Course Water And Substrates 2008

© DLV Plant

Fertilisation and Dripping in Softfruit

on substrates

Wim Roosen

12 March 2008

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Program of today:

1. The role of water in plants

2. Strategy of dripping and feeding

3. What is EC and pH?

Deficiency of elements

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1. The role of water in plants

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The role of water in plants

Water uptake (average):

• 1 % Fotosynthesis

• 9 % Growing

• 90 % Transpiration

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The role of water in plants

Fotosynthesis

• H20 + CO2 + Light ���� C6H12O6 + O2

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The role of water in plants

Growing = Cell splitting + Cell stretching

Cell stretching:

Water + fertilizers + sugars

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The role of water in plants

Transpiration:

- Water transport

- Feed transport

- To cool leafs

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Transpiration

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Leaf under microscoop

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Stomata

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Regulation of the stomata

• Licht gives stimulation:

H+ out and K+ in � OPEN

• CO2 low: Cl- channel blocked

� OPEN

• CO2 high: Cl-channel open -K+ out� CLOSED

• Waterstress: Cl-channel openK+ out� CLOSED

• Forced K+ uptake � swelling(by osmosis) � OPEN

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Transpiration

Open/close of stomata depends on:

- Light/Hormonal

- Amount of water in the leafs

- Humidity in the air around

- CO2-amount (ppm) in the air

- Salts K/Cl

Important to know for GH: fotorespiration =

Plants makes his own CO2 in case of low CO2-

concentration in the air! Costs a lot of energy.

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Transpiration

Stomata not good open = negativ for:

- No optimal growing – especially to non transpirating

parts of the plants, as ……..

- Transpiration is cooling

↑ plant temperature = ↑ energy loss by respiration

- uptake CO2 (fotosynthesis)

H2O + CO2 + Licht = C6H12O6 + O2 giving …….

less sugars, less growing, less quality, less yield

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Transpiration

How can we stimulate the transpiration on stomata level?

- enough light

- well feed level & balance in subtstrates – in plant

- supply of enough water: transpired + run off

- RH control (humidity)

» Outdoor: sprinkle if hot/dry

» Tunnel: vent enough, not too much & on right time

» GH: same, heat (min pipe)

- Apply CO2 up to 1000-1200 ppm or max. 20 gr/m2/hr

Closed GH or tunnel CO2 down to 250 ppm

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Water supply by the roots

The uptake of feed by the roots is an osmotic process:

Sugars in the plant and salt concentrations around the roots

give an attraction to water.

Water transport in the plant further by osmotic forces and

rootpressure.

Rootpressure at the end of the day when air temperature goes

down and RH goes up:

» Transpiration reduces/stops

» Root activity still there

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Root activity

Root activity depends on:

- Substrate-EC

- Moist of substrate

- Quality of the roots

- Substrate/roottemperature

- Level of transpiration – RH/HD

- Radiation

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Rootpressure:

- More uptake than transpired → capitation

- Quick changing increases the root pressure.

- 1 moment per day = positive (few hours end of day)

- Spreading of Calcium to not transpirating parts

(new trusses and leafs) to avoid tipburn.

- Spreading assimilates to parts with no or few

chloroplasts (fruits, roots, seeds)

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Rootpressure:

- Long time = negative

- Cells collapse & die by O2 deficiency

growing points die, brown stolons, petioles

- Wet plants leads to Rhizoctonia, Botrytis, etc.

- In combination with many sugars/assimilates:

brown, wet, glue fruits = lost or misshape

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RH on day high:

• Disturbing water transport

• Appearing of fungis (Botrytis, etc.)

• Weak growing (loosing speed, earliness)

• Weak fruit (loosing quality, firmness)

• Tipburn (loosing LAI – leaf area)

Solution: reduce RH by

�Venting

�Heating

�Air movement (fans in GH, doors open tunnels)

�Cool the GH (new developments now in Holland)

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How to increase rootpressure?

- (Quick) drop down RH

- Decrease of EC

- Create good moist during the day & night.

- Good root/substrate temperature

- Good radiation (for strong roots)

Actions?

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How to increase rootpressure?

• (Quick) drop down RH

• Decrease of EC

• Create good moist during the day & night.

• Good root/substrate temperature

• Good radiation (for strong roots)

Actions?

Vent, EC decrease on radiation (on comp), never dry

coir, heat if possible, clean glass, new plastic, ……

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How to avoid/decrease rootpressure?

- Stimulate transpiration = get out of humidity in tunnels/GH

- Increase of EC gives less easy water uptake

- Less drips, less run off, EC goes up.

Let struggle the plant to get water.

- Decrease temperature of substrate/roots: reduces activity.

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Not enough root activity

When the transpiration is getting too much the plant

protects himself by closing the stomata

→ less transpiration → RH down around leaf →further closing of the stomata, CO2 by respiration

Gives a (large) increase of plant temperature, and a

decrease till complete stop of growing processes (=

stress).

Plants start to use energy (burning sugars):

- Size of fruit drops, growing stops

- Quality decrease: pink, albinsm

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Actions to do:

→ Create a transpiring plant as plants are cooling machines- get the plants used to regularly low RH on the day

(that gives the power to …………..)

