Animal and Bird manure.

Animal manure is high in nitrogen, bird manure is high in potassium.
Suspend a hessian bag (tea bag) into the drum so that it’s covered with fresh water, give the tea bag a jiggle every couple of days, the brew will be ready for use within a fortnight. Dilute.

Comfrey. (herb plant)

In my garden my main source of fertilizer is the herb plant comfrey as a liquid. At the same time it is a foliage spray and insect deterrent. It is also a compost activator. The leaves will break down the compost heap in half the usual time (in two to three months). Or just chop up the leaves and place around the garden. You can also try trench digging. Dig a trench 150mm wide 150mm deep as long as you require, then half fill the trench with chopped up comfrey leaves, replace the soil, then sow your seeds on top. As the leaves decompose they will feed your plants the nutrients they require
Comfrey has nitrogen, calcium, potash and phosphorus, greater than any animal manures, and it is also a good foliage spray. The average garden will require around seven plants for a continual supply of leaves all year around.
Give the comfrey plants a hair cut, fill the drum half full of comfrey leaves, and then top up the drum with fresh water and replace the lid. The brew will be ready within a fortnight. Stir well every couple of days. Strain into watering can when ready. Dilute. N.B make a brew the colour of weak tea 25/75 for young plants, for more established plants 50/50. Comfrey is also a bug deterrent, so pour the brew all over the plant.

Compost.

Tea bag method, (good fresh compost)
Kitchen Scraps.
Let the scraps decompose in a bucket with a lid, for a couple of days then use the tea bag method. Dilute.
* Seaweed or Seagrass.
These are low in nitrogen but high in trace elements such as potash; also a good foliage spray.
Fill the drum half full of fresh seaweed and then top up with fresh water and replace lid the brew will be ready within a fortnight give a good stir every couple of days, when ready for use strain into a watering can. Dilute.
A good brew for young plants is 25% brew and 75% water. a weak tea colour. For older plants it is 50/50. This is a strong brew so be careful not to burn the plants.
Before applying liquid fertilizer give your plants a good watering. This will help the plants to absorb the nutrients from the liquid fertilizer and prevent the risk of burning the plants roots and leaves.
Most plants like liquid fertilizer, especially tomatoes, lettuce, the brassicas family, (cabbage ect.) cucurbits (cucumber, pumpkin.)
Plants that like a little liquid fertilizer when they are beginning to produce their crops are peas, beans, and onions when they are starting to bulb, (not before or they will not store well).
Plants that dislike liquid fertilizer, or any other kind of fertilizer are root crops (carrots, potatoes, turnips ect.) if they are fertilized they will be all tops and no bottoms or fork out with very hairy legs.
A good basic rule to remember is that crops above the ground (leaf and fruit crops) like liquid fertilizer, compost and manures, plants that grow below the ground (root crops) dislike liquid fertilizer, compost and manures.
It’s a good idea to plant a root crop after a leaf or fruit crop.
If you don't have the sources, or you don't have the time, there are organic foliage sprays you can buy off the shelf.