Vetch, a little known legume, improves profitability of cotton by increasing cotton yields by up to 18 per cent when grown in rotation with cotton.

Results from 2003 trials show that when vetch is used the cotton gross margin per hectare is increased by $390 within continuous cotton rotation and by $270 in wheat cotton rotation.

About one third of the usual nitrogen fertiliser applied is needed to maximise cotton lint yields in the cotton crop following vetch and in some cases no nitrogen fertiliser is needed at all.

Vetch also increases soil organic matter, improves soil structure making root penetration and cultivation easier, increases soil water holding capacity and reduces the incidence of some fungal diseases including black root rot.

Planted in February after a wheat crop or in May after cotton, vetch is grown through winter, then slashed and ploughed into the ground. The field can then be planted to cotton.

The eight year CSIRO Plant Industry study demonstrated that although vetch does not produce any direct income, it more than pays for itself in the commercial benefits it provides while improving soil fertility.

Like most other rotational crops, vetch may increase fusarium wilt, so fields should be carefully assessed before it is used.

This research is supported by the Australian Cotton Cooperative Research Centre and by cotton growers through the Cotton Research and Development Corporation.