Expanding Farm Partnerships to Trial Human-Urine-Derived Fertilizer on New Crops

Drip irrigation Emitter Trial Results and Discussion:

In our first trial, we used water with a hardness of 124 ppm, to assess under what conditions the minerals in hard water would react with the phosphorus in urine to precipitate struvite and plug the emitters. We carried out five consecutive irrigation sessions for each of the nine combinations of emitter type and application method. We measured the amount of time it took to apply 20 gallons of liquid (water or water + urine) and calculated flow rate. These graphs below show that flow rate did not change significantly for any of the emitter and application method combinations over the course of the five irrigation sessions.

For the second trial, we re-used the same emitters and increased the hardness to 255 ppm to increase the risk of clogging. We cut down the number of emitters in each experimental setup in order to reduce the total volume of liquid needed to carry out the experiment while keeping constant the volume passed by each emitter. The other difference was that instead of 5 distinct runs, we combined this larger amount of liquid into one combined run. For instance, in the Water-Urine-Water treatment, we did a single, long injection of urine into the line instead of 5 smaller ones. We can see that the Mix treatment resulted in a decreasing flow rate across all emitter types (worst with the Take-Apart emitters), while the Water and Water-Urine-Water treatments showed no decrease in flow rate in any emitter type. The mix treatment with the Take-Apart emitters was the treatment that resulted in some emitters becoming 100% clogged. Absolute flow rates are lower than the previous trial because fewer emitters were used in each test configuration.

Collaborative Farm Trials/Demonstrations Results and Discussion:

Detailed descriptions of each farm partner trial, resulting from the co-created plans, are included below. Rich Earth staff delivered fertilizer and assisted with application, documenting the process with photos, videos, and written notes. For this project, we opted to encourage each farmer-partner to conduct observations and documentation of plant development and health over the growing season as they had time or inclination to provide. We asked farmers to submit photos or other documentation of their experiences. The results noted below are based on qualitative assessments described during our site visits and follow up interviews.

Hubbard CBD: Adam Hubbard

Working with Adam, we determined that we would use his existing drip irrigation system to apply the urine, which consisted of drip tape laid underneath black plastic mulch. Adam's drip system is fed from a well onsite. Normally, Adam uses 2 organic fertilizers through the hemp growing season: first is a 12-0-1 soluble organic fertilizer for the first 10 weeks after the plants go in the ground to stimulate foliar growth, followed by a 5-0-20 soluble organic fertilizer for the flowering and budding growth stage. We determined that we would take 4 rows with the same variety of hemp and replace the 12-0-1 fertilizer with urine for 2 of these rows, with the 2 others having the usual 12-0-1 fertilizer treatment. Adam indicated that in an ideal world, he would apply fertilizer more heavily than he actually does, so we decided that to one urine-fertilized row we would apply enough urine to deliver as much nitrogen as the normal 12-0-1 treatment, and to the other urine-fertilized row we would apply twice as much urine. The plan was that every time the rest of the field was fertilized with the 12-0-1, Adam would fertilize these 2 rows separately, using inline valves to control flow to the drip tape.

The urine was injected into the drip system with a small battery-operated pump, connected to an individual drip tape using a tee. During a drip irrigation session, Adam temporarily turned off the flow of water into the drip tape using an inline valve, ran the pump to inject the desired amount of urine into the line, and then opened the water valve again to resume normal irrigation. The process approximated the "water/urine/water" treatment in our controlled drip irrigation experiment. We provided 50 gallons of urine for the summer and a measuring container so that each row got the right dose of urine each week for the trial.

Adam found the application method worked well. He said, "the urine is much easier for me to use ... I have an organic fertilizer that is a powdered form, and it's water soluble, so I mix up batches, and then inject it into my irrigation line, and apply it that way, whereas the urine fertilizer was very convenient for use, because it was pretty stable in its barrel over a period of time."  His usual fertilizer was not as stable, and needed to be re-mixed prior to each application.

