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Hosted by members of the University of Minnesota Extension Beef and Dairy Teams, The Moos Room discusses relevant topics to help beef and dairy producers be more successful. The information is evidence-based and presented as an informal conversation between the hosts and guests.
00;00;11;03 - 00;00;35;10
Brad
And welcome to the Moos Room. It's a beautiful day in western Minnesota today, April 10th. As I record this, the sun is actually shining. It's above 50 degrees. Yesterday it was still snowing. So we're still trying to figure out if we want winter or if we want spring here in Western Minnesota. That's kind of what happens when spring is coming.
00;00;35;12 - 00;01;00;28
Brad
I know I think there are cows are probably getting excited, wanting to go out to the pasture and the green grass. It's actually starting to green up. So but I think I've said before, our first day to grazing typically is around the 10th 15th of May, so we still probably have another month yet before grazing happens. And we've got a lot of research projects going on waiting to happen this summer.
00;01;00;28 - 00;01;29;04
Brad
Today I really wanted to talk about some of the ag tech stuff that we've been doing and how it relates to grasses and grazing. So just the other day we had a paper published by graduate student Sabrina Florentino, published a long awaited paper on Edgar Tex and its effect of forage, biomass and nutritive value in grasses and legumes for our grazing cows.
00;01;29;05 - 00;02;04;06
Brad
So basically, what grass or legumes works the best underneath solar panels? And we've been doing solar panel work for quite a few years. You know, we've found that you can reduce heat stress in cows by putting them underneath solar panels. Cows don't wreck solar panels there. It really works out quite well for grazing cattle underneath solar panels. We're starting to see more research come out on agro vortex, but we're still kind of the first ones, kind of at the forefront of this cattle grazing underneath solar panels.
00;02;04;06 - 00;02;22;29
Brad
And I still get lots of questions about it. And we're still trying to figure out a lot of things related to agro voltaic. Still quite a popular topic all over the world. And that was probably one of the big questions. And one of the reasons why we did this study was, you know, we found we could graze cattle underneath solar panels.
00;02;23;06 - 00;02;51;15
Brad
Lots of good benefits. Again, the cows don't wreck the solar panels. I have to tell people this so many times it just doesn't happen. We don't have issues with cattle underneath solar panels. But the biggest question was what can we grow under? There is grasses and legumes and other type of pollinator grasses. You know, that's probably one of the big things that solar developers try to figure out is what grasses work underneath these as they put up these solar panels.
00;02;51;15 - 00;03;12;03
Brad
And they're still a lot of solar panels going up here and in Minnesota and trying to figure out what what to plant under there. So we tried to answer that question, and we found some actually interesting results. At the time we did this study, we had three solar arrays. So we have a 30 K-1. And that's the one that we did our cattle work under.
00;03;12;06 - 00;03;34;13
Brad
Obviously not. We're not talking megawatts of solar here at all. These are more in development stages, really trying to figure out how can we answer some of these questions that people are asking. The other site was a 250 kilowatt, one, so a little bit larger than most. And that one's become now a half megawatt. It's just been expanded.
00;03;34;15 - 00;04;03;00
Brad
And then we had another 50 kW system that was a little bit different. So the 30 kW one was a fixed solar array mounted 35 degrees south. No single axis tracking or anything like that. The 50 kW was kind of a more of a flat top array, with using some reflectors that you could reflect the light and hopefully produce more solar that we use.
00;04;03;00 - 00;04;31;11
Brad
And that was mounted eight feet off the ground. The 30 K-1 was 6 to 8ft off the ground, so we could graze cattle underneath these as well. But then we also had a control pasture so close to the other tech systems. But we wanted to see, you know, how these species grew just out in the the natural world without being exposed to agro vortex.
00;04;31;13 - 00;05;11;09
Brad
So those are the, the, the three sites that we used. And we planted multiple grass species underneath these panels. So we used alfalfa, field peas, meadow fescue, orchard grass, red clover, sorghum, sedan grass, white clover. And then we used three grass and legume mixes which included either alfalfa, red clover or white clover. So we mixed meadow fescue, orchard grass and then one of the legume species.
00;05;11;11 - 00;05;35;15
Brad
So we planted these in plots underneath the solar panels. And we harvested these grass species for two years. So we did this for for two full years, two full grazing seasons. We didn't allow the cows to graze these. We kind of clipped this ourselves to sort of simulate grazing, because we wanted to see actually how much biomass these species certainly could produce.
00;05;35;15 - 00;06;06;07
Brad
So we harvested all these grass species. We took multiple cuttings I think 3 to 3 cuttings per year. So we analyzed these all these grasses for crude protein digestibility. So NDF, ATF and we analyzed them also for lots of different mineral concentrations in these species. We also looked at forage biomass and dry matter and see what we could find.
