Urine, pee – no matter what you call it, it can do more than you might think at first. Your pee is an excellent fertilizer. It’s actually quite logical: plants need certain substances to grow, they absorb them, store them, we eat them, keep some part and excrete the rest – and voilà, that’s of course exactly what the plant needs to grow.
Read here how fertilizing with urine works. Incidentally, this is not only possible with your own garden, but also on the balcony!
quick overview
smart alecks knowledge: fertilizer
There are 16 essential elements that plants need for healthy growth. The most important three, which are not already present via air, water or earth (O, H & C), are
Nitrogen = N
Phosphorus = P
Potassium = K
In agriculture and horticulture, these are added either individually or as compound fertilizers, so-called NPK fertilizers. It contains all three minerals in a fixed composition. The classic store-bought NPK fertilizer for the garden is the blue granules you may be familiar with.
There are many different classifications of fertilizers (solid or liquid, organic or minor fertilizers and so on). For your garden only one thing is particularly important: there are plant fertilizers and soil fertilizers. urine is a plant fertilizer It contains the nutrients exactly as the plant can and should absorb them. Just like the NPK fertilizers used in agriculture.
To ensure that the soil can retain the nutrients well, it is also worth fertilizing the substrate. You can do this with compost, for example, which you can make from your solid waste.
Everything you need to know about composting dry toilet contents you can read here.
what is in the urine?
The largest proportion of nutrients that we excrete finds its way out of the body via the kidneys, that means in the urine. This is very practical because your pee is largely germ-free, but rich in nutrients. A glance into the test tube reveals that urine contains an average of approx.
- 6g nitrogen
- 1g phosphorus
- 2g potassium
Compared to purchased NPK mixtures, the nitrogen content is higher and therefore the guideline in terms of quantity. 1 liter of urine corresponds to about 100 ml of liquid fertilizer from the hardware store. An adult pees 1-1.5 liters per day. But how much of it is allowed on the plants?
fertilize correctly with pee
the right amount
You should at least have a rough idea of how much fertilizer your plants need. Because what they don’t absorb is washed out and, in the worst case, ends up in groundwater or rivers, where it doesn’t belong. The right amount is based on the nitrogen required by the respective plant. Professionals also analyze the soil so that they know how much of the required substances are already available here.
The Leibnitz Institute of Vegetable and Ornamental Crops (IGZ) has published a practical brochure in simple language for the Urban Cycles project, in which the calculation is explained and you can look up the nutrient requirements of common vegetable plants.
A calculation example:
I plant 4 cucumbers on about 1 square meter.
cucumbers need 16 g of nitrogen per square meter.
1 liter of urine = 6 g nitrogen
1 g nitrogen = 0,17 liters of urine
16 g nitrogen = 2,7 liters of urine
I fertilize my cucumbers throughout the season with a total of just under 3 liters of the best pee.
Is urine suitable for all plants?
No, because: Urine increases the salt content in the soil. Plants that are sensitive to salt could therefore do more harm than good with urine fertilization. On the one hand, this applies to all seedlings – so do not give salt-tolerant heavy eaters pee too early. And also, for example, lettuce, radishes or some ornamental plants such as primroses, which should be fertilized sparingly.
Tomatoes, cucumbers, peas, spinach, cabbage, leeks and zucchinis, on the other hand, are ideal for fertilizing with urine.
How to contribute?
Fertilizer is applied from the growth phase, thus for summer species from around (late) spring . And then until about harvest time. Important again: Do not fertilize the seedlings with urine yet because of their sensitivity to salt.
Let’s take our example cucumbers again: The almost 3 liters are not given to the plants all at once, but every few weeks. Cucumbers need about 9 weeks from sowing to harvest. This means, for example, that you fertilize all four plants with 0.5 liters once a week from the 3rd week onwards.
To do this, dilute the urine about 1:10 with irrigation water and pour it onto the soil, not onto the plant itself. This is because the nitrogen it contains can cause burns to the leaves in high concentrations and in strong sunlight.
If you do not dispose of the urine completely fresh, but use the collection from your urine-diverting toilet, for example, you should store it in a closed container, otherwise the irritant gas ammonia will evaporate. Incidentally, this differs from urine fertilizer products such as Aurin, in which the nitrogen is stabilized so that it cannot evaporate.
Can you use any pee?
The kidneys not only release nutrients from the body, but also all kinds of things that you supply to the body that it no longer needs. Problematic here is particularly Medication, from aspirin to the pill. They don’t harm the plants, but firstly they store the substances and we eat them again and secondly they don’t just affect humans, but also other living creatures.
Why it is still problematic for urban trees when people pee on them
The dose makes the poison: too much fertilizer, especially when there is too little other water supply, as is often the case with urban trees, is harmful to the plants.
