V. Kleinhenz et al., EFFECTS OF LEGUME LIVE-MULCH ON CROP PERFORMANCE, SOIL AVAILABLE NITROGEN AND CROP N STATUS IN INTENSIVE TROPICAL VEGETABLE PRODUCTION, Biological agriculture & horticulture, 14(4), 1997, pp. 261-278
In an attempt to introduce legume green manure to intensive tropical v
egetable production, we studied the effects of live-mulch. Soil nitrog
en, crop-N status, and yields were closely monitored in a continuous,
year-round vegetable sequence from 1992 to 1995 in the rice-based lowl
and environment of southern Taiwan. When live-mulch was newly establis
hed at high density, vegetable yields were negatively affected. With c
hange in proportion and spatial arrangement, inter-specific competitio
n;was reduced. Besides direct competition between live-mulch and veget
able intercrops, incorporating legume biomass into the soil resulted i
n immobilization of available soil nitrogen. This effect was presumabl
y conditioned by seasonal cool temperature. Short-term negative effect
s of live-much on vegetable production were offset in the longer term
by a positive influence of previous year's biomass of legume clippings
on vegetable yields in 1994/95. No differences were found in minerali
zed soil nitrogen between no-mulch and live-mulch treatments, but ther
e was indication that crop-N status was better in live-mulch plots. Th
is might have resulted from a slow but sustained mineralization of soi
l organic nitrogen which was presumably improved by live-much applicat
ion and was readily absorbed by vegetables. From a practical viewpoint
, a live-mulch-vegetable system is probably too expensive and labour-i
ntensive to implement for the minimal positive longer-term effects.