in-row subsoil track. Starter applied was a 20-18-0 solution at a rate of 100 lbs/A, formulated from UAN and ammonium polyphosphate (APP). Although yields were increased, the in-row application reduced plant stand by 29 percent in one year. Yields averaged 14 percent higher for the three-year period when starters were used. Canola Balanced, effective fertility management is essential for producing quality, high- yielding canola. Canola uses more nitrogen than most other cereals. A 60 bu/A crop will require approximately 180 lbs/A of N, 80 lbs/A of phosphate Figure 1. Canola response to side-banded P in Canada. 0101520304045 P2O5 applied (lbs/A) Ont. --- Alta. --- Saak(irrig) --- Man. --- Sask. 1200 1000 800 600 400 200 0 Yield response to P (lbs/A)
Fluid Journal 1996-1998