1. Sheep organic fertilizer is one of the best fertilizer of the type. Maybe it sound silly, but you can collect sheep droplets on the fields ( ask for the permission the field owner)! To make liquid fertilizer from sheep droplets you will need one textile sack, some sheep droplets and a bucket full of water. Simply put the sack filled with droplets into water and wait for a while (1 kg manure to 5 l water). The same can be done with chicken manure. Before use, add some more water to the bucket to dilute the liquid (1:10 ratio), especially if you have chicken manure - high in nitrogen!
This is a fertilizer with high concentration of N and K, and has to be diluted in water before the use. I usually make 1:10 dilution. The nettle manure is not good for peas, broad bean and garlic.
The second bucket contains a mix of sting nettles and comfrey. All these plants may be used as mulch as well. You can add some other plants to nettles e.g. fern, chamomile, and horsetail.
3. Compost soup is very mild and can be used all the time. Easy to make: just put one bucket of compost into 15 l of water and wait for a day until it settles. Water plants with it.
4. Check this out Banana Peel Fertilizer by Fer. Very good for house plants and any other plant as well. (Banana peel N= 0 P= 3.25 K= 41.76)
5. Biodegradable mulches, such as grass clippings, tree bark, straw, spent mushroom compost serve as fertilizers as well by slowly realising the nutrients into the soil.