|Plant Part and Time:||The above ground portion at growth stages 3-10; or Flag leaf at growth stage 10 (boot stage).|
|Element and Sufficiency Range||Interpretation and Recommendations|
Deficiency due to inadequate N fertilization, excessive rainfall, and/or ineffective N application. If N is low in the tissue topdress with 30 to 60 pounds N per acre. Nitrogen applications should be made before GS 7. Excessive leaf N concentrations can result in induced S deficiency, poor seed set and kernel fill. It appears that the most critical period for determining N and its effect on yield is GS at 4-6.
Less than sufficient due to low soil P and/or inadequate P fertilization. Low pH and cool soil temperatures may also reduce P uptake. Soil test and follow soil test recommendations of future plantings. No corrective treatment is recommended for current crop.
Less than sufficient due to low soil K and/or inadequate K fertilization. If low levels are detected at early growth stages, apply 50-60 pounds K2O per acre by ground rig or 30 pounds K2O per acre through the irrigation system. Corrective treatment is not recommended past GS 7. For succeeding crops, soil test and apply K2O based on soil test recommendations.
Deficiency not likely to occur except on low pH soils.
Deficiency due to low soil pH (less than 5.4) and/or low soil Mg. If Mg is low in the tissue, apply 25 pounds Mg per acre using a soluble source of Mg. Magnesium deficiency is not likely to occur on soils maintained at the proper soil pH. For succeeding crops, soil test and apply dolomitic limestone to correct soil acidity and low soil Mg.
Low sulfur is a common occurrence on coarse-textured low organic matter Coastal Plain soils where S- free fertilizers have been used for an extended period. Sulfur deficiencies may occur due to low soil S and/or when the N:S ratio exceeds 18:1. For optimum growth, maintain the N:S ratio between 9:1 and 18:1. If low S is detected prior to application of topdress N, include 10 pounds S per acre with the topdressing. If topdress N has been applied, apply a foliar application of S using 10 pounds of ammonium sulfate or 1/2 to 1 gallon of ammonium thiosulfate in 30 gallons of water per acre. NOTE: Some foliar burn may occur with the latter material.
Deficiency may occur on Coastal Plain soils that are coarse textured, low in organic matter and that have been limed to a pH greater than 6.3. If Mn is low, apply a foliar application of Mn using 1/2 pound of Mn per acre as manganese sulfate or 1/4 pound Mn per acre as manganese chelate in 20-25 gallons of water. If deficiency symptoms exist, repeat the application in approximately 10 days. If Mn in the tissue is near 5 ppm, plants may not recover after treatment. High Mn is due to low soil pH and levels of 400 to 500 ppm are toxic. For succeeding crops, soil test and apply limestone according to soil test recommendations.
Deficiency not likely to occur.
Deficiency not likely to occur. If deficiency is detected, apply a foliar application of B at the rate of 0.2 pound B per acre in 20-25 gallons of water.
Small grains are sensitive to low Cu; however, deficiency is not likely to occur unless soils are sandy, near neutral in pH, and high in organic matter. If Cu is low, apply a foliar application at the rate of 1/4 pound Cu per acre as copper chelate or as a liquid Cu formulation in 20 to 25 gallons of water. Caution: Use of copper sulfate to supply the recommended amount of Cu will result in foliage burn.
Deficiency not likely to occur except on coarse textured sandy soils low in Zn and having a pH of 6.5 or higher. If zinc is low, in the tissue, apply a foliar application of Zn using 1/2 pound Zn per acre as zinc sulfate or zinc chelate in 20-25 gallons of water. Extreme cold weather will substantially lower the Zn level in tissue; however, as soil temperatures warm, the Zn level in the tissue will increase to within the sufficiency range.
High Al concentrations due to very low soil pH or water-logged soils. If Fe is also high, then high Al is due to soil and dust contamination. For an accurate Al or Fe assessment, leaves must be washed (See section on washing samples to remove contaminates.)