. Usefulness of rice straw mulch and groundnut residue in increasing N uptake and rice grain yield
was demonstrated in a similar rice-based cropping system in NE
Thailand (Thomsen et al., 1995; Kaewpradit et al., 2009). Thus, the
favourable growing environment created by mulch would have
resulted in improved crop growth and hence yield directly in addition
to its indirect effect through increased crop establishment.
Yield increase due to mulch was large in the two cases of low
weed pressure suggesting that the yield advantage was caused by
improved environment for mung bean growth, as in these cases,
crop establishment increased only from mean of 72 to 82%, and
hence unlikely to explain 78% increase grain yield. This suggests
the favourable conditions created by mulch promoted growth, in
addition to a small contribution from increased plant density