6 things every farmer needs to know about In trying to figure out the cause of a poorly-performing pasture, Ruth digs up crucial information about soil.
Exploring soil has turned into a far larger and vastly more interesting exercise than I anticipated. I have consequently failed to do what I set out in last month's column because I got carried away on a tangent and put off studying the hard bits of soil science in favour of the fascinating story of what's living in the soil and making it all work.
We did get all our soil test results back and some recommendations for fertiliser. I've included those at the end (see page 43), but I'm going to tell you about the more interesting stuff this month, before I get to grips with the chemistry theory later.
I used to think soil was the brown stuff which just lay there under the more interesting plants. But it's one of the most fascinating ecosystems there is. It's absolutely teeming with lifeforms, all interacting with each other as providers of food, either in and of themselves or because of the processes they exert on other things.
We can influence what goes on there for good or ill, and most modern farming techniques have primarily done the latter.
Nearly every farmer I have spoken to tells me they know less about their soils and soil in general than they feel they should. Why don't we know? Is it that the fertiliser industry has convinced us that it can solve any problem we perceive from above, so we don't need to bother with what's going on underneath? If your grass isn't green enough, it obviously needs factor X, so here, let me sell you this bag of chemicals or special ingredients to address that shortage.
We like the quick fix, especially when we're busy and there are seemingly more important things to be done, so we've abdicated responsibility for understanding the needs of our own soils.
Then there's all that complicated stuff like Cation Exchange Capacities (CEC) and Base Saturations (BS). For those of us who are a long way in time from our formal chemistry education, it all seems like an impenetrable wall of garble.
This column was intended to be a "this is what we found and this is what we will do to fix it" answer to last month's mystery of my variably productive paddock. But as I read and researched and thought about the things I had discovered, I realised that although that's what we all want to know about things which aren't quite right, biological systems don't work like that. There are no instant fixes, and always a complicated web of contributors.
Air, water and biological activity are integral to the make-up of soil. If soil was simply clay, sand and silt, any fertiliser we put on it would mostly wash through and out into the ground water.
It is the life in the soil which holds the nutrients in their bodies (many of these are only one cell) and in the substances they exude as they live, and from which plant-available nutrients are then released as waste products, or as the organisms die or are eaten by others.
A very ‘lively’ soil will be robust and able to stand up to too much wet, long periods of dry, the treading of animals and so on, all the things we need from farmed land.
I've always thought of earthworms as the representatives of whatever is going on, unseen and unknown, underground. As it turns out, earthworms are a very good indicator of soil health, because they eat a lot of the stuff we can't see - lots of bacteria,
protozoa, nematodes and organic matter. If there is lots of food, there will be lots of worms. If there are lots of worms, they are doing a huge amount of work to make the environment a happy place for all the things upon which their own lives and our enterprises depend. What surprised me, but explains information I've heard before, concerns clover. The bacteria which live in its root nodules are fixing nitrogen, as I think most people know, but it's not a one-way street. The clover feeds the bacteria via exudates from its roots, a process which uses up to 20% of the energy the clover obtains from photosynthesis.
But when farmers put nitrogen on clover, something interesting happens. The clover is quite happy and it doesn't bother to look after its bacterial helpers because it doesn't need anything from them, so there's a drop in the amount of nitrogen which is naturally fixed.
It's not just the nitrogen-fixing bacteria which form close associations with plants. All plants produce exudates which attract the sorts of bacteria and fungi they need to help them obtain nutrients from the soil.
The rhizosphere, an area about 1-2mm thick around any root surface, is the region in which most of this activity occurs. The bacteria which live in there constantly make nutrients available to plant roots by direct exchange, by excreting waste products and by dying and decomposing which releases the nutrients they hold in their bodies. Their presence is also often not random. Many plants form symbiotic relationships with particular fungi, the relationship named mycorrhizae. Mycorrhizal fungi can live on the outside or inside a plants' roots. They are able to grow chains of cells out over extraordinary distances, extending into areas plant roots can't reach, accessing and transporting back many nutrients their host plants require.
6even physically trap nematodes and consume them!
Fortunately, when I was a new farmer I was determined to adhere to the principle that I would first do no harm, shying away from chemically-activated fertilisers and from blanket spraying old pastures in favour of newly-sown species*, opting instead to take the longer route of raising fertility by the use of RPR (Reactive Phosphate Rock) and lime.
My belief was that I would gradually enhance the life and structure of the soil by that method, creating an improved environment for the plants I wanted to grow above ground.
If we pour something nasty onto our soils or the plants above, we may make life uncomfortable or impossible for some part of the web of life in the soil and throw the whole thing out of balance, sometimes with long-term consequences.
It would appear that my vague sense of the world underground was correct, but I did not previously understand how much plants contribute to the system, having presumed they were simply the beneficiaries of a healthy soil. It turns out they're an integral part of a balanced ecosystem. How did I forget those primary school science pictures of trees, grass and worms in constant interaction?
A paddock of two halves. This view looks down down the northern, 'better' half. The poorer-performing area is out of sight, to the right.
herself and jumped that just fine. But we didn’t know there were some old railway irons lying in the grass there. The end was poking just past the edge of the bank. And she clipped it with her knee and foreleg. It was a huge thump and I pulled her up straight away.
“The iron had gashed all the skin off her knee and then bumped down her shin, skinning that to the bone in two more places. She was still moving fine. I don’t think it was hurting her yet, so I just led her all the way back, bawling my eyes out.” Maria smiled. “Yeah, I know about that!” “I stopped at my friend’s place, the boys with the motorbikes, and their dad sat me down and made me a cup of tea and just would not be rushed until I had got myself together. Meanwhile, he had gathered disinfectant and bandages and stuff.
“So we washed her gashes, just like you did, and I led her home really quietly and my folks had the vet there by the time I got home. He stitched her up and bandaged her and gave her antibiotics.” “Did she heal up?” “Yes she did, but it took a lot of work, and boy, she hated those injections. She never ever accepted men in overalls after all the vet’s visits. Her knee ended up a bit lumpy, but it never troubled her or slowed her down. She was sound.
“Actually, it was good for us. Because I had to wash and tend her every day, and get her to trust me, even if taking the bandage off hurt. I did it as carefully as possible.
“I guess we learned from it all too. We both still loved to gallop around, but I made sure the way in front was safe. “What happened to her in the end?” “Oh, we had lots of years together. I sold her once when I first left home, but bought her back when I came north. She finally died when she was 42.” “Wow.” “Yes, that’s quite old for a horse, and after so long with her… well, I didn’t think another horse would ever replace that sort of history and bond.” “Gee, I hope Sheba lives that long.” The Vet piped up at that point. “Well, it will take more than this misadventure to stop her. Now, your job is to wash her leg every day, try to slough off any scabs to stop proud flesh developing. And she is going to need antibiotics for a week or so, depending on how it heals. No galloping about for a couple of months.
“Hopefully you won’t be as silly as some people I know.”