A stratified field survey was conducted of 240 maize fields from six agroecologically diverse districts in Malawi: Mulanje, Chiradzulu, Kasungu, Ntcheu, Mzimba, and Rumphi (Figure 1).

Within a district (Figure 1), one Extension Planning Area (EPA) was selected. Four sections were identified within each EPA, and within each section, ten contiguous maize fields were selected along a linear transect. Fields were surveyed during the rainy season when plants were generally no more than 45 cm in height. We assessed how current farmer practices compare to the national recommendation of 53,333 plants per hectare and evaluated the spatial dimensions ridge spacing, intra-row spacing, and plants per station, that drive deviations from this benchmark.

A standardized field protocol was used on all sampled farms. Along a continuous 20-m row in the field we counted the total number of ridges, the number of maize plants, and the number of planting stations (Figure 2). A planting station was operationally defined as a cluster of maize plants located within a 5-cm radius, representing a single sowing point. Measurements were replicated three times per farm.

We evaluated key agronomic variables—ridge spacing, intra-row spacing, number of plants per station, and overall plant population for all 240 farms. Differences across the districts were evaluated by using a one-way analysis of variance (ANOVA), with statistical significance assessed at p < 0.05. When significant treatment effects were observed, post hoc comparisons of means were performed by using Tukey’s Honestly Significant Difference (HSD) test to determine pairwise differences. All analyses were performed with IBM SPSS Statistics, version 22 (IBM Corp., Armonk, NY, United States).

While mechanization, e.g., tractors, could enable the planting scheme transition, access to tractors is mostly on large farms and access by smallholder farmers is limited, if it occurs at all. High upfront costs, limited extension service coverage, and farmer risk aversion all hinder adoption. Many smallholders are reluctant to invest in unfamiliar technologies or practices, especially without clear, demonstrated returns (Crentsil et al., 2020). This hesitation reflects a broader dynamic amongst smallholder farmers, for whom short-term subsistence needs often are more important than long-term productivity gains, and where institutional support for beneficial transformative changes is weak.

Mechanizing the transition from 90 cm to 75 cm ridge spacing, through plowing, harrowing, and ridge construction, costs approximately MWK 121,200 ($69.77) for 0.404 hectares. According to Omara et al. (2016), this spatial adjustment alone can increase yields by 25%, raising the national average from 1.3 to approximately 1.625 tons per hectare. On a 0.404-hectare plot, this translates to an additional 0.131 tons of maize. At MWK 1,050,000 ($630) per ton, the additional maize is worth MWK 137,550 ($82.36), which exceeds the mechanization cost and allows the investment to be recovered in the first season. When combined with additional improved agronomic practices, such as fertilizer, and integrated pest and disease management, total yields could reach 3 tons per hectare (Denning et al., 2009; Toungos, 2018), or 1.212 tons on 0.404 hectares. This yield is an increase of 0.686 tons over the current yield of 1.3 tons. At current prices, the total output would be valued at MWK 720,300 ($432.46), which means an investment in mechanized ridge spacing and agronomic enhancements is profitable in the first year even at the smallholder level.

In addition to increased financial returns, transitioning to improved spacing also increases land use efficiency. An average household of eight requires approximately 1.168 tons of maize annually for subsistence (Mazunda and Droppelmann, 2012). At the current yield in Malawi of 1.3 tons per hectare, satisfying this demand would require 0.89 hectares, which is more than twice the national average landholding of 0.404 hectares (National Statistics Office, 2019). Adopting the 75 cm × 25 cm spacing with one plant per station could deliver up to 1.625 tons per hectare and reduce the land required to 0.719 hectares. Additional agronomic upgrades, e.g., improved fertilizer management, better weed control, adoption of conservation agriculture practices, use of drought-tolerant maize varieties, and soil fertility enhancements from planting legumes or incorporating organic matter, could increase the yield to up to 3 tons per hectare (Denning et al., 2009; Toungos, 2018) and require just 0.39 hectare to feed an entire family of eight. Such productivity improvements make existing village land holdings more likely to enable household food security. For farms with more land than the national average, land no longer required for maize production could be used to produce legumes, horticultural crops, or other income-generating crops, and strengthen household resilience while expanding livelihood opportunities without requiring additional land to be cultivated.

