Experiment 1
In Vientiane, the yield without fertilizer N and
residues was 2.1 t ha–1 (Fig. 1). Addition of N
fertilizer increased yields by 0.9 t ha–1—an AE of
15 kg kg–1. There was a significant yield response
to all residues but the interaction between N and
residues was not significant (Fig. 1 and Table 5),
suggesting additive benefits from the combined
application of residues and fertilizer N. Average
yields across N treatments increased by 0.9, 0.6,