Exploring the use of compost & biochar as both soil amendments and as heat sources to extend the growing season inside high-tunnels on the Pine Ridge

View the project final report

Commodities

• Vegetables: beans, carrots, garlic, greens (leafy), greens (lettuces), onions, peppers, tomatoes
• Additional Plants: herbs, native plants, ornamentals

Practices

• Crop Production: high tunnels or hoop houses, irrigation, season extension, shade cloth, Biochar soil amendments, waste heat capture, composting and compost waste heat utilization
• Education and Training: demonstration, farmer to farmer, on-farm/ranch research
• Energy: anaerobic digestion, byproduct utilization
• Production Systems: agroecosystems, holistic management, permaculture
• Soil Management: composting, organic matter, soil analysis, soil microbiology, soil quality/health
• Sustainable Communities: local and regional food systems, sustainability measures

On the Pine Ridge Reservation in South Dakota, persistent poverty alongside historical discrimination and mismanagement of tribal resources has resulted in less than 1% of Lakota being agricultural producers. Agricultural income disparity is high, with two-thirds going to non-natives. Mismanagement of tribal lands have left the soils degraded with little organic matter and nutrient deficiencies. South Dakota’s short growing seasons and turbulent extremes of weather require high-tunnels for crop protection. The utilization of high-tunnels have gained in momentum in recent years. Eight high-tunnels went up last year and 11 were planned to go up in 2020 by the Oglala Sioux Tribe. To my knowledge, only one of these has gone up and the remaining 10 are still waiting to be put up by the tribe.

The season extension provided by a high-tunnel, isn't as long as we'd prefer. The length of extension in both spring and fall remain too limited for anything but the hardiest of cold season crops. We had to change covers multiple times, inevitably going away from roll up sides, due to our consistent high-wind events and replaced it in 2021/22 with full covers. We also had to re-build our high-tunnel's end-walls and cover the poly cover with a solid wooden endwall. This has kept the annual damage to the covers to a minimum. None-the-less, the manufacturer continues to send us sub-standard covers. Already two of our new covers, which have a four year warranty on them, have needed patching as they've started to tear along seems. This is a failure of the warrantied material and not caused by a storm wind, blowing debris, etc. 

In 2022, we did finish installing the interior trellis structure, have also built the pallet alley ways inside the middle of the high-tunnel and attaching the internal growing zones as laid out in our project. To do this, we attached regular hardware store poly/plastic sheeting to create the growing zones. We painted both steel 55 gal. drums and plastic 55 gal. drums black to absorb heat during the day. The drums are filled up with water and some antifreeze to keep them from freezing solid during the worst of the winter temperatures. We built the biochar tin-man, but haven't been able to test it in the making of biochar. The compost/manure pallet alleyways are built, but not filled up as we've struggled to find adequate amounts of affordable manure and compost. Originally we had a primary and secondary source lined up. But, when Covid hit, they didn't deliver in 2020, nor again in 2021 nor 2022. All alternative sites we contacted either couldn't provide the volume of manure and compost needed, or wanted to charge too much for delivery or to purchase, often times both. As the war in Ukraine raged on and global markets for fertilizer were hit by inflationary prices, local farmers and ranchers seemed to think they were sitting on a gold mine. We recently contacted a different rancher on Pine Ridge and a livestock yard that we "think" will be able to deliver the volume and quantity we need. If what they're saying to us now, holds, true, we hope to have the manure and compost on site before spring of 2023. 

When it comes to the biochar component, we build the Biochar retort system, as shown on the you-tube video, "Making Biochar, part-one" by Living Web Farms. This is the simplest of methods that involves the use of a 35 gallon steel drum, with holes on the bottom serving as the inner-retort chamber" and which is filled with biomass, in our case, wood, which will be baked inside a 55 gallon steel drum, or outer-retort. As the biomass inside is baked, it lets off gases which escape from the holes in the bottom.

Wood fuel is slid between the two drums and on top of the 35 gallon drum. Holes drilled near the bottom sides of the outside retort (55 gal) and near the top sides, allow for air to move upwards through the drum. A fire is lit on the top of the drum and is allowed to burn down the sides. As the fire burns the wood fuel down, oxygen and released gas is moved up and burns off. The inner-retort burns off all the gas and oxygen and what's left inside isn't ash, but almost pure charcoal.  Biochar, once charged inside compost, is an amazing soil-amendment. The plan involves taking biochar  made inside this sytem and adding it to the manure and compost inside the alleyways. As the biochar is charged inside the manure and compost, sucking in nutrients, it also absorbs any smell given off by the manure and compost, eliminating one potential drawback from the manure and compost alleyways, namely, the smell. At the end of winter, the compost and manure and charged biochar can be shoveled out and used to top dress the plant beds inside the same high-tunnel. That's the plan. Unfortunately, since we were unable to secure the manure and compost volumes needed, we elected to not produce any biochar this year as uncharged, biochar would suck up nutrients in the soil needed by our plants. It would have hurt production. Also, biochar, even once done processing, if left in a pile of pure biochar, can be flameable and so to avoid that risk, once again, we elected not to produce any biochar. Our current plan is to start producing biochar as soon as we have the manure and compost piles on site. Once we start a batch of biochar, a complete session takes about 4 hours, so while the first batch is baking, we'll move the manure and compost into the pallet alleyways in the two high-tunnels. 

