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Fluid Journal : Fluid Journal 1993-1995
2 Fluid Journal Winter 1994 hand place-ment becomes less critical if the soil test is rather high or phosphate application rate is high. Cotton responses to fertilizer nutrients placed near the seed at planting have been studied since the '50s. Early studies showed that cotton had greater resistance to adverse environmental conditions, such as lack of moisture, if starter was used. Patrick, et al. showed in 1959 that 500 lbs of 12- 12-12 improved yield and root development under thought conditions. Studies limited on cotton Although there is only a limited amount of research completed on starter effects on cotton, studies are in progress at several universities in the cotton-pro- ducing states where fertilizer rate recommendations are being formulated. Consequently, information that follows from these studies should serve as a guide -not a recommendation. Mississippi. The average of 18 repli- cated trials by Funderburg at different locations (1985-1987) showed lint yields from plots receiving fluid starter (10-34-0 or 11-37-0 at 12 gal/A) were 1,093 lbs/A while treatments receiving no starter yielded only 1,000 lbs/A (Figure 1). Many of the increases were statistically significant at greater than the .05 level of probability. Funderburg observed that yield increases were more dramatic in higher yielding environ- ments. He suggested that fields with a yield potential of about 850 lbs/A were more responsive to planter applied phosphate. Since the fluid starter fertilizer con- tained both nitrogen and phosphate, Funderburg ran another study to determine whether yield response origi- nated from nitrogen alone or from phos- phorus in combination with nitrogen. Based on the trials, he concluded that the NP combination significantly increased yields over check plots while nitrogen alone had little or no effect on yield Alabama. Touchton, et al. conducted studies (1985-87) on fluid starter combinations and placement for conventional and no-till cotton. Soils were silt loam and sandy loam. Tillage variables consisted of conventional till, no-till, and no-till plus in-row subsoil- ing Placement treatments consisted of deep fertilizer placement at 6 to 8 inches below the seed and 2 x 2 place-ment beside and below the seed, Fertilizer combinations were no starter, 15-0-0, 15-15-0 or 15-15-5 applied at 150 lbs/A. Starters did not affect early season plant heights on the silt loam soil, but starters increased plant height each year on the sandy loam soil. In one year, N alone was adequate. But in the other two years, NP combinations resulted in greater plant heights as compared to N alone. The 2 x 2 fertilizers were generally more effective than deep- Figure 2. Average lint yield response to varying fluid starter combinations, 2 x 2 placement, Touchton, Auburn University, 1986. 0-0-0 2500 2600 2700 2800 Yield (lbs/A) 15-0-0 15-15-0 15-15-15 Fluid Stater at 15- lbs/A Figure 3. Effect of APP starter placement on cotton yields, Guthrie, North C arolina State University, 1991. Application rate: N at lbs/A; P2O5 at 57 lbs/A Broadcast 700 800 900 Yield (lbs/A) Sidebanded
Fluid Journal 1996-1998