The garden on June 20, 2020
In this post from last year, I
discussed why I asked the 2020 garden what the effect would be of replacing my
previous source of garden nitrogen, cottonseed meal, with urine. I also
described a psychological issue associated with safely using urine and referenced
this 2019 post for information on potential environmental and health hazards,
and I described how I would collect and apply the urine. Now it’s time to let
you know how the garden answered my question.
When I wrote the post last February,
COVID-19 was in the US but not yet widespread. By the time the growing season
began, Mike and I, along with most people in the US, were under some form of
lock-down. COVID-19 can be carried in both urine and feces. If I knew I had COVID-19,
I would not used my urine on the garden, just as I would not have used it if I
had any of the other diseases whose infectious agents can be spread through
urine. As it happened, I have not experienced symptoms of COVID-19, nor has
anyone told me they exposed me to it, so I felt it was safe to fertilize with
urine throughout the growing season. As the 2019 post notes, there is as close
to no chance as I can imagine that any urine would find its way outside of our
property to be a health hazard to anyone.
I decided to apply urine to all of the
vegetable and grain beds to replace all of the cottonseed meal I would have
otherwise used. Thus I did not have any control beds in which I used cottonseed
meal rather than urine. In order to have space for control beds I would have
needed to expand the garden into areas covered with grass and weeds and
unprotected from rabbits. This would have introduced variability in newly
gardened versus previously gardened soil, variability in rabbit pressure, and a
reduction in the time I spent on each garden bed compared to what I have done
in past years, which would have made it harder to compare this year’s yields to
those of previous years. Instead, I compared the yields I obtained in 2020 to
the best yield I obtained for each of the varieties over the past six years,
after I had settled on Steve Solomon’s re-mineralization practice and the
spacing for all the crops that I grow. The only exception was for soybeans,
because the last time I grew them before 2020 was in 2011. Hence I compared the
soybean yield with a different variety grown in 2011 using the same spacing
between stations but more seeds per station.
When I began collecting urine I used
the same system as I had used in 2019: I urinated into a urinal and then
transferred the contents of the urinal to a 2 gallon bucket. The next morning I
emptied the collected urine from the bucket into a sprinkling can, added water
to fill the sprinkling can, and applied the diluted urine directly to the bed,
on top of the plants in it. However, I soon grew weary of leakage around
the edges of the urinal. For those of you with flexible appendages to deliver
urine, many possible ways to collect urine without making a mess suggest
themselves. For those of us who, like me, lack such appendages, avoiding messes when using a urinal is more difficult. Fortunately we have a camp toilet, inherited from my father-in-law.

The camp toilet, with the lid open to show its resemblance to a water-flush toilet. A sliding valve at the bottom allows the urine to drain by gravity into the bottom container and that container to be sealed off between uses. I collected and composted the toilet paper I used.
Side view of the camp toilet. The top chamber unbuckles from the bottom chamber so that the urine collected in the bottom container can be emptied into a sprinkling can.
Using the camp toilet to collect the
urine removed the mess factor from the collection experience. Each morning I
poured the urine collected the previous day into the sprinkling can, diluted
the urine with water to fill the can, and then sprinkled the urine onto the bed
and the plants it contained, following it with a sprinkling can of water to
wash the diluted urine off the plants and onto the soil. As in 2019, I
collected urine only when urinating was all I was doing, and I only collected
it during the day because the camp toilet was located in our basement and I had
no desire to descend the steps into the basement when I had to urinate
overnight. Thus I collected perhaps two-thirds to three-quarters of the total urine I produced in a 24
hour period, but I calculated how much urine to add to each bed as if I had collected all
of the urine I produced in a day.
