Successful demonstration activities in the use of toilet compost and
urine as a source of nutrients for growing crops.
Peter Morgan
Aquamor, Harare.
As the concept of
ecological sanitation becomes more well known throughout the world, so does the
need for adequate demonstration that the processed excreta, whether it be
toilet compost, urine or a combination of both, is valuable and can actually
play a useful role in increasing food production. Whilst the recycling of
nutrients derived from human excreta is one of the main tenets of ecological
sanitation, many if not most ecosan projects around the world concentrate first
on the provision of an ecological toilet, mostly of the urine diverting type,
with recycling the products taking very much a secondary place in project
initiatives. In practice and perhaps in the majority of projects, both urine
and dried faeces are more conveniently “disposed of” into shallow pits. Urine
may drain away unused.
It must be accepted that
not all users of ecological toilets are prepared to handle processed excreta at
all – it is indeed a very foreign concept to most. Those who are prepared to
handle the material are more likely to be “farmers” or “gardeners” and those
that practice some form of agriculture already and already know the benefits of
compost and manure. But even amongst this category, there is often doubt that
urine and human manure is safe, let alone that it can actually increase the
production of food.
Southern Africa is a
sub-region characterised by a diverse range of peoples. The majority are poor
with a much smaller proportion living under highly sophisticated conditions.
For this reason a wide range of eco-sanitary hardware is used in the sub-region
under the broadened umbrella of ecological sanitation, to cater not only for
people accustomed to modern flush toilets, but also for those who may only have
used the pit toilet before and in many cases no toilet at all.
The sub-region is also
characterised by poor worn out soils, and unless they are fertilised or treated
with manure, crop yields are often poor. Most people living in the rural areas
will practice some form of subsistence agriculture and in several countries
backyard agriculture is also practiced in both peri-urban and urban areas.
Where backyard agriculture
is already practiced, commercial fertiliser or manure may be used to increase
production, but an ever increasing proportion find these commodities either too
expensive to buy or difficult to acquire. Under these conditions, the use of
urine and compost derived from ecological toilets can actually make meaningful
increases in production, both of vegetables and maize. Such practices can
therefore have great practical value as well as forming strong links between
the disciplines of sanitation and agriculture. And this of course is one of the
most important aims of ecological sanitation. The back yard scenario is
particularly suitable for the recycling of human excreta. In several countries
in the sub-region, notably Malawi, Mozambique and Zimbabwe, backyard vegetable
and maize production is commonly practiced, even in the urban and peri-urban
areas. This is performed as a survival mechanism and perhaps because the
forefathers have practiced it for generations. It is in such places where there
may be huge potential for wider scale on-site reuse of processed human excreta.
It is also possible that with the new source of nutrient rich materials derived
from the toilet, those formerly disinterested in backyard gardening may develop
an interest.
Those living in highly
populated urban areas may not practice any form of agriculture at all - the
population density may be too high and the practice of back yard gardening may
never have taken root. Where backyard agriculture is not practiced at all, either
because space does not permit or because there is no history of growing food in
this way, excreta derived from ecological toilets must either be disposed of
into some nearby pit or removed on a commercial basis to be dumped or processed
elsewhere. The very considerable quantities of urine produced must also dealt
with in some way. In many locations of
this type it is still possible to plant hardy trees or shrubs to gain access to
the nutrients available in excreta.
At the present time there
is little knowledge, even amongst avid back yard gardeners in Southern Africa,
of the potential of processed human excreta to increase food production.
Perhaps this lies in the wake of an era when commercial fertilisers were
promoted with great vigour, not only by industry but also by government. Even
as the era of organic farming and permaculture takes route so does the
potential for reuse of all organic materials. But it is true to say that even
at thus time, organic farmers and those who practice permaculture caste eyes of
doubt about the recycling of human excreta.
Thus there is at this time
a need to adequately demonstrate and convince those that already practice some
form of agriculture that there may be potential in the re-use of processed
human excreta, particularly in the back-yard environment. This paper describes
a series of simple experiments where this increase in production of both
vegetables and maize has been demonstrated and analysed in the backyard
scenario.