00;06;06;10 - 00;06;30;16
Brad
So what did we actually find after we did all of this research for two years. So if we look at biomass, so obviously our first cutting of biomass had more compared to cutting two and three, which is what you would expect get more grass growth early on in the season, May and June probably produces the most biomass compared to July or August, when it gets hot and into the fall.
00;06;30;16 - 00;06;59;26
Brad
Our 50 K W solar site had less biomass compared to the 30 kW site, and the control pasture. Why was that? Probably just due to lack of solar radiation reaching the plant level. So this 50 kW site probably produced way more shade than what a typical solar installation does. You know, this particular solar installation was built in 2012, I believe.
00;06;59;26 - 00;07;21;28
Brad
So 14 years ago was one of the first prototypes that we did that we raised above the ground. But it's really hard for light to penetrate through the solar panels and to hit the ground. So there just was a lot more shade underneath this 50 kW system compared to the other. So it just produced less biomass because it had a lot less shade.
00;07;21;28 - 00;07;53;01
Brad
So what about if we compare the the other two? Well, they had similar biomass to in the 30 kW solar system compared to the control. So what about specific species. Well, we didn't find any difference for alfalfa or red clover or white clover underneath the solar panels. So they produced about the same biomass. Now sorghum sedan grass produced a lot more biomass in the control pasture than under shade systems.
00;07;53;01 - 00;08;17;17
Brad
Well, sorghum sedan grass is a warm season. Grass related to corn needs a lot more sunlight, so it just produced more in the control setting. Because a solar system does provide shade. So just a little bit of shade maybe stunted the growth of the sorghum sedan grass as well. It still grew quite well, but we just didn't produce as much as what we saw in the control pasture.
00;08;17;17 - 00;08;44;10
Brad
However, if we look at some of the grass species now, there were some grass species that produced more forage biomass underneath the solar panels than they did in the control pasture. So meadow fescue and orchard grass by themselves in a monoculture produced more forage biomass underneath solar panels compared to a regular control pasture. Now, why might this be?
00;08;44;10 - 00;09;12;23
Brad
Well, sometimes we think that the solar panels prevented evaporation of moisture for those grasses. So we had some more. So it just produced more biomass because it had more moisture. You know, obviously there's parts of the solar panels that get sunlight, but we just produced more biomass for these two grasses because we think the solar panels helped capture the water, keep the water in the grasses, and they did much better.
00;09;12;23 - 00;09;43;15
Brad
So these two grasses did really a lot much better. But like 20% more growth, maybe 25% more growth in the orchard grass compared to the control pasture. So that was a big benefit. Now, if you look at some of the mixes that we had, our mixture with meadow fescue, orchard grass and alfalfa, as well as meadow fescue, orchard grass and red clover had more biomass underneath the solar panels than what we found in the control pasture.
00;09;43;15 - 00;10;14;17
Brad
So a couple of these mixers were out producing the regular pasture by throwing underneath solar panels, so ones with white clover didn't do much, but we didn't see any difference in our field peas. We just they grew much better in the control pasture compared to underneath the solar panels. So really, meadow fescue, orchard grass by themselves and with some mixes had more biomass underneath solar panels than what they did in a control pasture.
00;10;14;17 - 00;10;49;03
Brad
So what about crude protein level for all these species? What did we find? The crude protein level for meadow fescue, orchard grass, red clover, white clover was all greater underneath solar panels than what it was in the control pasture. So we had higher forage quality from a protein standpoint underneath solar panels compared to the regular pasture. If you think about from the 50 kW solar system actually had higher, even higher crude protein than the control pasture or the 30 kW system.
00;10;49;03 - 00;11;13;13
Brad
So the more shade that these grass species got, the higher the crude protein. So grass species grown underneath solar panels had higher crude protein levels than growing out in regular pasture. So better forage quality. The mixes were about the same as far as crude protein level. The other ones, when you grow them in monoculture, higher crude protein levels.
00;11;13;13 - 00;11;42;23
Brad
Now we measured the digestibility of NDF with total track NDF digestibility. It comes out of Rock River labs out of Wisconsin. That's where we've sent all of our samples to be analyzed. And the 30 kW system TTN, DFD was 52.3. The control pasture 49.1. We didn't find any difference. It was similar numerically. The digestibility was higher underneath the solar panels of 30 kW.
00;11;42;25 - 00;12;18;16
Brad
The 50 kW system had higher digestibility than either the 30 kW or the control pasture, so the more shade, the higher digestibility, so was able to keep those grasses in a more vegetative state underneath the 50 kW system. But again, greater digestibility of grass species, legume species. Now here the mixes did really well. So mixes of meadow fescue, orchard grass and alfalfa, as well as one with red clover had higher digestibility underneath.
