cultivated genotype. Lehmann et al. (2002) argued that CA might
even limit soil N availability in N deficient soils due to the high C/N
ratio specific to biochar and, therefore, might reduce crop
productivity at least temporarily. Hence, it is necessary to assess
the effect of CA on crop productivity under field conditions and in
relation to agronomic practices and cultivars used at a given site.
However, such research is rare and little is known about possible
interaction effects. Therefore, we evaluated the effect of CA
techniques on the grain yield of upland rice, which is an important
staple food for Lao people. Our objectives were to characterize the
effect of CA on selected soil characteristics and crop parameters,
thereby evaluating the possible benefits of CA techniques in this
agro-ecological environment.