1. Brian Arnall Oklahoma State University Dept Plant and Soil Sciences
Sorghum Fertility
Brian Arnall Oklahoma State University Dept Plant and Soil Sciences

2. Outline
Nitrogen
Phosphorous
Potassium pH
Micro’s

3. Soil Testing OSU, Ward, ect. $10 - $15
20 lb N $9
20 lb P $7.2
¼ Ton Lime $5-10
Per Acre!!!!!
Some Co-Ops and Fertilizer Dealers,
Take and Process samples for FREE!!!!!!

4. Nitrogen
Determined by Yield Level

6. Strips and Sensors

7. Phosphorous
Independent of Yield

10. Potassium
Independent of Yield

12. Variability

13. pH Issues
Mixed Reports, some state more Al tolerant and others show less.

14. Micronutrients Needed by all Crops
Iron
Manganese
Copper
Zinc
Boron
Chlorine
Molybdenum
Soil (lb/a)*
14,000 – 1,100,000
40 – 6,000
40 – 1,800
Crop (lb/a)** 1
0.8
0.08
0.6 4
0.0008
*Range of total in soils. From Chemical Equilibria in Soils. W.L.Lindsay, Wiley & Sons.
**Calculated for 2 ton crop yield (67 bushel wheat).

15. Nutrients not found deficient in Oklahoma crops.
Calcium.
Liming prevents Ca deficiency.
Manganese.
Copper.
Molybdenum.

16. Nutrients seldom found deficient in Oklahoma crops.
Magnesium.
Sulfur.
Iron.
Zinc.
Boron.
Chlorine.

17. Mg Yellowing between veins, old leaves Dolomitic Lime Sul-po-Mag, K-Mag

18. Sulfur Can look like N, Yellowing between veins Gyp, S, Ammon Sulfate

19. Iron Yellowing between veins, new leaves Ferrous Sulfate, ect

20. Micro Nutrients
Zinc, Bronze between Margin and Midrib. Bleaching on either side of Midrib Zinc Sulfate, Zinc Chloride, Zinc Chelate
Boron, Borax
Chloride, Upper Leave Wilt, Muriate of Potash which K is usually also deficient

21. Soil Testing
Just Do It!

22. Thank You!
Corn and Sorghum Nutrient Need Pete’s Sheets coming soon