Sources of nutrients
Urine contains most of the
nitrogen produced in excreta and valuable amounts of potassium and phosphorus
which are the main nutrients used in plant growth. Urine is collected in all
urine diverting toilets and can also easily be collected in bottles, potties
and other containers. Green vegetables and maize can benefit enormously from
the large amounts of nitrogen found in urine.
Toilet compost can be
collected from those urine diverting toilets where soil and ash is added to the
excreta and where the mix is allowed to compost, either in the toilet vault
itself or in a secondary compost site. Toilet compost can also be collected
from shallow pit composters like the Fossa
alterna where a mix of excreta (urine and faeces) together with soil, ash
and preferably leaves too have been mixed and allowed to compost. Such compost
resulting from this mix of ingredients can easy be dug out of shallow pits
after a year of composting and mixed with topsoil. Trees also grow well on this
material and planting trees on old compost pits offers perhaps the simplest
method of recycling the nutrients in excreta. Fruit trees like banana and
mulberry do particularly well. Toilet compost is less rich in nitrogen that
urine, but it contains valuable amounts of all the major nutrients and is rich
in phosphorus. It also adds humus and living material to barren soils.
Dessicated faeces will also contain some potassium and phosphorus, but with
minimal humus and living content.
It is not difficult to
demonstrate the usefulness of toilet compost and urine on the plants commonly
grown in the sub- region. In the experiments described below the source of
toilet compost was the Fossa alterna
a popular low cost eco-toilet in countries like Malawi and Mozambique. An
analysis shows that, compared to many top soils, shallow pit toilet compost and
composted faeces from urine diverting toilets contain valuable nutrients which
plants can use.
Analysis of compost derived from urine diverting and pit composting
eco-toilets
Soil source pH N* P* K* Ca* Mg*
Urine diverting toilet
compost
(faeces, soil, wood ash) 6.72 232 297 3.06 32.22 12.06
Fossa alterna pit soil
Faeces, urine, soil, ash (mean of 10 samples) 6.75 275 292 4.51 11.89 5.14
Local topsoils
(Harare area. mean of 9 samples) 5.5 38 44 0.49 8.05 3.58
*Nitrogen
(N*) and Phosphorus (P*) are expressed as ppm and Potassium (K*), Calcium (Ca*)
and
Magnesium (Mg*) as ME/100gms. 1 ppm = 1
mg/kg.
1. Effect of enhancing vegetable growth by mixing toilet compost with
poor topsoil in containers.
In a series of simple
experiments vegetables like spinach, covo, lettuce, green pepper, tomato and
onion were grown in 10 litre containers filled with very poor local topsoil and
their growth was compared with plants grown in similar containers filled with a
50/50 mix of poor topsoil and toilet compost. In each case the growth of the
vegetables was monitored and the crop weighed after a certain number of days
growth. The following chart showed the results of these trials.
|
Plant and growth period.
|
Weight at cropping Poor top soil only |
Weight at cropping 50/50 mix topsoil/toilet compost |
|
Spinach. 30
days. |
72 grams |
546 grams (7 fold increase) |
|
Covo. 30
days. |
20 grams |
161 grams (8 fold increase) |
|
Covo 2. 30 days. |
81 grams |
357 grams (4 fold increase) |
|
Lettuce. 30
days |
122 grams |
912 grams (7 fold increase) |
|
Onion. 4 months |
141 grams |
391 grams (2.7 fold increase) |
|
Green pepper . 4 months |
19 grams |
89 grams (4.6 fold increase) |
|
Tomato. 3
months |
73 grams |
735 grams (10 fold increase) |
Left Photo: The
photo shows spinach grown on poor soil (from Epworth) in left bucket compared
to spinach grown on the same poor soil mixed with an equal volume of Fossa alterna soil (right bucket) after
30 days of growth. The harvest was increased 7 times (546 gms compared to 72 gms).