00;12;18;16 - 00;12;44;00
Brad
Solar panels compared to the control pasture. So we had higher crude protein, higher digestibility in these grass species grown underneath solar panels. Well, what about some of the minerals that we looked at? We didn't find much difference between forage calcium levels, except for the 50 kW was a little bit higher than the 30 kW system. The forages with the highest calcium levels were red clover and field peas, and the red clover and alfalfa.
00;12;44;00 - 00;13;23;05
Brad
All three of the different systems had different phosphorus levels, so the grass species grown underneath solar panels had a little more phosphorus level in the forage compared to the control pasture. And this was, you know, meadow fescue was one of the highest ones, alfalfa as well. So we found some interesting results related to our forage quality. So obviously species responses in agro voltaic systems, they really differed substantially, which really indicated that forage selection is an important consideration in these agro voltaic systems.
00;13;23;06 - 00;13;49;14
Brad
Now for us in this research, the cool season grasses of meadow fescue and orchard grass had stable biomass production under moderate shading and had acceptable nutritive value. The legumes, in particular red clover, had higher crude protein and forage quality across these different agro voltaic system, which really says that it's very adaptable to reduce light environments where you get some shading.
00;13;49;16 - 00;14;15;29
Brad
With the agro voltaic systems, however, the warm season grasses you know, didn't do as well. They had reduced biomass, had similar forage quality, but just less biomass underneath solar panels. So it really suggests that these cool season perennial grasses and legume mixtures, especially ones that included red clover, are probably the most reliable forage option for agro full grazing systems.
00;14;16;01 - 00;14;52;28
Brad
And it had high biomass production as well. So really selection of these shade tolerant perennial species may be a more important than maximizing forage biomass. When kind of designing systems and what to grow underneath solar arrays. So although forage biomass declined under more shade in these agro voltaic systems, the nutritive value of these grasses was maintained or improved, especially with higher crude protein, fiber digestibility and mineral content in these agro voltaic systems.
00;14;52;28 - 00;15;28;01
Brad
Compared to control pastures. So really agro volt takes in the form of forage production grown underneath. These ground mounted solar systems can provide suitable feed sources for grazing livestock and provide a green energy source for farms and additional income for farmers. So in the end, what's the take home message here? Well, you can have high forage biomass, greater forage quality for grasses and legumes, meadow fescue orchard grass did the best underneath agro voltaic systems compared to the control pasture.
00;15;28;01 - 00;15;51;21
Brad
We also tried to grow a few other things underneath the solar panels. Corn, soybeans, wheat and oats. We didn't maybe have quite as much luck, especially the more shade that they got. The growth was quite reduced, which is very difficult, at least how some of our systems were set up to grow corn. Soybeans did well, they just didn't get to maturity depending on the amount of shade that they had, and corn did well.
00;15;51;21 - 00;16;18;09
Brad
We're still going to keep exploring whether we can grow corn underneath solar panels or not, but I think the jury's still out there on how to grow some of these row crops underneath the solar panels. But in the end, we found some of the grass species that farmers can use if they're or solar developers that they can use, at least up here in the Upper Midwest for grazing cattle or sheep or anything underneath solar panels.
00;16;18;11 - 00;16;22;05
Brad
So if you want to find some more information.
00;16;22;07 - 00;16;58;02
Brad
We're having some webinar series on agro voltaic. So our first webinar is April 14th. So Tuesday, April 14th. And that's at 5 p.m. central time here in the US. We're going to talk about cattle and kilowatts. So we're going to have an in-depth webinar featuring some of the pioneers of cattle solar grazing. Our guest speakers include Will Harris and Dale Caldwell from White Oak Pastures and their leaders in regenerative agriculture, who have integrated solar grazing into their farm in Georgia.
00;16;58;04 - 00;17;23;01
Brad
We also have Josh Bennett from Who Enterprises in Colorado, an expert at the forefront of cattle solar design, as well as going to join the discussion. And these will be recorded too. So we'll put them on our YouTube playlist as well. And I'll kind of leave all this in the show notes. If you want to sign up for these webinars, we have a few more happening throughout the summer talking about solar developers.
00;17;23;01 - 00;17;43;06
Brad
One's about sheep grazing, one's about what we can grow underneath panels as well. So with that, I hope you found a little interesting information about what you can do underneath solar panels and what grasses or grass species work underneath solar panels. So if you have any comments or questions or scathing rebuttals, feel free to contact me at the newsroom.
00;17;43;06 - 00;17;58;00
Brad
That's tag m o s r o m at unmedicated or find us on the web at University of Minnesota Livestock Extension or and Rock dairy. And with that, I hope you have a great spring. Bye.