Adam felt that the urine-treated crop was bushier and taller than his typically-fertilized controls (using a soy-based fertilizer approved for organic production), but he did not observe a difference between the "high dose" and "low dose" treatments. He was not able to conduct yield measurements as the entire crop was purchased "on the stalk" prior to weighing.

Arthur Davis, of Rich Earth Institute, with urine tank, battery, and drip irrigation system.

Lush urine-treated hemp plant  

Elm Lea Farm: Pete Stickney

Elm Lea Farm is a working farm that is part of the Putney School, an independent high school in Putney, VT. Pete Stickney is the farm manager and was interested in using urine both because of its potential nutrient value to the farm, and also because of the educational value for the school. We initially considered applying urine using the farm’s irrigation system (connected to the lagoon used to manage liquid waste from their cow barn), but we determined not to do this due to a number of practical and logistical considerations. Instead, we decided to apply urine directly to hayfields at the farm using Rich Earth Institute's tractor-pulled urine applicator.  

Pete had known about our work previously, and was excited to get a chance to try urine fertilizer on one of the farm’s hayfields. He applied dairy manure to the entire field, and then applied urine to one side of the field only at an estimated rate of 40lbs/acre of nitrogen, leaving the other side as a manure-only control. The picture shows the urine-fertilized section (lower right - darker green) and the manure-only section (upper left - lighter green).           

Pete noted lusher production and greener color on the treated hayfield as opposed to the "control" which received manure only.  His qualitative assessment of yield, based on the size of the windrows after haying, was an approximate 20% higher yield for the urine-treated field after the first cutting. He had intended to check for an improved plant population on re-growth, but did not have time to do this. The fields were cut once more, with no additional applications. (Normally he gets three cuts but the extremely wet July in southern Vermont precluded an additional cutting.) He noted that the improved yield and green color he observed from his one application did not carry over into his second cutting, so he felt a second (and potentially even a third and a fourth) application would be valuable, but he planned to re-evaluate in the spring to see if he did seem improved re-population of the plants. 

Because of the question of whether urine-treated forage might affect palatability, Pete kept the urine-treated hay separate from the treated hay, and said he observed no difference  - the cows appeared to enjoy all the hay.

Hayfield with urine-treated section on right

Pete's Stand: John Janiszyn

John Janiszyn grows vegetables on a number of different plots in the Walpole, NH/Westminster, VT area. We worked with him to arrange a trial with sweet corn on a plot in Westminster, VT. The main challenge was to figure out the most effective (and easiest) way to apply the urine. John proposed that since he does a pass with his tractor down each row of corn to cultivate, that this would be a good opportunity for fertilizing with the urine. We built an experimental applicator using an old cabbage sprayer tank on a 3-point hitch. Urine exited the tank through a port on the bottom, then flowed through a ball valve and hose to a point under the tractor just above ground level, right in front of the cultivators. The goal was that urine would be immediately buried by the cultivating tines as they hilled the soil around the corn row. In practice we observed that no urine remained on the surface, indicating that this mechanism worked well. To control application rate in the field, we calculated a target tractor wheel RPM based on 1) the applicator’s characteristic flow rate (determined in a pre-test using water); 2) the desired application rate; and 3) the tractor wheel diameter. 

We fertilized 4 rows at a rate of approximately 55 lbs N/acre (rows 1-4), 1 row at a high rate of 103 lbs N/acre (row 5) and 2 rows at a middle rate of approximately 79 lbs N/acre (rows 6 & 7). Additionally, we fertilized a partial row at the lower rate of 55 lbs N/acre (row 8). We left 2 rows as unfertilized control rows and the rest of the field was fertilized with conventional urea fertilizer.

In mid-August, at the time of the first interview, the urine treated corn had done much better than the unfertilized controls: it was taller by about a foot, with stronger stalks, and about the same as the conventionally fertilized corn (urea), but that corn also had a side-dressing of extra urea which the urine treated did not. John felt that the high-dose urine treatment did better than the low dose. Overall, the entire crop suffered due to the excessive rain, but the urine-treated crop did not do any worse than the conventionally treated crop in this situation, and no differences in disease or pest pressure were observed.