To calculate how much urine to apply to each bed, I
proceeded similarly to the calculation for the 2019 corn bed experiment. The daily urine production of the averages adult contains about 0.024
pounds of nitrogen. My growing season is about 180 to 200 days long. Using 180 days
for my growing season, if I collect urine every day and apply all of it over
the course of the growing season:
180 days * 0.024
pounds of nitrogen per day = 4.3 pounds of nitrogen
According to Solomon, cottonseed meal
is 6% nitrogen, and he recommends applying 6 pounds of nitrogen to a 100 square
foot bed (twice that for potatoes). Thus the amount of nitrogen applied via
cottonseed meal is:
6
pounds * 0.06 = 0.36 pounds of added nitrogen to a 100 square foot bed
12
pounds * 0.06 = 0.72 pounds of added nitrogen to a 100 square foot bed of
potatoes
Dividing the 4.3 pounds of nitrogen from all the urine I
produce in a 180 day growing season by 0.36 pounds of nitrogen needed per bed, that amount of urine will supply all the needed nitrogen for twelve
100 square foot beds.
I grow a total of nine beds of vegetables and grains, two
beds of small fruits, and one bed of herbs and flowers in the garden. The
latter three beds are not re-mineralized. Since the potato bed needs twice as
much nitrogen as the other beds, then I needed to apply urine to the equivalent
of 10 beds. I had 12 beds’ worth of urine to apply during the 180 day growing
season. Thus I began collecting urine on April 1 and applied the collected
urine to bed 1 the next day. That day’s collected urine was applied to bed 2
the following day, with this rotation continuing through bed 6. For bed 10,
which held the potatoes, I collected and applied urine two days in a row, then
treated beds 11 and 12 as I had treated beds 1 through 6. After applying urine
to bed 12, the next day’s urine was collected and applied to the
subtropical trees and shrubs I keep in containers. Then I began again with
collecting and applying urine to bed 1 and so forth. When the soil was
saturated, I did not apply urine, waiting until the soil drained to resume the
application sequence. Later in the season I altered the collection and
application sequence, as discussed below.
Wood ashes are a potential source to
replace all of the calcium and some to all of the potassium required for
re-mineralizing garden soil. In 2020 I did not have enough wood ashes on hand
to remedy the full deficiency of potassium, and I had an excess of calcium.
However, the soil test indicated that magnesium was deficient. Wood ashes
contain about 3% magnesium. Therefore I added enough wood ashes to the
re-mineralization mix to supply 10% of the magnesium deficiency, as Solomon
suggests in the Acid Soil Worksheet. This avoids the risk of having too much
magnesium relative to calcium in the garden soil. I made up the remaining
potassium deficiency and the deficiencies in the other minerals in the usual
way.
Most years the weather has a strong effect
on the conversation between the garden and me. But unlike some other aspects of
2020, the weather gave me a break. The last spring frost was on April 18; the
first fall frost occurred on October 16, for a growing season of 181 days. April
and May were cooler and wetter than normal. June was warmer and drier than
normal, while July temperatures were close to normal but accompanied by
excessive rainfall. August was cooler and wetter than normal while September
was about average in temperature but drier than normal. October was near normal
in both temperature and rainfall, while November was warmer than normal with
about normal rainfall. Since there was nothing particularly unusual about 2020’s
weather (which is the only unusual thing about it), I do not need to take
weather into account when discussing what the 2020 garden taught me.
The yields for all the vegetable and
grain crops I grew in 2020 are shown in the following figures.
A first glance reveals that the 2020
yields varied compared to the best previous years. To better understand the
variability, I considered together the crops grown at different times during
the growing season. These fall into the following groups.
Group 1:
planted in autumn 2019 for harvest in late spring 2020. This group includes
garlic and potato onions.
Group 2:
planted in April 2020 for harvest later in spring or in summer. This includes
bok choy, cabbage, endive, spring lettuce, and potatoes.
Group 3:
planted in April 2020 for harvest in summer and autumn. This includes beets,
carrots, and leeks.
Group 4:
planted in May and June 2020 for harvest in summer and autumn. This includes
pole snap beans, dent corn, cowpeas, cucumbers, eggplant, muskmelon, sweet peppers,
soybeans, various squashes, and tomatoes.
Group 5:
planted in August 2020 for autumn harvest. This includes arugula, bok choy,
Chinese broccoli, Chinese cabbage, kale, fall lettuces, mustard greens, daikon
and winter radishes, and turnips.
Within Group 1, yields were around 15%
to 25% below the best previous value.
