Labour requirements are generally reduced by about 50%, which allows farmers to save on time, fuel and machinery costs [23–27]. In general, fuel savings in the order of around 60% or more are reported [28–30]. (Kassam et al., 2018, p.3) Field trials in cereal systems in the Indo-Gangetic Plains (IGP), India show a reduced production cost of up to 23% but volume of production was not statistically significant compared to conventional tillage system (Saptoka et al, 2015). A study in Zimbabwe showed that the economic viability of CA for smallholders is highly dependent on fertilizer application and subsidized fertilizer prices (Tui et al., 2015).

CA is highly knowledge intensive. Although the CA principles are common and have widespread applicability, actual practices towards these desirable objectives can vary across agro-ecosystems and socio-economic conditions (Erenstein et al. 2012). For example, the specifc components of CA-based management such as crop establishment methods, selection of farm implement, selection of crops in the rotation, management of plant nutrients, crop residue, water and the selection of genotypes can be different across environments (Harrington and Erenstein 2005). Hence not only farmers, but also researchers, extension agents and other institutions involved in agricultural development need to have proper knowledge to successfully adapt and adopt CA options suited to their specific farm typologies. Readily availability of scale-appropriate CA machinery and other inputs is another major reason for the lower uptake of CA particularly in eastern IGP. For example, simple ZT machine cannot seed over the previous crop residues as it drags loose residues retained on the surface. To avoid this, farmers generally burn the previous crop residue before planting new crop. However, with the development of Happy Turbo Seeder that can drill seed and fertilizer over the loose straw left in the field, this technological constraint has overcome recently (Sidhu et al. 2007). Its uptake, however, needs its own time. Weed management has been one of the constraints to adopt CA by smallholder farmers. This is, however, no more an issue with the recent advancements in weed management technologies including new herbicides molecules (Jat et al. 2014). As crop residue management is an important component of CA for continuous soil cover, competing uses of crop residue as livestock feed, fuel, mulch, and compost, can impose a substantial challenge for the expansion of CA (Erenstein and Thorpe 2010; Tittonell et al. 2015). Therefore, local adaptive researches are needed to strategically adjust residue management for different competing objectives that help sustainability of CA. (Saptoka et al, 2015, p.1529).

Southeast Asia has seen only marginal adoption in part because its main crop, rice, is usually grown under a tillage system (Kassam et al. 2009). (Parks, Christie and Bagares, 2015, p.62). Major constraints to the adoption of CA practices continue to be: knowledge about the existence of CA and how CA is applied, mind-set (tradition, prejudice), inadequate policies, for example, commodity-based subsidies (EU, US) and direct farm payments (EU), unavailability of appropriate equipment and machines (many countries of the world) and of suitable management strategies to facilitate weed and vegetation management, including mechanical, biological and chemical options as herbicides (especially for larger farms in low-income countries) [9,10,43]. Other area-specific constraints in semi-arid areas during the transformation to CA system relate to: initial low supply of crop and vegetation biomass for soil mulch cover development; initial short-term competition for crop residue as livestock feed; and initial adoption of new manual weed management practices when the soil mulch cover and integrated weed management practice is being established. (Kassam et al., 2018, p.5) Farmer uptake of CA is not only related to technology, but also with various socio-economic factors. Due to the conventional mind-set of clean cultivation, it is not easy to dissociate tillage and farming from the farmers’ mind and establish the new concept that farming is possible without tillage (Hobbs and Govaerts 2010). (Saptoka et al, 2015, p.1529). Globally, the number of countries practicing conservation agriculture jumped from 42 to 78 countries. The recorded land area using conservation agriculture has increased from 106 M ha of cropland in 2008/09 to 180 M ha in 2015/16. (Kassam et al., 2018) Access to land could be a constraint for both men and women. According to some of the literature, resource-constrained farmers, particularly those with little access to land and inputs, are less likely to adopt CA practices (Jones 2002; Knowler and Bradshaw 2007; Giller et al. 2009). In addition, women not having access to land tenure and not being full-time farmers might pose constraints, since researchers could interpret this to mean that women’s involvement is not needed in CA projects. This is significant because studies show that when women are not involved in the adoption of a (conservation) practice, it is less likely to succeed (Knowler and Bradshaw 2007; Magcale-Macandog et al. 2010).(Parks, Christie and Bagares, 2015, p.73). Short-term land management arrangements such as renting or mortgaging could be a constraint since there are limited benefits in the first 4 years of adoption and farmers want to maximize their profits during their tenancy. In the beginning, CA increases weeds and requires increased inputs, while not necessarily increasing yields. Farmers who are renting a plot of land for 5 years may be hesitant to adopt CA because they are more concerned about production and shortterm profits than increasing the quality of a soil that is only temporarily for their use.(Parks, Christie and Bagares, 2015, p.73).

When compared to a plow-based system, the soil organic content (SOC) and residual water content (RWC) in the CAPS increased over time. Other recorded positive effects are rainwater splash and erosion reduction. The SOC and RWC in the plow-based system showed a decline (Ella et al., 2016). CA enhances biological activity in soils, resulting in long-term yield and factor productivity increases, as well as increases in overall system-level biomass production (Kassam et al., 2018, p.2) CA complies with the generally accepted ideas of ecological sustainability because the three principles when implemented act like land with natural vegetation [2–4,15–17]. Increased cropping system diversity and stimulation of biological processes in the soil and above the soil surface, combined with reduced erosion and leaching, can lead to increased retention and use of water and nutrients and a decline in the application of mineral fertiliser and pesticides, including herbicides, in the longer term. Ground water resources are replenished through better water infiltration and reduced surface runoff. Water quality is improved because of reduced contamination levels from agrochemicals and soil nutrient through reduced leaching and soil erosion [18].(Kassam et al., 2018, p.3)