John was interested in learning about any differences in nutrient uptake between the various treatments. We sent tissue samples of each treatment for analysis, and found the results of interest. In the attached report, the urine treatment is referred to as the "pasteurized urea product." The nitrogen and phosphorus were similar in all samples (except lower in the unfertilized control), but the potassium measurement was higher in the urine-treated rows compared to  both the control and conventionally treated corn. John found this interesting because he normally applies a side dressing for potassium and speculated that urine fertilization might reduce the need for as much of this additional input. He said,"I'd like to try to see what it would be like if we could do a whole block of corn or something, side dressing with just urine and see what that would do. It seemed to do just as well as the conventional corn." Sulfur was also somewhat higher in the urine treatments as compared to both the control and conventional treatments. In addition, iron, manganese and zinc were all higher in the urine treatments as compared to both the control and conventional treatment. 

•  John Janiszyn - Tissue Results

Rebop Farm: Ashlyn Bristle & Abraham McClurg

Rebop Farm is a diversified hill farm in Brattleboro, VT doing small-scale dairy, raising pastured meats, and growing some specialty crops, including cold-hardy figs in a high-tunnel. Because of the high nitrogen needs of the figs, they were quite interested in using urine. Each year, they cut the figs all the way back to the ground, so they need to put on significant plant growth every growing season before setting and ripening the fruit. Ultimately, they are most interested in using a drip irrigation injection system like we used with Adam Hubbard, but the logistics were too challenging for using drip irrigations on such a small scale with different treatments, so they decided to apply the urine by hand for this experiment. In total, 2 rows were fertilized, each with 4 treatments: control (no amendments), composted manure only, urine only, and composted manure+urine. Urine dosages in the two rows ranged between 2.4 to 3.7 L/plant.

Ashlyn Bristle was very enthusiastic about the results she had observed through mid-August when the first interview/site visit was conducted. She described the urine-treated sections as having "the heaviest fruit-set" and best growth overall, and added "it's spectacular, fruit all the way down," and the crop was branching abundantly, providing opportunity for more fruit development.  She felt that the best results at that point were being seen in her urine + compost treatment, where she estimated three to four times the usual fruit set. The next best fruit-set was in the urine only treatment, then the manure only, then the control. Unfortunately, at the end of the season Ashlyn reported failure to ripen in all but one fig variety. This problem occurred across all treatments, and was not attributed to urine fertilizer. She believed that the problem was the excessive rain the region experienced, which led to "wet feet" in the soil even within the greenhouse (located on a hillside), which is not optimal for figs. She also noted some disease, also attributed to the wet conditions, developing later in the season and hampering ripening.

In the future, she would move her application timing up to early May, and do a second application in early June, and then no further fertilization. She did observe some extra vegetative side growth with the urine treatments, which could be excessive so she would reduce fertilization after June.

Tapalou Guilds: Hanna Jenkins & Andy Loughney

Tapalou Guilds is primarily a cut-flower farm that also grows some hemp for CBD production. They decided to hand-apply urine to a bed of cut flowers alongside an unfertilized bed of the same varieties of cut flowers to do a side-by-side comparison. Both beds also received their usual treatment of compost tea. They also decided to hand-apply urine to part of their CBD crop in two different dosings. For the hemp, a 1X treatment of 1.86L per plant  was divided into 2 fertilizations and a 2X treatment of 3.71L per plant was divided into 2 fertilizations. For the flowers, there were two 3’x50’ beds. One was treated with urine, one without.  The low dose was matched to the alfalfa fertilizer, while the high dose was three times higher.  

Hemp: Andy Loughney thought his "low-dose" treatment crop was bushier and taller than the high-dose, which was similar to his usual treatment. Because he was interested in any impacts on cannabinoid content, he submitted tissue from each treatment group for analysis. Upon receiving the results, he created this spreadsheet: Andy Loughney - CBDV trials

He wrote:  "Just got the test results back as well, and they are exciting! The 6% overall rise in cannabinoid content is solid, but the real excitement comes from the huge gains in the cannabinoid that this variety was bred for (CBDV). It shows as CBDVA in the test results because that is the acidic form before heat or decarboxylation. Big gains: 32% in the lo-N, 25% in hi-N trial…. I'm quite pleased with the numbers for the CBDVA and overall cannabinoid content and we will certainly explore nitrogen application at this point, even if it cannot be urine for our organic operation at this juncture."

