|Author:||Latta, J. ; O'Leary, G. J.|
|Book Group Author:||NA|
A long-term experiment was established in 1982 at the Mallee Research Station, Walpeup, Vic., Australia, to investigate the impact of different farming practices in this semi-arid region on the growth and yield of wheat, and the water balance of the soil/crop system. Two fallow management systems (a zero-tilled fallow with direct drilling and a traditional cultivated fallow without direct drilling) within three rotation systems (fallow-wheat (FW), pasture-wheat (PW) and pasture-fallow-wheat (PFW)) were evaluated in the study. Phosphorus was applied to each wheat crop but no nitrogen fertilisers were used. Simulation analysis was used to compare model performance against 16 years of observed data. Over the course of the experiment grain yields ranged from 0.44 to 3.90 Mg ha-1. Rotation had the greatest effect on yield with the long fallow (PFW) treatment averaging 0.46 Mg ha-1 more yield compared with the short fallow (PW). Whilst this yield increase was accompanied by an extra 11-33 mm (mean 16 mm) of pre-sowing root zone soil water in 9 of the 16 years, any causal relationship was at best limited. More important was the marked interaction of seasonal conditions and yield with the FW, and to a lesser extent the PW, suffering yield losses not evident in the PFW rotation in years of high yield potential; a result largely attributed to differences in mineral nitrogen. Conventionally tilled and zero-tilled fallow were similar in grain yield, stored soil water, water use and water use efficiency. As with the rotation treatments, there was a strong interaction of seasonal conditions and tillage response with the zero-tilled system reporting consistently lower yields than the conventional system in all but the very low and high yield potential seasons. The simulation analysis showed similar rotational and seasonal effects on yield (R2=0.47, RMSE=0.78 Mg ha-1) and water use (R2=0.67, RMSE=60 mm). However, the model overestimated water use at low yield and predicted higher yields in response to zero tillage over the 16-year period in contrast to the measured data. Whilst further attention to the model in this respect is needed the use of this model in similar environments should not be minimised because the problem is not large. New experiments that look critically at the evaporation reduction from stubble residues on light textured soils are needed.
|Pages:||173 - 190|
|Journal:||Field Crops Research|
crop yield, fallow systems, growth, no-tillage, phosphorus,phosphorus fertilizers, plant water relations, rotations, semiaridzones, tillage, water balance, water use, water use efficiency, wheat,yield losses, Australia, Victoria, Triticum, Triticum aestivum, Poaceae,Cyperales, monocotyledons, angiosperms, Spermatophyta, plants,eukaryotes, Triticum, Australasia, Oceania, Developed Countries,Commonwealth of Nations, OECD Countries, Australia, crop rotation,no-tillage systems, phosphate fertilizers, rotational cropping, soilcultivation, zero tillage, Field Crops (FF005) (New March 2000), PlantWater Relations (FF062), Plant Production (FF100), Plant CroppingSystems (FF150), Fertilizers and other Amendments (JJ700), Soil WaterManagement (Irrigation and Drainage) (JJ800) (Revised June 2002)[formerly Soil Water Management]