Smallholder farming systems need climate-proofing and sustainable intensification practices such as conservation agriculture (CA), are promising options. However, there is a general perception that the adoption of CA systems in southern Africa is low. Sentinel sites, where CA has been promoted for a long time, offer forward-looking new insights. This paper, thus, takes a deep dive at Nkhotakota district of Malawi to understand what could have led to the success of CA promotion and subsequent perceived high adoption. We use survey data from 620 farmers, with 298 farmers sampled from treatment areas – known to have had contact with host farmers and 320 from a control group. Overall, 31% of the farmers in both groups adopted full CA over at least a 2-year period. We also find that about 57% of farmers in the treatment area adopted full CA and only 7% of farmers in the control areas. This highlights that longer-term CA promotion with dedicated extension support can enhance the uptake of CA practices. In essence, this paper offers a different perspective to the current narrative that CA systems are too complex and knowledge intensive to be adopted despite its long-term promotion and significant investments. However, there are some nuances: sustained adoption even in sentinel sites is neither 100% nor persistent over the long term. We find an appreciable adoption decay, showing large declines from highs of 57 and 7% in adoption for at least 2 years for treatment and control, respectively, to 12% in the treatment group and practically zero in the control when we condition full CA adoption to at least 7 years. This means that fewer farmers adopted CA for a longer period and suggests some dis-adoption over time even in sentinel sites. The key adoption enablers in the sentinel sites include the availability of training, dedicated longer-term extension support coupled with farmer experiential learning through demonstration plots managed by host farmers. Based on our findings, there is need to consistently promote CA using farmer-centric approaches that include peer-to-peer learning over long periods. This allows farmers time to experiment with different CA options, enable behavioral and lasting change. At policy level, there is need to build and strengthen farmer groups to facilitate easier access to inputs like leguminous crop seeds for farmers practicing CA and to offer market-smart incentives to induce initial adoption in the short term to facilitate sustained adoption.

Production of cereal crops in sub-Saharan Africa is threatened by parasitic striga weeds and attack by stemborers and the invasive fall armyworm (FAW), compounded by increasing hot and dry conditions. A climate-smart push-pull technology (PPT) significantly reduces effects of these biotic challenges. To improve further resilience of the system to climate change, more adapted and suitable companion plants were identified and integrated in a new version of PPT, termed ‘third generation PPT’. Our study evaluates field performance and farmer opinions of this new version in comparison with the earlier version, climate-smart PPT, and farmers’ own practices of growing maize in controlling stemborers, FAW, and striga weeds. Trials were conducted across five locations in western Kenya for two cropping seasons in the year 2019 following a one-farm one-replicate completely randomized design. We assessed infestation on striga, stemborers, and FAW, and yield performance of the three cropping systems. We also sought the opinions of the hosting farmers through semi-structured questionnaires that were administered through individual interviews. Both PPT plots recorded significantly (P < 0.05) lower striga count, FAW, and stemborer damage, and higher grain yield than in plots that followed farmers’ own practices. There was no statistically significant difference between the two PPT plots except for stemborer damage for which the third generation PPT recorded higher damage than the climate-smart PPT. However, farmers preferred the third generation PPT for important traits possessed by its companion plants which their counterparts in climate-smart PPT are deficient. The cultivar Xaraes was rated as ‘very good’ for resistance to spider mites, biomass yield, and drought tolerance while Desmodium incanum was rated ‘very good’ for seed production and drought tolerance. The third generation PPT is based on companion crops that are more resilient to hot and dry conditions which are increasing rapidly in prevalence with climate change. This version therefore presents a better option to upscale the technology and meet different needs of farmers especially in arid and semi-arid conditions.

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.

We used choice experiment data collected from 542 farmers in Nigeria to assess smallholders’ preferences for shifting to Climate-Smart Agriculture (CSA). Results suggest that the higher the size of the incentive, the more the likelihood of farmers’ willingness to invest in CSA schemes. Similarly, the farmers were in favor of community development associations and non-governmental organizations-managed schemes over other project managements and also prefer government-based institutions as opposed to the private sector. Willingness to accept results suggest that an average farmer is willing to accept $540/ha/year and $386/ha/year to embrace good agricultural practices (GAPs) with and without manure application.

Resilient cropping systems are required to achieve food security in the presence of climate change, and so several long-term conservation agriculture (CA) trials have been established in southern Africa – one of them at the Chitedze Agriculture Research Station in Malawi in 2007. The present study focused on a longitudinal analysis of 10 years of data from the trial to better understand the joint effects of variations between the seasons and particular contrasts among treatments on yield of maize. Of further interest was the variability of treatment responses in time and space and the implications for design of future trials with adequate statistical power. The analysis shows treatment differences of the mean effect which vary according to cropping season. There was a strong treatment effect between rotational treatments and other treatments and a weak effect between intercropping and monocropping. There was no evidence for an overall advantage of systems where residues are retained (in combination with direct seeding or planting basins) over conventional management with respect to maize yield. A season effect was evident although the strong benefit of rotation in El Niño season was also reduced, highlighting the strong interaction between treatment and climatic conditions. The power analysis shows that treatment effects of practically significant magnitude may be unlikely to be detected with just four replicates, as at Chitedze, under either a simple randomised control trial or a factorial experiment. Given logistical and financial constraints, it is important to design trials with fewer treatments but more replicates to gain enough statistical power and to pay attention to the selection of treatments to given an informative outcome.

Influence of land tenure and property rights (LTPRs) on farmers’ willingness to accept (WTA) incentives to embrace climate-smart agriculture (CSA) to combat land degradation was examined with choice experiment data collected from 1,138 farmers drawn across 16 States in Nigeria. Data analysis within random-effect and mixed logit framework revealed the existence of strong linkages between the payment vehicle, LTPRs and farmers’ CSA preferences. While farmers who were dependent on leased and/or communal lands expressed implicit dislike for CSA-related investments, the majority with freehold titles, particularly those with registered titles, expressed positive WTA incentives to embrace CSA and combat land degradation.

Climate variability and declining soil fertility pose a major threat to sustainable agronomic and economic growth in Zambia. The objective of this study was to assess crop yield, land and labor productivity of conservation agriculture (CA) technologies in Eastern Zambia. On-farm trials were run from 2012–2015 and farmers were replicates of a randomized complete block design. The trials compared three CA systems against a conventional practice. Yield and net return ha−1 were determined for maize and legume yield (kg ha−1) produced by ridge and furrow tillage, CA dibble stick planting, CA animal traction ripping and direct seeding. The dibble stick, ripline and direct seeding CA systems had 6–18, 12–28 and 8–9% greater maize yield relative to the conventional tillage system, respectively. Rotation of maize with cowpea and soybean significantly increased maize yields in all CA systems. Intercropping maize with cowpea increased land productivity (e.g., the land equivalent ratio for four seasons was 2.01) compared with full rotations under CA. Maize/cowpea intercropping in dibble stick CA produced the greatest net returns (US$312-767 ha−1) compared with dibble stick maize-cowpea rotation (US$204-657), dibble stick maize monoculture (US$108-584) and the conventional practice (US$64-516). The net-return for the animal traction CA systems showed that maize-soybean rotations using the ripper were more profitable than the direct seeder or conventional ridge and furrow systems. Agronomic and economic benefits of CA-based cropping systems highlight the good potential for improved food security and agricultural productivity for smallholder farmers.