Within Group 2, I ignored endive since
it was first grown in 2020. Cabbage and bok choy yields were much below the
best previous, by a factor of 3 or more, and the romaine lettuce yield was
lower by a factor of about 8. The loose-leaf lettuce yield was about 25% lower
than the best previous yield, while the potato yield was about 40% lower than
the best previous.
Within Group 3, yields were about 40%
less than the best previous for the beets and about 25% lower than the best
previous for leeks. For the carrots, compared to the same variety the 2020
yield was about 15% lower, but it was much lower than for the other variety
shown.
Within Group 4, the 2020 yield of dent
corn was about half of the best previous, and the 2020 yield of cowpeas was
about 75% lower than the best yield (but of a different variety). On the other
hand, the pole snap bean yielded better in 2020 than in 2019, though not as
well as a different variety. The soybean yielded about half as much as a
different variety planted with more seeds per station in 2011.
The 2020 cucumber yield was higher than
the best previous for both the May and June plantings. The 2020 muskmelon and
winter squash yields were much lower than the best previous. One of the
zucchini varieties yielded poorly but the other one yielded about two-thirds of
the best previous (of a different variety). The ‘Desi’ summer squash yielded as
well as the better of the two zucchini varieties grown in 2020.
The three sweet pepper varieties
yielded 10-25% lower in 2020 compared to the best years, while two of the four
tomato varieties matched their best yields from previous years and the eggplant
variety yielded better than a different variety.
Within Group 5, the bok choy variety
doubled its best previous yield, and a different variety of Chinese cabbage
yielded almost a factor of 4 more than in previous years. The kale variety also
outperformed the previous best yield of a different variety; the same held true
for the two mustard varieties grown in 2020. On the other hand, the 2020 yields
of arugula, daikon and winter radishes, and turnips were all below the best
previous yields.
What can we learn from this data? The
first thing to notice is that overall yields were comparable to, though
somewhat lower than, the best previous year. The total weight of the crops
harvested in 2020 was 560 pounds, bested only by 2015’s total of 687 pounds and
considerably exceeding 2016 and 2018 (about 390 pounds each).
Within the groups, only in Groups 4 and
5 did some, but not all, of the crops grown match or exceed the best previous
yields. All other crops yielded below the best previous, some by a large
factor.
By June of 2020, as I observed the slow
growth of the cabbages compared to previous years, I began to suspect that
rotating applications of urine across the entire garden meant that I had not
applied sufficient nitrogen to shorter-maturity crops like the spring greens. I also wondered
if applying urine before I planted a crop meant that the urine I applied before
planting did not contribute to growth of the crop. The following figure gives
the bed number, the crop(s) planted in that bed, when the crop(s) were planted,
the days on which urine was applied to that bed, the total amount of nitrogen
contained in the applied urine, and how much of the nitrogen was applied while
the crop was present in that bed.

With the results from the figure in
hand, let us look at our five groups of crops again. My hypothesis is that for
crops which received 0.36 pounds or more of N from urine while they were in the
ground (0.72 pounds for potatoes), the yield would be about the same as for
previous years. Crops which received significantly less than this while they were in the ground would yield
lower than in previous years.
Group 1 (bed 4): when I planted the
potato onions and garlic in early November of 2019, I added a quarter of the
usual amount of cottonseed meal, which contained about 0.09 pounds of nitrogen.
This was to give them a good start, as they begin to grow after planting and
pick up growing again in early spring, before I began applying the urine. Thus
the total nitrogen applied was 0.23 pounds, about 63% of the amount that I
intended to apply. As hypothesized, observed yield is lower than the best
previous yield.
Group 2 (beds 10 and 11): the potatoes
and the spring greens received significantly less nitrogen than intended (the
spring greens received only about half as much nitrogen), and the yields were
less than the best previous yields, as hypothesized.
Group 3 (bed 11): while these beds
received more nitrogen in urine than from cottonseed meal, they yielded less
well than the best previous. There were other gardening issues with these crops
that I believe contributed to the lower yields. I did not keep up with removing
weeds in this bed after I harvested the spring greens; thus I suspect that the
weeds used some of the nitrogen and minerals that I had meant for the crops.
