CEL and Moulton Presentation 15 May 2013

Dr Mary Dimambro – Cambridge Eco

Dr Russ Sharp and Sam Brown – Moulton

Agenda 10:00 Welcome. Dr Russ Sharp, Moulton College

10:05 Introduction to anaerobic digestion and current research on the use of

digestates in horticulture. Jacks Guinness, WRAP

10:25 Introduction to the project on the use of digestates in novel growing

media for ornamentals. Dr Mary Dimambro, Cambridge Eco

10:35 Trial system design, growing media and results to date for black pine,

cyclamen and fern. Sam Brown – Moulton College

10:45 Potential application to industry. Dr Russ Sharp, Moulton College

11:00 Discussion

11:20 Viewing the glasshouse trials

11:45 Discussion, tea and coffee, networking

12:00 Close

About Moulton College Moulton is the only land-based college to

teach from ‘special needs’ through to

‘doctoral studies’.

Graded by OFSTED as Outstanding!

Campuses/academies in Moulton, Higham

Ferrers, Silverstone, Daventry and

Peterborough

About Moulton College Horticultural research currently funded on a

diverse range of subjects:

LED lighting

Growing media

Soil compaction (PhD)

Soil-borne diseases (PhD)

Plant propagation (PhD)

Urban cooling (PhD)

Alternative crops

Garden History

About Cambridge Eco

Advising Defra, WRAP, industry, growers

Experts in the use of

composts

digestates

Use of digestates as a liquid fertiliser for

commercial strawberry production

6 digestates

Grow bags with trickle irrigation

Digestate Control

Digestate Control Digestate Control

Admixtures Trial

bark

+ other sustainable materials

+ digestates

= novel growing media

Why bark and digestate?

Bark = Low bulk density, nitrogen content, and pH

+ an absorbent matrix

Digestate = High bulk density, nitrogen content, and pH

+ liquid digestate able to be absorbed onto matrix

Ornamentals chosen = non-food crop with high

tolerance to salinity and ammonium.

Use of digestates in novel

growing media for ornamentals

Project phases:

October-December: Desk study

January-February: Designing the admixtures

March-May: Glasshouse trial

June-August: Report

Design Considerations -

Admixtures

Bark admixtures optimised for

Fern

Cyclamen

Pine

All can grow in standard hardy nursery stock mix

Design Considerations -

Admixtures

Key parameters:

Particle size, air filled porosity and drainage

Electrical conductivity important

Ferns and cyclamen: up to 200µS/cm with low levels of

nutrients

Pines: 600µS/cm (pollution and salt tolerant) with base

fertiliser and long term controlled release fertiliser

Digestate analysis

Food

Separated Food

Whole 1 Food

Whole 2 Potato

Whole

Maize

Slurry

Separated Maize

Separated

Total

solids (%) 2.9 3.7 4.5 2.2 7.1 5.1

C:N 4.0 3.5 3.3 3.3 7.3 6.1

pH 8.5 8.4 8.4 8.2 8.2 8.2

EC (1:6)

(dS m-1) 4.4 5.4 7.0 4.2 4.5 3.8

Digestate analysis

Food

Separated Food

Whole 1 Food

Whole 2 Potato

Whole

Maize

Slurry

Separated Maize

Separated

mg/kg mg/kg mg/kg mg/kg mg/kg mg/kg

N 3700 4900 6000 2400 4200 4100

NH4-N 2990 3784 5260 2039 2044 2175

NO3-N (<) 0.1 0.1 0.1 0.1 0.1 0.1

P 202 315 456 128 514 246

K 1330 1869 1109 4752 4661 3382

Ca 797 2000 1974 126 1862 889

Mg 92.9 93.3 63 46 436 188

S 134 236 342 78 303 171

Fe 75 231 555 57 197 54

Mn 3.4 8.4 5.0 1.3 15.9 6.4

Na 1021 1146 2225 46.4 439 121

Can digestates replace

additives? Dolodust (magnesium limestone): Raise the pH level &

adds traces of magnesium

Digestates pH balances the low pH of the bark, and

contain sufficient magnesium

Nitrochalk (ammonium nitrate & calcium carbonate)

