25
identify the soil types most suited for CA. Another important result from the
meta-study by Corbeels et al. (2014) is that there is a stronger (+391 kg ha
−1
) effect
of CA compared to CT when more than 100 kg N/ha was applied, whilst the corresponding effect was low (+85 kg ha
−1
) when less than 100 kg N/ha was applied.
These meta- studies clearly show the importance of combining mulching with nitrogen application. Nitrogen application is important in order to reduce nitrogen
immobilisation in the soil, as a result of the organic inputs, and to ensure sufficient
mulch production every year.
A major challenge for the development of CA in Africa is the retention of crop
residues as mulch, as livestock graze freely in the dry season. A comparative study
of the use of crop residues in Africa and Asia showed that the use of crop residues
as a soil amendment is most likely to succeed if alternative, good-quality fodder is
available, or in areas where biomass production is high and the demand for stover is
low (Valbuena et al. 2012). Farmers will not practise mulching if the perceived benefit of using straw as mulch is higher than the perceived benefit of using stover for
fodder or other purposes. Hence, the agro-ecological and socio-economic conditions must be taken into consideration when promoting CA (Lal 2015). Options for
increasing the use of crop residues as mulch include reducing the use of crop residues as livestock fodder by developing alternative fodder resources and reducing
the number of animals by giving emphasis to more milk- and meat-producing animals. In such an intensification pathway, more of the fodder resources can be used
for promoting growth of the animal and not just body maintenance. There is also a
growing market for livestock products as a result of population growth and increasing wealth. The intensification of crop and livestock production should therefore
occur in parallel (Duncan et al. 2016).
The major reasons for the adoption of CA across the world are reduced fuel costs,
saved labour, timely sowing, improved profitability, carbon sequestration, improved
water-use efficiency and reduced erosion (Baudron et al. 2015a; Lal 2016). CA has
rarely been adopted to increase yield. For this reason, CA has been promoted in
areas where:
• Tillage is costly.
• Power for ploughing is limited.
• Planting is delayed as a result of power shortage.
• Water deficiency limits yield.
• Erosion is a threat to the productivity of farmland.
There are different views regarding the potential for CA in Africa. Giller et al.
(2009) claim that the potential for CA is very limited in Africa whilst Baudron et al.
(2015a) argue that CA has potential in Africa due to increasing tillage costs as a
result of higher energy prices combined with feed shortages for traction animals.
The areas affected by erosion will also increase due to increased cultivation of steep
slopes and reduced soil cover. Furthermore, climate change will also necessitate the
development of cropping systems that can ensure timely sowing and more droughtresistant farming systems.
The Prospects for Conservation Agriculture in Ethiopia
identify the soil types most suited for CA. Another important result from the
meta-study by Corbeels et al. (2014) is that there is a stronger (+391 kg ha
−1
) effect
of CA compared to CT when more than 100 kg N/ha was applied, whilst the corresponding effect was low (+85 kg ha
−1
) when less than 100 kg N/ha was applied.
These meta- studies clearly show the importance of combining mulching with nitrogen application. Nitrogen application is important in order to reduce nitrogen
immobilisation in the soil, as a result of the organic inputs, and to ensure sufficient
mulch production every year.
A major challenge for the development of CA in Africa is the retention of crop
residues as mulch, as livestock graze freely in the dry season. A comparative study
of the use of crop residues in Africa and Asia showed that the use of crop residues
as a soil amendment is most likely to succeed if alternative, good-quality fodder is
available, or in areas where biomass production is high and the demand for stover is
low (Valbuena et al. 2012). Farmers will not practise mulching if the perceived benefit of using straw as mulch is higher than the perceived benefit of using stover for
fodder or other purposes. Hence, the agro-ecological and socio-economic conditions must be taken into consideration when promoting CA (Lal 2015). Options for
increasing the use of crop residues as mulch include reducing the use of crop residues as livestock fodder by developing alternative fodder resources and reducing
the number of animals by giving emphasis to more milk- and meat-producing animals. In such an intensification pathway, more of the fodder resources can be used
for promoting growth of the animal and not just body maintenance. There is also a
growing market for livestock products as a result of population growth and increasing wealth. The intensification of crop and livestock production should therefore
occur in parallel (Duncan et al. 2016).
The major reasons for the adoption of CA across the world are reduced fuel costs,
saved labour, timely sowing, improved profitability, carbon sequestration, improved
water-use efficiency and reduced erosion (Baudron et al. 2015a; Lal 2016). CA has
rarely been adopted to increase yield. For this reason, CA has been promoted in
areas where:
• Tillage is costly.
• Power for ploughing is limited.
• Planting is delayed as a result of power shortage.
• Water deficiency limits yield.
• Erosion is a threat to the productivity of farmland.
There are different views regarding the potential for CA in Africa. Giller et al.
(2009) claim that the potential for CA is very limited in Africa whilst Baudron et al.
(2015a) argue that CA has potential in Africa due to increasing tillage costs as a
result of higher energy prices combined with feed shortages for traction animals.
The areas affected by erosion will also increase due to increased cultivation of steep
slopes and reduced soil cover. Furthermore, climate change will also necessitate the
development of cropping systems that can ensure timely sowing and more droughtresistant farming systems.
The Prospects for Conservation Agriculture in Ethiopia