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

Outline Nitrogen Phosphorous Potassium pH Micro’s

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!!!!!!

Nitrogen Determined by Yield Level

Strips and Sensors

Phosphorous Independent of Yield

Potassium Independent of Yield

Variability

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

Micronutrients Needed by all Crops Iron Manganese Copper Zinc Boron Chlorine Molybdenum Soil (lb/a)* 14,000 – 1,100,000 40 – 6,000 4 - 200 20 - 600 40 – 1,800 0.4 - 10 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, 1979. Wiley & Sons. **Calculated for 2 ton crop yield (67 bushel wheat).

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

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

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

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

Iron Yellowing between veins, new leaves Ferrous Sulfate, ect

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

Soil Testing Just Do It!

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