Bj. Radford et al., CONSERVATION TILLAGE INCREASES SOIL-WATER STORAGE, SOIL ANIMAL POPULATIONS, GRAIN-YIELD, AND RESPONSE TO FERTILIZER IN THE SEMIARID SUBTROPICS, Australian journal of experimental agriculture, 35(2), 1995, pp. 223-232
We compared 4 tillage practices (traditional, stubble mulch, reduced,
no tillage) during 10 years under rainfed conditions on an alluvial so
il in the semi-arid subtropics of central Queensland. In the final 4 y
ears, responses to applied fertiliser nitrogen (N), sulfur (S), and zi
nc (Zn) were determined. We measured soil water storage, soil nitrate
accumulation, grain yield (sorghum, wheat), grain protein content, and
populations of soil macrofauna, with the aim of identifying soil-cons
erving practices that also produce high yields of high quality grain.
Stubble mulch, reduced tillage, and no tillage all outyielded traditio
nal tillage when soil fertility was adequate. With applied N, S, and Z
n, the mean wheat yields from traditional, stubble mulch, reduced, and
no tillage were 2.44, 3.32, 3.46, and 3.64 t/ha, respectively. The yi
eld responses to tillage practices were due to increases in storage of
soil water or efficiency of crop water use or both. Populations of so
il macrofauna averaged (per m(2)) 19 (traditional tillage), 21 (stubbl
e mulch), 33 (reduced tillage), and 44 (no tillage). The effect of the
tillage practices on soil animal populations may be a factor contribu
ting to the measured differences in soil water storage and water use e
fficiency. We conclude that conservation tillage practices can greatly
increase grain yields, provided crop and fallow management practices
are appropriate. Potential yield advantages are realised if crop estab
lishment, crop nutrition, and control of weeds, pests, and diseases ar
e adequate.