Vegetable Agroforestry (VAF) System: Understanding vegetable ...

Tree – Vegetable Interaction in Vegetable Agroforestry

Systems

Progress Report

Agustin R. Mercado, JrICRAF

.

TMPEGS•Technology:

–Develop economically viable and ecologically-sound vegetable-agroforestry (VAF) systems

Overall hypothesisOverall hypothesis

In intensive vegetable production In intensive vegetable production system in the uplands, monoculture system in the uplands, monoculture systems are not sustainable, but systems are not sustainable, but integrating trees is feasible and integrating trees is feasible and offers better prospectsoffers better prospects. .

Vegetable Agroforestry System (VAF) Research goal:

Tree-vegetable integration on farm with minimal negative interaction,

thus increasing productivity, economic profitability, nutrient use

efficiency and environmental services

VAF Research Issues

• AF systems– Segregate– Integrate

• Boundary planting• Parklands• Alleycropping or hedgerow intercropping

• Tree species– Timber trees– Fruit trees– Canopy type: broad, medium, narrow

• Vegetable types– Crucifers: Cabbages, Broccoli, Squash – Tubers: Potato, – Solanaceous: Tomato, eggplant,

Specific hypothesesSpecific hypotheses• Vegetable based agroforestry (VAF) systems Vegetable based agroforestry (VAF) systems

provide better productivity, increase fertilizer provide better productivity, increase fertilizer use efficiency (FUE), increase profitability and use efficiency (FUE), increase profitability and improve environmental services than vegetable improve environmental services than vegetable monoculture systemmonoculture system

• Application of model allows a more rapid Application of model allows a more rapid progress in on-farm trials and site-management progress in on-farm trials and site-management designsdesigns

• Integration (domestication) of indigenous tree Integration (domestication) of indigenous tree vegetables offers additional option for vegetables offers additional option for sustained supply of vegetables for poor rural sustained supply of vegetables for poor rural households. households.

Two research topics:1. VAF tree-soil-crop interaction 2. Domestication of indigenous tree

vegetables

General objectivesGeneral objectives

• To understand the nature of vegetable-soil-tree To understand the nature of vegetable-soil-tree interactions in different types of tree integration on interactions in different types of tree integration on vegetable systems as the determinant for agro-vegetable systems as the determinant for agro-silvocultural management options for enhancing the silvocultural management options for enhancing the productivity of all components ( tree, vegetable, etc).productivity of all components ( tree, vegetable, etc).

• To examine service functions provided by VAF To examine service functions provided by VAF systems such as nutrient safety-net and nutrient pump systems such as nutrient safety-net and nutrient pump functions, carbon stocks (above-and belowground) and functions, carbon stocks (above-and belowground) and build up of soil organic matter (SOM)build up of soil organic matter (SOM)

Specific objectivesSpecific objectives• To determine existing VAF systems and understand its potential and To determine existing VAF systems and understand its potential and

constraints constraints

• To evaluate existing VAF systems on light capture and tree growth and To evaluate existing VAF systems on light capture and tree growth and spatial vegetable productivity in relation to tree distance.spatial vegetable productivity in relation to tree distance.

• To improve VAF systems by understanding vegetable –soil – tree To improve VAF systems by understanding vegetable –soil – tree interaction and employing appropriate agro-silvocultural practices in interaction and employing appropriate agro-silvocultural practices in order to attain optimum productivity of all components.order to attain optimum productivity of all components.

• To test the hypothesis that tree roots act as safety-net for leached To test the hypothesis that tree roots act as safety-net for leached nutrients in intensive vegetable production systemnutrients in intensive vegetable production system

• To collect and evaluate indigenous tree vegetables under farmers To collect and evaluate indigenous tree vegetables under farmers managementmanagement

Ongoing and planned research activitiesOngoing and planned research activities1.1. Vegetable farming system diagnosis (VFSD)Vegetable farming system diagnosis (VFSD)

2.2. Assessment of existing vegetable based agroforestry Assessment of existing vegetable based agroforestry systems. systems.

3.3. VAF system improvement. VAF system improvement.

• Optimum light transmission as basis for silvicultural Optimum light transmission as basis for silvicultural management (spacing, thinning, pruning, etc). management (spacing, thinning, pruning, etc).