Right Photo: The
photo shows covo grown on poor soil (from Epworth) in the left bucket compared
to covo grown on the same poor soil mixed with an equal volume of Fossa alterna soil (right bucket) after
30 days of growth. The harvest was increased 4 times (357gms compared to 81
gms)
Left Photo: The
photo shows lettuce grown on poor soil (from Epworth) in left bucket compared
to lettuce grown on the same poor soil mixed with an equal volume of Fossa alterna soil (right bucket) after
30 days of growth. The harvest was increased 7 times (912 gms compared to 122
gms).
Right Photo: The
photo shows onion grown on poor soil (from Epworth) in the left bucket compared
to onion grown on the same poor soil mixed with an equal volume of Fossa alterna soil (right bucket) after
4 months of growth. The harvest was increased nearly 3 times (391gms compared
to 141gms). Whilst this a significant increase in onion production, the best
crops are produced on very rich organic soil. Onions are hungry feeders.
2. Preparing and managing an eco-garden linked to an ecological
toilet
In this case a small
vegetable garden measuring 5m X 3.5m was prepared near an ecological toilet (Fossa alterna). The garden had been used
previously for growing vegetables and was already partly fertilised. The
compost produced from the toilet was dug out of the pit, after 9 months of
composting in this case, and piled in heaps over part of the garden and then
mixed in with the topsoil, thus enriching the soil further in that section. Another
section was untreated with compost. Rape and spinach were planted in both treated
and untreated sections of the garden. The main crop was harvested after 30 days,
with smaller crops being harvested over the following 60 day period. The
results are shown below, indicating an increased production for both spinach
and rape.
|
Plant and growth period.
|
Weight at cropping. Existing vegetable garden.
No. plants |
Weight at cropping Existing vegetable garden + toilet compost.
No. plants |
Increase
in production over 30 day growth period |
|
Spinach. 30
days. |
2349 gms (24) |
4153 gms (25) |
(X1.76) |
|
Rape. 30 days |
1928 gms (25) |
2478 gms (23) |
(X1.28) |
|
Plant and growth period.
|
Weight at cropping. Existing vegetable garden.
No. plants |
Weight at cropping Existing vegetable garden + toilet compost.
No. plants |
|
Spinach. Second 30 days |
508 gms (20) |
429 gms (19) |
|
Rape. Second 30 days |
622 gms (22) |
576 gms (19) |
|
Spinach. Third 30 days |
170 gms (18) |
172 gms (12) |
|
Rape. Third 30 days |
186 gms (14) |
179 gms (14) |
|
Total
vegetable (90days) |
5763
gms |
7987
gms (x 1.38) |
Most of the nutrients
available in the toilet compost were used up to provide the first major harvest
after 30 days. The relative increase in production would have been greater had
the soil been poor, as earlier experiments described in this paper show. By
linking the eco-toilet with the eco-garden, a direct link is made between
sanitation and agriculture. With a small family Fossa alterna about 700
litres of compost would become available annually for the garden. Fully composted
or dehydrated faeces from urine diverting toilets could also be used. In fact the
addition of a variety of composts (leaf, garden, toilet), could and should be
added to such a garden to increase soil fertility and crop production. In
addition, regular applications of diluted urine can lead to crop yields being sustained
over a longer period for green vegetables like rape and spinach where the
leaves are cropped regularly and new ones grow. Soaking the soil with a 5:1
mix of water and urine once a week, with intermediate watering, would be
sufficient to sustain production for the active life of these valuable plants,
which about 6 months. This method is described later for spinach and rape
planted in containers.
Preparing the bed
of the eco-vegetable garden. In this case an old vegetable bed is being
prepared by weeding, digging down and mixing the soil over an area of
approximately 15 sq.m. The vegetable garden was divided into three beds, each
of about 5 sq.m. each. Two heaps of Fossa alterna humus have been excavated.
