Liquid manure has many advantages over chemical fertilizers. Chemical fertilizer products are often composed of only one to three of the nutrients the soil needs, usually nitrogen, phosphorous and potassium (or potash). Because at least 14 important nutrients are required for healthy growth, this leads sometimes to subtle deficiencies in the soil and the crops. Liquid manure is composed of broken down plant or animal waste and therefore has a wide range of nutrients. Making and using liquid manure is something you can do at any level and scale, for the small box garden to large fields.
Fill the large bin with water to about the two-thirds level. The solid organic matter you are using will soak in this water for an extended period of time, which will release the nutrients inside. Note that animal dung makes a superior nitrogen fertilizer because of its high nitrogen content.
Place the organic matter into the burlap sack. If the organic matter you are using is animal dung, be sure to wear the gloves. Suspend the burlap sack in the bin by pulling the edges of the sack over the edges of the bin. Alternatively, if the sack will not stay on the edges of the bin, you can cut holes in the sack and insert one or more poles through them, arranging them so that the poles hold the sack in the water.
Allow the organic matter to soak anywhere from one to three months. The manure will require less time if the weather is warm. Animal dung requires only one month even if the weather is not warm. Check the color of the water regularly--if you are using plant matter to make a green liquid compost, it will be done when the water develops a strong barnyard smell.
Dilute the liquid from the bin until it is the color of weak tea. At this point more water can be added to the bin and a second batch can be made using the same organic material.
Apply the liquid manure to your garden. Avoid applying animal dung fertilizer to plants with exposed edible parts (such as salad lettuce or herbs). Be sure to apply the fertilizer directly to the ground rather than allowing any of it to get on the leaves. The manure can be applied to growing crops or to soil before crops are planted.