Undersowing Crops On Track for Optimal Results

Jim Heal runs a mixed cropping and sheep enterprise 40kms west of Three Springs, a region that receives an average annual rainfall of 430mls.

In the past, this rainfall has predominantly fallen throughout the typical winter growing season months. Still, Jim has seen the rainfall patterns start to change, with a noticeable increase in summer rainfall events. These changes have influenced Jim to begin implementing some adaptive practices to take advantage of any summer rainfall.

This year, Jim is trialling under sowing a lupin crop, with Lucerne and Izmir sub-clover and also with wheat in a slightly salty valley floor paddock. Doing so will provide a variety of potential benefits for both productivity, soil health, and sustainability.

The lucerne and clover will provide additional fodder for stock, especially during the summer/autumn feed gap.

  • Wind erosion can cause significant damage in the area, as has been very apparent in the last two years. Extreme wind events and heavy rainfall in summer and autumn cause the most damage to soils with less than 50% ground cover. An active summer crop can help mitigate these erosion risks by providing and maintaining ground cover.
  • All three crops are legumes, and Jim hopes this will help fix Nitrogen into his soils and give a growth response to future crops in this paddock. 
  • This approach can assist with weed management.
  • The summer-active lucerne will help to keep the paddocks greener for longer with living plants in the soil. This helps feed and protect the biology in the soil and increase carbon cycling through the system, improving soil health and increasing the soil’s water holding capacity. 
  • A multi-species crop helps to build biodiversity into the system, and diversity builds resilience.

All the seeds were sown together, which created a few challenges given the variety in seed size. They have germinated well, especially on the gravel sites, although sowing depth may need more adjustment or a different approach on the sandier country. The warm soils through April and May will have helped with germination, but the recent cold weather will considerably slow the summer active lucerne growth. The lupins will be harvested off the top come late October/November, and this will leave a mixed lucerne and clover crop, ready to take advantage of any summer rains.  

Jim has had some experience of growing lucerne before. In the past, he has used it to help establish perennial grasses. The fast-growing lucerne provides the slower perennial grasses with some protection.  Another advantage with the lucerne is its tolerance of certain chemicals, which provides an opportunity for clearing up weeds in the paddocks, particularly melons.

After harvesting the lupins, Jim plans to maintain this paddock for grazing for a couple of years. Jim is very interested in seeing if and how the sub-pasture affects the Lupin crop yield and is also interested in seeing how this approach affects the soil organic carbon levels in the paddock.  Jim has already been thinking about improving the process, mainly around incorporating different size seeds at their optimum planting depths. In the future, he may try spreading the clover and lucerne seed in front of the tractor before seeding the lupins over the top. We hope to check back in with Jim later in the year and see how everything is progressing.

For more information, please get in touch with our Regional Agriculture Landcare Facilitators. Annabelle (E) annabelle.garratt@nacc.com.au or (P) 0448 986 879

Lizzie (E) lizzie.king@nacc.com.au or (P) 0447 361 335.

Lizzie King – Regional Agriculture Landcare Facilitator

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