Unravelling farmers’ sticky varietal preferences against pro-nutritional crops: the case of biofortified sweet potato in Malawi

Abstract

Adoption of pro-nutritional crop varieties such as orange-fleshed sweet potato (OFSP) remains limited among smallholder farmers in Malawi, despite their proven superiority to conventional varieties in improving household nutrition and income. Understanding the behavioural and contextual factors underpinning varietal preferences is critical for designing effective interventions. This study employed a contingent valuation approach to elicit farmers’ differentiated willingness to pay (WTP) for clean planting materials of OFSP and non-OFSP varieties among 721 smallholder households across four districts. Using a Seemingly Unrelated Regression (SUR) model and a Triple-Hurdle framework incorporating a lognormal component and number-line concept, the study innovatively identified the determinants of awareness, preference formation, and the direction of preference thereby capturing both sustained and switching tendencies. Findings revealed that 41% of farmers had adopted OFSP, while the mean WTP for non-OFSP vines (USD 2.64) slightly but significantly exceeded that for OFSP (USD 2.57), confirming the persistence of resistance to biofortified varieties. Sustained preference for OFSP was positively associated with education, household size, off-farm income, and access to vine multipliers, whereas sustained preference for non-OFSP was reinforced by location, higher transaction costs, and mixed extension outcomes. Yield perceptions, market distance, and production purpose influenced potential preference switching. These findings highlight that varietal choices are adaptive responses shaped by perceptions, context, and household needs rather than simple awareness gaps. Policy interventions that integrate targeted nutrition education, strengthen extension messaging, subsidise clean vine access, and improve market linkages are essential to move farmers from indifference towards sustained preference for OFSP.