Cut flowers: Hanna Jenkins observed no major differences between the urine treated crops and those fertilized with her usual treatment, but some of the urine treated celosia, amaranth and sunflowers appeared taller, on average, than her controls. She was unable to quantify any differences in numbers of blooms (as she was pinching and pruning the plants throughout the season) but felt there were no negative outcomes. She had no significant disease or pest pressure on either the urine treated or control crops. The foliage on the urine application was darker, and appeared more "lush" which she found beneficial from an aesthetic point of view.

Tapalou Guilds Cut Flower trial - urine treated row is on the right

Hanna wrote: "Based on the results that I saw I plan on switching to using urine fertilizer as my predominant nitrogen source for field grown plants and potentially for use in high feeding plants in the hoop houses as well."

Farmer Interview Results and Discussion

Tatiana Schreiber interviewing Hanna Jenkins at Tapalou Guilds Farm August, 2021.

Below are some of the overarching perspectives and recommendations of farmer-partners based on interviews, email correspondence, and their participation in the field day and a final project meeting.

Motivations for Participation

Farmers were asked about their initial interest in participating in the project. All farmer-partners were intrigued by the possibilities of substituting urine for a part of their usual nutrient needs, trialing application methods, and participating in a research project that would yield valuable information while not requiring excessive time. As Adam Hubbard noted, "Learning is expensive, it takes time and effort, so [we we’re] trying to work out a system that minimizes my effort but gets results, and it's fun!" Closing loops (reducing external inputs), while keeping a potential pollutant out of the waste stream, were also key considerations. As Hanna Jenkins put it, "…one of the things for me is to look at things that may be defined or understood from a dominant standpoint as 'waste' and [thinking about] how we can reclaim things that we might label as wasteful and then through simple processes make them useful again?" Pete Stickney of Elm Lea Farm at the Putney school also noted the value of engaging students, faculty and staff who were interested in learning more about the possibilities of using urine fertilizer. Students at the school are currently doing urine fertilization experiments in one of their science classes, so this project was a way to extend that learning.

Decision-Making around Contamination & Risk 

As noted above, several farmers were interested in further testing for microcontaminants. Motivations for understanding the risk from microcontaminants within urine fertilizer included: consumer perception, buyer perception, and resulting "purity" of the crop… Ashlyn Bristle of Rebop Farm summarized her feelings about the risks from microcontaminants: “I think there’s a risk in everything all of the time and I think we’re fooling ourselves to think that food can be this perfect place where we don't have that. I can understand the concern but I think it’s not very reasonable to be overly concerned about it when you weigh the pros and cons. And I always think about organic ag using non-organic compost, that being allowable and the pharmaceuticals that I know are in that. If that’s not a concern, I’m not sure why this is. And I trust the soil to break down what it needs to.” 

Concerns around the residual pharmaceuticals in urine fertilizer were often closely linked to concerns of customer perception. This is seen in the case of Adam Hubbard’s concerns about his buyer’s perception of the purity of the hemp. Ashlyn Bristle also noted that the challenge of public perception also partly arises from the perceived categorical difference between human urine and manure, saying: “I think that there's this interesting marketing difference between what's coming out of our bodies and what's acceptable coming out of other animal bodies… I don't understand why those aren't the same in our minds, if there's an acceptable level, and that's acceptable on certified organic farms, I’m not sure why. Maybe it's the unknown…” 

Specific Experiments/Problems noted

With regard to the specific experiments that each farmer undertook, there was interest in understanding not only yield, but potential to combat disease or pest pressure; potential to increase cannabinoid content of hemp, and in the case of greenhouse figs, to get stronger initial growth to boost chances of getting a harvestable crop within the growing season. The farmers did not note any significant problems with the application systems they used. 

