A wet spring – getting some science on

James Rebanks in English Pastoral described the role of the farmer as one of close observation. Through examination of the interconnectedness of the landscape, Rebanks explains how farmers are able to build an intimate knowledge of every aspect of their farm. It requires farmers to walk their paddocks, getting their hands in the dirt, and examining the second and third order effects from their management decisions. It takes a lifetime to learn.

I don’t have a lifetime of experience behind me, nor do I have the time I would like to devote to unravelling this mystery. So I have to take a slightly different approach, and one method I can use to increase my understanding of my soil health is have soil samples analysed in a scientific laboratory.

I hope the analysis of our soil will answer one of the questions I have from an observation of the cattle’s behaviour. When I move them from a lush grassy paddock to another lush grassy paddock, the cattle seem to have a preference to chew the leaves from young elm suckers if they are present. This could be the cattle seeking roughage, or it could be seeking a mineral that the deep rooted elms have in their leaves that is lacking in the grass. Pat Coleby is a firm believer that the animals know which minerals they need, and their behaviour could be a clue to a mineral deficiency.

We had soil tests conducted not long after we moved to the not-so-rocky Rock Farm (https://rockfarming.com/2018/05/07/soil-analysis-results-are-in/) , so you can imagine when I saw the Local Land Services was offering a soil test program, I leapt at the chance to get onboard. It was three and a half years since our last test was conducted, and I am keen to see if there is a discernible difference in our results since we became custodians of our the 40 hectare Rock Farm.

The soil samples require multiple (around 30) 100mm cores to be taken along a transect. I chose two different areas, the first on our river flats, and the second on our shale slopes. Along the flats, the rod was easy to push in the required 100mm. On the slopes, the soil was barely more than 50mm thick, and I had to try really hard to find enough samples that met the 100mm requirement. After I had filled the buckets, I mixed the soil thoroughly, before bagging around 1.5kg of soil for testing. The colour difference in the soil samples was remarkable, but not unsurprising.

Since we bought this Rock Farm, we have not applied fertiliser to these paddocks. Our first two years experienced very low rain fall, and the last 18 months have seen much higher than average rainfall. We initially grazed sheep on the property, before buying our first cattle in May 2018. We sold our last sheep in January 2020 – just before the drought broke.

Instead of purchasing fertiliser, I have been happy to supplement the stock’s feed as required, bringing in hay and other feed as required, using the philosophy “If you want to run ten cows, feed ten cows until you can run ten cows.

We have also practiced cell grazing or rotational grazing. This means we graze a paddock heavily for around a week or so, before resting the paddock for as long as I can. I have around 13 rotations that I cycle the cattle through, meaning each area is only visited every three months or so. It doesn’t always work that way – some sections are significantly larger and have better water supplies, keeping the cattle happy for more than a week, and others they chew out after a couple of days. I also want to keep the grass around the house short in preparation for fire season, meaning this area is eaten out more than the others.

One variable I am not sure how will be reflected in the results is soil carbon. We scored between 3 and 3.6% on our last results, and whilst advocates of rotational grazing claim it increases the amount of organic carbon in the soil, field experience is lacking (https://soe.environment.gov.au/theme/land/topic/soil-carbon-dynamics). Soil carbon does increase the capacity of the soil to store moisture – but the amount of carbon may also be linked to soil moisture meaning rainfall may be the biggest factor in affecting our soil carbon levels. I will be particularly interested in this element of the analysis.

Either way, I am looking forward to the test results. Of course the ones who gain most benefit from healthy nutritious soils are completely oblivious of the science behind their condition.

The good news is they are fat as fools, healthy and happy. They show passing interest in a mineral lick I have available for them, which I take as a good sign. And it is such a pleasure moving them through the farm, especially when the grass reaches their bellies.

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