Carbon sequestration and selected hydraulic characteristics under conservation agriculture and traditional tillage practices in Malawi

Abstract

Conservation agriculture (CA) is increasingly promoted among smallholder farmers of sub-Saharan Africa in a quest to improve food security while sustaining the natural resource base of the agro-ecosystems where agriculture is based. The aim of this study was to investigate the effects of CA and traditional tillage on soil organic carbon (SOC) and selected hydraulic properties in two contrasting agro-ecological zones of Malawi. Six farmers hosted on-farm trials in each location, with each farmer having the following treatments: CA with continuous sole maize (CA-SM), CA with maize–legume intercrops (CA-ML), and traditional tillage with continuous sole maize (CT-SM). Soil samples were randomly collected in October 2015, from farmers’ fields located in Chipeni, Chinguluwe, Lemu, and Zidyana where CA had been implemented for 10 years (2005–2015) at six depth intervals: 0–10, 10–20, 20–40, 40–60, 60–80, and 80–100 cm. Bulk density, soil water characteristics, and pore size distribution were determined using undisturbed core samples. At all sites, CA improved total SOC, carbon stocks, and the stable fraction of particulate organic carbon. Maize–legume intercropping under CA had 35%, 33%, and 73% more total SOC than CT-SM in Chipeni, Lemu, and Zidyana respectively. In Chinguluwe and Lemu, CA-ML had 0.54 and 0.50 g kg–1 respectively more stable fraction of particulate organic carbon (POMP) than CT-SM; whereas in Chipeni, CA-SM had 0.73 g kg–1 higher POMP compared with CT-SM. CA also improved soil porosity, pore size distribution, and water retention capacity by increasing the proportion of mesopores and micropores compared with CT-SM. Thus, changing management practices from CT-SM to CA has the potential to improve the soil organic matter and soil hydraulic properties across agro-ecological zones in Malawi, which is important for sustainable agriculture. Farmers should be encouraged to minimise tillage, retain residues as mulch on the soil surface, and practice crop rotation.

Evaluating the merits of climate smart technologies under smallholder agriculture in Malawi

“…The results obtained here agree with literature findings suggesting increases in SOC stocks in no-till systems (Dey et al, 2020;Duval et al, 2020;Gonçalves et al, 2019;Yang & Wander, 1999) and Maris et al, (2021) who showed highly significant enrichment of SOC stocks in systems employing leguminous cover crops. Our results suggesting improvements in SOC and other soil properties under CA, also agree with findings in other studies in Malawi (Mloza-Banda et al, 2014 and on sites with CA having been implemented for up to 10 years (Simwaka et al, 2020). Yet our results contradict findings from a number of locations in southern Africa on which CA had been implemented for up to seven years where no significant differences in SOC stocks between CA and conventional till systems were observed (Cheesman et al, 2016).…”

A talajkímélő művelési rendszerek áttekintése az éghajlatváltozás hatásához alkalmazkodni képes talajok kialakítása és fenntartása céljából a szubszaharai Afrikában

“…Southern Africa has been under a dark cloud of adverse weather conditions for the past 4 decades (SHEPPARD et al, 2020) and it seems likely that the situation will change for the better. Projections by climate experts predict future negative impacts owing to climate change in the southern African region (SHONGWE et al, 2011). The predicted climate changes will threaten some of the current conservation goals such as soil and water conservation, enhanced crop yield and carbon sequestration.…”

“…Predicted changes in the future of African temperatures may be accompanied by a decrease in precipitation, thus altering soil fertility (SHONGWE et al, 2011). Various researchers stressed about high temperatures and precipitation, increasing the rate of soil fertility loss in the form of SOC and worsening nutrient drainage (ELBASIOUNY et al, 2022).…”

“…Distinct from CT, CST promotes the retention of crop residues and maintains permanent soil cover. Reduces soil disturbance (OBIA et al, 2020;SIMWAKA et al, 2020). The significance of these practices in agriculture is but not limited to enhancing soil hydrological dynamics and preventing soil erosion.…”

Environmental Services: A New Approach Toward Addressing Sustainable Development Goals in Sub-Saharan Africa

“…Relationships between these different elements have been discussed in several studies. For example, soil properties such as carbon content have been explicitly linked to minimal tillage conservation agriculture methods (e.g., Willcocks and Twomlow, 1993;Bationo et al, 2007;Mchunu et al, 2011;Simwaka et al, 2020). Here, conservation agriculture techniques give rise to changes in soil and water properties, with an increase in porosity resulting in an increased capacity for soil moisture storage, increase in soil carbon stock, and changes in particle size distributions within soils.…”