While the urine odor during application was significant, it was not more problematic than other farm odors. Once watered in, or covered with dirt, the odor dissipated rapidly. As Pete Stickney put it, "It wasn't entirely pleasant, spreading it, I'll say that, [laughing]  but you know, when you're putting something good on the field, the factor of doing something good… overrode any unpleasant odors." Abraham McClurg also noted that,"personally I would rather have some urine smell and know what it is and where it came from than some sort of pelletized, powdered, whatever, stuff that I'm like,'I better wear a respirator, I can't touch it.'" In other words, knowing the providence of the fertilizer was more important than any odor. 

Specific to high tunnel growing, Ashyln Bristle of Rebop Farm was interested in learning more about the effects of urine fertilization on protected culture and salt build-up: ​​”In protected culture, it would be really nice to do some soil sampling before and after so that we can figure out if there's salt build-up associated with it just because we're already sort of towing that line using animal based manures and compost. Just if it's going to add to how many times…we need to flush…it would be great to know.” Adam Hubbard agreed, saying: “Yeah, getting data on protected culture because that's big. A lot of people are growing in high tunnels…and having information for that would totally be valuable.”

Reflections on the Project as a Whole

Asked about price points for purchasing a urine-based fertilizer to make it feasible for themselves or fellow farmers, all expressed willingness to pay a price equivalent to their current fertilizer based on nitrogen content, and would consider paying slightly more because of other values (closing loops, keeping nutrients out of the waste stream) that they placed on this fertilizer, as long as it didn't jeopardize their overall profit margins. As Ashlyn Bristle put it, "if we can get it locally, if we know that we're supporting something meaningful then, then I think that we are willing to pay more than that, I think the question is…will it increase yield enough that it's worth it or not? So I think, to a certain extent, it's about how we feel about it and then beyond that it becomes about whether or not…it'll be another pebble that [sinks us] financially."

Thinking about how they might use urine on their farms in the future, participants imagined using it on different crops and pasture.  Ashlyn noted, "I think the entire garden, and a lot of the fruit, would really benefit from occasional fertilization like that, and there's not always enough compost to service them, so I think it would strengthen the resilience of the garden and especially the specialty fruit if we could do that regularly, so it would benefit more than just the figs." 

John Janiszyn was intrigued by the increased potassium, sulfur and micronutrients seen in the urine-treated corn. He noted, "you're getting, potassium along with the nitrogen when you're putting it in the soil, so as like something to side dress with, you know, a lot of plants need lots of potassium, so you can kind of get two birds with one stone, you know…."

Overall, participants seemed to find the project inspiring. As Adam Hubbard put it, "I really enjoyed it, I really support you guys. I'd take part in the future, I think you're part of something cool here…" Andy Loughney noted that the project seemed to free him up to consider using urine more widely, commenting that, "I think a large part of this whole thing, what I gather is, you know, just shifting people's perceptions about the use of urine. And so I think that that happened for me personally a little bit throughout this experiment."

 Evaluating Farmer/Institute Collaboration 

Rich Earth Institute practices a participatory action research approach in which developing respectful and equitable partnership between researchers and practitioners is a key goal. We took this opportunity to ask farmer-participants to candidly discuss what went well and whether there were any difficulties or concerns about the collaborative process itself. In all cases, the farmers expressed satisfaction with the collaboration, noting appreciation for the assistance Rich Earth provided with calculating dosage amounts, planning the experimental design, and facilitating an application strategy that would be successful. As Andy Loughney of Tapalou Guilds put it, "they really set us up for success, there seemed to be an understanding of what summer looks like farmers, so it was like two applications, came with a set of jugs, with lines on them, very straightforward, very simple, so we didn't have to think too much about the basics…". On the other hand, John Janiszyn noted that although he very much appreciated the dosage/method calculations provided, "it was different than how I would have done it, but I thought it was pretty brilliant, I thought 'Wait, how'd he do that? I want to know that..…'  but yeah, great, it worked fine…" Further discussion with the farmer-partners with regard to co-design of application methods and provision of printed-out guidance may have been beneficial.