Legumes lead to big benefits in Mallee rotation

Third-generation farmer Simon Martin operates on 3700 hectares at Wynarka, in the SA Mallee, with his parents Tony and Monica, wife Kylie and children Ravi, Macy, and Jai.

They grow Scepter wheat, Compass and Planet barley, lupins, canola, lentils, 150 hectares of Brusher oats for hay and 300ha of a vetch/cereal mix for feed for their 1600 Merino ewes. 20 hectares of vetch is also earmarked for hay this year, with plans to build on that component in coming years.

Simon said the decision to incorporate legumes into their rotation was made in 2014 and they are still discovering the advantages.

The decision was initially made for two reasons.

"We were looking for extra sheep feed during the early Winter phase and it was also the first stage of getting legumes into the system to see how they would respond to our soils and to see how well the crops following them would perform," he said.

"It was testing the waters at that stage and the crops following them seemed to be pretty good so we kept on exploring what other legume break crop options we could use."

Mr Martin said the benefits they have noticed include improved soil moisture retention, reduced disease risk due to paddocks getting a break, plus the nitrogen fixation benefits associated with legumes.

"Every paddock across the board has had at least one or two legumes on it since we've started and you can definitely notice an improvement in crop health," he said.

"We probably haven't got the financial side of legumes downpat just yet - we've still got things to learn in terms of growing them - but the long-term benefits are definitely there.

"With vetch for sheep feed, you get the opportunity to clean up some grass and being a feed crop we could spray that out early - August/September - and try to conserve moisture over summer."

When legumes were first introduced, the Martins had a rotation of a legume followed by two cereal crops, but Simon said they soon found controlling grasses required the addition of an extra break crop.

"We've built from one break crop to a three or four-year break crop sequence before we get back into cereals," he said.

"It might be a lentil or lupin, then canola, then oaten hay and back into vetch.

"It's about identifying paddocks that we need to keep on top of in terms of grass control and looking to do three to four-year sequences."

RELATED READING: New oats boasts higher yields

Climate diversity decreases crop risk

Mr Martin said their yield potentials had been increased due to improved soil health - contributed to by legume incorporation - as well as varietal improvements.

"We're still applying similar rates or more fertiliser because our soils are healthier and the yield potential has lifted," he said.

"We're trying to push our crops further than we used to and trying to maximise our yields.

"Our targets pre-growing legumes were about 1.4t/ha of wheat and 1.8t/ha of barley as an average. Now, our targets are closer to 2t/ha of wheat and 2.8t/ha of barley in an average year."

Incorporating legumes into their cropping and grazing operation has not come without its challenges for the Martin family.

Simon said trying not to overgraze legumes, particularly on their fragile sands, was challenging.

"Erosion is a big issue and we just had to learn how much we could graze it," he said.

"That was a big challenge initially and then figuring out how the sheep fitted into the cropping system was the next big issue over the following few years.

"We got to a point where we've separated paddocks specifically for sheep now. They're still using the stubbles over summer to capitalise on them and using the vetch for sheep feed is the exception to that rule."

The Martins also have the constant challenge of varying soil types, with their property incorporating limestone rubbles, sand over clay and non-wetting sands.

To counter that, Simon said they had added canola back into the rotation in the last two years as an extra break crop which could be planted over many different soil types.

"We have also dabbled in chickpeas," he said.

"We didn't sow them this year due to the dry start but that's an option."

As far as this year's crops are concerned, Simon said they're tracking "fairly well" and have the potential for an average year. He expects to start harvest in mid-November.

"In terms of yield potential, we're fairly happy with how we're placed."