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Nitrogen Management for Heavy Clay Soils. David Dunn, Andrea Phillips, & Gene Stevens University of Missouri Delta Center This Research Made Possible by a Grant from Cotton Inc. and the Missouri State Support Committee. University of Missouri Main campus. Kansas City. Columbia. St. Louis.
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Nitrogen Management for Heavy Clay Soils David Dunn, Andrea Phillips, & Gene Stevens University of Missouri Delta Center This Research Made Possible by a Grant from Cotton Inc. and the Missouri State Support Committee
University of Missouri Main campus Kansas City Columbia St. Louis Springfield Bootheel MU Delta Center Portageville
Objective: Develop a nitrogen management package for aggressively irrigated cotton on heavy clay soils in Missouri.
Methods and Materials:Site location • Sharkey Clay soil • very fine, montmorillonite, thermic Vertic Haplaquept • pH: 7.1 P: 105 lb/a K 536 lb/a; CEC: 28.6 meq/100gr • N recommendation: • 800 lb lint = 110 lb N/a • 1000 lb lint = 130 lb N/a
Methods and Materials: • 5 N rates • 0, 50, 100, 150, & 200 lbs/acre as NH4NO3 • 3 application timings • All pre-plant (PP) • 2 equal splits (pp + pin head square PHS) • 3 equal splits (PP + PHS + full bloom FB)
ANOVA Table for yield Year <.0001 N rate <.0001 N*year 0.0653 Splits 0.0142 Splits*year 0.5423 N*splits 0.7202 N*splits*year 0.3734
2-Year Average Lint Yields • N rate Splits Yield • 0 ----- 244 f • 50 1 469 e • 1 595 d • 100 2 604 d • 100 3 671 cd • 150 1 692 cd • 150 2 757 bc • 150 3 753 bc • 200 1 757 bc • 200 2 837 ab • 200 3 884 a
A B C D E 0 50 100 150 200 N-Rate (lb N/a) 2-Year Average yields for all application timings
900 A 800 Lint Yield (lb N/a) 700 AB B 600 1 2 3 # of Splits 2-Year Average yields for 100, 150 & 200 lb N rates
Fiber properties effects: 2005 Property + N-rate + Splits Turn out -- -- Mic + - Length ++ ++ Strength + + Uniformity ** ** Leaf + ++ Value - ** + = general increase: ++ = consistent increase - = general decrease: -- = consistent decrease ** = no consistent effect
Net Returns to Producers Were Calculated By: • Commodity Credit Corporation Cotton loan rates for 2006 crop year $0.5235 / lb lint • Nitrogen priced @ $0.24/ lbs N + application cost of $5.00/acre
2-Year Average net returns • N rate Splits $/acre • 0 ----- $127 • 50 1 $219 • 1 $230 • 100 2 $283 • 100 3 $312 • 150 1 $321 • 150 2 $350 • 150 3 $342 • 200 1 $343 • 200 2 $380 • 200 3 $400
$225 $211 $165 $98 50 100 150 200 N-Rate (lb N/a) 2-Year Average value added by N for all application timings
$225 $211 $189 2-Year Average value added by N for 100, 150 & 200 lb N rates # of splits
Conclusions: • Current MU N recommendations for cotton grown on heavy clay soils may be too low. • N-rates above recommendations continued to add value • 200 lbs N best rate • Splitting N applications a profitable practice • 3 splits best strategy • More study is needed
Mark your Calendar for the 46th Delta Center Field Day August 31, 2007 9:00 AM Portageville, MO