• Vegetable and tree growth and productivity. Vegetable and tree growth and productivity.

• Tree-vegetable matchingTree-vegetable matching

4. Testing the hypothesis that tree roots act as safety-nets. Increased fertilizer use efficiency and reduction of fertilizer leaching (particularly on nitrate) thus avoiding contamination to water sources. (If 15N enriched fertilizer is available).

5. Testing the hypothesis that trees act as nutrient pump. Use of depth placement of 15N method. (If 15N isotope enriched fertilizer is available).

6. Quantification of environmental services (C sequestration – contribution of trees to soil organic matter build up (use of 13C method) and aboveground C stocks. Develop tree growth and allometric models)

Deliverables1. Recommendation for vegetable- tree combination and

management with minimal negative interaction

2. Improved options for tree spacing and vegetable-tree intercrop patterns

3. Profitable vegetable-tree systems identified

Safety-net zone

Schematic diagram of tree-crop interaction in hedgerow intercropping system

+reduction of negative effects through silvicultural management

N 2 - fixation C0 2 - fixation

Yield of control (monocropping systems)

tree-crop nutrient transfer through pruning and roots and nodules turn-over.

leaching of nutrients to lower depths 0 - 100 cm depth

> 100 cm depth

uptake from safety- net zone (nutrient pumping below root zone of annual crops)

+

fertility, micro-climae, erosion control, nutrient pumping, safety-net, tree biomass and soil C stocks

=+competition: light, water nutrient=-

--

Net benefit = 2T+ (Y2-2Y1)-2Dwhere: T = value of tree products (inc above and below C stocks, N2

fixation)

Y1 = yield loss Y2 = yield gain D = value of displaced crop

D

Y1 Y1

Y2

Schematic diagram of tree-crop interaction under parkland system

N 2 - fixation C0 2 - fixationScenario 1. Competition

> 100 cm depth

0 - 100 cm depth

leaching of nutrient

+

+ uptake of H20, nutrients

- Tree is competitive

-

Net benefit= T+ (2y2-2y1)-D

D

Scenario 2. Complementary

+ +

Net benefit = T + (Y2 - D)

Schematic diagram of tree-crop interaction under boundary planting system

> 100 cm depth

0 - 100 cm depth

+ Y2

Y1

Y = T + (Y2 - Y1) - D

-

D

Activities conducted so far:• Assessment of existing VAF systems covering 21 farms, 2 AF systems, 6

tree species, 8 vegetables, 4 aspects. Data collected were tree parameters (stem diameter, tree height, canopy height and width), spatial performance of vegetables (height, stem diameter, crown width, biomass), spatial light transmission (fish eye photography/quantum light meter)

• Focus group discussion with 15 VAF farmers on various ways of integrating trees on vegetable farms and their practices and experiences on tree and vegetable managements addressing tree-vegetable competition and complementarity.

• Nursery establishment and management of indigenous tree vegetables and medicinal trees. ,

Eucalyptus robusta + tomato at Gunayan’s farm at Bul-ogan, Sungco, Lantapan.

D

Eucalyptus- tomato interaction under boundary planting system

Tomato height

0102030405060708090

100110120130140150

0 3 6 9 12 15

Distance from the tree

heig

ht (c

m)

Competition Complementarity Neutral

White bean yield under Maesopsis eminii hedge trees

0

5

10

15

20

0 5 10 15 20

Distance from the tree

Bea

ns (g

/plt)

M. eminii hedge

Competition zone Complementarity zone Nuetral zone

Three zones of tree-crop interaction in vegetable agroforestry systems

\

• Effect was due to: - Light competition (aboveground)- Nutrient competition

Effects were due to:Aboveround (light competition)

Belowground (water, nutrients, etc)

Maesopsis emini +white beans

y = 7.6748Ln(x) + 76.046R2 = 0.9125

0

20

40

60

80

100

120

0 5 10 15 20Distance from tree (m)

% li

ght t

rans

mitt

ed (m

ols

m2-

1 d-

1)

Proportion of total light transmitted spatially using fish-eye photography analyzed with gap light analyzer software. Farmer removed approximately 40% of the canopy

Net complementarity as a simple tool in assessing appropriate tree-vegetable integration

• Net complementarity = degree of complementarity-degree of competitiveness

• Degree of complementarity = relative yield (at complementarity zone) – 1 x distance of influence

