managing and amending soils for productive yields in high tunnels, 2015

Managing and Amending Soils for Productive Yields in High Tunnels

Terrance T. Nennich, Fruit and Vegetable Production

Carl Rosen, Dept of Soil Water and Climate

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© 2012 Regents of the University of Minnesota. All rights reserved.

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

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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

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IMPROVING SOIL PHYSICAL PROPERTIES

Compost addition– 1-2 lbs compost per

sq. ft.

Use good quality compost– Beware of herbicide

residuals

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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

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CROPS THAT DEMAND HIGH FERTILIITYTomatoes CucumbersEgg PlantsOkraPeppers

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CROPS THAT USE MEDIUM FERTILITY Strawberries

Raspberries Fruit Trees Beans Potatoes ?? Carrots

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LOW FERTILITY CROPS

Lettuce Spinach Greens Beans Some cole crops

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PUTTING A HIGH TUNNEL IN PERSPECTIVE

1 acre = 43560 sq ft. A 26 X 96 High Tunnel = 2496 sq/ft 26 X 96 High tunnel = .057 acres A little over 1/20th of a acre. So when a soil tests requires 300 pounds of

Nitrogen for Example 300 X .057 = 17 pounds of N applied in the

high tunnel

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SOIL FERTILITY

Start with a complete soil test

$Cost is about 35.00 Bring soil to high level

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SOIL FERTILITY If soil fertility is low from the beginning you

will not work your way out.

If you are planting a crop in rows test the rows

We blame it on Potassium

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FERTILIZER PLACEMENT It is important to keep the high tunnel

fertility to a high level through out the high tunnel

But— In high tunnels the fertilizer extraction

zone is very narrow as compared to field production

12- 16 inches as compared to 36 inches + in the field

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TOMATO FERTILITY DEMANDS IN HIGH TUNNELS Not hard to get 5-7 pounds per plant Usually enough fertility in soil with a little

extra compost 20 pounds per plant excellent fertility 25- 50 pounds per plant requires

extremely high fertility, supplied at the proper stages of growth in proper amounts.

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“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)

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Tomato Fertilizer Use 5lb Plant


Field Production 13.5 ton: ( 5 Lbs Plant)

81 lbs N/A 11 lbs P/A (25.3 lbs P 2O5) 127 lbs K/A (152 lbs K 2O)

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A 50 ton yield/A would require: ( 20 Lbs Plant)

300 lbs N/A 40 lbs P/A (92 lbs P2O5)470 lbs K/A (564 lbs K2O)

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A 100 ton yield/A would require: ( 40 Lbs Plant)

600 lbs N/A 80 lbs P/A (184 lbs P2O5)940 lbs K/A (1128 lbs K2O)

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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

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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

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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

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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

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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

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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)

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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

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– Use legume cover crops

– Warm season cover crops can be planted later in the season

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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

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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

http://www.mda.state.mn.us/

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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

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Solubility of Common Fertilizers

Material Composit ion Salt index Solubil i ty

% N %P2O5 %K2O lbs/gal H20Calcium nitrate1 15.5 0 0 53 8.5Potassium nitrate 13.0 0 44 73 1.1 Ammonium nitrate 33.5 0 0 105 9.8Urea 46.0 0 0 75 6.5Ammonium sulfate2 21.0 0 0 69 5.9 Potassium chloride 0.0 0 60 116 2.3Potassium sulfate2 0.0 0 50 46 0.6Diammonium phosphate2 18.0 46 0 30 3.6

1May cause clogging if irrigation water is high in bicarbonates2Not recommended for use with calcium nitrate or if irrigation water is high in calcium

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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

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RATE AND TIMING OF APPLICATION Preparing soils and applying preplant nutrients is

still important - compost or fertilizer

About 1/2 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

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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

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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

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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.

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TISSUE TESTING Plant tissue analysis at first flower. Tissue analysis:

– 10-15 whole leaves

– Collect from average plants

– Collect 4-5th leaf from top Most recent mature leaf

– Paper bags only!– Overnight or pickup

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FOLIAR SPRAYS Foliar sprays will help, but it is difficult to

raise the potassium levels 2-4% points as would be needed. Boron also plays a role in helping with the uptake of K, Ca, sulfur and Mg.

More research needs to be done with this.

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FERTILIZER Needs to be added at least weekly Up to Flowering 1-1-1 ratio After flowering 2 -1- 2 ratio Possible 1-1-4 after harvest.

Added fertilizer should have Micro Nutrients.

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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

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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 1assumes 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

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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

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Amount of UAN Solution for Various N Rates per Acre

N Rates lbs/ac

1 2 3 4 6 8 10

28% Gallons/ac

0.33 0.67 1.00 1.33 2.00 2.67 3.33

28% fl. oz/100 l inear ft of

row1

0.39 0.78 1.16 1.55 2.32 3.10 3.88

1Assumes a between row spacing of 4 ft.

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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

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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

managing and amending soils for productive yields in high tunnels, 2015

Education

university of minnesota

high tunnel fertility

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high tunnels terrance

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