There is a great website (http://www.adoptafarmer.com.au/) about carbon farming in Australia. I have mentioned before Dr Christine Jones, who features on here, in her crusade to store carbon in soil by year-round cover-cropping and other regenerative methods. I like the term "pulse-grazing", since I always think of a pulse as a powerful burst of energy of short duration; maybe fraction of a second as in scientific measurements. In the present context, the pulse is over a couple of days and involves moving grazing animals like sheep somewhere, before moving them on to do the same job on another plot of land.
The term is due to Colin Seis, in Gulgong who farms 4000 head of sheep and cereal crops including oats, wheat and lupins on ‘Winona’, an 840-hectare (2075 acre) farm in the central tablelands of New South Wales. In 1933 they were one of the first in the area to
use superphosphate fertilizer, which initially doubled wheat yields. However, in became clear to the family by the 1970s that their farming methods could not be sustained, when falling wool prices and rising superphosphate costs meant that fertilising pastures was not a long-term option. The initial benefits of adding fertilizers were no longer being recouped and plants were responding less vigorously to fertilisers meaning that increasingly larger amounts had to be added to achieve the same good yields.
Progressive dryland salinity, soil acidity and annual weeds were encroaching on their land too and in 1979 the farm was destroyed by a major bushfire. Because they didn't have enough money to simply "rebuild", Colin looked for more traditional approaches in family history records where he discovered that the original landscape of the tablelands had been grassland and scattered trees. He reckoned that the native grasslands must have had the innate ability to control ground water and not accumulate salinity.
Colin decided to combine grazing and cropping rather than considering them as separate activities and to stop using superphosphate fertilizer. He also changed from set grazing practices to a cell grazing method, i.e. "pulse grazing", where a herd of up to 3000 sheep is moved around his 51 paddocks (average size 16 hectares), to spend 2-4 days in each one before moving them on. After 3 months to allow the native grasses to recover, the ground is grazed again. Colin also took the line that it made no sense to plough a pasture to plant a crop on the land:
"It takes 6 months to prepare a paddock to grow a crop for 2 or 3 months, and then it might be affected for 10 years afterwards, all for 2 or 3 months feed," said Colin. "It’s lunacy to do that. There had to be a better way. My father always disliked ploughing up pastures to plant crops, but in his time the technology just wasn’t there to do it differently." Colin and his neighbour Daryl Cluff believed it would be possible to sow winter cereal crops directly into summer-growing native perennial pastures that were dormant through winter. The pasture could be grazed right up to the point of sowing and stock could be put back on the pasture after harvest to graze stubble and green perennial grasses. They found it works.
Sheep are put into the pasture at a density of 70-80 per hectare for up to 6 days to reduce the bulk of grasses. This is repeated 30 days later. The sheep control weeds, open the grass canopy, mulch the grass and help feed soil microbes. One week after the sheep are removed, a low rate of knockdown herbicide is applied to control annual weeds and the area is almost immediately sown with zero till seeding equipment. A one pass operation places oat seed and fertiliser in 30 cm rows with very little disturbance to the surface ground cover. Conservation cropping protects the soil flora and fauna and promotes biodiversity, i.e. it restores the health of the soil.
Colin’s intention is 100% ground cover, 100% of the time, including under crops. The Department of Agriculture found that the pasture cropping method of farming can be more profitable than traditional methods, and that the width of the profit-margin would depend on the current level of grazing overheads (such as pasture seed, pasture maintenance and casual labour).
Winona’s soils are becoming healthier as a result of the grazing and cropping methods with lower inputs of fertiliser and some crops have been grown no chemicals at all. Colin thinks that nutrients are now cycling through the soil and releasing phosphorous naturally, since 20% of the pastures are still healthy sub-clover.
"Pasture cropping and pulse grazing have dramatically increased pasture biodiversity," said Colin. "The pulse grazing definitely improves biodiversity in perennial grasses, but I was surprised to find that the pasture cropping took it to a whole new level. We had huge increases in plant diversity and numbers after just one year of sowing a crop that way. It was a spin-off that we didn’t expect at all, that the crop would actually stimulate the pasture. Looking at grasslands and soils is the key to turning salinity problems around. If we can get groundcover on the saline parts of the property, then they can actually be very productive, especially in dry times. I believe our native pastures act like huge sponges, holding water in suspension. If we can get back to that, I think a lot of our salinity problems would disappear."
"Don’t spend a cent," is Colin’s advice. "Put your animals into large mobs and start moving them around the infrastructure you already have. Focus on native perennial pastures – they’ve evolved here and obviously they are the best plants for Australia. Throw away your disc plough – if you’re going to grow crops, use zero till. Only kill the weeds that are competing with the crop, leave everything else alive. "The hardest thing to change in all of this is to change your head (thinking). Once you’ve done that, the rest is easy," he said.