History of Phosphorus in North Carolina

1. SERA 6 Meeting June 20, 2011 History of Phosphorus in North Carolina Dr. Eugene Kamprath Professor Emeritus North Carolina Statue University

2. North Carolina Soils Mountain, Piedmont, Coastal Plain

3. Norfolk- Coastal Plain Soil fine-loamy, kaolinitic, thermic Typic Kandiudult Cecil / Georgeville- Piedmont Soils fine, kaolinitic, thermic Typic Kanhapludult

4. Phosphorus • Soils initially low in P • Cultivated soils – buildup of P • Piedmont soils • High buffer capacity • Coastal plain soils • Low buffer capacity

5. Forms of P in NC Soils

6. Yield (%) of Check Plots Compared to Fertilized Plots related to STP

7. Corn Yield Increase to 22 lbs P / acre- Coastal Plain Soils

8. P32 Studies with Corn P rate = 18 lbs / acre banded Nelson et al., 1948

9. Effect of Anion on P Extraction Seatz, 1949, Ph.D Thesis, NCSU

10. Mehlich 1 (Double Acid) • 0.05 N HCl + 0.025 N H2SO4 • Addition of SO4 increased extraction of P from Al and FePO4 • (Seatz 1949 Ph.D. thesis- NCSU) • Suitable for soils in the southeastern US • Introduced in 1949

11. Critical M1P Levels for Cecil and Norfolk Soils

12. Critical M1P for Coastal Plain, Piedmont, and Mountain Soils

13. P Rate Needed to Change M1Pas Influenced by Clay

14. Critical M1P Level 3 Piedmont Ultisols

15. Piedmont – P Relationships • Al-P converted to Fe-P, rapid rate first 3 years after application • M1-P highly correlated with Al-P • Rapid decrease in M1-P first 2 years after application, followed by much slower rate of decrease • M1-P critical level for wheat, 8 – 10 ppm Shelton, 1960 Ph.D Thesis, NCSU Shelton & Coleman, 1960

16. Residual P – Georgeville Soil Kamprath, 1967

17. Tidewater Research Station

18. P Management on Portsmouth Soil • M1-P critical level for corn / soybean, 22 ppm • Long term study 1955 – 1985 • Annual band application of 16 kg/ ha (equal to P removal in grain) maintained critical level • No yield advantage to keeping soil test above critical level • M1-P of 100 ppm supplies adequate P for 14 – 16 yrs. McCollum, 1991

19. Effect of P Application on Soil Solution P

20. Effect of P Application on Soil Solution P

21. 100 % Phosphorus Saturation

24. Change in M1P in 3 Ulitsols14-Year Cropping with 0 P Applied

25. Effect of P Rate on M1P

27. Effect of P Rate on M1P

29. Mehlich 3 Extractant • NH4F, HOAc, NH4NO3, HNO3, EDTA • pH 2.5 • Introduced in 1981 • Extracts 1.5 – 2 times more P than M1P

30. Critical Levels Coastal Plain • Greenhouse millet • Norfolk M1P = 31 ppm • Field • Portsmouth corn M1P = 22 ppm • Norfolk corn M1P = 25 ppm M3P = 55 ppm • Portsmouth corn M3P = 43 ppm wheat M3P = 64 ppm soybean M3P = 50 ppm • Goldsboro soybean M3P = 40 ppm

31. Critical Levels Piedmont • Greenhouse millet • Cecil M1P = 16 ppm • Cecil, Davidson, Georgeville M1P = 12 ppm • Field • Davidson, corn & soybean • M1P = 6 – 8 ppm M3P = 10 – 13 ppm • Georgeville • Corn M1P = 8 ppm • Wheat M1P = 8 ppm

32. P Management • CP soil with initial M1P of 105 ppm after 14 years cropping had M1P of 60 ppm & M3P of 120 ppm – high soil test P • CP soil with initial M1P of 50 ppm supplied adequate P for 13 years, 17 kg P/ha/yr harvested • Piedmont soil with initial M1P of 10 ppm supplied adequate P for 12 years • Annual P rate of 20 kg P/ha maintains critical level

34. M3P Soil Test Levels over Time

35. Effect of Clay Content on M3P

36. P Loss Assessment Tool (PLAT) • Environmental regulation and P loss today • Mehlich 3 P now used as an input for this • Historical research and data important in making decisions about PLAT and P management today