Pw. Moody et Rl. Aitken, SOIL ACIDIFICATION UNDER SOME TROPICAL AGRICULTURAL SYSTEMS .1. RATESOF ACIDIFICATION AND CONTRIBUTING FACTORS, Australian Journal of Soil Research, 35(1), 1997, pp. 163-173
A paired site (developed v. undeveloped) approach was used to calculat
e acidification rates in several agricultural systems of tropical and
subtropical Queensland. The systems considered were summer crop-winter
fallow, grass or grass-legume pastures for hay production, tobacco, s
ugarcane, table grapes, and bananas. Mean acidification rates varied f
rom -2.4kmol H+/ha year for tobacco to 34.2 kmol H+/ha year for banana
s. Acidification rates were higher than for comparable systems in temp
erate Australia. Subsurface acidification occurred under all systems,
and was particularly severe under bananas despite the surface applicat
ion of at least 2.5 t lime or dolomite/ha . year. As bananas can be co
nsidered to be a generic perennial horticultural system, subsurface ac
idification may be a widespread problem in such systems despite surfac
e applications of amendments. There was a wide range in acidification
rates within a particular agricultural system, suggesting that managem
ent practices can be manipulated to reduce acidification. As the N cyc
le terms were the major contributors to the acidification under croppi
ng systems, N fertiliser management is likely to be the most critical
acidification factor.