Digestates have adequate or high levels of ammonia

and calcium

Fertilisers (base and controlled release)

Digestates contain sufficient nutrients

Trial design

Controls (industry standards)

Peat-based control (PC)

Peat-free control (bark and wood fibre based, BC)

4 digestates – each with 5 admixtures

5 replicates = 110 plants per trial

Trial design

Randomised plot design. Rearranged at fortnightly

intervals to minimise edge effects

Both labels and pot markings used to identify plants

in each treatment.

Extra plants bought in to allow grading of plants

before allocating treatments.

Trial Design

Plants irrigated to just below drip point to ensure that

digestate did not leak out and move between treated

plants.

Saucers not used to ensure no stagnant water was

present around the roots.

Plants monitored for signs of pests and diseases.

None currently found so far.

Electric heaters in use in early part of the trial and

then vents opened to ensure a cool growing

environment typical of an HONS nursery.

Subject species

Why Black pines? HONS plant highly tolerant to both

salt and heavy metal pollution.

Why Ferns? A HONS plant that thrives in organic

growing media rich in ammonium.

Why Cyclamen? A HONS plant that thrives in

organic growing media for which we can obtain

flowering data.

Making the admixtures

The main selection criteria were EC, structure and

consistency (not too wet or too dry)

Standard ingredients trialled

The final admixtures:

60% bark, 30% wood fibre, 10% top soil + digestate

Final admixtures

Digestate

feedstock

Digestate

Type

Volume of digestate in 5 litres of

admixture (ml)

100 250 500 750 1000

Food

waste

Separated

liquor FS1 FS2 FS3 FS4 FS5

Food

waste Whole FW1 FW2 FW3 FW4 FW5

Potato

waste Whole PW1 PW2 PW3 PW4 PW5

Maize Separated

liquor MS1 MS2 MS3 MS4 MS5

pH Cond. at

20 ◦C

Density Ammonia-

N

Dry

Matter

Nitrate-N

NAME uS/cm kg/m3 mg/l % mg/l

BC 6.4 435 468 48.1 52.9 6.9

PC 5.39 311 420 30.3 39.1 131

MS1 6 96 405 38.3 62 18.8

MS2 6.3 150 406 63.2 62.9 21.9

MS3 7 213 462 97 53.3 17.4

MS4 7.41 317 551 146 50.5 19.1

MS5 7.63 431 575 225.8 44.2 6.1

FS1 5.97 102 366 40.1 62 17.6

FS2 6.59 161 414 79.9 61.3 20

FS3 7.3 238 505 128.3 53.8 22.3

FS4 7.72 411 545 246 49 2.3

FS5 7.67 536 607 299.5 43.2 8.4

Available nutrients Total

Soluble

N

Chloride Sulphate Phosphorus Boron Potassium Copper

NAME mg/l mg/l mg/l mg/l mg/l mg/l mg/l

BC 55 77.7 927.8 27.3 0.17 460.5 0.08

PC 161.3 18.7 228.4 78.1 0.19 253.7 <0.06

MS1 57.1 43.7 20 5.4 0.18 88.9 0.07

MS2 85.1 81.4 43.8 10.5 0.16 130 0.13

MS3 114.4 134.4 32.1 26.7 0.2 210.5 0.21

MS4 165.1 181.2 40.5 36.3 0.15 290.6 0.21

MS5 231.9 215.4 41.5 54.3 0.17 410.4 0.31

FS1 57.7 53.3 28.6 6.1 0.16 80.9 0.1

FS2 99.9 119.9 38.1 10.5 0.19 90.4 0.11

FS3 150.6 207.5 41.5 16.5 0.14 108.5 0.12

FS4 248.3 337.1 45.6 24.2 0.15 174.5 0.16

FS5 307.9 424.9 43.7 29.7 0.15 221.9 0.17

Monitoring

Fortnightly assessment

Pines: Plant height and number of branches.

