Managing and
Amending Soils for
Productive Yields
in High Tunnels
Carl Rosen
Department of Soil, Water, & Climate
Universi...
Topics
   Considerations before planting
       Site selection
   Yield potential in a high tunnel
       Satisfying n...
Site Selection

   Ideal soil is a well-drained sandy loam to silt
    loam

   Medium to high organic matter levels (3....
Improving Soil Physical Properties

   Compost addition
       1-2 lbs compost per
        sq. ft.


   Use good qualit...
Yield Potential & Nutrient Needs
   Yields in a high tunnel can be 2
    to 4 times the yield obtained in
    the field

...
“Book Values” for Tomatoes
                   N                P               K
Plant Part         -------- lb per ton F....
Satisfying Nutrient Demand in a
High Tunnel System

   Release of nutrients from the soil
       Importance of good prep...
Amendments Before Planting
   Have soil tested before
    applying amendments
       pH, OM, nitrate-N, P, K,
        Ca...
Soluble Salts (EC)
   Based on saturated paste:
       < 2 mmhos/cm (dS/m) - no
        problems
       3-4 some plants...
Soil pH
   Acceptable range: 5.5-7.5

   Adjust before planting
       Acid soils – use calcitic or dolomitic
        l...
Phosphorus and Micronutrients
   Base P application on soil test level
       Greater than 41 ppm is considered very hig...
Nitrogen and Potassium
   A portion should be applied before planting

   Base K fertilizer application on soil test – m...
Nutrient Management
        Without Fertigation

   Organic systems
       Composted manure
            Type of compost...
Nutrient Management
       Without Fertigation

   Use legume cover
    crops

   Warm season cover
    crops can be pla...
Nutrient Management
         Without Fertigation
   Conventional system
       Composted manure
       Soluble fertiliz...
Nutrient Management
        With Fertigation

   Injection of one or more nutrients into the
    irrigation water

   Re...
Nutrient Management
          With Fertigation
   Primarily used for nitrogen and
    potassium
       Urea-ammonium nit...
Solubility of Common Fertilizers
Material                    Composition             Salt index        Solubility
        ...
Mixes to Avoid
   Phosphorus compounds with calcium or iron

   Calcium with sulfate and bicarbonate

   To avoid preci...
Rate and Timing of Application
   Preparing soils and applying preplant nutrients is
    still important - compost or fer...
Fertigation
   Use a batch loading fertigation approach

   Inject total volume of nutrient during an irrigation event

...
Meeting the Demands for Crops
          with Different Requirements
   Fertigate crops at different
    times
       All...
Determining the Rate of N and K
     to Apply
   Most conventional
    recommendations are
    based on lbs N or K2O/A

...
N and K Fertigation Schedule for
           Tomatoes - lb/A basis

Days after Planting   Daily N Weekly N Seasonal N Daily...
N and K Fertigation Schedule for
             Tomatoes – oz per 100 ft basis

Days after Planting    Daily N Weekly N Seas...
Calculating the Rate of Fertilizer
     to Inject
   Example for urea-ammonium nitrate (28%)
       Area to fertilize – ...
Amount of UAN Solution for
       Various N Rates per Acre
N Rates lbs/ac         1        2       3        4         6   ...
Summary
   Soil test before planting

   Incorporate compost if needed to improve soil physical
    and chemical propert...
Summary
   For conventional systems, use fertigation
    with soluble N and K sources or use
    controlled release ferti...
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High Tunnel Soil Management

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Presentation by University of Minnesota professor Carl Rosen for the 2009 Minnesota Statewide High Tunnel Conference, held in Alexandria, MN on Dec. 2-3, 2009.

