M,
So nice to see your livestock looking so well and with high quality pasture in front of them today. We talked about diverse cover crops vrs perennial pasture for soil improvement. I have put together some research around why I think permanent diverse pasture is better for improving the soil than cover crops, even diverse ones, because I am seeing more and more confusion about this not just in New Zealand but around the world.
Gabe Brown had found cover crops were a useful practice to improve degraded soil on his North Dakota arable farm as a band-aid for inherently soil destructive arable farming. Back-to-back arable crops in the US have degraded once deep rich topsoils down to just subsoil on 35% of the corn belt and the average soil organic matter percent is less than two. Ultimately, Gabe found when he incorporated livestock and managed to promote high plant diversity using holistic planned grazing, his soil organic matter lifted about TWICE AS FAST as it had when he tried to heal soil just with cover crops.
You are not the only farmer experiencing confusion around cover crops. For this reason, I asked Gabe Brown at the Eco Ag Conference back in December 2020 if cover crops are appropriate for pastoral farmers in humid temperate climates. See his reply here.
I have been worried about pastoral farmers like yourself reducing their summer grazing area with low yielding winter cover crops (remember cover crops are the band aid not the cash crop. If they were high yielding, they would be the crop). There is no evidence that cover crops improve soil health better than perennial pasture that I could find, and my twenty-five years’ experience farming has taught me (and Gabe) the opposite.
The problem can only be seen when you look at whole farm production. With area for crop taken out for up to fourteen months, winter cropping can make it harder to have enough grazeable area in the summer to prevent livestock from getting ahead of the grass which means your grass grows slower on the entire farm! Grass grows grass. You found you didn’t get the yields with your cover crops which you would get from a proper winter crop either which put even more pressure on your grass which is the solar panel covering your farm. Does it make sense to put money and chemicals into a winter crop that yields less than the pasture would have over the year?
You are concerned about how you would feed your livestock with no winter crop.
Since you have mostly sheep and want to improve your soils, what if you decide to lift your average summer recovery by one half of a leaf stage on your perennial ryegrass every year to promote pasture diversity? With my cattle only situation, one extra half leaf of recovery per year lifted our grazing height and residual five centimetres per year. For your mostly sheep farm, an extra half leaf in summer may only lift your covers one or two centimetres. This gradual lift though, would allow high quality plants like timothy, cocksfoot, red clover, and other drought tolerant plants to come in on their own over time while maintaining the quality you need for animal performance. If you went into winter this year with 200 kgs/ha more grass (1cm) on all your 1600 hectares you have grown 320 tonnes more kgs of dry matter.
You have tried some of my ideas for achieving optimal summer recovery such as the deferred paddock by the roadside which next time we want to graze earlier when it is still green. Without executing grazing plans for each block so you can monitor when to add or remove stock based on your residual as the weather changes, it is very difficult to nail that optimal recovery in the summer and see the true potential your farm has to grow grass. I know my stock always got ahead of the grass in the summer on my farm until I started using a holistic grazing plan. Part of the planning process will look at how we can push more spring surplus into summer with rolling deferred grass where we endeavor to graze it green as possible.
You could also boost summer grazing by taking one third or half your crop area and putting in a spray free diverse summer annual crop with the likes of oats, millet, buckwheat, beans, vetch, rape and kale or something similar or even use straight turnips with the chemicals required for best yield. This summer crop will take pressure off all the other pastures if we get another summer dry to allow you to achieve your optimal recovery which will grow grass as fast as possible, making it easier to go into winter with higher covers. After grazing off the summer annual crop at its optimal recovery in 90-120 days, you can re-grass the area in March with a solid diverse perennial mix which Gabe Brown says is the best cover crop for the soil. You will still have some other paddocks in winter crop to make you feel secure.
Farmers all around the world are starting to believe despite evidence to the contrary that cover crops, a “less bad” practice for destructive arable farming practices, are better for the soil than permanent pasture. It has become a strongly held belief even though Gabe Brown who developed the idea says the opposite. I showed Gabe’s video to a sheep and beef farmer who worked out that she had only harvested four tonnes of dry matter from her diverse winter crop in twelve months based on the days of grazing she got. I was on the farm late winter and there was much more bare soil where she had grazed the crop over winter than on her permanent pasture along with visible compaction. There also were fewer plants left per square meter growing green to feed the soil. Even with all this not so regenerative evidence, she insisted she needed to plant the large area again to a diverse winter crop because the previous one had not done the job yet. It defies logic, will cost her a lot of money, and makes my job harder. Farmers don’t realize the power of regeneration is all in the grazing as Gabe, myself, and long-time cover crop aficionados like Jack Lazor in Westfield Vermont have found out the hard way in the last three decades.
