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¶ Sweet potato (Ipomoea batatas)
| Table No: | Growth stage: | Plant part: |
| Table A | Early vining | Mature leaves |
| Table B | Mid-season (prior to root enlargement) | Mature leaves |
| Table C | Root enlargement | Mature leaves |
| Table D | Prior to harvest | Mature leaves |
¶ A: Early vining
Plant Part: Most recent fully-developed, mature leaves
Sampling Procedure: Collect first fully expanded leaf from the growing point, generally the 3rd to 5th leaf from the terminal leaf. Collect leaf blades from 20 to 25 plants, discarding petioles. Collect leaves that are free of insect or disease. Submit at least a pint of loosely packed tissue (a ball about 4 to 5 inches in diameter). Place samples in paper bag, not plastic, for shipment.
| Analysis | Tissue Concentration Guidelines | ||||||||
| Low/Marginal Range | Sufficiency Range | Excessive, toxic? | |||||||
| Nitrogen, % N | 3.30 | - | 3.50 | 3.50 | - | 4.50 | |||
| Phosphorus, %P | 0.25 | - | 0.30 | 0.30 | - | 0.50 | |||
| Potassium, % K | 2.00 | - | 2.90 | 2.90 | - | 4.30 | |||
| Calcium, % Ca | 0.60 | - | 0.70 | 0.70 | - | 1.50 | |||
| Magnesium, % Mg | 0.28 | - | 0.35 | 0.35 | - | 0.90 | |||
| Sulfur, % S | 0.15 | - | 0.20 | 0.20 | - | 0.60 | |||
| Zinc, ppm Zn | 20 | - | 25 | 25 | - | 50 | |||
| Iron, ppm Fe | 30 | - | 40 | 40 | - | 100 | |||
| Manganese, ppm Mn | 35 | - | 40 | 40 | - | 250 | |||
| Copper ppm Cu | 3 | - | 5 | 5 | - | 10 | |||
| Boron, ppm B | 20 | - | 25 | 25 | - | 75 | |||
| Nitrogen-to-sulfur ratio (N:S) | 15 | - | 18 | 10 | - | 14 | |||
| Sodium, % Na | 0.25 | - | 0.50 | ||||||
| Chloride, % Cl | 0.30 | - | 1.00 | ||||||
| Nitrate, ppm NO3-N | |||||||||
| Phosphate, ppm PO4-P | |||||||||
¶ Figure A.
¶ B: Mid-season (prior to root enlargement)
Plant Part: Most recent fully-developed, mature leaves
Sampling Procedure: from the terminal leaf. Collect leaf blades from 20 to 25 plants, discarding petioles. Collect leaves that are free of insect or disease. Submit at least a pint of loosely packed tissue (a ball about 4 to 5 inches in diameter). Place samples in paper bag, not plastic, for shipment.
| Analysis | Tissue Concentration Guidelines | ||||||||
| Low/Marginal Range | Sufficiency Range | Excessive, toxic? | |||||||
| Nitrogen, % N | 3.00 | - | 3.30 | 3.30 | - | 4.50 | |||
| Phosphorus, %P | 0.20 | - | 0.23 | 0.23 | - | 0.50 | |||
| Potassium, % K | 2.00 | - | 2.90 | 2.90 | - | 4.30 | |||
| Calcium, % Ca | 0.60 | - | 0.70 | 0.70 | - | 1.50 | |||
| Magnesium, % Mg | 0.25 | - | 0.30 | 0.30 | - | 0.80 | |||
| Sulfur, % S | 0.15 | - | 0.20 | 0.20 | - | 0.50 | |||
| Zinc, ppm Zn | 20 | - | 25 | 25 | - | 50 | |||
| Iron, ppm Fe | 30 | - | 40 | 40 | - | 100 | |||
| Manganese, ppm Mn | 35 | - | 40 | 40 | - | 250 | |||
| Copper ppm Cu | 3 | - | 5 | 5 | - | 10 | |||
| Boron, ppm B | 20 | - | 25 | 25 | - | 75 | |||
| Nitrogen-to-sulfur ratio (N:S) | 15 | - | 18 | 10 | - | 14 | |||
| Sodium, % Na | 0.25 | - | 0.50 | ||||||
| Chloride, % Cl | 0.30 | - | 1.00 | ||||||
| Nitrate, ppm NO3-N | |||||||||
| Phosphate, ppm PO4-P | |||||||||
¶ Figure B.
