REFERENCE SUFFICIENCY RANGES
FIELD CROPS

Rice

Paul F. Bell and John L. Kovar

• Critical Values

  A critical value is defined as the concentration of an essential element at which there is a 5–10% reduction in growth or yield.

• Sampling Procedures

  Mid-tillering
  Leaf samples should be taken from the youngest, fully developed leaves. About twenty leaves should be collected. Critical values for sulfur (S) were developed from analysis of whole plant (above-ground) samples.

  Panicle initiation
  Leaf samples should be taken from the youngest, fully developed leaves. These are the Y-leaves. About twenty leaves should be collected. The panicle should be at least 2 mm in length.

• Sufficiency Ranges
  
  
  • Mid-tillering
    
    

    Macronutrients
    N	P	K	Ca	Mg	S
    2.8–3.6%	0.14–0.27%	1.5–2.7%	0.16–0.39%	0.12–0.21%	0.17+ %

    
    

    Micronutrients
    Fe	Mn	Zn	Cu	B
    90–190 ppm	40–740 ppm	20–160 ppm	6–25 ppm	5–25 ppm

    
    

    Important Ratios

    For adequate N and S, the N/S ratio should be <10, with N>1.6% and S>0.15%.

  • Panicle Initiation
    
    

    Macronutrients
    N	P	K	Ca	Mg	S
    3.0–3.4%	0.18–0.29%	1.5–2.7%	0.19–0.39%	0.15–0.39%	0.15+ %

    
    

    Micronutrients
    Fe	Mn	Zn	Cu	B
    70–190 ppm	40–800 ppm	20–160 ppm	6–25 ppm	6–15 ppm

    
    

    Important Ratios

    For adequate N and S, the N/S ratio should be <10, with N>1.6% and S>0.15%.

• DRIS Norms
  
  

  Nutrient Ratio	Mean	CV (%)	Nutrient Ratio	Mean	CV (%)
  N/P	9.8174	13.2	10 P/Fe	0.6195	80.7
  N/K	1.19847	32.5	K/Mg	20.0648	21.7
  N/Ca	6.7736	33.5	K/S	16.0629	66.5
  N/S	17.2864	53.3	K/Cu	6.4452	18.7
  N/Mg	19.7246	18.8	K/Fe	0.6012	91.7
  10 N/Cu	6.3309	15.0	Ca/S	3.00039	82.8
  P/K	0.12042	23.2	10 Ca/Fe	0.873	59.2
  P/Ca	0.71713	28.2	Mg/S	0.94908	60.5
  P/Mg	2.12043	17.8	Mg/Cu	0.3302	20.7
  P/S	1.80124	56.4	10 Mg/Fe	0.298	85.6
  10 P/Cu	6.811	13.8	Fe/Mn	0.15069	35.1

• Remarks

  The information presented in the section is based on the published research cited in the reference list. DRIS norms were developed from a database of eastern Arkansas rice tissue analyses and yields (Counce and Wells 1986). A reliable sufficiency range for S diagnosis was not available. Rice varieties differ in both their requirement for N and leaf N critical values (Brandon and Wells 1986).

  In addition to sufficiency ranges, nutrient and other ion toxicities also have been reported. Aluminum (Al) toxicity is likely if whole plant Al is >300 ppm (Tanaka and Yoshida 1970). Research (Baker and others 1976) has shown that rice is sensitive to soil arsenic (As). The critical level in shoots ranges from 20–100 ppm. In roots, the critical level is 1000 ppm. Paddy rice is more susceptible to As toxicity due to the presence of more readily absorbed arsenite (As III). In some cases, ferrous iron (Fe II) may also pose a toxicity problem. Toxicity is possible in rice if chloride (Cl) reaches >10,000 ppm and nitrate >1600 ppm (Helms 1994). Leaf concentrations of manganese (Mn) in the range 4000–8000 ppm are toxic to rice (Adriano 1986). Molybdenum (Mo) toxicity is very rare, but an approximate value would be >100 ppm for leaves from grass species such as rice (Jones 1991). In Louisiana, sodic injury can occur when leaf Na in pre-boot-stage rice exceeds 2000 ppm. Zinc (Zn) toxicity was reported by Chino (1981) when rice shoots contained 100–300 ppm and rice roots contained 500–1000 ppm.

  With respect to deficiencies, rice and other cereal grasses are not sensitive to low Mo. For whole plants at boot stage, 0.09–0.18 ppm are considered sufficient. Deficiency of silicon (Si) may occur when Si is <5% in straw sampled at maturity (Tanaka and Yoshida 1970).

• References

  Adriano DC. 1986. Trace elements in the terrestrial environment. New York: Springer-Verlag.

  Baker RS, Barrentine WL, Bowman DH, Hawthorne WL, Pettiet JV. 1976. Crop response and arsenic uptake following soil incorporation of MSMA. Weed Sci 24:322–6.

  Brandon DM, Wells BR. 1986. Improving nitrogen fertilization in mechanized rice culture. Fert Res 9:161–70.

  Chino M. 1981. Metal stress in rice plants. In: Kitagishi K, Yamane I, editors. Heavy metal pollution in soils of Japan. Tokyo: Japan Science Society Press. p 65–80.

  Counce PA, Wells BR. 1986. Rice Y-leaf nutrient analyses and midseason, foliar fertilization. Commun Soil Sci Plant Anal 17:1071–87.

  Helms RS. 1994. Rice production handbook. Little Rock: University of Arkansas Cooperative Extension Service. Publication MP 192-2M-4-94R.

  Jones JB Jr. 1991. Plant tissue analysis in micronutrients. In: Mortvedt JJ, Cox FR, Shuman LM, Welch RM, editors. Micronutrients in agriculture. Madison (WI): American Society of Agronomy. p 477–522.

  Jones JB Jr, Wolf B, Mills HA. 1991. Plant analysis handbook: a practical sampling, preparation, analysis, and interpretation guide. Athens (GA): Micro-Macro Publishing. p 130.

  Jones US. 1982. Fertilizers and soil fertility. Reston (VA): Reston Publishing Co.

  Sedberry JE Jr, Amacher MC, Bligh DP, Curtis OD. 1987. Plant-tissue analysis as a diagnostic aid in crop production. Baton Rouge: Louisiana Agricultural Experiment Station. Bulletin No. 783.

  Suzuki A. 1978. Sulfur nutrition and diagnosis of sulfur deficiency of rice plants. JARQ 12:7–11.

  Tanaka A, Yoshida S. 1970. Nutritional disorders of the rice plant in Asia. Manila (Philippines): International Rice Research Institute. Technical Bulletin 10.

  Yoshida S, Chaudhry MR. 1979. Sulfur nutrition of rice. Soil Sci Plant Nutr 25:121–34.

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