1. Long-Term Application of N, P and K in Continuous Cotton, 1972-2006

2. Site characteristics Initiated in spring of 1972 by Dr. Billy Tucker At the Irrigation Research Station, Altus Clay loam

3. Variety, dates, seed rate, irr. Frequency 1972- 1974 1975- 19771978-19881989-19941995-20002001-2004 Cultivar Stone ville 213 Lankart LX571 Westburn M Paymaster 145 Paymaster HS26 Paymaster 2326 BG/RR Fertilization date Mid MayApr- May Mar-MayMayMar- Apr Planting datesMay May-JunMay Ave seed rate, kg/ha252322211918 Ave. frequency of furrow irrigation244345 Harvest dateDecNov-Dec Oct- MarOct- Nov

4. Treatments Incomplete factorial combination of N, P and K N rates 45, 90, 135, 180, 225 kg/ha P rates 20, 39, 59 kg/ha K 75 kg/ha

5. check plot

6. highest N rate

7. At maturity

8. Lint yield by variety, Altus, OKlahoma

9. Response to continuous application of N by variety cotton experiment, Altus, Oklahoma.

10. Response to P application by variety, cotton experiment, Altus, Oklahoma.

11. Response to K application by variety, cotton experiment, Altus, Oklahoma.