The 360 litres of humus was divided into two piles of 180 litres each. This
volume of humus was sufficient to enrich two of the three beds in this
vegetable garden. The humus was applied to each bed by distributing 12 piles,
each of 15 litres over the bed with 0.5m between each pile. Thus 12 piles were
made over each bed (12 X 15 litres = 180 litres). The humus was spread out over
the surface with a hoe (badza) and then dug in and mixed with the local soil to
a depth of about 10cm. This was then spread out over the surface as evenly as
possible with a rake and then dug in and mixed with the topsoil.
The beds were watered and then seedlings planted. In this case spinach
and rape. 50 plants were sown in each of three beds making a total of 150
plants. After 4 weeks a good harvest of green vegetables has grown ready for
the first cropping. In the bed mixed with extra Fossa alterna soil, the spinach harvest was increased by 1.7 times,
and rape 1.4 times, despite the
existing bed being already quite adequate in terms of soil nutrients. After 6 weeks and two croppings the
increase had been reduced slightly to1.6 times (spinach) and 1.3 times (rape).
After 8 weeks and three croppings the total weight of spinach cropped on Bed A
was 4754 gms, compared to 3027 gms on Bed B. After 8 weeks and three croppings
the total weight of rape cropped on Bed A was 3233 gms, compared to 2736 gms on
Bed B . Thus overall the application of the humus increased the spinach crop by
1.57 times and the rape crop by 1.18 times. The vegetables in this case were
prepared for sale in neat bundles. Urine
application, best diluted with water (3:1 or 5:1) once or twice a week to the
plants would increase the output further.
3. Toilet compost as a potting soil
Toilet compost
(particularly from the Fossa alterna) can also be used as a
good potting soil. Its relatively high level of phosphorus and moderate level
of nitrogen is good for establishing seedlings and young plants. It is an
excellent medium in which to plant maize and vegetable seeds, which grow well
without extra feeding prior to the later application of urine (diluted in the
case of vegetable and undiluted in the case of maize).
The compost is dug out,
sieved to extract stones and other material and then added to seeds trays or
small pots in which the seeds are planted. In the case of maize planting, a
hollow is made in the topsoil and a measured amount of toilet compost (500gms)
is added. The seeds are planted in this compost. Toilet compost is valuable and
can be stored in sacks after being dug out of pits or urine diverting secondary
composting sites.
The toilet compost, in this case Fossa
alterna humus is dug out of the pit and stored in sacks. To make potting
soil, sieve this and also break up larger lumps. The sieved soil is ideal for
the germination of seeds. In the photo on the right, fly larvae shells can be
seen, attesting to the origin of the material. This potting soil is then added
to a series of small plastic pots or seedling trays. The seeds are planted, in
this case spinach. The small pots can be placed in a tray of water to keep
moist. Without further feeding they grow into healthy seedlings. When the
seedling is about 10cm high it can be transferred from the small pot into a 10
litre bucket or into a vegetable bed.
4. The effect of urine application on growth of green vegetables
Several experiments have
been undertaken with the effect of diluted urine on vegetables grown in
containers. The effect is shown clearly here on Rape and Spinach, two popular
green vegetables in Zimbabwe. It should be noted that those plants held in
containers and water fed only will eventually use up most of the nutrients held
in the limited volume of soil, whilst those regularly fed with nutrients
derived from urine will flourish by comparison, as the plant food in the form
of diluted urine is regularly supplied. Thus the effect of urine application in
containers is more noticeable than plants grown in beds.
4a Rape
Rape is one of the most
popular vegetables grown in Zimbabwe. It is used a great deal in relish eaten
with maize meal in combination with onion, tomato and meat. It responds well to
being grown in containers which are fed urine diluted with water. In this
trial, rape was fed diluted urine (3:1) twice a week. The urine application led
to a 5 fold increase in harvest
after 28days. This is an excellent response to urine.
Plant Liquid plant food frequency of application weight harvested
Rape water only normal watering 160 gms (9 plants)
Rape 3:1
water/urine 0.5 litres 2 X
per week 822 gms (9 plants)
Left: Photo shows 3 basins (on left) which were water fed and on right 3
basins fed with a 3:1 water/urine mix, twice a week. The effect only became
noticeable after 10 days treatment. After 28 days water/urine application the
effect is very noticeable (photo on right with water treatment below and urine
treatment above. Some of the basins are obscured. Rape yield was increased
about 5 times.