- strong and working roots (EC-decrease, dripping)

→ Cool down the plastic/glass: roof sprinklers→ If RH < 55-60%: - overhead sprinklers (inside)

- air humifying systems

→ Climate steering: less vent on wind side and decrease tolee side as well. Better temp a bit higher and better RH +

CO2 levels.

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Relative Humidity:

• Optimum RH during growing 70-75%

• During flowering/pollunation: 60-70%

• While harvest: around 70%

• At night: > 85% (rootpressure)

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2. Strategy dripping and feeding

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Drippers to discuss

• CNL

• PCJ

• French capillair

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Strategy dripping and feeding

Always a steering to a certain EC/moist level that the plants

do need at that moment and the week after:

WaterEC-FeedStage / Needs of

Growing

Flowering

Harvest

Rooting

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Dripping EC and pH

Crops on coir, except blues is a mix

5,62,7-2,91,3-1,51,3-1,51,2-1,5Everest

1,2-1,5

2,5-3,0

2,0-2,5

1,6-1,8

Run off

4,52,0-2,50,9-1,21,1-1,5Blues

5,64,5-5,52,0-2,52,0-3,3Blacks

5,64,0-5,01,7-2,52,0-3,0Rasps

5,63,0-3,21,4-1,71,2-2,0Elsanta

pHSum ECHarvest Growing EC

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Dripping

Around planting strawberries:

• Before planting substrates moist is preferred.

• Coir to wet up with EC 1,3

Shower/flush after planting:

• To clean the leafs (sand and dirt delays)

• To contact roots to substrate

• To avoid dry places around the roots

• To get feed in (in case of coir) EC 1,3

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Dripping

Start dripping after planting strawberries:

• Keep the whole substrate (espec. bags - corners) at

good moist level. WET probe 50-60%. FEEL!

• Peat: no feed added on fertilized peat + bare root

plants during first week. Trayplants EC 1,0-1,2

• Coir: start with trays/misted tips at EC 1,3-1,4

• When rooting goes on: increase EC - slow/fast?

• Only in Winter time: few drips a week EC 2,5 on wet

bags to get some feed in.

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Dripping

Growing stage Elsanta

• Increase drip EC 1,5-1,7

• Get run off to EC 1,5-1,6 as an always minimum for all crops.

• Drain-%:

0-5 % when less activity

10-20% when good growing

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Dripping

Flower and green fruit stage Elsanta

• Drain-EC to build up to 1,7-2,0

• Drain % 10-15 % when less activity

25-30 % when good growing

• From 1 week before harvests starts:

decrease EC to 1,7 till 1,4 when hot ta avoid high EC

• During picking: run off EC 1,7-1,8 target

• What to do if EC run off = 3,0?

• ……..

• ……..

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Dripping

Not only the % of run off counts!

- Drip times: 2,5 – 3 minutes on strawberries

- Amounts of drips

- Stage of crop

- Radiation, radsum

- Wind & RH

- Start and stop times on sunny weather…..

and on cloudy weather…..

- Moment that run off falls: AM, PM, night?

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Dripping – how much?!

The substrate may never be dry on the root-ends:

- Drip as much as needed! FEEL!

- The equipment needs to be reliable and enough

capacity to give up to 3 drips x 3 minutes per hour

- In Winter Elsanta / Tulameen to double crop:

- pH goes down � drip pH 6,0 from October

- EC goes up as plants do not use much �

EC 1,0-1,2 to drip (“only acid”)

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Water usage table top Elsanta

• Crop full grown and fully loaded fruit

• 30ºC

• RV 50%

• Wind: 7 m/s

• Run off included

Water usage outdoor: up till 8 liter/m2/day!

With 4 drippers/mtr (400 ml drip): 25 drips/day

Water usage tunnels: up till 6 ltr/m2/day!

Around 20 drips/day.

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EC-decrease

When there is much transpiration by heavy sun:

- less need to feed, water!

- to avoid accumulation of salts

EC-decrease on the day, f.i. EC1,8 – 0,3:

- from 10.30 en 15.30 hr (when long distances)

- on radiation also possible on short distances, but the

traject W/m2 needs regular adjustments!

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Start en stop times

• Too wet substrate at night gives too low oxigen in the

substrate � leads to weak and dying roots

• But: a loaded crop with ripening fruits needs to stay on

rootpressure for size and taste and to avoid.

So avoid dry moments at night and early morning!

• Growing and flowering stage to drip 1-2 hours before sun

set.

• From white fruit stage drip till around sun set

• And spread well the drips over the day:

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Spread the drips over the day:

1 drip 11

2 ,, 10-13

4 ,, 9-11-13-15

8 ,, 8-10-11.30-13-14-15-16-17.30 (average)

12 ,, 7-8.30-10-11-12-13-14-15-16-17.30-19.30

16 ,, 7-8-9-10-11-11.45-12.30-13-13.30-14-14.30-15.15-

16-17-18.30-20

20 ,, 6-7-8-9-10-10.45-11.30-12-12.30-13-13.20-13.40-

14-14.30-15-16-17-18-19.30-21

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GOLDEN RULE IN DRIPPING:

IF THE 1st DRIP IN THE MORNING GAVE RUN OFF THEN:

………..……………………...

