Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Agroforestry for restoration of phosphorus mines in china jianchu xu

288 views

Published on

Long-term sustainability of agricultural systems requires that soils stay productive and that necessary inputs remain available in the future
- Soil loss occurs more rapidly than soil creation in many agricultural landscapes, and the soil that remains declines in quality
- One-way fertilizer nutrient flows simultaneously cause pollution and scarcity
- E.g., Phosphorus: essential plant nutrient; expected to become increasingly expensive to mine and process; at the same time, P runoff causes eutrophication of water bodies.

Published in: Environment
  • Be the first to comment

  • Be the first to like this

Agroforestry for restoration of phosphorus mines in china jianchu xu

  1. 1. Jianchu Xu, Stefanie D. Goldberg, Peter E. Mortimer, Anne Ostermann, Kai Yan AGROFORESTRY – a new opportunity for P pollution management and ecological restoration Sep 9th 2016
  2. 2. Sylvopasture Riparian buffer Alleycropping Windbreaks Mixed planting Agroforestry
  3. 3. -  Agroforestry systems: adaptable to the needs of farmers, crops, the landscape and local environment -  Systems include: Mixed planting, alleycropping, windbreaks, riparian buffers and sylvopasture -  Systems selected according to local needs and requirements, eg: shade tolerant crops -mixed planting, high light crops -wind breaks or alleycropping. -  Tree and crop management: canopy pruning; pollarding; understory and litter management; cropping density; soil management Types of agroforestry systems
  4. 4. -  Use of agroforestry system as a means of rehabilitating degraded landscapes – above and below ground restoration, social upliftment, ecosystem productivity -  “Return to function” for damaged ecosystems Agroforestry concept
  5. 5. -  Agriculture is the largest anthropogenic land use (38% of the land surface of the earth) -  Long-term sustainability of agricultural systems requires that soils stay productive and that necessary inputs remain available in the future -  Soil loss occurs more rapidly than soil creation in many agricultural landscapes, and the soil that remains declines in quality -  One-way fertilizer nutrient flows simultaneously cause pollution and scarcity -  E.g., Phosphorus: essential plant nutrient; expected to become increasingly expensive to mine and process; at the same time, P runoff causes eutrophication of water bodies Agriculture – challenges of growing demand
  6. 6. -  Growing consumption of inorganic phosphorus (P) fertilizers derived from mining has contributed to major increases in crop yields since the 1950s -  Concurrent growth in fertilizer use and livestock production has more than tripled global P flows to the biosphere over preindustrial levels, resulting in P accumulation in some agricultural soils that acts as a driver of eutrophication in freshwater and coastal systems -  At the same time, limited availability of P fertilizers in other regions has contributed to prolonged P deficits that can deplete soil P and limit crop yields. Although agricultural P surpluses and deficits have been documented for several regions, there is still limited understanding of the spatial patterns of P imbalances at the global scale. Imbalances of agronomic P
  7. 7. MacDonald et al. 2011.Agronomic phosphorus imbalances across the world's croplands. Proceedings of the National Academy of Sciences, 108(7), 3086-3091. P balances calculated by spatial estimates of P inputs (P fertilizer and manure applications) and outputs (P in harvested crops) for cropland soils Spatial patterns of agronomic P imbalances
  8. 8. Different soil P management strategies Soil P deficit -  Liming acid soils, -  Increasing organic matter, -  Proper placement of P fertilizer affecting how efficiently P is used by crops Soil P surplus -  Reducing over-fertilization and thereby reducing P losses due to erosion and runoff Agroforestry is a suitable tool to address both issues -  Permanent vegetation on agricultural watersheds as upland buffers and streamside riparian buffers has been shown to improve water quality parameters: reduce runoff, sediment, TN, and TP losses Riparian buffer Mixed planting -  Intercropping was shown to increase P availability in rhizospheres -  P availability was enhanced especially in a low P soil
  9. 9. Different strategies of trees to mobilize P -  Dual symbiotic trees: symbiosis with two different types of mycorrhiza, that both have different strategies to access P (e.g., Alnus nepalensis) -  Non-mycorrhizal trees; forming cluster roots (e.g., Macademia) -  Creation of diverse agroforestry systems to increase P mobilization due to different strategies and/or rooting depths naturalmedicinefacts.info resilience.org infonet-biovision.org
  10. 10. Benefits of agroforestry on phosphorus mining restoration
  11. 11. Benefits of agroforestry on over-fertilized sites -  Trees stabilize the soil reducing run-off, while the intercrops are typically of high P demand and successive harvests remove the excess P
  12. 12. Risk areas for P runoff
  13. 13. Example of P pollution -  Lake Dianchi is the sixth largest lake in China (ca. 298 km2). -  Large P deposits are located in the southern and south-eastern areas of the Dianchi basin. -  Following the government’s "reform and openness" policy, industry and agriculture developed rapidly and Lake Dianchi became seriously polluted. The continued pollution has been under control, but P content still high, and ecosystem needs further recovery.
  14. 14. -  Reducing over-fertilization -  Creating buffer zones Suggested management strategy -  Agroforestry as sustainable approach to use soil P Riparian buffer Mixed planting
  15. 15. P situation in agricultural land P source Solution Suggested tree species High soil P concentration Natural deposits Stabilize P in the system: e.g., by permanent crop cover, trees, dense root networks, buffer zones to reduce run-off in water bodies Fabaceae (Leguminous) species: e.g. Albezia, Dalbergia , Millettia, Crotalaria Over-fertilization with mineral fertilizer Short term solution possible by reducing the input to an optimum Over-fertilization with organic fertilizer Structures of high livestock densities and resulting over-fertilization often develop based on local demands and market structures, difficult to solve in the short term à Stabilize P in the system: e.g., by permanent crop cover, trees, dense root networks, buffer zones to reduce run-off in water bodies, while working on long-term solutions to reduce manure input. P deficiency Depleted soils/ naturally low concentrations + economic situation doesn’t allow for fertilizer use Trees that can utilize less available P sources and thus increase P availability to adjacent crops Broussonetia, Grewia, Erythrina, Leucaena, Michelia, Robinia, Shorea, Zizyphus species. Acacia species Immobilized P resources Enhance soil microbial activity (P mobilization)
  16. 16. -  Provides context-specific solutions -  Dynamic: does not imply only a certain scenario, but is applicale on a huge variety of problems Agroforestry - Conclusion
  17. 17. Thank you for your attention! Stefanie D. Goldberg Anne OstermannKai YanPeter E. MortimerJianchu Xu Email: j.c.xu@cgiar.org

×