The establishment and yield of fodder crops grown in Townsville stylo (Stylosanthes humilis) leys at Katherine, NT

Abstract

Two experiments were done at Katherine, N.T. to compare the effectiveness of minimum cultivation techniques for establishing both bulrush millet and grain sorghum for stock feed in weedy leys of Townsville stylo (Stylosanthes humilis). Measurements were made of crop yield and regeneration and weediness of the swards after cropping. In the first experiment, tyne cultivation ('chisel ploughing') in the dry season was compared with mouldboard ploughing and rotary hoeing in the wet season and with shallow tyne cultivation ('chisel sweeps') in the early wet season. In the second experiment chisel sweeps in the early wet season and chisel ploughing and rotary hoeing in the wet season proper were used. Crops were established in 6-inch drills and 3-feet rows in both experiments. In the first experiment, chisel sweeps gave yields within 14 to 28 per cent of those obtained by mouldboard ploughing or rotary hoeing, and in the second experiment there were no yield differences between cultivation treatments. Climatological data suggest that no difficulty would be encountered in using chisel sweeps at Katherine in at least three years in five. In the first experiment, establishment technique had no effect on crop yield, but in the second seasonal conditions were more favourable and yield in 6-inch drills was higher than in 3-feet rows. Both crop species completely suppressed the ley and in the second experiment, but not the first, Townsville sty10 content in the year following cropping was 23 per cent greater in the cropped compared with the uncropped treatments. Millet produced more dry matter than sorghum (17420 cf. 13120 lb an acre), but the same nitrogen yield (83.4 lb an acre). In millet 1.2 per cent dry matter and 3.2 per cent nitrogen were in the heads, and for sorghum the figures were 24.8 and 53.7. Sorghum appears to have potential as cattle forage.