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Fluid Journal : Fluid Journal 1993-1995
1 Fluid Journal Winter 1994 n the fall issue of the Fluid Journal, we took a look at the use of starters on corn and the impact the switch to conservation tillage is having on fertilizer placement. We will continue the study of responses to fluid starters, focusing on cotton in this second of a three-part series. Our report will cover research studies in Mississippi, Alabama, and North Carolina. The underlying thread that should be kept in mind throughout this series is the key role fluid starters play in improving crop yields. They operate in cooler temperatures, offer both precise placement and higher efficiency, as well as reduce weed pressure, stratification and nutrient tie-up. Funderburg (Mississippi Cooperative Extension service) defines starter fertil- izers as "an amount of nitrogen/ phosphate fertilizer banded near---but not on---the seed at time of planting." He stresses that large amounts of starter fertilizer should not be in direct contact with the seed and notes that fertilizer contact with the seed can result in severe stand reductions. Cotton responsive Cotton, like most other crops, produces a range of responses to starter fertilizers. In the East, starters appear to enhance yields regardless of planting date. There is a greater probability of a yield increase on lighter-textured soils and where there are substantial legume residues. Using starter on cotton grown in legume residue may enhance seedling vigor. Placement beside and below the by Dr. PaulE. Fixen and Dr. Raun D.Lohry I Fl uid Star Fluid Star Fluid Star Fluid Star Fluid Starters Boost Cotton Y ters Boost Cotton Y ters Boost Cotton Y ters Boost Cotton Y ters Boost Cotton Yields ields ields ields ields Studies in Mississippi, Alabama, and North Carolina show that cotton reponds well to starters. seed (2 by 2) appears to optimize yields. Soil conditions predict the efficacy of subsoiling. In addition, N and phosphate applied at 15 lbs/A has been the pre- ferred nutrient ratio. Occasionally, small amounts of K2O have increased yields. In the South, NP starters have shown yield increases even when soil P levels are very high. There may be soil types where surface band applications outper- form in-furrow placement, but more research is needed. Placement of NPK mixes has enhanced root growth and thought resistance. Finally, it is relative- ly easy to set up cotton planters for starters. The economics appear to favor a small amount of strategically placed starter to augment the regular fertilizer program. Cotton is a deep tap-rooted species that responds well to nitrogen and side- banded phosphate. Recommended nitrogen rates vary from 50 to 100 lbs/ A. The optimum range of nitrogen depends on soil texture, the preceding crop, and the amount and distribution of rainfall. Producers use split N appli- cations to maximize nitrogen use efficiency when nitrogen loss potential is high. One bale of lint will remove approxi- mately 70 pounds of nitrogen, 14 pounds of phosphate, and 35 pounds of potassium. In spite of the relatively low amount of P taken up, phosphate fertil- ization is very important. Cotton soils tend to he low in phosphorus. Adequate phosphorus is essential for seedling vigor, drought stress, proper boll maturity, and seed development. Banded nutrients are generally more efficient than broadcast. Oklahoma State University recommends phosphate be placed where soil is likely to he moist and root contact is imminent. OSU does not recommend surface P applications because they are inefficient under Oklahoma conditions. The recommended placement is two inches beside and below the seed. However, Figure 1. Average lint yield increases, showing cotton response to applica- tions of fluid starters (10-34-0 or 11-37-0 at 12 gal/A), Funderburg, Louisiana State University, 1988. No Starter 900 1000 1100 Yield (lbs/A) Fluid Starter
Fluid Journal 1996-1998