Restarting carbon flows to repair a degraded clay pan
We all know that poor management degrades paddocks, BUT, have you ever considered what is going on with the degradation process? The answer: slowly less and less life exists in the paddock, both above and below ground.
Getting back to the basics, because all life relies on flowing carbon to exist, it is the reduction of flowing carbon, with poor management, that degrades paddocks. Look at the first photo of the long-term claypan. Prior to the saltbush being planted, the claypan had become bare and lifeless.
Photo 1: Planting saltbush in degraded country
This series of photos will demonstrate how increasing the amount of carbon flowing through the claypan turned it into productive country. The images will help you understand the important processes that moving (flowing) carbon activates. You will note I used the word moving, not sequestration. A leading soil scientist estimated that there would be 15-25 t/ha (0-30 cm) of long term soil carbon in the claypan pictured here. Yet this type of carbon, on its own, was not able to make the claypan respond to rain. It took the arrival of short-term carbon, after planting hardy saltbush, to complete the mix of carbon required for production.
These photos are about restarting carbon flows. It is an extreme example to highlight that functional landscapes rely on carbon flowing through them.
Old man saltbush
Saltbush seedlings, that can establish in degraded country were planted to provide a source of carbon flows, when nothing could establish naturally from seed to do the job.
The top left hand image is Old Man Saltbush 12 months after the seedlings were planted. The second photo is another year later. Sheep are responsible for the lack of leaves on the saltbush. They were chasing a bit of protein to go with dry grass elsewhere in the paddock before the rain.
In the bottom right hand image you will notice carbon is now flowing into the area around the shrubs. In other words, the landscape is slowly building resilience. The carbon flows introduced by the planted saltbush provided a food source for soil life, with the resultant soil life improving the soil. As the soil improved, grass and other plants were able to germinate and further expand the area that carbon is flowing through.
All this happened over a two year period at Yelarbon, when rainfall was well below average.
Photo 2: Clover adding more nitrogen and carbon to the system (3 years after the saltbush was planted)
Three and five years after planting
Photo 2 was taken 3 years after the saltbush was planted. The clover is now adding nitrogen to the system as it further contributes to carbon flows.
Photo 3 was taken 5 years after the saltbush was planted. Again the sheep are eating the saltbush to compliment the dry grass.
Photo 3: 5 years after the saltbush was planted
Photo 4: Prolific grass growing 5 years after the saltbush was planted
After carbon started flowing again, energy, nutrients and water all followed. All producers appreciate the importance of energy, nutrients and water, so this puts flowing carbon in a new perspective for them. Plants are now growing, which is introducing energy. The build-up of organic matter in the soil is increasing nutrient supply. Looking at the prolific grass, water is obviously getting in now. It wasn’t before, as photo 5 shows.
Photo 5 was taken immediately after a few millimetres of rain. This photo also highlights the linkage between management of carbon flows and keeping sediment and nutrients off the Reef.
Photo 5: Rain pooling on the soil surface before carbon flows were restored.
Carbon flows determine resilience
The wet decade of the 1970’s, with all the rain that arrived, couldn’t repair this claypan. Nor the big rain in the early 1990’s. However, during a period of below average rainfall, the claypan repaired because of carbon flows introduced by the planted saltbush.
The point I am alluding to is that many producers form too close a linkage between rainfall, rural production and healthy landscapes. This linkage is only true up to a point.
Producers have no control over how much rain arrives but they do have control over the level of carbon flows generated by what rain does arrive. The level of flows generated by rain depends on how well their management allows plants to grow following rain. Rain is obviously a major driver of production but it is not the final determinant, it is the level of flowing carbon that determines the level of rural production and landscape health.
After seeing the positive outcomes in these pictures, I tell producers to think in reverse to appreciate how management that reduces the flow of carbon into paddocks, also reduces production and degrades paddocks. As paddocks become less resilient, droughts turn up sooner. This claypan was in a state of drought during normal years.
Next week's discussion: “Why carbon suddenly turned up in extension.”