Tree-Crop Interactions

386 views

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
386
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
6
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Tree-Crop Interactions

  1. 1. Frédéric Baudron CIMMYT Ethiopia f.baudron@cgiar.org Agroforestry & Food Security: Assessing the Direct Effects of Trees on Annual Food Crops
  2. 2. Challenges faced by Annual Food Crop Production  Water scarcity  Nutrient scarcity – N, P  Climate change  Pests and diseases  Energy scarcity – Labour, ADP, fuel  Slow yield gains – Yield gap – Land scarcity – Undernourished people (Water scarcity in 2050, from Wallace, 2000)(from Cairns et al., 2012) (from FAO, 2009)
  3. 3. A Question of Efficiency?  Only 10-30% of water is used by the crop (Wallace, 2000)  Only 20-50% of N ferilizers applied is used by cereal crops (Cassman, 2002)  Less than 0.1% of pesticides applied reach their pest target (Pimentel, 1995) Management response: Precision agriculture Genetic response Management response: Exploiting positive interactions between species
  4. 4. (from Cox et al., 2006) An Example of Genetic Response: Developing Perennial Grain Crops
  5. 5. Precision Agriculture: when, where, how much?
  6. 6. 1.When does it occur? 2.What are the mechanisms? 3.How to maximize it? Tree - Annual Food Crop facilitation
  7. 7. Increasing Water Availability The problem: high water loss through runoff, evaporation and deep drainage; shallow root distribution of annuals Reduced evaporation (from Ong et al., 2000) Increased soil water (from Joffre and Rambal, 1993) Hydraulic lift (from Emerman and Dawson, 1996)
  8. 8. N Fixation and Recycling The problem: production of N fertilizers dependant on fossile energy; highly mobile nutrient,
  9. 9. P Mobilization & Acquisition The problem: poorly mobile nutrient, mainly in non-available forms in the soil (from Cox et al., 2006) Exudation of organic acids by proteoid roots of e.g. Grevillea robusta (Watt & Evans, 1999) Ectomycorrhizae of e.g. Caesalpinioideae (Högberg, 1992)
  10. 10. Heat and water stress (from Ong et al., 2000)
  11. 11. Pest control Rodents: 0.1-0.5 t/ha of field damage in Tigray (Yonas et al., 2010) (from Koh, 2008)
  12. 12. Interactions Effect of water availability on heat stress of maize (from Lobel et al., 2011)Effect of nutrient application on water productivity (from Penning de Vries and Ditèye, 1991)
  13. 13. Minimizing Competition  Tree species selection – Phenology – Pattern of root activity – Plasticity of the root system  Management – Spacing – Supply of limiting factors – Shoot pruning – Tillage (from Burges et al., 1998) (from Schroth et al., 1995)
  14. 14. (Gc × Gt) × E × M  Gc: Diversity of maize varieties – Productivity (e.g. land, water) – Resistance or sensitivity to e.g. heat, drought, low N, pests & diseases  Gt: Diversity of tree species – Morphology (above and below ground) – Phenology (inverse or not)  E: Diversity of environments – Climates (semi-arid vs. sub-humid) – Soils (N limited vs. P limited)  M: Diversity of management options – Geometry – Fertilization – No-till vs. Ploughing 0% 20% 40% 60% 80% 100% 0 100 1000 3000 Waterusebysorghum Surface mulch (kg DM ha-1) Transpiration Runoff Soil evaporation Drainage (from Baudron et al., in prep)
  15. 15. What to measure (near and away from trees)?  Environmental parameters – Radiation and temperature – Soil water content – N and P balance  Productivity – Crop yield – Biomass production (crop & trees)  Crop stress indicators – NDVI – Canopy temperature  Crop damage inside and outside bird- exclosures  Fate of biocides - phytoremediation
  16. 16. Conclusion: Answering Practical Questions for Maize Farmers  What happens near trees?  What to plant near trees?  What management is needed near trees?
  17. 17. Thank you!

×