In areas where tobacco (N. tabacum) is cultivated as a cash crop, the 75 cm maize ridge spacing must be adapted to enable maximum tobacco production. Recommended ridge spacing for tobacco is 100 cm (Kharazmi et al., 2014), with most farmers using 90 cm spacing, and in adjacent countries some ridges may be spaced at 80 cm (Krishna et al., 2004). Thus, there appears to be flexibility in the ridge spacing for tobacco. Such flexibility may be adaptable to include ridges spaced at 75 cm, and thereby eliminate the need to reconfigure ridge layouts between seasons. Developing a zigzag or staggered intra-row planting pattern, could allow tobacco to still perform well on narrower ridges without compromising yield. The ability to use ridges spaced at 75 cm for both maize and tobacco would streamline rotational practices, reduce labor demands, and promote wider adoption of improved maize planting techniques, without undermining tobacco’s role in supporting household income.

To enable conversion to 75 cm ridge spacing, the government could subsidize the one-time cost of mechanized land preparation and redefinition of row spacing. Currently, the Farm Input Subsidy Programme (FISP) provides each beneficiary household cultivating an average size farm of ~0.404 hectares with two bags of fertilizer and one pack of seed. This subsidy costs the Malawi government about MWK 144,000 ($86.40) per household annually (National Statistics Office, 2019). The cost of fully mechanized land preparation, including plowing, harrowing, and ridge construction, is approximately MWK 300,000 per hectare, or MWK 121,200 ($69.77) for 0.404 hectares. Thus, the current government subsidy is 24% more than the amount required to prepare the land for optimal use. Unlike the annual subsidies, however, mechanization is a one-time investment with lasting structural benefits. Once ridges are realigned to the recommended 75 cm spacing, they can be maintained with an effort similar to that previously used to maintain a field with 90 cm ridge spacing in previous seasons. Thus, the tighter ridge spacing does not increase labor demand, but does increase the efficiency with which critical resources such as fertilizer (Piao et al., 2022), water (Welde and Gebremariam, 2016), and seed (Omara et al., 2016) are used, while increasing long-term yield and the return on the public subsidy investment.

Intercropping is a common strategy used by smallholder farmers to manage risk and diversify livelihoods on limited land (Snapp et al., 2002). The recommended 25 cm intra-row spacing often is incompatible with intercropping. Intercrops, e.g., legumes, require more space between maize plants to minimize competition for light and root resources, challenges that often are exacerbated in densely planted maize stands (Giller et al., 2009). Thus, intra-row spacing recommendations must be flexible depending on the intercrop grown in order to maximize the combined maize and intercrop yield, ensure agronomic compatibility, and incentivize adoption by the farmers (Beedy et al., 2010; Rusinamhodzi et al., 2012).

While mechanization can improve ridge-based systems, alternative approaches, may offer even greater potential under certain conditions. For example, flat or basin-based planting systems, particularly under conservation agriculture (CA), are a promising alternative (Nyagumbo et al., 2016). Studies from Malawi, Mozambique, and broader Eastern and Southern Africa have shown that CA practices, centered on flat planting, minimal tillage, and crop rotation, can all increase plant population density, improve soil structure, and stabilize yields over time (Mupangwa et al., 2021; Nyagumbo et al., 2016, 2020). These systems enable more precise plant spacing and reduce soil disturbance, two critical factors for optimizing yield potential. Moreover, research in South Africa indicates that high-density CA systems may yield up to 9 tons per hectare (Haarhoff and Swanepoel, 2018). However, scaling such systems requires context-specific adaptation, particularly access to appropriate mechanization, a need already identified as a national priority in Malawi’s agricultural policy framework (Government of Malawi, 2016).

While our study provides robust empirical insight into maize planting practices across six districts in Malawi, several limitations must be considered in drawing conclusions from our results. First, intercropping was frequently observed during the survey, but its influence on spacing decisions and resulting plant population densities was not systematically assessed. Second, the study effectively maps patterns of suboptimal planting, but does not explore the behavioral, economic, and institutional drivers that may be hindering the adoption of the recommended agronomic standards. A third limitation is the lack of a direct link between observed planting densities and yield outcomes. The national spacing guidelines are premised on agronomic trials indicating optimal plant populations for yield maximization, but we did not empirically validate those assumptions under current farmer-managed conditions. Even so, our findings provide a foundation for follow-up research to quantify yield impacts and unpack adoption barriers, enabling the design of context-specific interventions to close the yield gap.