281-11 Source and Timing of Nitrogen, Potassium, and Sulfur Sidedress Applications in Virginia Cotton.

Poster Number 2114

See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Soil Fertility and Plant Nutrition Division and Nutrient Management and Soil and Plant Analysis Division Graduate Student Poster Competition (MS degree)

Tuesday, November 5, 2013
Tampa Convention Center, East Exhibit Hall

William Hunter Frame, Tidewater Agricultural Research and Extension Center, Virginia Tech, Suffolk, VA and Austin Brown, Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA
Abstract:
Five upland cotton field studies were implemented in Virginia and North Carolina to: 1) establish an optimal nitrogen (N) fertilizer rate and timing; 2) agronomic evaluation of potassium sulfate coated urea; 3) assess the value of side-dressed potassium fertilizer on mitigating potassium deficiencies observed during the mid to late bloom period in upland cotton production. A total of 16 fertilization treatments were applied in 2012 using urea ammonium nitrate (UAN) solutions, granular urea and potassium (K) sulfate coated urea (KSCU) formulations, along with foliar applied potassium nitrate. Only fourteen treatments were implemented in 2013 with a greater emphasis placed on N rate and KSCU formulations. Side-dress N applications were applied at 1st square and 1st bloom, with petioles and leaves being sampled at the 1st and 4th weeks of the bloom period. Petiole samples were analyzed for total N, K, and sulfur (S) in 2012. In, 2013, petiole and tissue samples were collected with petioles being analyzed for nitrate-N, total N, K, and S and a complete nutrient analysis completed on the tissue samples. In 2012, petiole N was strongly correlated to side-dress N rates during the 1st week of bloom with Rvalues of .95 and .84 at locations 1 and 2 respectively. Side-dress N rates were weakly correlated to N concentrations by the 4th week of bloom during 2012. Only location 2 responded to the added sulfur from the potassium sulfate coated urea during 2012; while potassium concentrations in the petiole were not affected at either location. In 2013, initial data show N rates applied at 1st square correlated to petiole nitrate levels during the 1st week of bloom with R2 values of  .78 and .59. Petiole results from the early bloom period are more responsive to side-dress N applications and were a stronger predictor of yield during 2012. The high correlations of N rates and lint yield to petiole N levels during the first week of bloom show promise as an in-season N management tool.

See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Soil Fertility and Plant Nutrition Division and Nutrient Management and Soil and Plant Analysis Division Graduate Student Poster Competition (MS degree)