Crop Stubble Management
Leading local farmers speak to us about crop stubble management on their properties.
As one of the three pillars of conservation farming, Stubble Management is one of the key ingredients in maintaining healthy soils. Stubble plays two very important roles. The first one is actually physically protecting the soil surface from erosion, whether that be wind erosion, or rain erosion, Australia has had more than it’s fair share of erosion over the years, and we don’t have a lot of great soil so we’ve got to protect what we can.
Stubble Is a Food Source for Micro-Organisms
The other role that it plays, which is very significant, is actually the food source for the microorganisms that live in the soil. So, rather than burning it, by leaving it in the field, the energy that was captured from the sun that is now in that plant material can be made available to the soil micro organisms.
And those organisms have a plethora of roles. They make up the soil organic carbon fraction of the soil which is great for holding nutrients and water and also the cycling of nutrients. So, I guess when we talk about stubble, yes it’s protecting the soil in a physical sense, but it’s also the food for the soil that keeps it moving and keeps it working. And I think what we’ve discovered is that the more activity you have in your soil the greater you get things like water holding capacity, infiltration rates, resilience to finish crops in dry seasons?
Reduction in Wind Erosion
Well, the key benefit of stubble staying on the soil and no cultivation is wind erosion. Wind erosion’s our biggest limiting factor in our environment and if we don’t control wind erosion, the later sown crops get blown away in July and then they recover, but the yield is never as good as the crops that are sown early.
Going to a no till system and having good stubble cover and sowing into stubble makes sure that we eliminate that erosion factor and therefore it increases our yield, average yield across the whole farm. Yeah, we try and limit the times that we actually draw from the paddock, but removing the sheep out of the system, that was one of the things that was was trying to retain our stubble there.
The trials in Canada that I saw, the higher the stubble, generally the higher the yield of the next crop it just shades the soil and keeps it all alive through those hot summer months. We’d like to try and keep as much stubble as possible, I guess first part of that is basically for wind erosion.
Allows Earlier Sowing
By taking that out of the equation, which is effectively what we’ve done, it just opens up a world of possibilities. It does mean you can sow early. It means you can sow on no moisture pretty much and it can sow dry because that’s no longer an issue. And so by doing that it actually opens up the Mallee to whole heap more potential There’re huge benefits in retaining your stubble and microbial population and for nitrogen fixation by free living rhizobium top stuff, within your cropping system. If the soil is the growing medium, and the soil microorganisms are the powerhouse that get that to happen, then to give them both protection and the food that they need.
Retaining the stubble does both of those things, so it really is a key.