Bill Kerr, a vegetable specialist and breeder of a range of vegetables, has been no-tilling for 18 years and says he’s seen a range of benefits. He’s used no fertilizer for 15 years and had flourishing crops.
“The dry grazing vetch mulch on the beds helps maintain a high level of active carbon in the soil, maximizing microbial activity and increasing the level of passive carbon,” he said in a recent post for Farmers Weekly.
Kerr adds that growers who use conservation practices can build their soils up to a point where they can realize maximum yields, higher water-holding capacity, greater disease resistance, better eelworm control and better-tasting vegetables with longer shelf life.
“The humus in my soil can hold 750,000 liters of water per hectare, like a reservoir,” he says. “ Rain is absorbed easily and I save on irrigation costs.”
One hectare of soil 6 inches deep weighs approximately 2,000 tons, he says. If the organic content of the soil is 3%, that area would contain 60 tons of organic matter. This includes 50 tons of passive carbon.
Carbon occurs in an active and passive form. Active carbon is present in all soil organisms and decaying organic material and gives rise to passive carbon. This breaks down more slowly, contributing to soil structure, cation exchange capacity and water retention, amongst others, and helping to suppress eelworm. It is vital for soil health.
The 3% humus also represents 4 tons of organic nitrogen and 2 tons of organic phosphorus. “It took me years to build up to about 5% humus, but I still managed to produce good crops during this process,” he says.
Increasing the humus level in the soil is like building up an investment or bank balance for the future. We pay for this investment with good no-till practices and can later live off the interest,” Kerr notes.
Initially, growers will have to carry out a soil analysis to determine which elements need to be topped up and how this should be done.
“You will most probably have to use fertilizer in the beginning. I also had to,” he says. “You will require a tractor and implements to do the initial preparation, but you won’t need them again, as no further tillage is carried out.”
Kerr says if farmers need to work in elements such as phosphorus or lime that don’t move readily down the soil profile, now is the time to do it. “In addition, you should apply as much manure as possible to fast-track humus build-up. The manure will start feeding the crops, as well as the humus formation,” he says.
Kerr suggests applying cattle manure at a rate of 80 tons per hectare and poultry manure at a rate of 10 tons a hectare. Cattle manure contains a high level of potassium, and poultry manure has a high phosphorus content. These elements are usually deficient in new soils.
“The soil analysis will indicate how much lime you need, but I suggest that you be generous and apply to the upper limit of what is recommended,” he says.
Cover Crop Allelopathy Can Fight Weeds
Cover crop residue leaches allelochemicals, which help control weeds. But to achieve prolonged results farmers still need to implement effective weed control, says Suzette Bezuidenout, scientific manager of Cedara’s crop protection unit, in an article for Farmers Weekly.
Weed management should focus on combining different methods to prevent and control weed populations. Cultural weed management practices are important as well, such as production practices that improve crop competitiveness such as cover crops in combination with conservation tillage.
Bezuidenhout says allelopathic cover crops release allelochemicals into the environment and can be used to enhance weed management. Researchers are constantly conducting field and tunnel experiments to evaluate the weed control abilities of various cover crops and cultivars in combination with the application of herbicide.
Recently, researchers evaluated the effects of Italian ryegrass and stooling rye without herbicide use on the growth of maize and yellow nutsedge in the field. The trial involved three control treatments, namely weed residue left on the soil surface, herbicide application, and weed control by hoeing, the magazine reported.
In a tunnel experiment, oats, stooling rye and three cultivars of annual ryegrass were used to evaluate their influence on maize and yellow nutsedge growth and development.
The field experiment examined the desiccation times of cover crops on their weed-control abilities by spraying them with glyphosate 4 and 1 weeks before planting and at planting. Minimum-till maize was planted into the residue with selected spraying of pre- and post-emergence herbicides, and its growth and development were evaluated.
In the first field experiment, maize emergence and growth were delayed in the presence of residues of both cover crop species, and especially in annual ryegrass residues.
Yellow nutsedge growth was significantly inhibited in the area between the maize planting rows by the cover crops for the first 14 days after maize emergence. This growth-suppressing effect diminished after 28 days.
In the tunnel experiment, maize and yellow nutsedge growth were suppressed, especially by the root residues of the cover crops. The annual ryegrass cultivar Midmar was the most suppressive.
The field experiment indicates that spraying annual ryegrass at planting reduced weed and maize growth the most.
Adequate weed control was not achieved by applying only post-emergence herbicides.
Combining annual ryegrass residues sprayed at planting with only post-emergence herbicides applied later in the season resulted in the lowest maize yields, Farmers Weekly writes.
Weed growth can be reduced by the allelochemicals leached from cover crop residues, but to achieve prolonged, effective weed control, a farmer needs to apply herbicide and retain mulch on the soil surface.
Tipping Point for Regenerative Ag
Ian Pigott, a grower in Harpenden, U.K., says the constantly emerging challenge of blackgrass on his farm pushed him to adopt regenerative practices.
The pest infected his wheat fields every year, always doing more damage and hurting yields, he said in a Global Farmer Network post.
