| dc.description.abstract | Early growth and development are often lower when wheat is sown into standing stubble. A study
was conducted to determine whether this difference in early growth could be explained by the effects of
stubble on soil temperature in the vicinity of the young plant. The roles of nitrogen nutrition and soil
strength were also assessed. Three crops were monitored (1990–1992), with the wheat being sown into
either standing wheat stubble after a no-till fallow (NT), or into no-tilled plots from which the stubble had
been removed by burning (NB). Measurements were made of wheat growth and development, soil and plant
N, soil temperature and penetration resistance. The site was on a black earth near Warialda in the northern
wheatbelt of New South Wales, Australia. In 1992 wheat was also grown under simulated stubble to isolate
the shading and soil temperature effects of stubble from other factors. A significant (P<0.05) relationship
was found between average soil temperature and above ground dry matter (DM) at 65 days after sowing
(DAS) but not at 107 DAS. This relationship accounted for differences in DM production at 65 DAS
between NT and NB treatments in 1991 and 1992, but not in 1990. In that year the lower DM production in
NT plots was associated with poorer N nutrition, and possibly disease. Laboratory incubations indicate that
immobilisation of N as stubble decomposed could have contributed to this. Burning stubble produced no
immediate increase in soil N availability, so that it is unlikely that N contained in stubble contributed to the
difference. Soil strength differences between treatments and phytotoxic effects are unlikely to have
contributed to growth differences in this soil. | en_US |
