Impacts of conservation agriculture on soil structure and hydraulic properties of Malawian agricultural systems

Eze, Samuel; Dougill, Andrew J.; Banwart, Steven A.; Hermans, Thirze D. G.; Ligowe, Ivy Sichinga; Thierfelder, Christian

doi:10.1016/j.still.2020.104639

Cited by 61 publications

(43 citation statements)

References 34 publications

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“…In recent decades, there has been a growing body of research on the links between soil characteristics, tillage and crop performance, although studies under the specific environmental conditions of southern Africa and also integrating soil biological and Eze et al, 2020). Our study was conducted under both controlled conditions (i.e., in on-station trials), and under smallholder farmer-managed conditions to acknowledge the diversity and heterogeneity of more real farm situations.…”

Section: Impact Of Management On Maize Productivitymentioning

confidence: 99%

Toward greater sustainability: how investing in soil health may enhance maize productivity in Southern Africa

Thierfelder¹,

Paterson

Mwafulirwa

et al. 2021

Renew. Agric. Food Syst.

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Climate change and soil fertility decline are major threats to smallholder farmers' food and nutrition security in southern Africa, and cropping systems that improve soil health are needed to address these challenges. Cropping systems that invest in soil organic matter, such as no-tillage (NT) with crop residue retention, have been proposed as potential solutions. However, a key challenge for assessing the sustainability of NT systems is that soil carbon (C) stocks develop over long timescales, and there is an urgent need to identify trajectory indicators of sustainability and crop productivity. Here we examined the effects of NT as compared with conventional tillage without residue retention on relationships between soil characteristics and maize (Zea mays L.) productivity in long-term on-farm and on-station trials in Zimbabwe. Our results show that relationships between soil characteristics and maize productivity, and the effects of management on these relationships, varied with soil type. Total soil nitrogen (N) and C were strong predictors of maize grain yield and above-ground biomass (i.e., stover) in the clayey soils, but not in the sandy soils, under both managements. This highlights context-specific benefits of management that fosters the accumulation of soil C and N stocks. Despite a strong effect of NT management on soil C and N in sandy soils, this accrual was not sufficient to support increased crop productivity in these soils. We suggest that sandy soils should be the priority target of NT with organic resource inputs interventions in southern Africa, as mineral fertilizer inputs alone will not halt the soil fertility decline. This will require a holistic management approach and input of C in various forms (e.g., biomass from cover crops and tree components, crop residues, in combination with mineral fertilizers). Clayey soils on the other hand have greater buffering capacity against detrimental effects of soil tillage and low C input.

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Section: Impact Of Management On Maize Productivitymentioning

confidence: 99%

Toward greater sustainability: how investing in soil health may enhance maize productivity in Southern Africa

Thierfelder¹,

Paterson

Mwafulirwa

et al. 2021

Renew. Agric. Food Syst.

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“…The 'Solver' function in Microsoft Office Excel (2016 version) was used to estimate the best fit parameter values for q r , a, and n, based on values that produced the smallest residual error between measured and calculated values for q (Eze et al 2020).…”

Section: Soil-water Characteristic Curves and Pore Size Distribution (Psd)mentioning

confidence: 99%

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

Simwaka

Tesfamariam

Ngwira³

et al. 2020

Soil Res.

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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.

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“…The CA systems were maize-based and consist of maize monocrop systems, as well as maize intercrop or rotation with cowpea, pigeon pea, and velvet bean. Soil health indicators of conventional maize monocrop under ridge and furrow system with crop residues removed after harvest were compared with those of the CA practices [23,24]. Farmers' awareness and use of soil health indicators influence their choice of land management practices when these also reduce pests and diseases and reduce labour demands.…”

Section: Resultsmentioning

confidence: 99%

“…Results from soil studies show that maize-based CA systems in the case study regions improve soil structure [23], which is an important indicator of soil health that influences numerous soil processes and functions such as water and nutrient retention, aeration, resistance to physical erosion, microbial activities, and crop root growth. The main challenge to realising the full benefits of the CA systems in terms of improving soil structural properties and the resilience of the agro-ecosystem is the implementation of crop residue management practices which are often labour-limited due in part to limited village healthcare systems [16].…”

Section: Ghanamentioning

confidence: 99%

Evaluating Climate-Smart Agriculture as Route to Building Climate Resilience in African Food Systems

et al. 2021

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Efforts to meet the growing demand for food across Africa have led to unsustainable land management practices that weaken the resilience of African Food Systems. Soil health is key to building more climate-resilient agricultural systems and can be improved through Climate-Smart Agriculture (CSA) practices that also enhance soil carbon storage. Many CSA practices are being implemented by African farmers, whereas others are being actively promoted but adoption remains low due to multiple factors including weak policy integration, limited institutional support, and inadequate agricultural extension advice. This Short Communications paper presents overview findings from trans-disciplinary research projects from Southern, East, and West Africa to evaluate the potential importance of integrated participatory soil health studies designed to inform context-specific recommendations and policies for resilient African food systems. The use of soil health indicators to measure the effectiveness of implemented CSA practices including Conservation Agriculture in maize-based systems and Soil and Water Conservation in Highland African systems are discussed. The paper identifies how more integrated research can help to enable shared learning and the enhanced knowledge exchange required for the upscaling of sustainable land management practices enabled through enhanced farmer participation in the chain of CSA activities from intervention design to community evaluation of impacts.

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Impacts of conservation agriculture on soil structure and hydraulic properties of Malawian agricultural systems

Cited by 61 publications

References 34 publications

Toward greater sustainability: how investing in soil health may enhance maize productivity in Southern Africa

Toward greater sustainability: how investing in soil health may enhance maize productivity in Southern Africa

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

Evaluating Climate-Smart Agriculture as Route to Building Climate Resilience in African Food Systems

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