Our design for the internal grow zone system is designed to seal up the micro-climate of a high-tunnel and heat it using the very same processes Lakota farmers need to build up the health of their soils: using the waste heat from compost and manure inside pallet alleyways inside the central grow zone inside the system and capturing waste heat from the production of biochar in a system outside of the high-tunnels. The majority of this system, by design, is built around mostly locally-sourced materials: pallets, steel drums, compost, waste wood, agricultural residues and manure (for compost & biochar). This makes the system affordable and fixable for our targeted audience.

When the global Covid-19 pandemic hit, our ability to progress on this project was significantly challenged, due to travel restrictions, in-person meeting restrictions, lack of vaccines, fear, etc. As 2020 rolled into 2021 and 2022 and vaccines began to finally reach our area, the fear of catching Covid-19 lessened a bit. Although due to both a cultural/historical mistrust of vaccines amongst tribal peoples, especially a vaccine designated, until recently, as "emergency use," vaccine use on Pine Ridge Reservation isn't as high as we'd like.

As the year has progressed, more vaccines got into arms on the Pine Ridge Reservation, and our partner, Feather Two Farms completely shut down their operations in 2020, had limited operations in 2021 and although they started having their program return closer to normal, it won't be until spring of 2023 that they expect to get back to normal. So in 2020 and 2021 we immediately had to switch gears and the plan to test our system, still in two high-tunnels, but just on one site (Rebel Earth Farm). The tribal incubator-farmer from Feather Two Farms, Theodore Pourier, Sr. has moved to Rebel Earth Farms to be one of its farmers, bringing with him son, Theodore Pourier, Jr. as another incubator-farmer. Also, recently Emit Vine King, another tribal member has joined the Rebel Earth Incubator Farmer group, bringing our total farmers from three to five. Cory True did recruit a non-native incubator farmer for Feather Two Farms, (Devo) however, they planted outdoors in 2021. In 2022 they did plant vegetables inside both of their high-tunnels, but they didn't complete the internal trellis system, so in 2022, we once again focused on getting the two high-tunnels at Rebel Earth Farm ready for the system. 

The main delays at Rebel Earth Farms, beyond the Covid-19 ones mentioned above, have been the increased costs on lumber, steel and aluminum (caused by tariffs, shortages and breakdowns of global and national supply chains). We finally were able to get the exhaust vents, fans, shutters, etc. on Rebel Earth Farms hooked up to electricity. Inflation on steel has also increased the costs of ordering the steel drums as planned, so we were only able to afford enough steel drums to fill the north side of one high-tunnel. The southern side we had to use black painted plastic drums. This means one high-tunnel we'll be able to test the full system in, the second high-tunnel will be our control. What does this mean?

So, this next spring and fall, we'll be able to record temperatures in two standard high-tunnels, as is, no grow-system, passive heat or waste heat collection inside. Then a third high-tunnel will have the interior plastic grow zone system in place and the pallet alley ways with manure and compost, but no barrels and no capture of waste heat from biochar production. The fourth high-tunnel will have the full sytem inside of it. Once all four are planted in spring of 2023, we'll be able to compare and contrast internal temperatures during both shoulder cold growing seasons, as well as to test the full system's season extension vs only the grow zones and compost alley waste heat. This will actually allow us to look at each component of our proposed system and evaluate how many degrees of warmth it adds as well as look at how long a particular crop's growing season can be extended by each part of the system. We have trays seeded and ready to go. We're just waiting on manure and compost. Then we'll add that and start making biochar. We'll be able to test the temperature part as soon as those start happening and we'll be able to test the growing season extension of the system, starting in spring of 2023 and again in fall of 2023. 

The other delay we're having is the price and availability in our area of copper tubing. Both global events, inflation/supply and demand logistical challenges, as well as having to compete for copper tubing with the developers building the boom around Rapid City, SD getting ready for an airforce base expansion, means we haven't been able to get access to enough copper tubing, volume wise, period, let alone at an affordable price. So, we haven't purchased the copper to connect the water/antifreeze filled drums inside the high-tunnel to the biochar tin man. We have a hot-water heater, we have the tin-man built. We just need manure/compost and we need copper tubing, at an affordable price to proceed.  We are contemplating forgoing the copper tubing and just using all polytubing or pvc piping to move the heated water from the biochar waste heat collection through the system. 