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High Tunnel Soil Management

  1. 1. Managing and Amending Soils for Productive Yields in High Tunnels Carl Rosen Department of Soil, Water, & Climate University of Minnesota © 2009 Regents of the University of Minnesota
  2. 2. Topics  Considerations before planting  Site selection  Yield potential in a high tunnel  Satisfying nutrient needs  Preplant amendments  Importance of soil testing  Nutrient management  Without fertigation  Nutrient sources – organic and controlled release  With fertigation  Nutrient sources & timing of application © 2009 Regents of the University of Minnesota
  3. 3. Site Selection  Ideal soil is a well-drained sandy loam to silt loam  Medium to high organic matter levels (3.5 to 6%)  Consider growing green manure crops before planting/establishing the tunnel  Sorgum-sudan  Rye or oats  Legumes such as field peas, clover © 2009 Regents of the University of Minnesota
  4. 4. Improving Soil Physical Properties  Compost addition  1-2 lbs compost per sq. ft.  Use good quality compost  Beware of herbicide residuals © 2009 Regents of the University of Minnesota
  5. 5. Yield Potential & Nutrient Needs  Yields in a high tunnel can be 2 to 4 times the yield obtained in the field  Higher yields will require more nutrients, but knowing how much to apply is a challenge  Lack of nutrients – deficiencies  Excessive nutrients – salt build up  Both situations affect yield and quality © 2009 Regents of the University of Minnesota
  6. 6. “Book Values” for Tomatoes N P K Plant Part -------- lb per ton F.W. ------------ Fruit 3.4 0.4 6.0 Vines 2.6 0.4 3.4 Total 6.0 0.8 9.4 A 50 ton yield/A would require: 300 lbs N/A 40 lbs P/A (92 lbs P2O5) 470 lbs K/A (564 lbs K2O) © 2009 Regents of the University of Minnesota
  7. 7. Satisfying Nutrient Demand in a High Tunnel System  Release of nutrients from the soil  Importance of good preparation  Addition of fertilizer  Preplant  During the growing season  fertigation © 2009 Regents of the University of Minnesota
  8. 8. Amendments Before Planting  Have soil tested before applying amendments  pH, OM, nitrate-N, P, K, Ca, Mg, micronutrients, soluble salts  Retest yearly, especially if problems are occurring © 2009 Regents of the University of Minnesota
  9. 9. Soluble Salts (EC)  Based on saturated paste:  < 2 mmhos/cm (dS/m) - no problems  3-4 some plants affected  5-7 many plants affected  >8 only salt tolerant plants survive  Most soils in Minnesota have low salts, but salts may accumulate with excessive fertigation © 2009 Regents of the University of Minnesota
  10. 10. Soil pH  Acceptable range: 5.5-7.5  Adjust before planting  Acid soils – use calcitic or dolomitic limestone  Alkaline soils – use compost, sphagnum peat, elemental sulfur © 2009 Regents of the University of Minnesota
  11. 11. Phosphorus and Micronutrients  Base P application on soil test level  Greater than 41 ppm is considered very high for most vegetables/fruit  Incorporate before planting if soil test indicates a need  Potassium phosphate, DAP, MAP  Numerous micronutrient sources  Composted manure  Use starter solutions high in P for transplants © 2009 Regents of the University of Minnesota
  12. 12. Nitrogen and Potassium  A portion should be applied before planting  Base K fertilizer application on soil test – most can be applied preplant  Greater than160 ppm is considered very high for most vegetables/fruit  potassium chloride (0-0-60)  potassium sulfate (0-0-50)  potassium magnesium sulfate (0-0-22); acceptable organic source  For soluble N sources, apply about 1/3 – 1/2 of the required N before planting  urea (46-0-0)  ammonium nitrate (34-0-0)  calcium nitrate (15.5-0-0)  potassium nitrate (13-0-44)  composted manure (variable) © 2009 Regents of the University of Minnesota
  13. 13. Nutrient Management Without Fertigation  Organic systems  Composted manure  Type of compost  Moisture content  Crops grown  To supply equivalent of 100 lbs available N/A:  Dairy manure compost: 2700 lbs/1000 sq. ft.  Poultry manure compost: 900 lbs/1000 sq. ft.  Incorporate 6 to 8 inches into soil © 2009 Regents of the University of Minnesota
  14. 14. Nutrient Management Without Fertigation  Use legume cover crops  Warm season cover crops can be planted later in the season © 2009 Regents of the University of Minnesota
  15. 15. Nutrient Management Without Fertigation  Conventional system  Composted manure  Soluble fertilizers  Controlled release N fertilizers  Coated urea  Osmocote  Be sure that release rate is fast enough for the crop being grown  For most vegetables – 50 to 70 day release is needed  Temperatures are warmer in a high tunnel – faster release © 2009 Regents of the University of Minnesota
  16. 16. Nutrient Management With Fertigation  Injection of one or more nutrients into the irrigation water  Review the Minnesota Chemigation/Fertigation Permit Application and Safety Requirements  www.mda.state.mn.us  Submit the Minnesota Chemigation/Fertigation Permit Application to MDA  Main requirement is to have recommended anti-pollution and safety devices © 2009 Regents of the University of Minnesota
