Banded wetting agent and compaction improve barley production on a water-repellent sand

Large areas of cropland in Western Australia exhibit severe annual water re pellency. Crop establishment is frustrated by the staggered emergence of pl ants, despite significant amounts of rain falling prior to the desired time of seeding. Three techniques were used to investigate improvements in barl ey (Hordeum vulgare L.) establishment on a water-repellent sand: (i) sprayi ng various rates of banded (2 cm wide) wetting agent while furrow seeding w ith press wheels, (ii) seed placement either in a furrow or in the side of a ridge, and (iii) compaction with press wheels or a Flexi-Coil land packer . The application of wetting agent increased seedling emergence from 110 to 170 plants m(-2), dry matter production from 4.2 to 6.0 t ha(-1) and grain yield from 1.96 to 2.60 t ha(-1), despite more weeds occurring with increa sing rate of banded wetting agent. Use of press wheels, which also resulted in a furrow solving condition, increased seedling emergence from 72 to 101 plants m(-2) and grain yield from 1.70 to 2.13 t ha(-1). In the absence of heavy press wheel compaction, furrow sowing at 18-cm row spacings with ful l soil disturbance had no effect on seedling emergence or grain yield. The application of wetting agent increased topsoil wetting. Increased soil wett ing may have increased plant nutrient availability (from fertilizer and soi l), reduced soil water evaporation, and possibly reduced water loss to subs oil on this duplex soil. The optimum degree of compaction required on water -repellent soils is not known and needs further research.