Left: The relative yields of water fed and water/urine fed rape grown on
10 litre basins after 28 days application. The plants have just been harvested
for the first time. Right: the same plants almost a month later just before the
second crop was harvested. Yellowing and mauve colour on some leaves begin to
show after 2 months of urine application at this rate, indicating that the
plants are beginning to weaken. This is probably due to over application of
nitrogen from the urine. Longer trials like this provide the best indications
of the most suitable water/urine treatment under these conditions. A weaker 5:1 application given to the plants
once a week may be better in the longer term
4b Spinach
Like rape, several harvests
can be taken from the same plant over a period of several months. It is ideally
suited for growing in containers which are fed diluted urine as shown below.
During the first month, the urine application (3:1, 0.5 litres, twice per week)
led to a 3.4 fold increase in
harvest after 28days, compared to water fed plants. During the second month the
urine dose was reduced to 5:1, twice a week and during the third month and
after, the urine dose was reduced further to 5:1, once per week. 0.5 litres of
the diluted urine is applied to each basin (containing 3 plants) per treatment.
The plants are watered at all other times.
Plant Liquid plant food frequency of application weight harvested
At
28 days
Spinach (22plants) Water
only normal watering 741gms
Spinach (22plants) 3:1
water/urine 0.5litres 2 X per
week 2522gms
Photos taken of the 16 basin spinach trial.
Basins to the left of the green band are urine fed (3:1 water/urine mix
with 0.5 litres of the diluted urine being applied to each treated basin twice
per week). Those to the right are water fed only. Photo on left taken on 3rd
December 2003 on the first day of urine treatment. Photo on right taken on 31st
December 2003, 28 days after first urine treatment. The effectiveness of the
urine treatment is very positive and very clear to see
The total collected spinach harvest of urine treated spinach on the left(
2522gms) and water treated spinach on
the right (741gms) after 28 days of growth.
This is a 3.4 fold increase in production. All plants are watered at all other times. Spinach responds very well
to this type of treatment.
5. Effect of urine application on maize planted
on poor sand soils
Maize is a vitally
important crop in Southern Africa and it responds remarkably well to the
application of urine (usually applied undiluted). Extensive trials have been
carried out on the effects of urine on maize growth (Guzha (2004), Morgan
(2002). The growth of the plant and the final size of the cob is closely
related to the supply of nitrogen if all other factors like rainfall and sunlight
are not restricting. With standard commercial fertilisation the seed is planted
together with 10gms a general fertiliser known as compound D (1:2:1) which
contains about 1 gm of N. A second application of ammonium nitrate, (containing
34.5% nitrogen). provides another 3.4gms of N, making a total of
nearly 5gms. Sometimes more nitrogen is applied as the grain filling stage
begins. For most people in Southern Africa who do not have a rich protein diet,
urine contains about 5gms per litre nitrogen (Håkan Jönsson pers. comm.). Thus
one litre of urine provides about the same amount of usable nitrogen as a dose
of standard commercial fertiliser.
In various pre-field trials
with growing maize on poor sandy soil in containers (not reported here), there
was a close relationship between volume of urine applied and final cob
weight. More urine led to larger cobs
as the graph below shows.
The maize yield
is related to the amount of urine supplied
Left: The maize plant on the
right is being fed with a 3:1 mix of water and urine (0.5 litres) three times
per week. The maize on the left is irrigated with water only. The difference is
striking. Right: Urine treatment also
improves maize cob yield significantly. The total yield of cobs from maize
planted in three 10 litre basins is shown. On the left the maize was fed
1750mls urine per plant over the 3.5 month growing period, resulting in a crop
of 954 gms. A reduced crop resulted from reduced input of urine (middle). Maize
plants on the right were irrigated with water. This is a very high rate of
urine application, but one happily accepted by the maize plants in the
containers which were irrigated frequently with water to keep the maize plants
healthy.
