Cp. Horn et al., SOWING TIME AND TILLAGE PRACTICE AFFECT CHICKPEA YIELD AND NITROGEN-FIXATION .2. NITROGEN ACCUMULATION, NITROGEN-FIXATION AND SOIL-NITROGENBALANCE, Australian journal of experimental agriculture, 36(6), 1996, pp. 701-706
Following long-term studies at Warra, on the western Darling Downs, ch
ickpea (Cicer arietinum) was selected as a useful grain legume cash cr
op with potential for improvement of its nitrogen (N) fixing ability t
hrough management. This 2-year study examined the effect of sowing tim
e and tillage practice on dry matter yield, grain yield (Horn et al. 1
996), N accumulation, N-2 fixation, and the subsequent soil N balance.
Generally, greater N accumulation resulted from sowing in late autumn
-early winter (89-117 kg N/ha) than sowing in late winter (76-90 kg N/
ha). The amount of N-2 fixed was low in both years (15-32 kg N/ha), an
d was not significantly affected by sowing time or tillage. The potent
ial for N-2 fixation was reduced in both years due to high initial soi
l nitrate levels and low total biomass of chickpea because of low rain
fall. Nitrogen accumulation by grain was higher under zero tillage (ZT
) than conventional tillage (CT) for all sowing times, and this affect
ed the level of grain N export. The consequence of low N-2 fixation an
d high N export in chickpea grain was a net loss of total soil N, (2-4
8 kg N/ha under CT and 22-59 kg N/ha under ZT). Management practices t
o ensure larger biomass production and lower soil nitrate-N levels may
result in increased N-2 fixation by chickpea and thus a positive soil
N balance.