Profitability and opportunity of conservation agriculture in acid savannah grasslands of Laos Pascal Lienhard a,b∗ , Khamke ´o Panyasiri b , Sengphanh Sayphoummie c , Bounma Leudphanane c , Guillaume Lestrelin b,d , Lucien Se ´guy e and Florent Tivet a a CIRAD, UR SIA, Montpellier cedex 5, France; b NAFRI, NCAC, Vientiane, Lao PDR; c MAF, PROSA, Vientiane, Lao PDR; d IRD, UMR220 GRED, France; e Agroecoriz, Montpellier, France In north-eastern Laos, the savannah grasslands of the Plain of Jars cover vast areas of potentially cultivable land. However, soil acidity, low inherent fertility, and the absence of alternatives to tillage represent significant constraints to the development of sustainable smallholder agriculture. Our objective was to evaluate the potential for conservation agriculture (CA) to enhance soil productivity and farming system profitability. A three-year rotation of rice/maize/soybean was tested under three fertilization levels and four agricultural systems: one conventional tillage-based (CT) system and three CA systems based on no-tillage with cover crops. After four cropping seasons, our results show that, compared with CT, CA systems led to similar-to-higher grain production, similar-to-higher profits, higher opportunity of livestock system intensification, and higher labour productivity regardless of fertilization levels. While CA represents a relevant alternative to current practices, our results suggest that its contribution to the emergence of a sustainable smallholder agriculture is conditioned by broader institutional transformations, including the enrolment of local manufacturers and traders for deploying no-till implements and seed market channels for cover crops, long-term public support to maintain active research and technical mentoring to farmers, and possibly the integration of ecosystem services in agricultural policy. Keywords: acid tropical soils; no-till; cover crops; soil productivity; system profitability; rainfed agriculture; crop – livestock systems; smallholders; two-wheel tractors; scaling-up conditions Introduction The rapid increase in global food demand recorded over the past 50 years and the projected dou- bling of this demand over the next 50 years put land resources under very significant pressure to increase and sustain agricultural production (Tilman et al. 2002). This pressure is further accen- tuated by a rapidly growing demand for non-food agricultural products (Lal 2008). Increase in agricultural production can be achieved through intensification and diversification of farming systems on existing cultivated land and expansion of agriculture on marginal lands (IAEA 2000). One of the greatest potentials for expansion lies in savannah regions of humid and sub- humid tropical areas. These regions comprise a sizeable amount of land resources in many countries of Africa, Latin America, and include also the largely anthropic savannahs of tropical Asia (NASA 2012). They are suitable for rainfed cropping conditions, yet considered marginal due to low inherent fertility and susceptibility to rapid degradation (IAEA 2000, Fageria and Baligar 2008). In particular, the cultivation of these soils under intensive tillage-based agricultural # 2013 Taylor & Francis ∗ Corresponding author. Email: pascal.lienhard@cirad.fr International Journal of Agricultural Sustainability , 2014 Vol. 12, No. 4, 391–406, http://dx.doi.org/10.1080/14735903.2013.806419