Part of the total harvest in the M14 experiment in basins showing the
effect of urine treatment on maize. The maize plants held in basins which were
fed only water produced a pathetic yield as the available nutrients were
quickly used up by the maize. However where diluted urine was applied regularly,
the growth of maize was considerably enhanced in proportion to the amount of
urine added.
Also various experiments both
in containers and in field conditions have shown that on porous sandy soils
this one litre of urine is best applied in a series of smaller applications to
avoid losses of nitrogen due to leaching following heavy rain during the active
vegetative growth and grain filling stages. The rainfall pattern in Southern
Africa is often characterised by heavy storms followed by lengthy periods
without rain, as the graph below shows.
Applying urine
Where undiluted urine was
applied a urine applicator made from a pill bottle with 125mls capacity was
used in both backyard and field trials. The first 125mls was applied on
planting day (day 0) under the seed (the seed is planted in 500gms of toilet
compost). Further applications of 125mls urine were applied 0+3, 4, 5, 6, 7, 9,
and 11 weeks to make a total of 1000mls.
Field Trial with maize in Epworth
Epworth is a large
peri-urban settlement of about 200,000 people close to Harare. It was chosen as
an experimental site to demonstrate the effectiveness of urine as an
alternative to commercial fertilizer for maize production because it is
characteristic of the conditions under which millions of people live both in
peri-urban and rural areas in Southern Africa. Natural Epworth topsoil is
sandy, porous, almost without nutrients and applied nutrients can easily be
lost by leaching during heavy storms. Without commercial fertilizer or manure,
maize and vegetable crops are generally very poor on soils of this type.
However despite this backyard soil in Epworth is characteristically patchy with
variable nutrient level. This is because over the years sections of land have
been fertilized with manure and compost, and sometimes commercial fertilizer, particularly
in delineated vegetable gardens. So there is some carry over of nutrients from
year to year, particularly from manure and compost.
In the current trial a
small existing backyard maize field was chosen which also housed an ecological
toilet (Fossa alterna). 200 maize were planted and individually treated
with a total of one litre urine during the vegetative and grain filling stages.
A further 40 plants were not treated with urine. 40 additional plants were
treated with standard fertilizer. At harvesting and for comparison a small
sample of cobs was also taken from an adjacent field where no treatment of any
type had taken place. Seed was planted in mid November and cobs harvested in
mid March a period of 4 months.
Results
There was much variation
between individual plants in all sections (apart from field 2) of the trial,
mainly due to the variable existing nature of the soil even within each section
of the experimental field, and probably due to earlier applications of manure,
compost or fertilizer. This variation is characteristic of such fields and
gardens. This variation was less evident in the urine fed section, where the
treatment had a significant effect on maize growth and cob size – with more
consistently larger cobs.
Section No.
Plants Mean
cob Equivalent
Wt. (gms) grain wt. (gms)
Untreated (field 2) 15 82.4 41
Untreated (field 1) 36 138.11 75
Treated: commercial fertilizer (field 1) 34 166.97 97
Treated: urine (1 litre per plant – field 1) 196 243.11
148
Overall mean cob weight was
increased by 1.76 times (138gms to 243gms) by urine application when compared
to the untreated section. When plotted against grain weight, this increase in
cob weight (X 1.76) represents a doubling in the yield of grain. When plotted
on a graph, a 138gm cob yields around 75gms of freshly stripped grain compared
to the larger 243gm cob which yields 148gms of grain.
The relatively high mean
for untreated maize (field 1) was probably due to a sub-surface bed of manure
or compost in one patch of the control zone which promoting healthy growth of a
few plants making up 27% of the total cob weight in this section. The mean cob
weight of urine treated maize (243gms) was about three times the mean cob
weight (82gms) of sample cobs taken from another untreated field nearby, more
typical of the area, where cob weights were more consistently poor. In terms of
grain weight this is an increase of four times.
The urine was produced by
the family itself and probably contained about 5gms/litre nitrogen,
approximately the same as the nitrogen applied with commercial fertilizer.
