Fallow management, soil water, plant-available soil nitrogen and grain sorghum production in south west Queensland
1992
Gibson, G. (Queensland Dept. of Primary Industries, Warwick (Australia). Hermitage Research Station) | Radford, B.J. (Queensland Dept. of Primary Industries, Biloela (Australia). Biloela Research Station) | Nielsen, R.G.H.
The effects of tillage frequency (conventional, reduced and zero), primary tillage implement (disc, blade and chisel plough), stubble management (retention and removal), gypsum application, and paraplowing were examined with respect to soil water storage, soil nitrate accumulation, crop establishment, crop growth, grain yield and grain nitrogen content for 4 successive sorghum crops on a sodic, texture-contrast soil in south west Queensland. Retention of sorghum stubble (v. removal) produced an increase in mean yield of sorghum grain of 393 kg per ha, due to increased soil water extraction and increased water use efficiency by the following crop. The highest mean yield occurred after reduced blade tillage with stubble retained. Zero tillage with stubble removed gave the lowest mean grain yield. Zero tillage always had the lowest quality of soil nitrate-nitrogen at sowing. In one fallow, increased aggressiveness of primary tillage (disc v. blade plough) increased the quantity of nitrate-N in the top 60 cm of soil at sowing. These effects on available soil N did not result in corresponding differences in grain N content. Results indicate that for soil in south west Queensland, sorghum residues should be retained, tillage frequency should be reduced, but not to zero, blade ploughing should be preferred to discing, and gypsum application should not be practiced.
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