  17. 17. Nutrient Management With Fertigation  Primarily used for nitrogen and potassium  Urea-ammonium nitrate (28%N) (liquid)  Calcium nitrate (15.5% N)  Potassium nitrate (13% N; 44% K2O)  Potassium chloride (60%; K2O)  Blends eg. 20-20-20  Soluble sources of organic fertilizers are available, but are expensive and may cause clogging  Some fish emulsions have been successfully used © 2009 Regents of the University of Minnesota
  18. 18. Solubility of Common Fertilizers Material Composition Salt index Solubility %N %P2O5 %K2O lbs/gal H20 Calcium nitrate1 15.5 0 0 53 8.5 Potassium nitrate 13.0 0 44 73 1.1 Ammonium nitrate 33.5 0 0 105 9.8 Urea 46.0 0 0 75 6.5 Ammonium sulfate2 21.0 0 0 69 5.9 Potassium chloride 0.0 0 60 116 2.3 Potassium sulfate2 0.0 0 50 46 0.6 Diammonium phosphate2 18.0 46 0 30 3.6 1May cause clogging if irrigation water is high in bicarbonates 2Not recommended for use with calcium nitrate or if irrigation water is high in calcium © 2009 Regents of the University of Minnesota
  19. 19. Mixes to Avoid  Phosphorus compounds with calcium or iron  Calcium with sulfate and bicarbonate  To avoid precipitation problems two stock tanks should be used, one for calcium nitrate and iron chelate and the other for the remaining fertilizers  Alternatively apply P fertilizer preplant © 2009 Regents of the University of Minnesota
  20. 20. Rate and Timing of Application  Preparing soils and applying preplant nutrients is still important - compost or fertilizer  About 2/3 of N and K needs can be applied through fertigation  Timing is not as critical as rate  Once per month  Once per week  Every time there is an irrigation event © 2009 Regents of the University of Minnesota
  21. 21. Fertigation  Use a batch loading fertigation approach  Inject total volume of nutrient during an irrigation event  Total volume of fertilizer for batch loading depends on the area of the irrigated zone and the desired nutrient rate  The injection rate does not need to be precisely controlled  The injector should apply the chemical solution in a time period that does not result in over-irrigation, otherwise leaching will occur © 2009 Regents of the University of Minnesota
  22. 22. Meeting the Demands for Crops with Different Requirements  Fertigate crops at different times  Allows for varying rates to be applied  Fertigate to meet the demands of the crop needing the lowest amount of nutrients  Make up difference with preplant fertilizer © 2009 Regents of the University of Minnesota
  23. 23. Determining the Rate of N and K to Apply  Most conventional recommendations are based on lbs N or K2O/A  Ounces per linear feet of row is more practical for high tunnels  Based on 4ft spacing between rows  100 linear ft = 400 sq. ft. © 2009 Regents of the University of Minnesota
  24. 24. N and K Fertigation Schedule for Tomatoes - lb/A basis Days after Planting Daily N Weekly N Seasonal N Daily K2O Weekly K2O Seasonal K2O ----------------------------------------- lb/A--- ---------------------------------------------- Preplant ---- ---- 50.0 ---- ----- 100.0 0- 21 0.5 3.5 61.5 1.0 7.0 121.0 22- 49 0.7 4.9 81.1 1.4 9.8 160.2 50- 70 1.0 7.0 102.1 2.0 14.0 202.2 71- 91 1.1 7.7 125.2 2.2 15.4 248.4 92-112 1.0 7.0 146.2 2.0 14.0 290.4 © 2009 Regents of the University of Minnesota
  25. 25. N and K Fertigation Schedule for Tomatoes – oz per 100 ft basis Days after Planting Daily N Weekly N Seasonal N Daily K2O Weekly K2O Seasonal K2O --------------------------------- oz/100 linear row ft -------------------------------------- Preplant ---- ---- 7.3 ---- ----- 14.7 0- 21 0.07 0.50 9.0 0.15 1.1 17.8 22- 49 0.10 0.70 11.9 0.21 1.5 23.5 50- 70 0.15 1.05 15.0 0.29 2.0 29.7 71- 91 0.16 1.12 18.4 0.32 2.2 36.5 92-112 0.15 1.05 21.5 0.29 2.0 42.6 1 assumes 4 ft spacing between rows; lb/A X 0.147 = oz/100 linear ft of row. lbs/A x 0.147 = oz/100 linear ft of row © 2009 Regents of the University of Minnesota
  26. 26. Calculating the Rate of Fertilizer to Inject  Example for urea-ammonium nitrate (28%)  Area to fertilize – 200 linear feet (800 sq. ft.)  Liquid (28% N) – 3 lbs N/gallon  Recommendation is 10 lbs N/A  10/3 = 3.33 gallons/A  3.33 gal * 800/43560 * 128 oz/gal = 7.8 fl oz  Use similar approach for granular except conversion to lbs product rather than fl. oz. is made © 2009 Regents of the University of Minnesota
  27. 27. Amount of UAN Solution for Various N Rates per Acre N Rates lbs/ac 1 2 3 4 6 8 10 28% 0.33 0.67 1.00 1.33 2.00 2.67 3.33 Gallons/ac 28% fl. 0.39 0.78 1.16 1.55 2.32 3.10 3.88 oz/100 linear ft of row1 1Assumes a between row spacing of 4 ft. © 2009 Regents of the University of Minnesota
  28. 28. Summary  Soil test before planting  Incorporate compost if needed to improve soil physical and chemical properties  If needed adjust acid soil pH with lime  Incorporate P and micronutrients before planting based on a soil test  For organic production use composted manure before planting © 2009 Regents of the University of Minnesota
  29. 29. Summary  For conventional systems, use fertigation with soluble N and K sources or use controlled release fertilizers  A portion of the N and K can be applied before planting  Total rate applied is more important than timing  Use the tables provided to estimate amounts of nutrient required on a linear foot basis © 2009 Regents of the University of Minnesota

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