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Why we're excited about stubble


Oat Stubble that is!

Last week I headed out to Jamie Anderson’s farm as part of Dirty Clean Food’s involvement in Phase 2 of Perth NRM’s Natural Capital Accounting project. 

This is a snippet of what Bonnie and I found when we were doing the ecological assessments in one of Jamie’s oat paddocks. The ecological assessment in a paddock largely focuses on diversity and density. Although Steve and Jamie have previously grown oats as part of a multi species mix, this paddock was seeded to straight oats after a few years as a multi species pasture paddock. 

These oats were harvested in December last year, and we were there for the assessment on the 23rd of February. If you’ve ever driven through the Wheatbelt or Great Southern in the middle of summer, you’ll notice it is quite common for the paddocks to look very bare - on a windy day you can often see the topsoil being picked up by the breeze and blown across the paddock. Not so here on Jamie’s farm!

The density of the oat stubble is what is really exciting! The standing stubble is about 500mm tall, and very thick, with lots of plants growing close together. The stubble itself has very thick walls, which is a sign that the plants are strong and resilient. 

The sheep have been sent in to graze the stubble, and they also knock the stubble down onto the ground. This is what creates the thick mulch layer you can see in the video. In a brittle environment like ours, where there is low humidity and only seasonal rainfall or humidity, plant matter does not decompose on it’s own because it is too dry. The plant matter needs to be in contact with the ground for the microbes to digest it - so the microbes need the sheep to provide the animal impact to both trample the stubble, and also provide moisture in the form of poo and wee to kick start the decomposition process. 

The mulch in this area of the paddock was about 250mm deep - so as deep as my hand! That’s like putting a thick layer of mulch on the plants in your garden. This mulch will keep the topsoil cool, prevent it from losing moisture, and hold onto any summer rain that falls. This is incredibly important, as up to 80% of rain that falls on bare ground in our climate will evaporate. 80%! That number still blows my mind. By leaving cover on the ground, the water is drawn down to the soil rather than running off, and infiltrates through the soil profile, filling up dams, recharging aquifers, and ultimately rehydrating our landscape. 

So it might come across a bit weird to get excited about oat straw, but this is why! This is regenerative agriculture rehydrating our Great Southern region at scale, which, when applied across the whole south west of WA, has the power to restore a resilient landscape that can wear the impact of our changing climate. And if we can get farmers all across the world doing this, we can influence how the climate is changing worldwide.


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