Residents in the area were impressed by the effect of urine treatment, which
was plainly visible and cost nothing, but did require effort on the part of the
householder. Put in simple terms the
treatment of individual maize, planted on poor sandy soils, with one litre of
urine spread over the growth period resulted in a doubling of grain output.
This must be seen as a result worth the effort in such conditions.
The response of the maize
in this trial to commercial fertilizer was surprisingly (and
uncharacteristically) poor, with only a 1.2 times increase in mean cob
weight. This may have been due to the
very poor and irregular rainy season characterized by single heavy storms
followed by long periods without rain. Under these conditions soluble nitrogen
(from urine or ammonium nitrate) may be quickly lost into deeper soil by
leaching in these porous sandy conditions. The more regular weekly application
of urine, undertaken in this experiment, appears to have partly overcome the
leaching effect.
The
field is prepared by digging and holes are made 30cms apart in rows 90cm apart.
The 20 litre drum of collected urine is shaken up (to mix the phosphorus) and
added to a 20 litre bucket. Date 5.11.2004
Using
a dispenser, 125mls of urine is added to every hole
This
is followed by one pea tin full (500gms) of toilet compost taken from the Fossa alterna or other composting
toilet. Two seeds are then planted in the compost and pressed down and then
covered with the topsoil. If seeds are in short supply then a single seed can
be planted. Over 90% of registered maize seed will germinate. Another seed can
be planted if a single seed does not germinate.
The
seeds are pressed into the compost and covered with topsoil awaiting the rains
If
two seeds had germinated, which was normally the case, one was removed and
planted elsewhere. Urine is decanted from the larger 20 litre plastic storage
vessel and poured into a bucket from where it is poured next to the plant with
a small urine applicator made from a plastic pill bottle – volume 125mls.
This
photo was taken at the time when the last of the urine was applied. In the
treated area (right) the growth of maize has been good and cobs are already
forming. On the left the untreated area shows smaller and paler plants with reduced
cob formation. The effect of urine is clearly visible.
Comparisons
with maize growth in more fertile soil
For comparative reasons a
similar trial was undertaken at the Friend Foundation in Tynwald near Harare.
In this case a plot was chosen where animal manure (mainly donkey and dog) had
been previously added to the soil over a period of time. This may be similar to
a field or garden where kraal manure has been regularly added. This had the
overall effect of enriching the soil, although the enrichment can be patchy.
Area 1 of the plot was
planted with 70 maize which were treated with 1000mls of urine, applied over
the growth and grain filling period in 5 applications. The seed was planted in
500mls of toilet compost. Area 2 of the plot was planted with 50 maize in
toilet compost with a single 125ml application of urine. Area 3 of the plot was
planted with 70 plants which were not treated with toilet compost or urine. The
remainder of the plot (area 4) was planted with maize growing on manure treated
soil without any further addition of urine or toilet compost. Maize was planted
on 6th December 2004 and reaped on 24th March 2005. In
each area the weight of each cob was measured. In area no. 4 which was the
largest, a sample of 20 plants were measured. The results are as follows.
Area Additional Treatment total wt cobs (no.)
mn.cob wt.
1 toilet compost + 1litre
urine 24 354gms (68) 358.14
2 toilet compost + 125mls
urine 18 050gms (51) 353.92
3. Original manure only 13 457 (66) 203.89
4. Original manure only 6 708 (20) 335.40
Under conditions where the
soil is already enriched with manure, the presence of toilet compost and urine
appears to have made little difference to the overall growth of the maize
plants and final weight of cobs. The patchiness of the general area in terms of
soil fertility is revealed by the differences in cobs weights from areas 3 and
4, neither of which were treated with either urine or toilet compost. The
fertility derived from the manure enriched soil appears to have overridden the
effects of toilet compost and urine in this experiment, where the application
of either 1000mls urine or 125mls urine made little difference to the final
yield of plants. The experiment also revealed that even within a small plot or
field there can be much variation in the growth of maize plants depending on the
nature of previous additions to the soil over localized areas. This was also
revealed in the maize trial undertaken in Epworth.
