History of Phosphorus in North Carolina

Dr. Eugene KamprathProfessor Emeritus

North Carolina Statue University

SERA 6 MeetingJune 20, 2011

North Carolina Soils Mountain, Piedmont, Coastal Plain

Norfolk- Coastal Plain Soil

fine-loamy, kaolinitic, thermic Typic KandiudultCecil / 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

Soil Form P

----lbs/ac----Norfolk Al-P 188

Fe-P 88

Ca-P 68

Org-P 132

Georgeville Al-P 100

Fe-P 333

Ca-P 44

Org-P 164

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- ppm P % Uptake from Days after Planting

29 Days 86 Days 102 Days

---------------------------%----------------------------

15 52 17

35 16 7

P32 Studies with Corn

P rate = 18 lbs / acre banded Nelson et al., 1948

Acid % P32 Extracted

Al-P Fe-P

HCL 33 8

H2SO4 39 16

Effect of Anion on P Extraction

Seatz, 1949, Ph.D Thesis, NCSU

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

Critical M1P Levels for Cecil and Norfolk Soils

Critical M1P for Coastal Plain, Piedmont, and Mountain Soils

P Rate Needed to Change M1Pas 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, NCSUShelton & Coleman, 1960

Residual P – Georgeville Soil Initial P Application

(1956)M1P

(1964)Corn Yield

(1964)

---lbs/acre--- ---ppm--- Annual P- lb /acre

0 22

---bushels / acre---

0 1 27 92

150 2 64 100

300 4 89 110

600 11 114 115

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

Effect of P Application on Soil Solution P

100 % Phosphorus Saturation

Soil M1P M3P

-----------ppm-----------

Coastal Plain sandy soils 165 (275)

Piedmont clayey soils (335) 470

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

Effect of P Rate on M1P

Effect of P Rate on M1P

Mehlich 3 Extractant

• NH4F, HOAc, NH4NO3, HNO3, EDTA

• pH 2.5

• Introduced in 1981

• Extracts 1.5 – 2 times more P than M1P

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 ppmsoybean M3P = 50 ppm

– Goldsboro soybean M3P = 40 ppm

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

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

1990 2000 2010

SoilLevel Tob. Corn Pasture Tob. Corn Pasture Tob. Corn Pasture

----------------------------------------% of samples--------------------------------------------

High 23 31 21 21 37 19 23 35 17

V. High 63 32 27 70 37 53 62 35 57

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