1. First drip was too early or

2. Previous day 1 drip too less given

WE WANT RUN OFF JUST STARTING DURING THE 2ND

DRIP IN THE MORNING

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Run off control

Drain collection:

• check drain EC en pH

• check amount of drainwater

• minimum 1 draincollection per valve

• check run off moments over the day

Every drip needs some run off: 2-5-10-20-30%, so not

the last drip giving 90%....... pumping up your %.

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Why run off?

• Moistening whole volume of substrate

• Compensates differences in drippers, plants, volume

• Even balance in feed elements, close to recipe

• To flush out salts as sodium and chlorides, and so to avoid accumulation of these

• Too much run off:

• decrease of oxigen – weak roots etc.

• loss of fertilizers, gras growing too fast…

• increases degeneration in case of peat

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Run off collection point

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3a. What is EC and pH?

3b. Deficiency of elements

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Feed elements

• Macro-elements

• N, P, K, Mg, Ca, and S

• Micro-elements

• Fe, Mn, Zn, B, Cu, Mo

• Passive or active uptake by the roots

• Antagonism with active uptake

• Mobile (N+, K+, Mg2+)

Immobile elements (Ca2+, Mg2+, PO4, SO4)

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Ions uptake

• Uptake of the ions by the roots is regulated by

exchange: f.i. K+ <> H+ or NO3 <> OH

• Uptake positive ions: pH drops

• Uptake negative ions: pH goes up

• Plants prefer single-loaded ion (K, NO3)

Good balanced recipes in each stage of crop!

• What is important to know to make a good recipe?

• The basic water contents: rain, river, mains,

borehole, salty water (to coast)

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Elemental Chemistry

• Atom (f.i. N, O, H)

• Molecule (Bijv. CaCl, H2O, CaNO3)

• Ion = electrical loaded element pos + or neg -

2+/3+/4+ or 2-/3-/4-

• Calcium (Ca2+) + Nitrate (NO3-) � Ca(NO3)2

ion + ion = fertilizer

• Calciumnitrate = 14,5% N-NO3

1,0% N-NH4

19,0% CaO

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EC in mS/cm

• Only ions are taken (exchanged) by the roots

• Ions in water give a conductivity.

More ions in water give more conductivity.

Ions do differ in conduction: 3+ more than 1+

• Electrical Conductivity = EC in mS/cm

• Does high run off EC mean high NO3?

• Concentration: more salts � higher EC

• Water: less water/dry �………….

• Temperature: warmer gives more EC

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Crop, growth and EC

• Optimum EC for strawberries = LOW compared to

other crops.

• Strawberries are salt-sensitiv crops!

Drip EC 1,3 - 2,0 and blackberries EC 1,5 - 3,5

What does that mean? (think on the basic water)

• Low EC: easy possible deficiency

• High EC: bad rooting, less growth, poor yield, size

& quality

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pH

• pH = concentration of free H+ ions

• Most crops pH 5,5-6,0 is optimum = just a few H+

• Mmol/liter – the more H+ � the lower pH

pH4 = 10x more acid as pH5 = 10x more acid as pH6

• Acids available: nitric, phosphoric, sulphuric

• What happens when we add acid to bicarbonate?

• HNO3 + HCO3-� H20 + CO2 + NO3

• Hard water = much Ca and HCO3 (takes time to react)

We need the recipes to calculate well: Ca & NO3

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pH tabel

• Optimum pH 5,5-6,0

• Too low: roots die

• 1st problem high pH:

– Manganese (leaf)

– Iron (add Eddha - red)

– Boron (flowers!)

• EC up � pH down A/B

• EC low � pH control OK?

• Pre acid water pH 6,0

contains NO3

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Sampling, what?

• Substrate: give long term (some weeks) average

To check the recipe + water adjustments.

Feed can be perfect, but dripped wrong gives poor crop.

To Holland / BLGG in case of doubts.

• Leafs: gives ……. Good levels on bad crop possible.

Yellow leafs: wrong recipe, high pH, forgotten in tanks.

• Run off: only when dripping enough > 20% run off very actual situation = short term. Adjust every 2 weeks.

• Dripwater: to test the whole system. Try it.

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Nitrogen deficiency

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Deficiency to Phosphorus

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Deficiency to Potassium

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Deficiency to Calcium - tipburn

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Deficiency to Magnesium

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Deficiency to Sulphur

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Deficiency to Iron – high pH

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Deficiency to Manganese

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Deficiency to Boron - flowers

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Too much Boron – black

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Deficiency of Zinc

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Deficiency of Molybden

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Salt damage

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Albino fruit

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Where does the coir come from?

• Palmae of Arecaceae

• Cocos nucifera

• 30 mtr high, - 6 mtr leaves

• Big industry: oil-shampoo, milk-

pina colada, jewelery, bounty,

fibres (drainpipes, door-mats,

carpets)

• “dust” was left….. till some

Dutchmen saw it in 1990.

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Thanks for your attention

Questions?