1. Introduction
Land degradation, a persistent decline in soil quality and its productivity caused by natural or anthropogenic factors, has adversely affected food production, the supply of ecosystem services and livelihoods globally (Kotiaho and Halme, 2018). Even though it occurs throughout the world, the extent and degree of degradation vary with regions. For instance, dryland areas of African countries and Australia; mountain ranges of the Himalayas; and densely populated areas of South Asia are more vulnerable (Bai et al., 2008; Nachtergaele et al., 2011). The consequences of land degradation are severe as it impacts adversely on farm-productivity, and hence, on food security (Conacher, 2009). By 2030, the demand for food is expected to increase by at least 50%, which requires conservation and restoration of the productivity of agricultural land. It is estimated that a 60% increase in agricultural productivity, will be necessary by 2050 in order to overcome hunger and food insecurity (Alexandratos and Bruinsma, 2012).
Many factors are responsible for the global spread of agricultural land degradation. The spread and growth of populations, inappropriate land-use practices, excessive use of chemicals, mechanized agriculture and natural phenomena such as erosion, floods and drought are the proximate causes of degradation (Conacher, 2009). In countries like Nepal, where the demographic pattern is changing substantially due to the outmigration of the economically active population, agriculture land degradation is becoming a serious issue (Jaquet et al., 2015). In a subsistence economy, farmers are forced to cultivate marginal lands; use agrochemicals; and follow intensive farming and mechanized agriculture to sustain their livelihoods. All these activities have supported a gradual decline in soil fertility (Rasul and Thapa, 2003; Westarp et al., 2004).
Reducing further degradation and restoring the degraded agricultural land may contribute to the first three sustainable development goals (SDGs) including no poverty; and good health and well-being substantially. Since the underlying causes of land degradation are multifaceted, it requires an integrated approach of farmland management (Conacher, 2009). A single strategy may be counterproductive, for instance, reduction in chemical fertiliser application may result in decreased crop yield and hence, food insecurity. In this context, agroforestry, which is an integrated tree-based farming system, has come into the forefront given the potential to address land degradation with additional environmental and social benefits (Jose, 2009; Ramachandran Nair et al., 2009). Agroforestry supports biodiversity conservation (Dhakal et al., 2012; Harvey et al., 2006; Kabir and Webb, 2008; Moguel and Toledo, 1999) Similarly, it has higher financial returns compared to that of the conventional agriculture (Neupane and Thapa, 2001). It also provides biosafety as it is less likely to have crop failure compared to the treeless system (Dhakal, 2013). This may be because the agroforestry system restores soil fertility (Neupane and Thapa, 2001; Schwab et al., 2015), and rehabilitates degraded agricultural land (Acharya and Kafle, 2009).
Having so many economic and environmental benefits, agroforestry should be a widely adopted practice. However, the adoption status of such promising land use is not encouraging and not widespread as expected even though there are several national and international organizations working in the promotion of this agricultural practice. There might be disincentives to establishing trees including lack of knowledge, upfront costs, length of time until there is a return and a short to medium-term reduction in cash flow and/or household food production (Cockfield, 2005). Nonetheless, there has been a wealth of research works on agroforestry adoption (Mercer, 2004). Most of the existing literature is focused on the socio-economic, and environmental contributions of an agroforestry system (Mbow et al., 2014; Tscharntke et al., 2015; Waldron et al., 2017).
However, the main question to be answered is what the determinants of adopting an agroforestry system are. This study assesses the determining factors of agroforestry adoption in Nepal. The findings of the study are useful for policymakers, development agencies and academicians.