1. Cotton Research Oklahoma State University

2. Exp. 439, Altus OK 1972-2006

5. N Rate Algorithm Trial Location: Lake Carl Blackwell Plot Size: 20 x 10’ Alley width: 5’ Total area: 95 x 150 Planting Date: May 15, 2006 Harvest Date: October 9, 2006 Fertilizer P applied preplant and incorporated, 30 lb P2O5/ac as 0-46-0 Tillage: 2 disc’s preplant followed by a rolling coulter Location: Lake Carl Blackwell Plot Size: 20 x 10’ Alley width: 5’ Total area: 95 x 150 Planting Date: May 15, 2006 Harvest Date: October 9, 2006 Fertilizer P applied preplant and incorporated, 30 lb P2O5/ac as 0-46-0 Tillage: 2 disc’s preplant followed by a rolling coulter

6. Treatment Structure TRTPreplant N RateTopdress N RateGrowth StagePIX 100-As needed 2500 - As needed 31000 - As needed 41500-As needed 52000-As needed 650 Early squareAs needed 750100Early squareAs needed 850150Early squareAs needed 90100Early squareAs needed 100150Early squareAs needed 110200Early squareAs needed 120SBNRCEarly squareAs needed 1350SBNRCEarly squareAs needed 14500+ PIX 152000No PIX

8. N Rate Algorithm Trial Variety: Monsanto NG3273B2RF The Cotton Variety was NexGen 3273B2RF. It is a stacked trait variety with Roundup-Ready Flex (allows for multiple applications of Round-up throughout the growing season) and Bollgard 2 (newest Bt product for cotton). NexGen cotton varieties are stripper varieties Variety: Monsanto NG3273B2RF The Cotton Variety was NexGen 3273B2RF. It is a stacked trait variety with Roundup-Ready Flex (allows for multiple applications of Round-up throughout the growing season) and Bollgard 2 (newest Bt product for cotton). NexGen cotton varieties are stripper varieties

15. If too much N has been applied what are the visible indicators? Delayed maturity Compared to zero-N plots Leaf N will be higher in the over- fertilized plots Delayed maturity Compared to zero-N plots Leaf N will be higher in the over- fertilized plots

16. If not enough N has been applied, and more is needed mid-season, what should we look for? Leaf N < 90-95 % of over-fertilized plots or strips. New fruits can shed Developing bolls will be smaller Leaf N < 90-95 % of over-fertilized plots or strips. New fruits can shed Developing bolls will be smaller

17. What to do? Zero-N Strip Farmer Practice Nitrogen Rich Strip N management in Texas and Oklahoma is too N rich. Zero-N Strip Farmer Practice Nitrogen Rich Strip N management in Texas and Oklahoma is too N rich. ENVIRONMENT ?

18. Improved Mid-Season N Management Can we estimate RI in cotton similar to wheat and corn? Can we estimate yield potential and use a YP0 * RI algorithm approach? The Ramp Calibration Strip should help us to define optimum N rates and to avoid excessive vegetative growth Improved Mid-Season N Management Can we estimate RI in cotton similar to wheat and corn? Can we estimate yield potential and use a YP0 * RI algorithm approach? The Ramp Calibration Strip should help us to define optimum N rates and to avoid excessive vegetative growth

19. N Management Preplant Soil Test 0-24” Dryland: 30-50 lb N/acre Irrigated: 60 lb N/bale of yield goal Mid-season N (June, 1 st square) Use of N Rich and 0-N (visual) Last N Applied (peak bloom) Preplant Soil Test 0-24” Dryland: 30-50 lb N/acre Irrigated: 60 lb N/bale of yield goal Mid-season N (June, 1 st square) Use of N Rich and 0-N (visual) Last N Applied (peak bloom)

20. Sensor Based N Algorithm On-off based on vegetative Green optimum and coverage threshold On-off decision of “if/then, and/or” for N or growth regulator To start, these decision tools need to be simple (yes/no). Management zones, (high-med-low) approaches can come later. On-off based on vegetative Green optimum and coverage threshold On-off decision of “if/then, and/or” for N or growth regulator To start, these decision tools need to be simple (yes/no). Management zones, (high-med-low) approaches can come later.