REFERENCE SUFFICIENCY RANGES
FIELD CROPS

Small Grain (Barley, Oats, Rye, Wheat)

C. O. Plank and S. J. Donohue

• Critical Values
  
  The values given here are best estimates based on extensive experience. They apply to all samples and growth stages.
  
  

  Macronutrients
  N	P	K	Ca	Mg	S
  3.0%	0.15%	2.0%	0.15%	0.10%	0.10%

  
  

  Micronutrients
  Fe	Mn	Zn	Cu	B	Mo
  25 ppm	15 ppm	15 ppm	3 ppm	1 ppm	0.05 ppm

• Sampling Procedures

  Seedling to Tillering
  Whole plants should be collected by cutting 1 inch above the soil surface. Samples can be taken by grasping existing growth at a given site and cutting at the recommended level above the soil with a small knife. Dead leaves should be avoided as much as possible. After collecting subsamples from several locations in a field, clippings should be combined for a representative sample.

  Jointing to Flag Leaf Emergence
  Break the top two to three leaves (growing point) from representative plants in several locations of the field. Combine for a representative sample. Stems should be included.

  Flag Leaf to Maturity
  Flag leaves from representative plants in the field should be collected randomly. A minimum of 15 to 20 leaves should be collected from a given field or area.

  Problem-solving Samples
  These samples can be taken at any time during the growing season. Comparative samples from "good" and "bad" areas should be taken according to guidelines at the stage of growth.

  Monitoring samples
  These samples should be taken at full tillering (Zadoks 30; Feekes 5) to predict nutritional status and additional nitrogen required to optimize yield. Final monitoring samples should be taken at flag leaf emergence (Zadoks 45; Feekes 10) to evaluate nutrient program.

• Sufficiency Ranges
  
  

  Important Ratios

  The N:S ratio should be between 10 and 15 for optimum yields. N:S ratios greater than or equal to 18 indicate that sulfur is limiting in relation to nitrogen.

  • Seedling to Tillering; Jointing to Flag Leaf Emergence
    
    

    Macronutrients
    N	P	K	Ca	Mg	S
    4.0–5.0%	0.2–0.5%	2.5–5.0%	0.2–1.0%	0.14–1.0%	0.15–0.65%

    
    

    Micronutrients
    Fe	Mn	Zn	Cu	B	Mo
    30–200 ppm	20–150 ppm	18–70 ppm	4.5–15 ppm	1.5–4 ppm	0.1–2.0 ppm

  • Flag Leave Maturity
    
    

    Macronutrients
    N	P	K	Ca	Mg	S
    4.0–5.0%	0.2–0.5%	2.0–4.0%	0.2–1.0%	0.14–1.0%	0.15–0.65%

    
    

    Micronutrients
    Fe	Mn	Zn	Cu	B	Mo
    30–200 ppm	20–150 ppm	18–70 ppm	4.5–15 ppm	1.5–4.0 ppm	0.1–2.0 ppm

• DRIS Norms

  DRIS norms for small grains have not been reported.

• Remarks

  Sufficiency ranges are based on available literature and experience interpreting plant samples.

  Results are less reliable as crop approaches maturity. Comparative "good" and "bad" samples should be used when sampling at various stages of maturity.

  Sufficiency ranges can generally be applied for wheat, oats, rye, and barley although most of the research has been done on wheat.

• References

  Mills HA, Jones JB Jr. 1996. Plant analysis handbook II: a practical sampling, preparation, analysis, and interpretation guide. Athens (GA): Micro-Macro Publishing.

  Plank CO. 1989. Plant analysis handbook for Georgia. Athens (GA): University of Georgia Cooperative Extension Service. p 37–8.

  Westfall DG, Whitney DA, Brandon DM. 1990. Plant analysis as an aid in fertilizing small grains. In: Westerman RL, editor. Soil testing and plant analysis. 3rd ed. Madison (WI): Soil Society of America, Inc. p 495–519. (SSSA book series; 3).

Electronic Document Prepared by:
Catherine Stokes, Communication Specialist
Agronomic Division of the N.C. Department of Agriculture and Consumer Services. July 2000.