In terms of cob size
harvested, those from Tynwald were considerably larger than those from Epworth.
The overall size of cobs harvested from all areas in the Tynwald soil was
305gms (overall mean) considerably larger than the overall mean of 211gms
harvested overall from Epworth. This is entirely due to the quality of the soil
in which the plants were growing and the fact that Tynwald soil had far more
humus and was able to retain water better than the sandy soil of Epworth. Maize
plants treated with one litre urine in Epworth had an overall mean size of
243gms compared to 358gms in Tynwald. These simple experiments also reveal that the overall effect of
urine on the growth of plants is not only related to the amount of urine
applied, but also to the quality of the parent soil. The poorer the soil, the
more noticeable the effect.
The real test of the
practicability of this type of treatment comes during subsequent growing
seasons following the demonstration. Will the urine treatment method be
repeated and copied by others? For a small maize field of 200 plants a total of
200 litres urine was required and the man and wife of the household coped with
this production during the period of the experiment. But if larger numbers of
maize plants were treated in the same way, collection and storage of urine
would need to take place prior to the planting of maize. Urine can be stored in
20/30 litre plastic containers. Whilst the cost of these containers would be
high initially, their use would continue over many years, making the overall
investment worth while.
Use
of urine on fruit trees
The regular application of
diluted urine on fruit trees can also have beneficial effects. For trees like
banana, mulberry and mango, for instance, the weekly application of diluted
urine (2 litres of urine + 10 litres water) can increase both natural
vegetative growth and fruit production, although no statistical evidence is
available at the present time. The health and size of plants is the best
indicator, and this is revealed by the regular application of urine. Fruit
trees also benefit from extra potash which can be supplied from applications of
wood ash. The application of manure or compost and a leafy mulch can also help
the growth of all trees.
Overall
Conclusions
These simple experiments
and demonstrations show very clearly that both toilet compost and urine can
have considerable value in enhancing the yield of both vegetables and maize –
the most important components in the diet of most people living in Southern
Africa. This is particularly the case where plants are grown on poor soils,
which are common in Sub Saharan Africa. The toilet compost and urine are best
used in combination, each providing special benefits. The greatest value of the
toilet compost is its living component, which can bring beneficial organisms of
various types to a dead and worn out soil, and also to its humus like properties,
which helps retain water and also to the valuable supply of phosphorus as well
as other important elements. The conversion of urine nitrogen into nitrate
which the plants require is performed by soil bacteria. The greatest value of
the urine is its generous supply of nutrients, particularly nitrogen, which can
increase the yields of green vegetables and maize in a spectacular way.
The experiments described
in the paper are of the simplest type. They fall within the realm of
bucket-science - literally! They are easy to replicate and demonstrate. Planting
hardy plants like spinach in containers and applying urine to some and water to
others quickly demonstrates the beneficial effects of urine. It is the
demonstration of the effect which most impresses those yet to be convinced.
Simple as the experiments
are, the implications are considerable. At its best the application of toilet
compost and urine to the most important food plants of the sub-region on the
worst of soils can lead to significant increases of harvest, particularly in
the back yard garden scenario. The improvement of harvests can be achieved
further by using human material in combination with other organic materials
like manure or compost. In a continent where the majority live on poor soils
and are also hungry – such considerations must be taken seriously.
Acknowledgements
The writer wishes to thank the following people for
their support and advice on the agricultural aspects of ecosan. Christine Dean,
Baidon Matambura, Felix Murenga, Marianne Knuth, Annie Kanyemba, Jim and Jill
Latham, Edward Guzha, Paco Arroyo,
Almaz Terrefe and Gunda Edstrom, Håkan Jönsson, Björn Vinnerås, Anna Richert
Stinzing, Paul Calvert, Arno Rosemarin and Ingvar Andersson. Also to staff of SEI, Stockholm and Bengt
Johansson and Sida for their support which has made this work possible.
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*Available on CD
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