Conservation agriculture has three main principles: zero or
minimal soil disturbance, a permanent soil cover provided by a
growing crop or a dead mulch of crop residues, and diversified crop
rotations (FAO, 2008). Questions remain regarding whether leaving
crop residues in the field is the most sensible, efficient or profitable
use of crop residues (Giller et al., 2009). This is because crop
residues (a) improve soil fertility and soil moisture thus boosting
grain yields, (b) provide a resource for livestock feed, household
heating and cooking demands and (c) provide ground cover to reduce
erosion potential. These trade-offs become more pronounced when
markets for goods that are substitutes for crop residues are incomplete,
as often occurs in developing countries. For example, if access
to alternative sources of livestock feed or household heating materials
is not feasible, households will use crop residues for these
purposes. This creates tensionswith retaining crop residues as mulch,
even though the alternative sources of livestock feed or heating are
more efficient. Crop residues often have significant value in developing
country farming systems. For example, Magnan et al. (2012)
estimated that crop residues removed from the field comprise approximately
25% of the value of cereal production on a sample of
mixed farms in Morocco. Hellin et al. (2013) raise the idea that partial
residue retention could reduce trade-offs in Mexican farming systems.
Conservation agriculture has three main principles: zero orminimal soil disturbance, a permanent soil cover provided by agrowing crop or a dead mulch of crop residues, and diversified croprotations (FAO, 2008). Questions remain regarding whether leavingcrop residues in the field is the most sensible, efficient or profitableuse of crop residues (Giller et al., 2009). This is because cropresidues (a) improve soil fertility and soil moisture thus boostinggrain yields, (b) provide a resource for livestock feed, householdheating and cooking demands and (c) provide ground cover to reduceerosion potential. These trade-offs become more pronounced whenmarkets for goods that are substitutes for crop residues are incomplete,as often occurs in developing countries. For example, if accessto alternative sources of livestock feed or household heating materialsis not feasible, households will use crop residues for thesepurposes. This creates tensionswith retaining crop residues as mulch,even though the alternative sources of livestock feed or heating aremore efficient. Crop residues often have significant value in developingcountry farming systems. For example, Magnan et al. (2012)estimated that crop residues removed from the field comprise approximately25% of the value of cereal production on a sample ofmixed farms in Morocco. Hellin et al. (2013) raise the idea that partialresidue retention could reduce trade-offs in Mexican farming systems.
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