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

North Carolina Soils Mountain, Piedmont, Coastal Plain

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

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

SoilFormP ----lbs/ac---- NorfolkAl-P188 Fe-P88 Ca-P68 Org-P132 GeorgevilleAl-P100 Fe-P333 Ca-P44 Org-P164 Forms of P in NC Soils

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

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

Truog P- ppmP % Uptake from Days after Planting 29 Days86 Days102 Days % P 32 Studies with Corn P rate = 18 lbs / acre banded Nelson et al., 1948

Acid% P 32 Extracted Al-PFe-P HCL338 H 2 SO Effect of Anion on P Extraction Seatz, 1949, Ph.D Thesis, NCSU

Mehlich 1 (Double Acid) 0.05 N HCl N H 2 SO 4 Addition of SO4 increased extraction of P from Al and FePO 4 – (Seatz 1949 Ph.D. thesis- NCSU) Suitable for soils in the southeastern US Introduced in 1949

Critical M1P Levels for Cecil and Norfolk Soils

Critical M1P for Coastal Plain, Piedmont, and Mountain Soils

P Rate Needed to Change M1P as Influenced by Clay

Critical M1P Level 3 Piedmont Ultisols

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

Residual P – Georgeville Soil Initial P Application (1956) M1P (1964) Corn Yield (1964) ---lbs/acre------ppm---Annual P- lb /acre bushels / acre Kamprath, 1967

Tidewater Research Station

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

Effect of P Application on Soil Solution P

100 % Phosphorus Saturation SoilM1PM3P ppm Coastal Plain sandy soils165(275) Piedmont clayey soils(335)470

Change in M1P in 3 Ulitsols 14-Year Cropping with 0 P Applied

Effect of P Rate on M1P

Mehlich 3 Extractant NH 4 F, HOAc, NH 4 NO 3, HNO 3, EDTA pH 2.5 Introduced in 1981 Extracts 1.5 – 2 times more P than M1P

Critical Levels Coastal Plain Greenhouse millet – NorfolkM1P = 31 ppm Field – Portsmouth cornM1P = 22 ppm – NorfolkcornM1P = 25 ppmM3P = 55 ppm – Portsmouth cornM3P = 43 ppm wheatM3P = 64 ppm soybeanM3P = 50 ppm – GoldsborosoybeanM3P = 40 ppm

Critical Levels Piedmont Greenhouse millet – Cecil M1P = 16 ppm – Cecil, Davidson, Georgeville M1P = 12 ppm Field – Davidson, corn & soybean M1P = 6 – 8 ppmM3P = 10 – 13 ppm – Georgeville Corn M1P = 8 ppm Wheat M1P = 8 ppm

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

M3P Soil Test Levels over Time Soil LevelTob.CornPastureTob.CornPastureTob.CornPasture % of samples High V. High

Effect of Clay Content on M3P

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