Of Maize and Manure

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Of Maize and Manure
Learning experiences and experimenting in Yucatán
David Parsons Leonardo Cocóm
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Objectives (for this presentation)

• Characteristics of smallholder sheep farmers in
  Yucatán state
• Brief description of Ph.D. studies
• Milpa experiment
• Researchers Producers
• (with Leonardo Cocóm)

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Smallholder sheep production
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Smallholder sheep production

• Relatively recent but expanding agricultural
  enterprise.
• Little is known about the interactions between
  sheep farming, household economics, crop
  production and the environment.

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1. Sheep Farmer Survey

• 2004 survey of Yucatan sheep farmers
• Villages randomly chosen from 5 zones
• 65 farmers interviewed
• Household
• Livestock
• Cropping
• Infrastructure
• Technical Financial Assistance

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Farmer categories

• 78 (51) smallholders
• lt50 ewes
• lt10 cows
• Commercial sheep producers
• Cattle ranchers with sheep

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Principal sources of income for smallholders
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Strategies for feeding animals

• 71 grow forage
• Grazed, cut carried
• 90 harvest tree foliage
• Many leguminous species
• 79 use crop products

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Crop cultivation

• 75 cultivate field crops

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Motives for crop cultivation
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Home garden cultivation

• 82 cultivate home garden
• Poultry
• Bees
• Vegetables
• Herbs
• Fruit trees
• Medicinal plants
• Forage
• Firewood
• Building materials

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Choice of location for manure use
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Sheep system diversity
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The house
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The house
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The house
4 km
Milpa
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The house
4 km
Milpa
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The house
4 km
Milpa
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Forest
1 km
The house
4 km
Milpa
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Forest
1 km
The house
4 km
Milpa
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Significant points

• These practices have implications for
  agricultural sustainability, the environment and
  the household
• Agricultural systems are complex
• We find it easy to over-simplify, generalize
• It is difficult to assess the implications of a
  combination of agricultural practices

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Hypotheses

• Producers who combine livestock and cropping
  should have more opportunities for improving
  nutrient recycling
• Potential to direct flow towards cropping,
  extending the cropping period

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Sheep farming systems model

• Diverse combinations of agricultural practices
  include different techniques of
• feeding
• crop and forage production
• use of crop and animal products
• Examine the potential long-term outcomes of these
  suites of practices using a systems approach and
  a dynamic modelling framework

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Milpa

• Slash and burn
• Roza-tumba-quema

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Source Hernandez (1981)
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Milpa practices

• 2-3 year cultivation
• 10-20 year fallow
• Based on maize, often mixed with squash and beans
  
• Nutrients released from resident organic matter
  for growth of the planted crops
• Average maize yield is 750 kg/ha

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Milpa cycle
First year crop Plot age 1
Second year crop Plot age 2
Clear and burn plot
Fallow period
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Milpa Experiment
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Background

• With most shifting cultivation systems the main
  reasons for abandonment of a plot are nutrient
  depletion and weed infestation.
• on fertile soils weed infestation is the main
  reason, and
• on less fertile soils nutrient depletion.
  (Sanchez, 1976)
• The reason for abandonment in Yucatán is unclear
• Farmer and researcher opinions vary

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Weeds or Nutrients?

• Weisbach et al. (2002) There is concern
  amongst farmers, that the decreased length of
  fallow is insufficient to fully restore soil
  fertility.
• Perez-Toro (1981) El principal factor
  limitante es el deshierbe.

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Source adapted from Morley, 1981
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Caamal-Maldonado et al. (2001)

• Use of leguminous cover crops
• Mucuna reduced weed biomass, increased corn yield
• Due to weed control or nitrogen fixation?
• What about other nutrients that cannot be
  supplied by legumes?

