Pomegranate Irrigation and Nutrient Management

Transcription

1 Florida Pomegranate Association 2018 Growers Meeting (GCREC Feb 9, 2018) Pomegranate Irrigation and Nutrient Management Shinsuke Agehara Assistant Professor, Plant Physiology Gulf Coast Research and Education Center

2 Irrigation management begins with water quality 1) ph & Alkalinity - Affects nutrient availability 2) Salinity - Electrical conductivity (EC) affected by all ions 3) Ion toxicity - Caused by individual ions

3 Ion toxicity ph/alkalinity Salinity

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5 General water quality guidelines Parameter Optimum level ph Alkalinity <100 ppm CaCO 3 EC Sodium Chloride Boron <1 ms/cm <70 ppm <70 ppm <0.5 ppm Source: Bailey et al. (1999)

6 Acid injection Hydrogen ions in acids can lower ph by reducing the amount of carbonates and bicarbonates (alkalinity). H + (from acid) + HCO 3 (in water) CO 2 + H 2 O

7 Which acid type? Acid type Conc Cost per Nutrient in Relative meq/l per one fl oz per hazard 1000 gal 1000 gal Citric acid 99.5% $0.59 Low None Nitric acid 67% $0.26 Very high 1.6 ppm N Phosphoric acid 75% $0.44 Moderate 2.9 ppm P Sulfuric acid 35% $0.16 High 1.1 ppm S Citric acid is an ideal acidifier in terms of safety and reactivity with fertilizers or pesticides but is more expensive than other acids. Check added nutrient amounts by acids phosphoric acid can add too much P. Sulfuric acid is the cheapest and most common acid used for acidification.

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10 Electrical conductivity (EC) EC is a measure of total dissolved salts salinity indicator. ds/m = ms/cm = 1000 μs/cm = mmhos/cm Salinity damage is similar to drought stress (water uptake ). Water EC should be below 1 ms/cm. Soil EC should be below 2 ms/cm, but pomegranate is known to be moderately tolerant to salinity (up to 10 ms/cm).

11 Test water for ion toxicity Chloride, Sodium, and Boron are the most common toxic ions. Ion toxicity inhibits nutrient uptake or metabolism of other nutrients. The toxic level depends on the type of crop, ion, growth stage, etc.

12 Nutrient management

13 Soil & leaf tissue analysis Develop your fertilization program (ph, NPK, Ca, Mg, micronutrients, etc.) Monitor plant nutrition status and adjust your fertilization program if needed

14 Soil sampling Divide the field into different homogenous units based on the visual observation and your experience Remove the surface litter at the sampling spot. Sampling depth: from 0 to 12 Collect at least 10 to 15 samples from each sampling unit and place in a bucket or tray. Make one composite sample for soil test

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16 Soil ph and nutrient availability

17 NPK recommendations Recommendation rate (lb/tree) Age (year) N P 2 O 5 K 2 O *Recommendations by Dr. Zekri at UF/IFAS

18 Leaf sampling Divide the field into different homogenous units based on the visual observation and your experience Sample leaves from non-fruiting branches Collect at least 75 to 100 leaves

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20 Interpreting leaf tissue analysis Sufficient Farm 1 level Normal Tip-burn Farm 2 Farm 3 N (%) P (%) K (%) ( ?) Ca (%) (1.5-2?) Mg (%) Mn (ppm) Zn (ppm) Fe (ppm) B (ppm) Cu (ppm)

21 Pomegranate nutrient deficiency N P K Ca Mg Source: Marathe et al. (2016) S Cu Fe Zn Mo

22 Iron deficiency

23 Nutrient deficiencies on old leaves Old leaves Lower leaves only Developing to a whole plant Intervenial chlorosis Marginal chlorosis/scorch & petiole browning Uniform chlorosis and slow growth Reddish-purple coloring Magnesium Potassium Nitrogen Phosphorus

24 Nutrient deficiencies on new leaves New leaves Necrosis of terminal buds Intervenial chlorosis without necrosis of terminal buds Incomplete flower & fruit formation Tip-burn & curling Green border with green veining Copper & Zinc Marginal & interveinal necrosis when severe Chlorosis starting at base, uniform bleaching when severe Boron Calcium Manganese Iron

25 Leaf sampling Healthy plant Nutrient deficient plant Leaf #3 Largest fully matured leaf Leaf #2 First fully matured leaf Leaf #1 Young developing leaf 1) To monitor nutrient status of healthy plants Sample Leaf #2 2) To identify deficient nutrients Sample Leaf #2 and Leaf #1 or/and Leaf #3

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27 Soil sensors to monitor ph/ec Manufacture: Decagon Devices Data logger: Em50G (wireless data transmission) Sensor: GS3 (soil moisture & EC) Data access Software in PC Web browser

28 Interpreting data Insufficient irrigation Saturation = Target moisture Insufficient fertilization

29 Acknowledgments Collaborators Drs. Zhanao Deng and Gary Vallad Florida Pomegranate Association Florida pomegranate growers Florida Specialty Crop Foundation Funding FDACS Specialty Crop Block Grant Program Plant Physiology Lab Tia Silvasy (Biological Scientist II) Bill Wang (Lab/field technician) Evan McClenthan (Lab technician) Chris DelCastillo (Field technician) Anthony Ellis (Field technician) Evangelon James (Field technician) Lukas Vallad (Field technician) Syuan-You Lin (PhD) Stephen Deschamps (MS) Sana Shahzad (PhD visiting scholar)