Profitability and opportunity of conservation agriculture in acid savannah grasslands of Laos

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

Principes et fonctionnement des écosystèmes cultivés en semis direct sur couverture végétale permanente.

Ouvrage de vulgarisation In : Manuel pratique du semis direct à Madagascar. Volume I. Chapitre 1. CIRAD-GSDM, Antananarivo

Multi-functional assessment of soil health under Conservation Agriculture in Cambodia

As a response to the worldwide challenge raised by soil degradation, Conservation Agriculture (CA) was proposed to help restoring the three main soil functions, i.e. carbon transformation, nutrient cycling and structure maintenance. However, there is still a lack of integrative studies that assess the overall impact of CA on soil health. To fill the gap, Biofunctooll (R), a set of in-field indicators, was developed to monitor changes in soil biological functioning. In this study, Biofunctool (R) was used to assess the impact of a conventional tillage (CT) and three CA annual-based cropping systems on soil health on a Cambodian Oxisol. Eight indicators related to the three soil functions were monitored and integrated into a Soil Quality index (SQI), i.e. the Biofunctool (R) Index. Overall, we found that soil health was twice higher under the CA treatments than under CT treatment. Although it was similar in the three CA treatments, the contribution of each soil function to the soil health diverged. An analysis of soil carbon dynamics also showed that CA support short-term soil organic carbon stabilization compared to CT. This study demonstrates that Biofunctool (R) is a robust, relevant, time-and cost-effective in-field assessment tool that can be used in multiple ways including cropping system management, capacity building of local stakeholders, and policy dialogue

La gestion des écosystèmes cultivés en semis direct sur couverture végétale permanente.

Ouvrage de vulgarisation In : Manuel pratique du semis direct à Madagascar. Volume I. Chapitre 2. CIRAD-GSDM, Antananarivo