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Aims

• Examine the relative importance and potential
  interactions of declining fertility and weeds in
  reducing maize yields
• Better understand levels of available nutrients
  in milpas of different plot ages
• Assess the ability of sheep manure to supply
  needed nutrients for maize production

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Experimental Design

• 2 farms (only red soils)
• Don Angel ( Don Victor), Don Leonardo
• 3 manure treatments
• None, low, high
• 3 weed control treatments
• None, slash, chemical
• 2 plot ages
• First year (milpa roza)
• Second year (milpa caña) or Third year
• 3 Replicates (blocks)

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Layout
Farm Leonardo Fallow period 12 years
Second year milpa Age 2
First year milpa Age 1
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Layout
Farm Angel/Victor Fallow period 25 years
First year milpa Age 1
Second year milpa
Third year milpa Age 3
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Example block

• Factorial design
• M manure
• W weed control

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Weed control

• Chemical control
• Glyphosate or Tordon pre-planting
• Tordon end of July
• Hand weeding
• Done with coa
• 3 weedings
• Early June (at planting)
• Mid July
• Mid August

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Manure

• Sourced from UADY sheep and goats

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Measurements

• Pre-burn
• Soil nutrients
• Pre-plant
• Soil nutrients
• Weed cover densities
• Crop growth
• Weed cover
• Harvest
• Grain yield quality
• Biomass yield quality
• Soil nutrients
• Weed cover and species

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Angel 1st year pre-burn
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Angel 1st year post-burn
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Angel 3rd year pre-plant
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Leonardo 1st year burn
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Leonardo 2nd year pre-plant
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Manure application
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Planting
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Leonardo 1st year early corn growth
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Leonardo 2nd year weeding
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Leonardo 3rd year visible differences in corn
High manure Chemical control
Low manure Slashed
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Leonardo 2nd year no weed control
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Examining corn cobs
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Results
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Grain yield - Angel
Plot Age 1
Plot Age 3
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Grain yield - Leonardo
Plot Age 2
Plot Age 1
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Biomass yield - Leonardo
Plot Age 1
Plot Age 2
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Implications

• Differences between (potential) grain yields
  depending on plot age
• There may be no large effect of treatments on
  first year milpa with a sufficiently long fallow
  period
• However, treatments carried out in the first year
  may affect subsequent years
• (no data to show this)

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Implications

• Above average grain yields can be maintained in
  2nd and 3rd year plots with appropriate inputs
• More biomass available for animal production
• Results will depend on the year in which the
  experiment was carried out

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Fallow dynamics
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Manure production and use

• 30 kg sheep ? 125 kg dry manure per year
• 32 sheep weighing 30 kg each ? 4000 kg dry manure
  per year
• (low manure rate for 1 ha)
• Manure could be placed around plants rather than
  spread
• Who owns the land?

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Data analysis

• Adjust for
• Plant numbers
• Soil surface rockiness
• Initial weed numbers and cover
• Initial soil nutrients

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Limitations/Problems

• Birds low plant numbers in some plots
• Variability of experimental plots
• Hard to get a 1515m block all of red soil
• Often transitional soils near edges of the block
• Need more years
• Any takers?
• Many interacting variables
• Herbicide types, herbicide rates, weeding
  frequency, manure quality, manure rates, weather,
  previous plot history etc. ? treat results with
  caution

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Researching with Producers

• Not participatory research
• Leonardo
• Provides land
• Shares opinions
• Explains typical practices
• Enthusiasm to keep me motivated

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Researching with Producers

• David
• Provides the inputs and labor for the work
• Designed the experiment, in consultation with
  Leonardo
• Introduce new ideas perspectives

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Perspectives of Leonardo

• What did you learn from this work?
• Que ha aprendido al realizar este trabajo?
• What do you think is the value of researchers
  working together with producers?Cuál cree que
  es el valor del trabajo de investigadores y
  productores en conjunto?

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Perspectives of Leonardo

• As a producer what is the value of having both
  crops and livestock?Cómo productor cual cree
  que es el valor de tener cultivos y cría de
  animales?
• If we were with a group of producers, what do you
  think are the most important messages that they
  could receive from this experiment?Si
  estuvieramos con un grupo de productores, Cuáles
  crees que serían los mensajes más importantes que
  podrían recibir de este experimento?

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