Once completed, it is our plan to test one high-tunnel as our control, utilizing just the internal trellis-skeleton and internal plastic growing zones with a central compost alley of pallets, with the barrels (painted black) full of water to see how much further these passive heating options and growing zones can push the growing season of both warm season (starting spring, summer  2023) and cool season crops (starting spring and fall 2023 ). In the second high-tunnel the full system will be tested (trellis and plastic growing zones, black painted drums with water, connected together via PVC pipe, with heated water pumped through them; the heating of the water coming from the production of biochar outside of the high-tunnel via waste heat capture); in addition this high-tunnel will also have the central pallet compost alley way, the two steel drum ovens. When we compare the length of the growing seasons, the heat and humidity inside both high-tunnels (control and full-system), the crop yields, etc. throughout 2023, we'll be able to report on a full-year (two cold crop seasons with a warm season in-between) and also add results from Fall of 2021. 

In terms of activities and timelines, we were able to plant successfully this spring and summer 2022 with full covers on, and with the ability to power fans and vents. We have many trays already seeded for spring of 2023 and we've already ordered most of our seeds for this spring and summer season. We are waiting on results from soil tests (pre-biochar) now. 

With the full-system installed in one high-tunnel and up and running by spring of 2023, we'll be able to compare the heat, temperature, frost-kill (length of growing season) humidity and crop yields amongst them all and get a truer report on the efficacy of our proposed system. The incorporation of incubator-farmers from both Rebel Earth and Feather Two Farms, means that farmers from both partner groups helped install the system in 2022 and will be directly involved in the testing of the full system this spring 2023 and through out the full production year, thus meeting the objectives of our grant. 

1. Evaluate biochar and compost to regenerate degraded soils, reduce the buildup of soluble salts inside high-tunnels: as we were waiting on the prices of copper tubing and steel drums to go down, we were only able to add drums to one high-tunnel. We purchased two (a 55 gallon and a 30 gallon) and built the biochar tin-man retort. This will allow us to begin creating biochar and fine tuning our process this winter and spring 2023, once we have secured enough compost and manure to add the biochar to. Once we have the compost/manure on site, we'll begin producing biochar outside the high-tunnels and then add it to be "charged" with compost/manure inside the pallet alleyways. We are waiting on test results (pre-biochar) to get back to the lab. Then we'll test the biochar/compost combination and finally the soil inside the high-tunnels once the biochar/compost combo has been added. We'll do these tests in 2023. 
2. Use waste heat from compost, and biochar generation, to heat water, pushing it through a tube (Copper, poly and/or pvc pipe-) connected network of steel drums filled with water and antifreeze in winter. Exhaust vents will be closed, fans reversed in winter to circulate the air, sucking the cover down to the ground. In summer, fans and shutters will vent hot air. We'll have the biochar tin man system operating this winter, once we have the compost and manure in the alleyways. We'll be able to test that part of the system (heating the water and pushing it through the barrels to prevent freezing and prolonging the growing season) starting this spring with crops and through both cold crop production seasons in 2023. 
3. Use plastic sheeting to create micro-growing zones based off of crop hardiness and growing season inside high-tunnels: We have the trellis system in place, and have installed the regular plastic, creating our growing zones).  
4. We adjusted the biochar tin-man waste heat capture system, through the addition of a water heater, to help facilitate the captured heat's heating of the water, which will then flow from the water heater, down into an insulated water reservoir inside the main high-tunnel (with the full system) and water from the reservoir will be heated via a propane powered water-heater and then will be pumped, via a water pump, through pipe (better able to hold up to frost than drip irrigation as originally planned), through the system of barrels in the high-tunnel. The basic water heater's internal components are a match to our biochar tin-man waste heat capture components and thus can be connected. The water heater will be housed inside an insulated "outhouse" sized shed to keep it from freezing. Our main delay here is access to enough volume of copper tubing and the high price of what little 1/2" copper tubing is available. As mentioned in our summary above, we are considering proceeding this spring with pvc and/or a combo of some copper, some pvc pipe and some polytubing. This will allow us to test the system. This compromise means we have to break the biochar production and biochar waste heat production testing outside the high-tunnels,  from the heating and movement of the heated water through the system inside the high-tunnels. In other words, we're still going to produce biochar outside the high-tunnel and try and capture the waste heat from it, to heat water inside a water heater. We'll report on the findings of this part of the system. And we'll use a propane powered second water heater, insulated inside the high-tunnel, to test the efficacy of using heated water, pumped through the tubing, to keep the drums from freezing in deepest winter. We'll just test each of these two parts separately and then examine if combining these two elements together will be plausible or not. If the waste heat from biochar production is successful at heating water at volume, it should be possible to utilize the heat capture from biochar to provide the heated water necessary inside the tubing and drums. If the heating of water, pumped through the tubing and drums is not useful, then there is no reason to test linking biochar production to that part of the system. 
5. As Feather Two Farms isn't planning to have additional farmers on its site until late 2023 or even 2024, we are planning to test the system at Rebel Earth, using farmers from both Rebel and Feather Two, so that if it works, we can install a working version on Feather Two farms (via another grant's funds) in later years. However, in order to test the system in full we need to proceed with the grant project on Rebel, where we have both staff and incubator farmers from both sites on hand (in one high-tunnel, have a control high-tunnel with everything but the waste heat from the tinman and the barrel ovens), as well as in two unheated high-tunnels).