The weeds also shaded the crops to an extent, reducing their productivity. I
did not thin the carrots or the beets, which caused overcrowding, another
factor that may have contributed to reduced yields. Finally, many of the
carrots in the carrot patch rotted over the summer, reducing the carrot
yield.
Group 4 (beds 1-3, the summer planting
of bed 4, beds 5 and 6, and bed 12): I will take a closer look at the various
beds and their crops below.
Beds 1, 2, and 3 all grew corn and
pumpkins. All were planted on the same date; all received some of the urine
before planting. As hypothesized, because the amount of nitrogen applied after
planting was about 52% of the amount I calculated would be required, the yield
was lower than that obtained the previous year. I also note that some of the
stalks lodged (fell over) in July after applying urine, and more lodged during
a windstorm. Ears of corn that lay on or near the ground were predated on,
presumably by small mammals. I suspect this accounted for some of the yield
loss, but I believe that the lower than intended amount of urine accounted for
a large part of the yield loss. This is bolstered by the 2019 results, when all
of the intended nitrogen was applied to the corn bed to which I applied urine, and
which yielded as much as the two beds to which cottonseed meal was applied for
nitrogen.
The summer planting of bed 4 did not
receive as much nitrogen from urine as intended. It was, however, sufficient to
grow a much higher yield of cucumbers than I obtained from the same variety
planted at about the same time in 2019, as well as about half the yield of
soybeans compared to a variety planted more densely (same spacing but more
seeds per station) in 2011. Possibly using the intended amount of urine would
result in higher yields for both of these crops. The zucchini variety planted
at this time yielded poorly, and did not perform well in the main crop planting
in 2019. I will not grow this variety again, as it seems poorly suited to my conditions.
Beds 5 and 6 both received some urine
before planting, but the total amount received after planting was about 80% of
that intended. Compared to the same varieties grown in previous years, the
cucumbers yielded more, two of the tomatoes yielded about the same, the peppers
yielded somewhat less, and the melons and squash yielded much less. This
suggests that factors other than the amount of nitrogen applied affected some
of these crops. However, because some of them yielded as well or better than previously,
this suggests that urine can supply all the nitrogen these crops need when
enough of it is applied.
Bed 12 contained legumes: lima beans,
cowpeas, and pole green beans. Only the last was the same variety as grown
previously. While it yielded more in 2020 than in 2019, other factors need to
be considered. In July 2019 a rabbit fed on some of the plants as they began to
vine, setting them behind in growth. Also, I had not added any
re-mineralization mix to the legume bed in 2019, because legumes can supply
their own nitrogen through rhizobacteria in root nodules, and to conserve on
the re-mineralization mix. I did not remember this until late July of 2020,
after which I ceased applying urine; the 2020 legume bed received the same
re-mineralization mix as the other beds. I cannot untangle the effect of the
urine from the other factors discussed.
Group 5 (bed 10, planted 8/23/20): this
bed received more than the amount of nitrogen I had intended to give it. This
was in part due to a lessening need for urine on other beds as I finished harvesting from them, and in part because I made sure to apply at least as much as I had
calculated it needed. Notice that all of the leaf crops except for arugula
out-performed the previous best yield, but none of the root crops did so. One
possible explanation is that I did a better job of thinning the leaf crops than
the root crops. Because I left too many roots in each row for too long, they
competed with each other, so that I harvested too many small roots rather than the larger roots that are easier to use in the kitchen. Another possibility is that the ratio of
nitrogen to phosphorus and potassium became too large; the latter two are
needed for good root growth, so that the turnips and radishes may have grown
their leaves at the expense of their roots.
Overall, considering that I did not apply
enough urine to fully meet the needs of most of the crops, the 2020 yields are
high enough to justify continuing to use urine in place of cottonseed meal for
most of the crops that I grow. I will need to adjust the application schedule
to ensure that I apply enough urine to each crop I use it on to replace all of
the nitrogen that had been met by applying cottonseed meal in past years. The
details of that schedule are yet to be worked out; when it is available, I will
post it here, as well as anything else I want to share about what I’ll ask the
garden in 2021. Till then, enjoy life!