Conservation agriculture in Southern Africa: Advances in knowledge

Abstract

The increasing demand for food from limited available land, in light of declining soil fertility and future threats of climate variability and change have increased the need for more sustainable crop management systems. Conservation agriculture (CA) is based on the three principles of minimum soil disturbance, surface crop residue retention and crop rotations, and is one of the available options. In Southern Africa, CA has been intensively promoted for more than a decade to combat declining soil fertility and to stabilize crop yields. The objective of this review is to summarize recent advances in knowledge about the benefits of CA and highlight constraints to its widespread adoption within Southern Africa. Research results from Southern Africa showed that CA generally increased water infiltration, reduced soil erosion and run-off, thereby increasing available soil moisture and deeper drainage. Physical, chemical and biological soil parameters were also improved under CA in the medium to long term. CA increased crop productivity and also reduced on-farm labor, especially when direct seeding techniques and herbicides were used. As with other cropping systems, CA has constraints at both the field and farm level. Challenges to adoption in Southern Africa include the retention of sufficient crop residues, crop rotations, weed control, pest and diseases, farmer perception and economic limitations, including poorly developed markets. It was concluded that CA is not a 'one-size-fits-all' solution and often needs significant adaptation and flexibility when implementing it across farming systems. However, CA may potentially reduce future soil fertility decline, the effects of seasonal dry-spells and may have a large impact on food security and farmers' livelihoods if the challenges can be overcome.

Phenotyping Conservation Agriculture Management Effects on Ground and Aerial Remote Sensing Assessments of Maize Hybrids Performance in Zimbabwe

“…Conservation agriculture practices have been proposed as potential systems to increase crop yield, [1,2,48,49]). As can be seen in our results, CA plots out-yielded conventional agriculture.…”

“…As can be seen in our results, CA plots out-yielded conventional agriculture. Positive responses to CA are principally the result of the interacting effect of soil characteristics and climate [1]. One of these benefits is attributed to the water-harvesting effects of minimum-tillage practices [50,51].…”

“…However, this mechanical disturbance is leading to a decline in organic matter, an increase of the loss of water by runoff, and, finally, to soil erosion [1]. Together with increasing threats of climate change, the loss of soil and its fertility is expected to become more critical for global agricultural production [2].…”

Potential for Conservation Agriculture in the Dry Marginal Zone of Central Syria: A Preliminary Assessment

“…In Syria, the prominence of olive trees and pruning waste provides one avenue-as do other forms of compostable waste. Grass, leaf litter and other dead-plant biomass may also be utilized as a source of ground cover, and these are showing promise in parts of sub-Saharan Africa [37]. Suggestions have also been made to incorporate a range of agro-industrial waste combinations into supplemental sources of livestock feed (e.g., molasses and olive-oil pomace) with potential beneficial outcomes for joint products produced-such as milk and yoghurt quantity and quality [38].…”

Smallholder Farmer Innovation and Contexts in Maize-Based Conservation Agriculture Systems in Central Malawi

“…Area under CA (100,000 ha) high rainfall areas; d) inadequate residues in very dry areas; e) land insecurity leading to unwillingness to invest in the CA; f) shifting of CA labour to women; g) lack of good markets for input purchase and sale of produce; h) tradition, believes and communal peer pressure (Wall, 2007;Thierfelder & Wall, 2011;Corbeels et al, 2013;Thierfelder et al, 2015b).…”