Ferns: Number of fully extended fronds and length of

longest frond

Cyclamen: Number of leaves and flowers

Monthly assessment

Foliage quality:

SPAD chlorophyll meter (ferns and cyclamen)

Visual assessment (all)

Results to date

Trials will finish over the next few weeks

All data collected so far show no significant

difference in the response of all three species to the

different growing media for all parameters tested.

Analysed via ANOVA and Kruskal Wallace tests.

Full results in final report, including changes over

time and final harvest measurements.

Results: Fern

0

20

40

60

80

100

120

140

160

PC BC FS1 FS2 FS3 FS4 FS5 FW1 FW2 FW3 FW4 FW5 MS1 MS2 MS3 MS4 MS5 PW1 PW2 PW3 PW4

Fro

nd

le

ng

th / m

m

Treatment

Results: Fern

0

5

10

15

20

25

30

35

PC BC FS1 FS2 FS3 FS4 FS5 FW1 FW2 FW3 FW4 FW5 MS1 MS2 MS3 MS4 MS5 PW1 PW2 PW3 PW4 PW5

Nu

mb

er

of

fon

ds

Treatment

Results: Fern

Results: Cyclamen

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5


Ave

rag

e l

ea

f n

um

be

r

Treatment

Results: Cyclamen

Results: Pine

0

50

100

150

200

250

300


Ave

rag

e i

nc

rea

se

in

he

igh

t /

cm

Treatment

Results: Pine

0

2

4

6

8

10

12

14

16

18

20


nu

mb

er

of

ste

ms

Treatment

Cost benefit analysis

Comparing the costs of the admixtures to standard

growing media

Digestate Requirement

1m3 digestate enough for

~ 5 m3 - 50 m3 growing medium

One lorry load digestate

~ 25 t digestate

~ 5 – 50 lorry loads of growing media

Digestate Storage

Volume Type Cost

/m3/year

over 10

years

1 m3 White 1000 Litre IBC container £ 7

1 m3 New IBC, timber pallet £ 10

10 m3 CT2200JA Tank £ 12

19 m3 V19000 £ 13

36 m3 Elliptical Concrete Tank £ 15

72 m3 Small AD storage unit £ 24

4500 m3 Steel / concrete above ground £ 3.5

4500 m3 Earth bank lagoon £ 2

Transport

Transport cost depends on

Distance

Volume

Frequency of deliveries

Typical digestate transport costs per 26t lorry:

£4 /m3 if using infrastructure of digestate producer

£6 /m3 if 4 lorry loads per day are delivered

£23 /m3 if 1 lorry load per day is delivered

Ingredients Cost of peat has increased

Due to adverse weather conditions during harvest

World shortage of peat in 2013

Lacking peat content is replaced with bark and

woodchip and other materials

Now less than 80% peat in some peat based growing

media

Cost of growing media ingredients is volatile

Currently the cost of some peat free growing media is

artificially lowered to encourage uptake

Cost of raw ingredients is only a snapshot / estimate

Growing Media Cost

Peat Free

Nursery

Stock

Peat Based

Nursery

Stock

Digestate / Bark

Admixtures

£60 - £78 /m3

£60 - £177 /m3 Bark fine 60% £ 38.50

Wood fibre 30% £ 18.50

Top soil 10% £ 9.30

Digestate storage £ 1

Digestate

transport

£ 4

Total £71 - £78 /m3 £71 - £177 /m3 £ 71.30 /m3

*Delivery costs included

Potential application to industry

New growing media

Potential for use as liquid fertiliser (diluted)

Potential for closer links with plants for disposal of waste

material, especially infected material that should not be

composted.

Unlike other peat-alternatives, peat and digestates are

produced on in massive volumes, thus able to satisfy a

large proportion of current demand.

Challenges: the grade of bark to use and optimising

nutritional content of media for different species.

Dr Mary Dimambro

[email protected]

07731451899

Heavy metals (mg/kg)

CEL and Moulton Presentation 15 May 2013

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Transcript of CEL and Moulton Presentation 15 May 2013