Agriculture Reference
In-Depth Information
Ruminant livestock production systems
Solely livestock systems
Mixed farming systems
Rainfed
Landless
Grassland-based
Irrigated
Arid, semiarid
tropics
Meat, dairy
Arid, semiarid
tropics
Arid, semiarid
tropics
Humid,
subhumid
tropics
Humid,
subhumid
tropics
Humid,
subhumid
tropics
Temperate,
highland tropics
Temperate,
highland tropics
Temperate,
highland tropics
FIGURE 4.3
Livestock production systems classification. Shaded boxes represent ruminant
livestock grazing systems that are most important to smallholder households, which are the
focus of this chapter. (Adapted from Sere, C. and H. Steinfeld, 1996. World livestock produc-
tion systems: Current status, issues and trends. Animal production and health paper no. 127.
Food and Agriculture Organization of the United Nations, Rome.)
we will focus on grassland-based livestock systems as well as rainfed, mixed crop,
forest, and woodland-based ruminant grazing systems, as these are the most domi-
nant systems for smallholder households. The types of grazing systems vary across
climate regimes as well as by land tenure (Table 4.2).
4.1.3 S
oIl
-p
lant
-a
nImal
-e
nvIronmental
l
InkaGeS
In
G
razInG
S
yStemS
For annual cropping, soil quality is generally defined in terms of physical, chemi-
cal, and biological components of the soil. In grazing lands, soil quality and integ-
rity of the vegetative and faunal communities are intrinsically intertwined, and both
are influenced by grazing systems. These are critical relationships in the plant root
zone, which provides nature's buffer against precipitation and nutrient deficits. Soil
water storage capacity is determined by root depth and plant-available water-holding
capacity, and both are likely to be altered by plant and soil faunal activity. Canadell
et al. (1996), in a global review of maximum root depth of vegetation types, reported
that temperate grasslands had maximum root depths between about 1.2 and 6 m, with
a median of about 2.5 m. Reports of maximum root depths for grassland/savannah
range between about 1.5 m (presumably the grass components) and >60 m (pre-
sumably the tree component). In a study from savannah in the Upper Burdekin of
Australia, Williams et al. (1997) estimated total plant-available water capacity in the
rootzone to be 140 mm for grass and 380 mm for trees. We have found no reports
describing the effect that grazing might have on the rooting depth of pastures;
