When I was in Canberra for the Nuffield CSC in March, there was a drinks reception where I met someone who was the head of agriculture, or something similar, at one of the big universities. I asked him what he thought of Pasture Cropping and the answer was “it’s rubbish, it doesn’t work”. This was a signal to me that there was probably something interesting going on, and I resolved to find out some more about it.
Colin Seis is a 4th generation farmer who produces Merino wool, and also a bit of grain. Like a lot of other farmers that have come up with very novel ideas, it all started with some extreme hardship. In the ’70s the farm had been going well, but in 1979 there was a severe bush fire which burnt all the pasture, all the crops, all the buildings, and killed 3000 sheep. With almost everything lost, it was time for desperate measures as there was not enough money to just continue on with the high input system that had been standard up until then.
What came out of it eventually evolved into Pasture Cropping. In the traditional system, pastures were established, grazed for 3 years, then ploughed up and drilled with a cereal. The problem is fairly obvious – getting a pasture going is expensive and quite time consuming, so it seems a waste to kill it off after such a short period of time. The answer is to not kill it off at all, but to drill straight in, and then let it regrow after the cereal is harvested.
But the key to making this possible is the climate. Australia is pretty hot, it’s been 35C today. In the winter it cools down quite a bit, and critically, the difference between summer and winter just crosses over the boundary that separates cool season and warm season plant growing conditions.
[Brief science lesson: warm season (C4) plants use a different chemical process for converting CO2 from the atomosphere to cool season (C3) plants. The crossover point between the two types is about 27C, and although being out of the right zone will not kill a plant, it will not be able to photosynthesise efficiently]
In this region there are 2-300 native pasture plant species, of which only 10 or so are cool season. This means that during the winter, almost all of the pastures’ productivity stops as the warm season plants become dormant. This is the perfect time to plant a cool season cereal, such as oats or wheat, as there will be no competition from the perennials that are already there.
One quarter of the farm is cropped every year, and to prepare a field to go into oats it will be grazed harder than usual, perhaps three times in the autumn (normally paddocks have 120 days rest between grazings on average). The oats can then be direct drilled in May, grazed a couple of times in the spring, and harvested in November. Yields are comparable to a conventional system, and immediately after harvest there is a fully established warm season pasture ready to go. I didn’t see it this time, as the drought it so severe, but normally at harvest the underlying grasses will already be greening up and starting to come out of hibernation. Of course, this can cause problems in a warm spring if they grow too big and interfere with combining. But that is apparently a rare occurrence.
I was surprised to see that Colin uses a tine drill, I had assumed it would be impossible without a disc because of the amount of plant residue he was drilling in to. He can get away with it because the perennial plants have much better rooting than annuals and so they are much less likely to be pulled out of the ground and bung up the drill. He also mitigates the problem by using wide rows (12″) and recently cutting discs were added in front of each tine.
Does it work? Colin’s brother farms next door, and still uses the system he grew up with, so there is a great benchmark over the fence line. When two 50cm deep samples were taken from 15m apart, the difference was amazing. There is roughly double the nutrient density on Colin’s land, and double the SOM. Amazingly, over a 10 year period, the levels of plant nutrients in the soil have actually increased under pasture cropping, with almost no inputs at all. And that is not just plant available nutrients, but total nutrients. So somehow, from somewhere, phosphorus and all the other trace elements are being brought into the soil. To my mind it can only be coming up from deeper down in the soil profile, which is allowed to happen because of the deeper rooting plants which are encouraged with the cell grazing. It’s an incredible result, and unsurprisingly, a lot of scientists are skeptical about it. Nitrogen is also increasing, which is interesting because there are not very many legumes in the pastures. Colin is convinced that this is due to free living nitrogen fixing bacteria in the soil, which if true, is a real incentive to maximise soil health/life/whatever you call it.
But these are just theoretical numbers, practical results are more important: Colin’s land will hold over double the stock density of his brother’s, and yield the same with grain, but with fewer inputs. Why doesn’t his brother follow suit then? “He’s my older brother, and older brothers will never listen to younger brothers”. It also brings back something Gabe Brown says, “I get visited by farmers from all over the world, but I’ve never had one of my neighbours come and see me”.
The latest iteration of Pasture Cropping is to stop growing monoculture cash crops, and instead plant a more diverse mix earlier in the year. Oats are still the base, but legumes like peas and vetches are added, and also brassicas which provide excellent forage for the sheep. These mixes are sown in March, and are then grazed 3 times. On the last grazing, the animals are left on a bit longer, which kills off the legumes and brassicas, but leaves the oats to grow though and be harvested later. The sheep are effectively acting as a herbicide. Colin is pretty excited about this development, as it allows legumes to come into the rotation, and it also gives another boost to plant and root diversity.
There is an elephant in the room: Pasture Cropping will not work in the UK.
However, this was an excellent visit, and very inspiring. It’s a system that goes completely against convention, and steps on some toes in the process. It’s very logical (to my mind anyway) when you think about it, and it begs the question – what is our equivalent going to be at home?