1. Modeling smallholder crop-livestock systems in the Yucatan Peninsula, Mexico David Parsons

2. Yucatan - background

3. Location

4. Climate Tropical sub-humid Dry & rainy seasons Average rainfall 800- 1000mm Hot Rainfall distribution is variable on peninsula

5. Soils Soils formed on Tertiary limestone, flat terrain Shallow and stony, limited cultivation

6. Soils Alkaline, limited in nitrogen, phosphorus, manganese, iron, zinc Low water holding capacity

7. Vegetation Low-stature tropical dry forests (wet season)

8. Vegetation Low-stature tropical dry forests (dry season)

9. Vegetation Dominated by leguminosae

10. Milpa Slash and burn, 0.5 to 2.5 ha 2-3 year cultivation 10-20 year fallow

11. Milpa Maize mixed with melons and beans Weeds and pests controlled manually

12. Sisal production – the Boom… Sisal production from henequén, the foundation of the Yucatán economy Drop in demand post WWII, due to surplus production and synthetic fibers

13. …and the Bust Industry collapse in 1992, after withdrawal of Government subsidies “Henequén zone” left underemployed

14. Rural poverty in Yucatan In 1996, 63% of children in Mayan communities were chronically malnourished (Balam, 1996) In 2000, nearly twice as many counties in the Yucatan Peninsula were classified as extremely poor compared to 1995 (41 v 21 - - Yucatan census)

15. The livestock revolution Expected 7.7 B people by 2020 Greater demand for food will aggravate agricultural pressure on the environment Increasing global demand for livestock products By 2020 developing country consumers will eat 87% more meat and 75% more milk

16. The consequences Opportunities & challenges for rural poor Potential to alleviate poverty & spur economic growth Negative consequences e.g. environment How can livestock production increase to meet this demand using sustainable methods? We need to avoid generalizations about livestock and their relationship with the environment

17. Global Animal Production Systems Grazing Industrial Mixed farming “Systems utilizing native grasslands with little or no integration with cropping systems.”

18. Global Animal Production Systems Grazing Industrial Mixed farming “Systems where the animals are detached from the land base of feed supply.”

19. Global Animal Production Systems Grazing Industrial Mixed farming “Systems where livestock rearing and crop cultivation are to a greater or lesser extent integrated components of one farming system.”

20. 3 Production Systems Production systems –Grazing –Industrial –Mixed farming What are the implications of these practices for the sustainability of the agricultural systems, the environment and farmer livelihoods

21. Smallholder sheep farmers

22. Why hair sheep? Adapted to the tropics High fertility Adept at browsing fibrous biomass Low entry level, accessible to small producers Strong demand in Mexico City

23. Sheep Farmer Survey 2004 survey of Yucatan sheep farmers Villages randomly chosen 66 farmers interviewed –Household –Livestock –Cropping –Infrastructure –Technical & Financial Assistance

28. The house

30. ‘Milpa’ The house 4 km

31. ‘Milpa’ The house 4 km

32. ‘Milpa’ The house 4 km

33. ‘Milpa’ Forest The house 4 km 1 km

34. ‘Milpa’ Forest The house 4 km 1 km

35. And the point is….. Each of these practices has implications for agricultural sustainability, the environment and the household Agricultural systems are complex People like to simplify, generalize, detach It is difficult to assess the implications of a combination of agricultural practices

36. System Dynamics A thinking and modeling approach that emphasizes the role of the structure of a system in determining the evolution of a problematic behavior over time Problems often arise from feedback processes rather than simple one-way causal relationships A mechanistic rather than empirical approach to modeling

37. Basic System Dynamics

40. ‘That, detective is the right question.’

41. Research Proposal

42. Problems/Issues In Yucatán there exist seemingly competing goals for forest use, including agriculture, livestock production, and preservation for biodiversity. Smallholder sheep farming is a relatively recent but expanding agricultural enterprise. Little is known about the interactions between sheep farming, household economics, crop production and the environment.

43. Research Questions How do the presence of sheep alter nutrient availability and recycling, and other biophysical attributes, and what are the consequences of this? How do specific agricultural management practices, both currently used and hypothetical, affect the system? Can integration of livestock and cropping potentially result in longer use of a milpa, thus intensifying agricultural production?

44. Hypotheses Livestock can increase the income of smallholder farmer households Livestock can accelerate the flow of nutrients in a mixed cropping system, making them available for crop growth Livestock and cropping can be synergistic Livestock facilitate the importation of nutrients The use of animal manure on crops can maintain soil fertility

45. Types of data Soil Plant Animal Manure Household - including economic data and labor

46. Methods of data collection for model Existing data Experimentation –Corn response to sheep manure –Forage response to sheep manure? ‘Case study’ farms

47. Farm selection 8 ‘Case Study’ Farms –4 different villages Mixed sheep & cropping (Milpa) Solely cropping Sheep farms chosen to characterize a range of representative mixed farming management practices –e.g. growing forages, forest browsing, forest cut and carry, stubble utilization, manure use

48. Simplified Physical Structure

49. Smallholder Crop-Livestock Model Brief overview of model Policy optimization example

50. Model overview Model sections –Crop production (Corn, no weeds) –Forage (Taiwan grass) –Nutrient cycling (Nitrogen) –Sheep (No aging chain) –Manure –Feeding options

51. A Farmer Policy Optimization Maximize: –the amount of corn harvested –Maximize animal production (through fed forage) –1kg corn grain = 2kg forage produced What can the farmer do ( in this example )? –Change number of sheep (0-50) –Change area of forage (0-10 ha) –Change area of maize (0-4 ha) –Change proportion of manure applied to forage (0-1) –Decide whether or not to graze corn stubble (0 or 1)

52. Optimization Results

58. Points to consider… The forage is receiving some fertilization This assumes corn is to be grown on the same plot of land, so the farmer has to maintain fertility to get a corn yield Constraints of labor and cash A lot depends on: –The structure of the model –How the optimization is weighted

59. Improving the model Get the parameters ‘right’ –Data collection –Literature review –Sensitivity analysis Get the structure ‘right’ –Level of model aggregation –Appropriate boundary

60. Model Application Generate an accounting of nutrient flows and economic characteristics of 8 farms with different management practices Increase understanding of how these crop- livestock systems function Test the possible outcomes of farming strategy combinations outside the range of experimental data collection Prediction of the effects of potential interventions, including a better understanding of possible ‘side-effects’

61. Model Misapplication The model should not be asked to answer questions that it is not equipped to answer “I’m sorry. My responses are limited. You must ask the right question.”

62. Model Misapplication The model should not be used as a ‘magic’ black box

63. Model Misapplication This is not a model for farmers to use

64. Conclusions Livestock have the potential to improve rural livelihoods in Yucatan However, there is a need for better understanding of interactions between livestock and cropping systems They are complex, dynamic and variable systems, best studied using systems thinking and methods