Dry matter masses [dt/ha]

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Eidgenössisches Departement für Wirtschaft, Bildung und Forschung WBF

Agroscope

Roy Latsch and Joachim Sauter

Dock-control

in organic farming

by hot-water treatment

07.07.2014

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Problematic substances of content

Oxalic acid in Rumex species with taproots Broad-leaved dock (Rumex obtusifolius)

Curled dock (Rumex crispus)

• Absorption of oxalic acid in the gastrointestinal tract

• Chemical bonding at Calcium => water-insoluble Calcium oxalate

• Can block the renal tubules => possible kidney damage

• Acalcinosis leads to:

− Cramps and vomiting

− Diarrhoea and colics

− Cardiac arrhythmia

− Irregularities of pulse and blood pressure

− Cardiac damage and death in serious cases

bääh !

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Seeds and roots

Quelle: wikipedia,de

Seeds

Plant Quantity/Plant.*a germinable

Broad-leaved dock 60’000 83 % after 21 a

Curled dock 40’000 50 % nach 50 a

2 % nach 80 a

Pasture: 1236 dock seeds per m²(Hunt & Harkess 1968)

100

200 0

Kutschera & Lichtenegger 1960

Roots

• Taproots can reach 2 m depth

• Storage of starch and tanning agents

• Aerenchyma in roots (compacted soil)

• Ability for regeneration: upper 10-15 cm

• Very small fragments can resprout

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Yield losses

Oswald & Haggar 1983

Quantity of dock plants per m

²

D ry m a tt e r m a sse s [d t/ h a ]

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Development of hot-water treatment I

Pretest in a cooking pot:

Water temperature: Ø 88 °C Treatment time: >10 s Mortality rate: 100 % Promising approach..!

Kärcher I:

Water temperature : Ø 120 °C Treatment time : 30 s

Water amount: 2.7 l

Fuel oil requirement: 0.05 l/Plt.

Problems:

- Energy consumption too high - Treatment time too long

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Development of hot-water treatment II

Kärcher II: 5 different application heads Dirt blaster^® as preferred treatment

Water temperature: Ø 93 °C

Treatment time: 10-12 s

Water amount: 1.6-2.0 l/plant Fuel oil requirement: 0.02 l/plant

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Film of treatment

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Results 2011 – 2013 (overview)

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Results 2011 – 2013

Dying rate of 80 % as a function of water amount and temperature for three different soil textures.

Soil moisture: 42.5 vol.-%.

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96.6

0.9

2.5 3.4

dead [%[ Adult plants [%] Juvenile plants [%]

Resprouted plants – one year after their treatment n = 564 plants

Resprouted plants

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Spade test

One year after treatment:

• Active root zone

• Good earthworm activity

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Working time requirement

Working time requirement:

• Total time of treatment: 1 h 50 min

• Quantity of treated plants: 236

• Quantity of vehicle movements: 2

• Water heating: 82.8 s

• Ø Treatment time: 19.76 s / plant

• Ø Search time for plants: 8.97 s / plant

• Performance (incl. vehicle movements & dysfunctions): 128.7 plant / h

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Procedural costs

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Conclusions hot-water treatment I

Hot-water treatment is practicable.

Mortality rate of 80 % reached at:

• Water temperature: >80 °C

• Water amount: Ø 1,6 litre per plant

• Fuel oil requirement: Ø 0,02 litre per plant 50 plants per litre fuel oil

Handling:

• Treatment time ca. 10-15 seconds

• Spot stream of rotary nozzle breaks up the soil structure

• „Contactless“ treatment

• Mud has to properly enclose the dock root

• Mud should reach a depth of about 15 cm

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Conclusions hot-water treatment II

Advantages compared to manual digging:

• No transportation of material

• Work performance two to three times higher than manual work

• Slightly more expensive compared with manual work

• A lot less strenuous

Example:

• At a weed infestation of 2000 dock plants per hectare, 3200 l of water and 32 l fuel oil for water heating would be needed.

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Introduction in practice

Construction, sales and distribution of a hot-water treatment device for dock control by a small Suisse enterprise.

Hans Bachmann

Hochdruckanlagen AG CH-9606 Bütschwil

40 sold units from 2013 until today Demonstration at “Technical Tour 1”

Thursday, 10.07.2014, Agroscope Tänikon

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