The other strongly held belief which I have seen no evidence of in the New Zealand context is that to improve soil, farmers need to let grass over recover and go to seed. Farmers and ranchers using holistic management in semi-arid areas like Zimbabwe, Australia, and the Sonoran Desert in Mexico get positive results from this. I believe in places where you can grow grass all season it is far better to manage for green leaves because of the positive outcomes we got. Because I was worried about pastoral farmers in New Zealand who were enamoured with cover crops and over recovered grass they didn’t need and losing money, I brought over Holistic Management Educator Ian Mitchell-Innes from South Africa to New Zealand twice in 2019 and 2020 to help regenerative farmers learn how to make more money. He also helped dispel another myth that you need to destock if you are regenerating soil. If you are building topsoil your stocking rate should go up logically. Some of Ian’s clients have doubled their stocking rates and Allan Savory has quadrupled livestock numbers at Dimbangombe, their holistically managed ranch in Zimbabwe. Many New Zealand farmers cottoned on to Ian’s ideas that profit must come first if farmers are going to be around to do any good with the land.
About fifteen years ago when Gabe Brown started to really get his soils improving rapidly with his grazing, we were discovering on our dairy farm that we didn’t need to let pasture over recover and go to seed to lift soil carbon. Been there, done that. It wasn't profitable. Simply managing for more diversity while keeping more grass green and growing fast lifted soil carbon in our wetter temperate climate in a pastoral context (Gabe gets 480mm and we get up to 850 of precipitation annually). We grew dairy quality pasture that was profitable on our farm using mob grazing, but it also resulted in profound restoration of our soil and the environment our farm was embedded in. We didn’t need over recovery. Allan Savory mentions one of the reasons farmers benefit from doing a grazing plan is to “reduce or eliminate over rested plants and soil surfaces” (The Holistic Management Handbook, p 57). I showed some evidence of our results in my last blog “Farm Regeneration is about Results”. Since meeting Christine Jones here in New Zealand, I have a better understanding of how our soil carbon lifted so quickly since green growing plants can pump more liquid carbon from their roots to feed the soil.
How is all this relevant for New Zealand’s aspirations for a climate healthy agricultural sector? Well by adhering mostly to pastoral farming you have avoided much of the soil damage seen in the US and you are well on your regenerative journey without cover crops as a band aid unless you are in the arable sector. BUT - When we managed for only perennial ryegrass and white clover for ten years before starting mob grazing in 2008, we did not see a lift in soil carbon. We were not losing carbon either. The same trend is observed in New Zealand where soil carbon is not going up either – yet.
You have been hearing me say for years that New Zealand pastoral farmers are going to be climate superhero’s one day. It is likely the sheep, beef, and dairy sector, simply by managing for more diverse perennial pastures and reducing annual crops could off-set the entire country’s greenhouse gas emissions if they learn to build soil carbon like we did on our dairy farm just by doing what you are so good at - grazing. New Zealand farmers have developed the best grazing infrastructure in the world and have exceptionally skilled pastoral farmers, so you are better positioned than anywhere to draw down carbon on the ongoing basis required for our climate emergency. Livestock are essential because ruminants evolved with grasslands and grassland soils and are an inseparable part of the grassland ecology that performs the soil building process. Now that the new NASA’s Earth Surface Mineral Dust Source Investigation mission has identified the largest super emitters of methane by far are from fossil fuel extraction and rubbish dumps, not livestock, the logical path for carbon neutrality is through soil carbon sequestration enhanced by livestock.
One reason perennial grasslands can improve soil best is clear in this photo.
Sunflower roots do not go down much deeper than the red circle. The prairie system on the left is the long-term solution to climate change and the diversity crisis which we are trying to mimic. Gradually moving that way by managing green vegetative grass will move you there safely and profitably if you monitor that your productivity is ever increasing. I recommend you use your grazing plan to monitor to make sure you are getting more productive outcomes in both pasture growth and meat production. Then stick to the recoveries that achieve the maximum total meat sold per hectare per mm of rainfall. You can use this same data from monitoring your plan to see if the paddocks you had grown cover crops on perform better than ones which didn’t. With holistic management it is important to assume you are wrong and collect actual data so if something doesn’t work you see it right away. I may be wrong about the cover crops so am keen to see the results. I am looking forward to helping you set up this seasons grazing plans at our next meeting.
Kind Regards
Siobhan
The supporting data:
Gabe Brown has documented his soil health progress indicating mob grazed perennial pasture was the best practice to build soil carbon and general health and you can see this on his video’s. Other scientific evidence comparing diverse cover crops to perennial pasture is hard to find. An American study did compare full tillage to no-till and set stocked pasture and found the same trend that tillage was the worst for the soil, no till less bad, but the soil carbon after three years of perennial pasture had lifted soil carbon twice as much as conservation tillage.
Another study found soil under management intensive grazing had twenty percent more carbon than extensively grazed or hayed land.
The coolest paper by Teague et al. looks at the potential to combine regenerative arable practices (of course using cover crops) with holistic planned grazing to make farming on the whole net carbon negative.
These studies look at the extent of damage to American soils I mentioned.