Lambert’s best-known bush image, Across the blac k soil plains was inspired by his memories of horse teams hauling heavily laden wool wagons across the bare, miry, flat lands of Snakes Plain from Warren to the railway station at Nevertire. He encountered this landscape while droving sheep in the 1890s and was reminded of it during a visit to Warren in 1899. Lambert suggested that Jim Smith, a known identity of the district, was the model for the teamster walking beside the wool wagon and urging the horses onwards (ML MSS A1811, p.54). It has also been claimed that the teamster was Luke Rollins from Moree, and Henry Sharkey, who carried a record load from Louth to Bourke.

By portraying the rhythmic rise and fall of the horses’ heads and the tilt of the wagon, Lambert created a sense of movement in his image. The horses strain as they pull the load through the mud which sticks to their hoofs like glue, with the leader leaning into the chains to pull others into line. He dramatised the scene by placing the horses in silhouette against the sky and using the chiaroscuro of light and dark, showing the light making its way through the billowing clouds and illuminating the horses’ backs. In adopting a low viewpoint Lambert also made the team dominate the image. Apart from the blue in the sky the painting is a harmony of tonally balanced browns, beiges and white.

Placing the large canvas diagonally across the garden shed or washhouse at his mother’s home in the Sydney suburb of Hornsby, Lambert began to work on it. He had made colour notes of the landscape, as well as sketches of Jim Smith’s team of horses while staying at Meryon in about 1895–6 (ML MSS A1811, p.17). He commented that:

As a boy in the bush I did much work with draft [sic] horses ... [One] called Barney had such fine action and such imposing carriage ... and possibly what knowledge I displayed in connection with horses in ‘Black Soil Plains’ originated with my association with this exceptionally fine animal (ML MSS A1811, pp.54–5).

He later scoured the area around his mother’s home for further models for the horses, and for each one in the team he made two or three oil studies (ML MSS A1811, pp.54–5).

The painting echoes the spirit of a poem by the Scottish–Australian narrative poet and horseman, Will Ogilvie, ‘How the Fire Queen crossed the swamp’. This poem, published in Ogilivie’s first collection, Fair girls and gray horses (Sydney, 1898), included the lines:

With straining muscles and tightened chains – sixteen pulling like one; With jingling harness and droning wheels and bare hoofs’ rhythmic tramp, With creaking timbers and lurching load the Fire Queen faced the swamp!

Across the black soil plains inspired other poems such as ‘Across the black soil plains’ by ‘Mousquetaire’ (Gordon Tidy), which was published in the Bulletin , 30 October 1902 and was illustrated by Lambert’s painting.

O nobly manned must be the land, and nobly horsed as well, Has such a sight as this to show, such story has to tell, The teamster who so sternly strides, the team so strongly strains Till stride and strength be come at length across the Black Soil Plains

The picture received an enthusiastic response from contemporary critics. The Sydney Morning Herald wrote on 18 August 1899 ‘In this long narrow canvas the young artist paints with astonishing vigour and sense of movement ... in every conceivable attitude the horses tug and strain at the heavy load.’ It was purchased by the Art Gallery of New South Wales at the New South Wales Society of Artists exhibition in 1899 and was subsequently awarded the 1899 Wynne Prize for landscape painting.

More critical of his own work than many others, Lambert wrotein the Australian Magazine , 18 September 1899:

It is strong, ‘masculine’ if you like; the horses are well drawn and painted, the movement and action are ‘all there,’ the teamster (and his dog) are realistic, the sky is good, the colour is harmonious, the subject is popular, and the picture has been purchased for the National Art Gallery – what more can we say? This: that when G.W. Lambert has studied and worked hard for a few more years, both here and abroad (as we hope he will) – well, then he may paint the ‘picture of the year’.

The painting inspired variations in other media such as Tom Woodman’s glass painting Load of wool 1940, at the Carinda Hotel, New South Wales, as well as a plaster version.

About 1855 Edward Roper painted a landscape entitled Bringing down the wool from a Murray station (National Library of Australia, Canberra), which included a bullock team with a load of wool. Frank Mahony also treated the subject of a wool wagon several times. These images have none of the action or drama of Lambert’s painting, nor the spirit of place. Out of the particular and the personal Lambert created an enduring icon conveying the toil of man and horse and their relationship with the land.