Tree Vegetable Interaction in Vegetable Agroforestry Systems Progress

Tree – Vegetable Interaction in Vegetable Agroforestry Systems Progress Report Agustin R. Mercado, Jr ICRAF

TMPEGS • Technology: –Develop economically viable and ecologically-sound vegetable-agroforestry (VAF) systems

Overall hypothesis In intensive vegetable production system in the uplands, monoculture systems are not sustainable, but integrating trees is feasible and offers 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 hypotheses • Vegetable based agroforestry (VAF) systems provide better productivity, increase fertilizer use efficiency (FUE), increase profitability and improve environmental services than vegetable monoculture system • Application of model allows a more rapid progress in on-farm trials and site-management designs • Integration (domestication) of indigenous tree vegetables offers additional option for sustained supply of vegetables for poor rural households.

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

General objectives • To understand the nature of vegetable-soil-tree interactions in different types of tree integration on vegetable systems as the determinant for agrosilvocultural management options for enhancing the productivity of all components ( tree, vegetable, etc). • To examine service functions provided by VAF systems such as nutrient safety-net and nutrient pump functions, carbon stocks (above-and belowground) and build up of soil organic matter (SOM)

Specific objectives • To determine existing VAF systems and understand its potential and constraints • To evaluate existing VAF systems on light capture and tree growth and spatial vegetable productivity in relation to tree distance. • To improve VAF systems by understanding vegetable –soil – tree interaction and employing appropriate agro-silvocultural practices in order to attain optimum productivity of all components. • To test the hypothesis that tree roots act as safety-net for leached nutrients in intensive vegetable production system • To collect and evaluate indigenous tree vegetables under farmers management

Ongoing and planned research activities 1. Vegetable farming system diagnosis (VFSD) 2. Assessment of existing vegetable based agroforestry systems. 3. VAF system improvement. • Optimum light transmission as basis for silvicultural management (spacing, thinning, pruning, etc). • Vegetable and tree growth and productivity. • Tree-vegetable matching

4. Testing the hypothesis that tree roots act as safetynets. Increased fertilizer use efficiency and reduction of fertilizer leaching (particularly on nitrate) thus avoiding contamination to water sources. (If 15 N enriched fertilizer is available). 5. Testing the hypothesis that trees act as nutrient pump. Use of depth placement of 15 N method. (If 15 N isotope enriched fertilizer is available). 6. Quantification of environmental services (C sequestration – contribution of trees to soil organic matter build up (use of 13 C method) and aboveground C stocks. Develop tree growth and allometric models)

Deliverables 1. 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

Net benefit= T+ (2 y 2 -2 y 1)-D 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.

Eucalyptus- tomato interaction under boundary planting system D

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)

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

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 -0. 23 1 Eucalyptus robusta 0. 48 7 Eucalyptus torillana -0. 30 3 Gmelina arborea -0. 85 8 Maesopsis emini -1. 67 1

Influence of vegetable crops on net complementarity Vegetables Net complementarity n Bell pepper 0. 14 3 Brocolli -7. 54 1 Cabbage 0. 98 2 Cauliflower 0. 44 2 Chinese cabbage 0. 57 7 Tomato -0. 48 4 White beans -1. 67 1 Maize -1. 55 1

Influence of aspects on net complementarity Aspects Net complementarity n East (vegetables on west side) -1. 74 7 West (vegetable on east side) -1. 06 4 North (vegetable on south side) -0. 54 3 South (vegetable on north side) -2. 09 4

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

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