¶ C: Root enlargement
Plant Part: Most recent fully-developed, mature leaves
Sampling Procedure: Collect first fully expanded leaf from the growing point, generally the 3rd to 5th leaf from the terminal leaf. Collect leaf blades from 20 to 25 plants, discarding petioles. Collect leaves that are free of insect or disease. Submit at least a pint of loosely packed tissue (a ball about 4 to 5 inches in diameter). Place samples in paper bag, not plastic, for shipment.
| Analysis | Tissue Concentration Guidelines | ||||||||
| Low/Marginal Range | Sufficiency Range | Excessive, toxic? | |||||||
| Nitrogen, % N | 2.70 | - | 3.00 | 3.00 | - | 4.00 | |||
| Phosphorus, %P | 0.16 | - | 0.20 | 0.20 | - | 0.40 | |||
| Potassium, % K | 1.70 | - | 2.00 | 2.00 | - | 4.00 | |||
| Calcium, % Ca | 0.65 | - | 0.80 | 0.80 | - | 1.60 | |||
| Magnesium, % Mg | 0.20 | - | 0.25 | 0.25 | - | 0.50 | |||
| Sulfur, % S | 0.15 | - | 0.20 | 0.20 | - | 0.60 | |||
| Zinc, ppm Zn | 20 | - | 25 | 25 | - | 50 | |||
| Iron, ppm Fe | 30 | - | 40 | 40 | - | 100 | |||
| Manganese, ppm Mn | 35 | - | 40 | 40 | - | 100 | |||
| Copper ppm Cu | 3 | - | 5 | 5 | - | 10 | |||
| Boron, ppm B | 15 | - | 20 | 20 | - | 50 | |||
| Nitrogen-to-sulfur ratio (N:S) | 15 | - | 18 | 10 | - | 14 | |||
| Sodium, % Na | 0.25 | - | 0.50 | ||||||
| Chloride, % Cl | 0.30 | - | 1.00 | ||||||
| Nitrate, ppm NO3-N | |||||||||
| Phosphate, ppm PO4-P | |||||||||
¶ Figure C.
¶ D: Prior to harvest
Plant Part: Most recent fully-developed, mature leaves
Sampling Procedure: Collect first fully expanded leaf from the growing point, generally the 3rd to 5th leaf from the terminal leaf. Collect leaf blades from 20 to 25 plants, discarding petioles. Collect leaves that are free of insect or disease. Submit at least a pint of loosely packed tissue (a ball about 4 to 5 inches in diameter). Place samples in paper bag, not plastic, for shipment.
| Analysis | Tissue Concentration Guidelines | ||||||||
| Low/Marginal Range | Sufficiency Range | Excessive, toxic? | |||||||
| Nitrogen, % N | 2.50 | - | 2.80 | 2.80 | - | 3.50 | |||
| Phosphorus, %P | 0.16 | - | 0.20 | 0.20 | - | 0.40 | |||
| Potassium, % K | 1.70 | - | 2.00 | 2.00 | - | 4.00 | |||
| Calcium, % Ca | 0.65 | - | 0.80 | 0.80 | - | 1.60 | |||
| Magnesium, % Mg | 0.20 | - | 0.25 | 0.25 | - | 0.50 | |||
| Sulfur, % S | 0.15 | - | 0.20 | 0.20 | - | 0.60 | |||
| Zinc, ppm Zn | 20 | - | 25 | 25 | - | 50 | |||
| Iron, ppm Fe | 30 | - | 40 | 40 | - | 100 | |||
| Manganese, ppm Mn | 35 | - | 40 | 40 | - | 100 | |||
| Copper ppm Cu | 3 | - | 5 | 5 | - | 10 | |||
| Boron, ppm B | 15 | - | 20 | 20 | - | 50 | |||
| Nitrogen-to-sulfur ratio (N:S) | 15 | - | 18 | 10 | - | 14 | |||
| Sodium, % Na | 0.25 | - | 0.50 | ||||||
| Chloride, % Cl | 0.30 | - | 1.00 | ||||||
| Nitrate, ppm NO3-N | |||||||||
| Phosphate, ppm PO4-P | |||||||||
¶ Figure D.
Note: Interpretations are based the relationship between nutrient levels in a particular part of a "standard" tissue in a specific time in the growing season.
These plant tissue ranges and interpretations are not considered valid with plant parts or growth stages other than those specified. These interpretations are developed from data collected across a wide range of crop, soil, and climate conditions.
Results from a single sample may be affected by time of day, climatic conditions, plant stress, age, or disease, that are not directly related to fertility status. Nutrient concentrations are not uniform throughout the plant and may change as the tissue matures.Tissue analysis trends should be evaluated by variety, growing season, and yield/quality goals. Collecting plant samples from the same location as soil samples allows comparison of soil nutrient availability with plant nutrient status.
Low nutrient levels may be due to deficiency or to dilution by intensive growth. High or excessive nutrient levels may be a sign of restricted growth allowing nutrients to accumulate in the plant tissue. Nutrient imbalance may be secondary to the primary problem.