“We tried to kill it with crop-protection products, but the more we spent on inputs the less we seemed in charge,” he says. “Blackgrass requires a 97% control just to retain status quo. The weed continued to grow and thrive in its menacing tufts.”
Six years ago he decided to make big changes as costs soared and blackgrass become herbicide tolerant. He’d met Sarah Singla of France in a meeting and says she gave him the confidence to believe their cultivation equipment could be sold, insecticide use could be halted, and cover crops and catch crops could be included in his rotation.
To defeat blackgrass, Pigott delayed autumn planting, though the hazards of British weather in October made that hard. “We now plant sheep mixes in the spring to replace a break crop, and we bring the sheep of other farmers on our land to graze these covers. We have reduced our use of fungicide. We rely on less fertilizer and more on biostimulants.”
Pigott believes regenerative agriculture involves a commitment to four fundamental actions: intention, invention, conscience, and legacy:
- Intention means a willingness to change your mind, he says. “We have to look at what we’re doing wrong and make it right.”
- Invention is an openness to new ways of doing things, based on creative thinking and sound science. “We should accept change but not merely surrender to it,” he says. “We must become agents of positive change as we search for solutions to soil erosion and water scarcity.”
- Conscience is a recognition of our responsibility to the resources of air, water, and soil, he notes. “As farmers, we must make use of them all, but we have to give back as much as we take out. That’s why we speak of ‘regenerative agriculture’ rather than ‘degenerative agriculture.’”
- Legacy is all about what farmers leave behind: Farms that are healthier and more robust for grandchildren, who inherit land full of organic matter that can continue to provide food security for ourselves, our country, and our world.
Pigott says he works with scientists at Rothamsted Research to measure the effects of regenerative agriculture on his farm.
“We aren’t yet ready to publish our findings because we’d like a little more time to elapse, but we’re seeing major improvements in the health of our soil,” he says. “One interesting measure involves earthworms: We’re counting more than 170 per square meter. If worms love our healthy soil, so will our crops.”
Input Needed for Canadian Carbon Program
The Saskatchewan Soil Conservation Association (SSCA) is calling for farmers to review the Government of Canada’s proposed Greenhouse Gas Offset Credit System regulations and provide their feedback.
The proposed regulations are currently open for comments and will remain open until May 5. Jocelyn Velestuk, an SSCA director, says there are points the group wants farmers to think about as they provide their feedback.
“Some of the things that the SSCA has been pushing for, and we’ve been quite solid on our position, is that we need to separate biological carbon sinks from industrial point source emissions in order to have carbon offset markets. But that encompasses agricultural soils as a carbon sink,” she says.
“The other thing we would need to include is no-till continuous cropping, which greatly increases the amount of carbon sequestered in the soil. There are also issues with words like ‘additionality’ and like ‘businesses as usual’, there’s a 40% penetration rate for practices before they’re considered ‘business as usual’ and basically taken off the system completely.
“The third point we would be pushing for is that we need transparency in the carbon offset market, which means that we need to know where the money’s flowing and we need the person who is creating the offset to the farmer to own the carbon credit and be able to even bank that credit if need be.”
She says that the Government of Canada had invited the SSCA to help develop the regulations, which Velestuk notes was an opportunity for the organization to voice concerns on behalf of Saskatchewan producers.
“For the past year we were involved in representing a lot of the farm groups. APAS (The Agriculture Producers Association of Saskatchewan) and SARM (The Saskatchewan Association of Rural Municipalities) were represented as well and were invited to participate in a technical working group for industrial carbon sequestration and carbon offsets in agricultural soils. There was also the Ministry of Ag and Ministry of Environment folks that were on that technical working group,” said Velestuk.
“We worked for a year on that technical working group and we were very solid in our position because this is the way we see forward, as a way for farmers to really be involved in the carbon offset system.
“We have research backing us up with this, too, and SSCA is a long-standing organization that’s always been industry-driven. So when no-till was first getting adopted 30 years ago is when SSCA came to be.”
In 1995 SSCA initiated the Prairie Soil Carbon Balance project, which has been sampling soils on a large scale in Saskatchewan to determine carbon change over time with conservation practices. That project was initially introduced with no-till in 1995 and soils were measured four times in the last sampling that happened in 2018.
“So we have data saying that yes, farmers are sequestering more carbon than they’re taking out, so we know that we have a net positive carbon change in our soil with our current practices, which includes our no-tilled continuous cropping.
“We know this happening, we know you’re probably not going to go back to when we started this practice, but if we totally ignore the fact that with our current practices that we’re sequestering carbon, then we’re missing out on huge opportunities.”
If you want to measure real change and real carbon offset, “we can’t just throw away an entire practice,” she adds. “So we’ve really been standing by that in our discussions with the government.”
Velestuk says that the SSCA's main goal is to have zero-till farming acknowledged as a practice by the Government of Canada for the proposed Greenhouse Gas Offset Credit System, noting that a vast majority of Saskatchewan farmers take part in the practice.
“Each year, through no-till practices, Saskatchewan farmers sequester about 9 million new tons of carbon dioxide. We’re committed to achieving a regulatory environment that recognizes this significant positive impact,” she says.
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