• Degree of competitiveness = 1- relative yield (at competition zone) x distance of influence

• Relative yield at complementarity zone = yield at complementarity zone/neutral zone

• Relative yield at competition zone = yield at competition zone/neutral zone

White bean yield under Maesopsis eminii hedge trees

0

5

10

15

20

0 5 10 15 20

Distance from the tree

Bea

ns (g

/plt)

M. eminii hedge

Competition zone Complementarity zone Nuetral zone

Three zones of tree-vegetable interaction in vegetable agroforestry systems

Influence of timber tree species on net complementarity

Tree species Net complementarity n

Acacia mangium

Eucalyptus robusta

Eucalyptus torillana

Gmelina arborea

Maesopsis emini

-0.23

0.48

-0.30

-0.85

-1.67

1

7

3

8

1

Influence of vegetable crops on net complementarity

Vegetables Net complementarity n

Bell pepper

Brocolli

Cabbage

Cauliflower

Chinese cabbage

Tomato

White beans

Maize

0.14

-7.54

0.98

0.44

0.57

-0.48

-1.67

-1.55

3

1

2

2

7

4

1

1

Influence of aspects on net complementarity

Aspects Net complementarity n

East (vegetables on west side)

West (vegetable on east side)

North (vegetable on south side)

South (vegetable on north side)

-1.74

-1.06

-0.54

-2.09

7

4

3

4

Relationship between tree height (m) and

net complementarity

y = 0.3034x + 12.696R2 = 0.14

0

2

4

6

8

10

12

14

16

18

20

(10.00) (5.00) - 5.00 10.00

Net complementarity

Tree

hei

ght (

m)

Relationship between proportion of canopy left vs net complementarity

y = 2.0991x + 62.359R2 = 0.03

0

20

40

60

80

100

120

(10.00) (5.00) - 5.00 10.00

Net complementarity

Prop

ortio

n of

can

opy

left

(%)

Relationship between canopy width and net complementarity

y = -14.254x + 560.37R2 = 0.08

0

100

200

300

400

500

600

700

800

900

(10.00) (5.00) - 5.00 10.00

Net complementarity

Can

opy

wid

th (c

m)

Tree spacing vs net complementarity

y = 0.1164x + 3.5417R2 = 0.08

0

1

2

3

4

5

6

(10.00) (8.00) (6.00) (4.00) (2.00) - 2.00 4.00

Net complementarity

Tree

spa

cing

(m)

Domestication of indigenous tree vegetables

• Objectives: - Collect and propagate indigenous tree vegetables- Household food and nutritional security (available 365 days a year)- Environment friendly (no pesticides, better carbon sequestration)

- Seed banking (in situ)- Reduced production risks

• Indigenous tree vegetable species:– Gnetum gnemon – “Bago”– Abelmuchos manihot – “Lagikway”– Sesbania sesban – “ Katuray”– Moringa oliefera – “Malunggay”– Looking for more entries

Evaluation activities:- Propagation methods (clonal propagation and nursery establishment at Claveria) - As contour hedgerows - As live fences

• Medicinal trees– Cinnamomum mindanensi (Kalingag)– Cinchona pubescens (Kenina)– Camella sinensis (Tea)– Cinnamomum verum (Cinnamon)– Vitex negundo (Lagundi)

• Evaluation activities:- Clonal propagation methods- As hedgerows (farmers –managed) as SPA- As live fence (farmers –managed) as SPA

• Progress so far– Clonal chamber has been established– Potted seedlings of 1000 pcs for each of the species have been

raised – Collection of more entries

Summary and initial findings 1. Integration of trees on farm is only feasible if :• Complementarity is greater than competition (Net complementarity is > 0). Net complementarity

can be a simple tool for assessing appropriate tree-vegetable integration.

• The cumulative value of tree products is greater than the cumulative values of yield loss and crop displacement area (cropped area loss).

2. Optimum tree spacing or tree line (hedge spacing) in AF system can be achieved when two complementarity zones meet. Approximately 25-30 meters apart.

3. Eucalyptus robusta, Eucalyptus torillana and Acacia mangium are promising trees for VAF system

4. Cabbage, Chinese cabbage, cualiflower and bell pepper are suitable vegetables for VAF

Thank you very much indeed for listening!!