REFERENCE SUFFICIENCY RANGES
FRUIT & NUT CROPS

Pecan

C. Owen Plank and C. C. Mitchell

• Critical Values

  None established.

• Sampling Procedures

  Sample the middle pair of leaflets from the mid-portion of terminal growth 56 to 84 days after catkin fall. The sampling time will vary among states, but in Georgia and Alabama the preferred sampling time is from July 7 to August 7. Under normal conditions, rainfall is frequent enough to keep leaf surfaces fairly free from dust and soil particles. If the leaflets are contaminated with residues from foliar sprays, they should be washed in a mild detergent solution (0.30%) and rinsed in a water bath or running water. Do not prolong the washing procedure or allow the plant material to "stand" in either the washing or rinsing solutions.

• Sufficiency Ranges
  
  
  • 56–84 Days after Catkin Fall
    
    

    Macronutrients
    N	P	K	Ca	Mg	S
    2.50–3.30% §	0.12–0.30%	0.75–2.50%	0.70–1.75%	0.30–0.60%	0.20–0.50%
    § If irrigated, the optimum range is 2.80–3.00%. For the 'Desirable' variety, the sufficiency range is 2.30–3.00%.

    
    

    Micronutrients
    Fe	Mn	Zn	Cu	B
    50–300 ppm	100–800 ppm	50–100 ppm	6–30 ppm	15–50 ppm

• DRIS Norms
  
  Preliminary DRIS norms for pecans are given by Beverly and Worley (1992), as follows:
  
  

  Nutrient Ratio	Mean	CV (%)	Nutrient Ratio	Mean	CV (%)
  N §	27.2	9.4	Mn	324	54.5
  P	1.4	18.1	Zn	126	60.0
  K	10.2	20.9	Cu	9.69	32.4
  Ca	14.5	33.4	Mo	6.3	28.1
  Mg	3.82	29.9	B	40.1	34.7
  Fe	89.4	40.9	Al	1380	34.3
  N/P	19.8	18.2	Ca/Zn	0.168	75.4
  N/K	2.74	20.9	Ca/Cu	1.62	47.8
  N/Ca	2.44	130.0	Ca/Mo	2.27	29.2
  N/Mg	7.74	36.7	Ca/B	0.325	41.6
  N/Fe	0.349	36.4	Ca/Al	0.0109	135.0
  N/Mn	1.107	47.4	Mg/Fe	0.0518	45.2
  N/Zn	0.306	76.5	Mg/Mn	0.0158	58.3
  N/Cu	3.13	41.0	Mg/Zn	0.0438	71.9
  N/Mo	4.56	28.0	Mg/Cu	0.470	49.4
  N/B	0.746	40.2	Mg/Mo	0.565	42.9
  N/Al	0.0257	138.0	Mg/B	0.111	45.0
  P/K	0.143	25.4	Mg/Al	0.00389	155.0
  P/Ca	0.123	117.0	Fe/Mn	0.354	46.0
  P/Mg	0.414	46.5	Fe/Zn	1.04	91.7
  P/Fe	0.0175	32.0	Fe/Cu	9.98	42.9
  P/Mn	0.00535	41.3	Fe/Mo	18.6	45.8
  P/Zn	0.0164	76.4	Fe/B	2.77	46.5
  P/Cu	0.163	38.9	Fe/Al	0.0958	149.0
  P/Mo	0.301	25.6	Mn/Zn	3.23	83.6
  P/B	0.0412	40.0	Mn/Cu	35.4	56.6
  P/Al	0.00143	154.0	Mn/Mo	70.0	45.3
  K/Ca	0.948	151.0	Mn/B	10.2	65.0
  K/Mg	2.97	46.3	Mn/Al	0.328	171.0
  K/Fe	0.134	35.9	Zn/Cu	14.8	57.6
  K/Mn	0.0409	50.7	Zn/Mo	21.5	54.7
  K/Zn	0.121	77.3	Zn/B	3.69	66.5
  K/Cu	1.23	41.7	Zn/Al	0.125	183.0
  K/Mo	1.86	32.4	Cu/Mo	1.70	41.1
  K/B	0.319	53.6	Cu/B	0.276	43.8
  K/Al	0.0104	137.0	Cu/Al	1.00954	148.0
  Ca/Mg	4.13	42.0	Mo/B	0.183	71.5
  Ca/Fe	0.193	54.2	Mo/Al	0.00586	159.0
  Ca/Mn	0.0583	58.5	B/Al	0.0384	170.0
  § N, P, K, Ca and Mg expressed in g/kg (parts per thousand); other elements in mg/kg (ppm).

• Remarks

  The sufficiency ranges given above were taken from Plank (1989). The ranges have been developed over the past 25–30 years utilizing research data from various sources, surveys, and plant analysis summaries.

• References

  Beverly RB, Worley RE. 1992. Preliminary DRIS diagnostic norms for pecan. HortScience 27(3):271.

  Plank CO. 1989. Plant analysis handbook for Georgia. Athens (GA): University of Georgia Cooperative Extension Service. 64 p.

  Sparks D. 1976. Magnesium nutrition and the pecan—a review. Pecan South 3(3):384–7.

  Sparks D. 1977. Methods of predicting the nutrient needs of nut trees. [place unknown]: Northern Nut Growers Association. 68th Annual Report. p 25–30.

  Sparks D. 1977. Nitrogen—re-evaluation of its effects on pecan yield and nut growth. Pecan South 4(May/June):16–9.

  Sparks D. 1978. Nutrient concentrations of pecan leaves with deficiency symptoms and normal growth. HortScience 13(3):256–7.

  Sparks D. 1978. Predicting the nutrient needs of pecan—a review. Pecan South 5(6):280–4.

  Sparks D. 1993. Threshold leaf levels of zinc that influence nut yield and vegetative growth in pecan. HortScience 28(11):1100–2.

  Worley RE. 1974. Effect of N, P, K and lime on yield, nut quality, tree growth, and leaf analysis of pecan (Carya illinoensis W.). J Am Soc Hort Sci 99:49–57.

  Worley RE. 1985. Use of leaf analysis for basing N application for Stuart pecans. Proc SE Pecan Growers Assoc 78:79–83.

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