Tim Gainsford from the Macquarie Valley has been trialling cover cropping in his flood furrow cotton system for three years. A practice he adopted to manage infiltration issues in red soils, but this year, Tim’s experience shows how results can vary.

Success in previous years

When Tim first established a cover crop, he planted wheat into his cotton preparation area, incorporated it with a clod packer, and sprayed it out before head emergence. This approach allowed him to plant cotton directly into the residue without extra preparation.

“The presence of the cover crop, even after it was sprayed out, helped keep the soil open and soft,” Tim said. “It retained moisture better, and at planting time we had improved conditions for the seed to follow. It also allowed irrigation water to sub to depth more effectively, which was a big benefit.”

Over the first two years, these results gave Tim confidence that cover cropping could be an effective way to manage water infiltration in flood furrow systems, particularly in the red soils of the Macquarie Valley.

A very different year

This year, however, the results have been unexpectedly different. “We did everything right, or at least everything we thought was right,” Tim said. “But we’ve seen much higher water infiltration than in previous years. Water use is through the roof, and we’re having a lot of trouble getting water to flow from one end of the furrow to the other.”

The issues have been most pronounced in fresh fields coming out of rotation with cover crops. In pre-watering back-to-back fields water usage was relatively normal. “It was only in those new fields out of rotation that we’ve had trouble getting the water to flow,” Tim said.

To try and manage the flow, Tim has been using some unconventional methods, including furrow rolling with tractors to flatten stubble and add compaction. “It’s helped slightly, but not to the degree we need to get full coverage,” he said.

Looking ahead

Tim is already thinking about next steps once the fields dry out. “We’ll probably look at cultivating the furrows to clear some stubble to help the soil seal up a bit,” he said.

While cover cropping has been adopted as a tool to overcome infiltration issues in flood furrows, Tim’s experience this season shows that there’s no one-size-fits-all solution. Seasonal conditions, soil types, and field history can all influence how cover crops affect water movement.

“These unexpected results have thrown a spanner in the works for cover cropping as a widely adoptable practice,” Tim said. “But it’s a learning opportunity, and understanding what’s happening in the field will help us refine management practices for the future.”