Cotton Research Oklahoma State University

Exp. 439, Altus OK

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 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 Tillage: 2 disc’s preplant followed by a rolling coulter

Treatment Structure TRTPreplant N RateTopdress N RateGrowth StagePIX 100-As needed As needed As needed As needed As needed 650 Early squareAs needed Early squareAs needed Early squareAs needed 90100Early squareAs needed Early squareAs needed Early squareAs needed 120SBNRCEarly squareAs needed 1350SBNRCEarly squareAs needed PIX No PIX

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

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

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

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 ?

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

N Management Preplant Soil Test 0-24” Dryland: 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: 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)

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.