What is the perfect soil? Well it’s a bit like asking what’s the perfect diet. It largely depends on the crop and how well the soil has been manipulated. Every soil can be improved and manipulated to the benefit of the farmer and this is what us as farmers must do in order to grow our crops and pastures profitably.
Our farm has extremely varied soil types but by in large the soils are naturally very fertile and as I often say; shit just grows here. My father spent a huge amount of time and money filling in erosion gulleys, moving boulders and moving rocks out of the lands. Most of what I now farm on was created by his vision and desire to produce something from land that was previously unproductive. If you looked at our farm 33 years ago when he first bought the land, you would scarcely recognise it. Dams, roads, pivots, draglines, dairy, maas factory, milk powder factory, and houses were all built by my father. My mother was in charge of the dairy for 25 years before I returned to the farm. They made a good team and he could focus his energy on growing things and developing the farm while mum managed the cows who paid the bills. There is nobody I know who has transformed any farm as my old man has in a relatively short space of time. What’s more he did this from a “standing start”. He started out as a school teacher who leased land and grew cabbages and potatoes. On our farm nature has been harnessed and manipulated to make something out of almost nothing. It’s far from an easy farm to manage, but it’s very rewarding looking back on the progress we have made.
So back to that perfect soil. I have always been fascinated at ways of farming with nature rather than against it. I get incredibly excited about finding earthworms and mushrooms in my pastures. Earthworms and mushrooms have come in over the years due 20+ years of no-till perennial pastures. In anyone’s books, our soils are highly productive and very healthy. There is no standard measurment of how productive a soil is. Yield and quality are the most important criteria for a farmer, but the soil plays a secondary role. The most important aspect of a high yielding and high quality crop are management. A poor farmer with the best soils will fail. A good farmer with poor soils will likely succeed.
A good soil in my books should be well drained clay loam soil, high in organic matter, and no acidity problems. High organic matter levels are hugely desirable to have, and with the high organic matter levels come high microbial activity. How you get there is another story, but we have done it with the use of conventional agricultural practices. I am not saying my soils couldn’t be better, but they are vastly improved from the natural veld that it used to be.
Amongst organic and biological farmers and consultants there is a belief in the perfect soil with an ideal ratio of nutrients. This idea was first suggested about 100 years ago. Dr William Albrecht first popularised the idea about 70 years ago and others more recently such as Neal Kinsey, who’s book I have read. The nutrients are measured as a percentage of the base saturation of a soil. To the non-farmers visualise the soil as a sponge. Each sponge has a varying amount of water that it can hold and some sponges hold more water than others. This amount of water is known as the cation exchange capacity or CEC. A heavy clay soil with high organic matter can hold more nutrients than a light sandy soil with low organic matter. The theory amongst biological/organic proponents is that it is the nutrient ratios that’s the most important thing, and once you get that right, everything falls into place. The 4 main nutrients in question are Calcium (Ca), Magnesium (Ca), Potassium (K) and Sodium (Na). These need to be in specific ratios for optimal plant growth. I have heard many different ratios but off the top of my head they are roughly Ca: 75%, Mg: 15%, K: 3 – 5% and Na: 1 – 3%. Other nutrients take up the rest of the of the space on the cation exchange sites.
According to 1000’s of controlled scientific studies done on nutrients required for plant growth and crop growth, there is a very wide range of these ratios where optimal yields can be obtained, as long as there is no deficiency, toxicity or imbalance in pH. There have been no controlled scientific trials done that prove the soil balancing theory whereas plenty studies disprove the theory. Most recently Dr Mark Schoenbek was employed by the Virginia Biological Farmers Association to test the soil balancing theory. This study was a large scale field trial over 3 years, where they corrected soils to the “correct” ratios and measured everything from soil structure, organic matter, brix (sugar) levels of the crop, and obviously yield. Mark Schoenbek acknowledged that the study was not comprehensive enough to disprove the theory completely, but it is interesting to note that the two most “unbalanced” soils had the highest yields. There was no significant difference in yield, brix levels, soil structure, organic matter and microbial activity between the “balanced” and “unbalanced” soils. This is not what was supposed to be found and the results were no doubt unpalatable to many biological consultants who follow the balanced soil principles. However I’m sure it has saved many farmers prepared to listen, a lot of money as it can be a very expensive exercise to ballance a soil.
One thing to remember with the “sustainable agriculture” movement, is that it’s a holistic system that involves a drastic change in almost every aspect of farming. It’s therefore very difficult to work out what is making the difference once farmers change their systems. As an example. A farmer who has converted to biological or organic farming will start using crop rotations, cover crops, adding compost, focusing on building organic matter and probably spending a whole lot more time in their fields too. Along side this they embark on an expensive soil balancing program. They will invariably see an improvement in soil and plant health. Why? Well to me it’s obviously the fact that many of the above changes in management can help in some way, but you never know which one is making the difference. There is almost never a control and a treatment that would be used in a scientific trial. It’s a holistic system they always say. That’s just a poor excuse for not knowing what is really working and what’s not. Science is about testing things out and trying to disprove a theory. So far that’s unfortunately all that science has managed to do, disprove the theory. Another thing that invariably happens is that farmers get really excited about what they do and so spend a lot more time in their crops. This naturally leads to be ter decisions being made.
I recently employed the services of a well known consultant who has a lot of experience in growing vegetables. Being new to the veggie game I needed some advice. He has a wealth of knowledge about different crops and how to manage and sell them. I gained a lot from his services, but I can’t help disagree with the advice given on soils. I am prepared to do an experiment to test it out for myself. If only to put my ever curious mind at rest. I even took some soil samples and sent them to Brookside laboratory in the USA. I have already received the results which is incredibly quick service. The results predictably say I need lime. Lots of it. My Cedara agricultural college results have very seldom recommended any lime at all. I was told that I have soils with the potential to be highly productive! Holy smokes I thought to myself when he said this! These soils of mine are highly unbalanced, full of organic matter, full of earthworms and are growing the biggest and most beautiful cabbages I have ever seen. If there’s is such a thing as a perfect crop then this must be pretty close. I’m not bragging about them, just proud of them and using them to illustrate my point. The potatoes in the nextdoor field arent looking too bad either, but they are difficult to judge as the crop is all underground and they are a way off being ready. Maybe I’m missing something here? Maybe my crops aren’t as good as I think? Or maybe growing a good crop is about more than just the perfect ballanced soil, maybe a decent soil, with a bit of love attention to detail is all you need.
To me the perfect soil is one that can grow a crop like this! I have enjoyed many things in farming over the years, but growing this particular crop of cabbages has to be the highlight of it all. Now let the fun and games begin. It’s one thing to grow the crop, it’s another to sell it!
So cheers to my “unballanced” and potentially productive soils. If balancing them improves my yield and profit, then I’m in, so watch this space over the next few years to see if my soil balancing experiment yields any results. It’s going to be a pretty hard task to improve on this crop but that would be pretty boring if there was no room for improvement.
As I write this I have started selling my crop. I have a problem. My cabbages are too big to fit in a pocket! I now have to persuade my big customers to buy them loose rather than pockets.
Here is a link to a good summary of the soil balancing method from the farmers weekly magazine.
Wikipedia also cites a number of references to numerous scientific studies done on the subject. Check out “Soil Base cation ratios”.