Sandplain soils on the south coast of Western Australia have multiple limitations to crop production that include water repellence, low water and nutrient retention, subsoil acidity, and high soil strength. Crops on sandplain soils achieve, on average, almost 85% of their rainfall-limited yield potential; however, where there are multiple limitations the corresponding value is often <50% in any given year. Previous research has shown the value of applying clay-rich subsoil ('claying') to ameliorate water repellent soils and improve nutrient retention. Other studies have shown that deep ripping is effective in reducing compaction in sandplain soils. This paper quantifies the effects of 5 subsoil clay rates (0, 50, 100, 200, and 300 t/ha), with and without deep ripping to 0.5m, on soil properties, crop growth, and profitability in a replicated field experiment.Crop yields were increased by 0.3-0.6 t/ha as result of added clay. The clay content of the surface soil required to alleviate water repellence and achieve the highest yield increases was 3-6% in soils with~1% organic carbon. Longer term effects of claying included increased soil organic carbon by 0.2%, pH by 0.6 units, potassium by 47 mg/kg, soil strength by 250 kPa, and cation exchange capacity by 1.3 cmol c /kg to a depth of 0.1 m. However, changes in plant-available water (mm/m) were inconsistent between the clay treatments. Deep ripping to 0.5 m increased crop yields by 0.1-0.5 t/ha. These crop yield responses were still evident 3 years after the ripping treatment had been applied. Soil strength measurements indicate that re-compaction of the ripped treatments had occurred to a depth of 0.2 m in the second year following ripping. Crop responses to claying and deep ripping were additive. Claying and deep ripping, while almost doubling yields, achieved only 50-70% of the rainfall-limited yield potential on these marginally fertile soils. The highest clay rates (>3-6%) had cumulative discounted cash returns $AU100-200/ha higher than the unclayed 'control' treatment and $300/ha higher than the lowest clay rates. For most of the clay treatments, deep ripping increased discounted returns between 2005 and 2007 by $80-120/ha.

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Large areas of cropland in Western Australia exhibit severe annual water repellency. Crop establishment is frustrated by the staggered emergence of plants, despite significant amounts ofrain falling prior to the desired time of seeding. Three techniques were used to investigate improvements in barley (Hordeum vulgare L.) establishment on a water-repellent sand: (i) spraying various rates of banded (2 em wide) wetting agent while furrow seeding with 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 increasing rate of banded wetting agent. Use of press wheels, which also resulted in a furrow sowing 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 full soil disturbance had no effect on seedling emergence or grain yield. The application of wetting agent increased topsoil wetting. Increased soil wetting may have increased plant nutrient availability (from fertilizer and soil), reduced soil water evaporation, and possibly reduced water loss to subsoil on this duplex soil. The optimum degree of compaction required on water-repellent soils is not known and needs further research.

In a glasshouse, a split-root experiment was used to determine the ability oflupins (Lupinus angustifolius L.) to take up manganese(Mn) from dry soil either when young or at mid-flowering of the primarybranches. Three soil-watering regimes (maintained at field capacity,maintained below wilting point, and alternating from field capacity to wellbelow wilting point) were imposed after taproots had grown through topsoil andinto a nutrient solution below. Four sequential harvests (11, 22, 37, and 49days after sowing) were taken to determine the effect of soil drying on lupingrowth, Mn uptake, and soil-extractable Mn.Soil drying early in the lupin plant's life stopped the growth of lateralroots in the soil and slowed the growth of roots grown in subsoil solution andthe growth of lupin tops. Soil drying decreased uptake of Mn in the tops to13% of that under continuous wet soil conditions. Of the 13%,most (11%) was taken up while the soil was drying. Soil re-wettingenabled the plants to resume uptake of Mn and soil re-drying (just beforeanthesis) decreased the Mn concentration in the lupin stems to 4·8µg/g, whereas stems of lupins grown in the wet and dry soilscontained 10·3 and 3·3 µg/g, respectively. Easilyreducible and plant-available soil Mn were not affected by soil wetting anddrying treatments.This study confirms that the uptake of Mn by lupin may be severely restrictedby drying of surface soil at both the beginning and the end of the lupinplant's life. The decrease in root length rather than the chemical form of Mn restricted Mn uptake.

Pasture establishment and production is reduced by water-repellent soils. Ameliorative techniques are explored with this study. Two field experiments were conducted on water-repellent soils to investigate (i) the improvement in emergence of pasture species with furrow sowing and the use of a press wheel and banded wetting agent and (ii) the residual effectiveness (applied 2 years previously) of a wetting agent on pasture growth and composition. In the first experiment, conventional level sowing (flat planting) was compared with furrow sowing using press wheels. Five pasture species were included, and the furrow-sown treatments involved a banded wetting agent applied at four rates. Furrow sowing with a planter having press wheels increased the average emergence at 14 days after sowing by 133% relative to the conventional treatment and emergence was further increased 44% by banding 4 L ha-1 of wetting agent in the furrows. There was a large (up to sixfold) increase in early pasture production (330 to 2010 kg ha-1 ) and a large effect on pasture composition due to the residual effect of a wetting agent applied 2 years previously.The proportion of subterranean clover (Trifolium subterraneum L.)in the pasture increased from 6 to 33% due to the use of a wetting agent. This study shows that the effect of water repellency on pasture emergence and productivity is severe and that these ameliorative techniques are useful tools for improving pasture emergence. P ASTURE ESTABLISHMENT on water-repellent soils is affected by nonuniform infiltration of water into soil. Farmers commonly report large reductions in emergence for pasture sown into water-repellent soils with