Gardening and manure
Animal manure has been used as a soil improver (particularly in vegetable gardens) for as long as people have been gardening. Using animal manure has huge advantages — it adds organic matter and fertility to the soil, improving soil structure so that water is more available to plants and excess water drains away quickly. A good helping of manure can make hungry plants like squash and fruit bushes produce bumper crops, and it helps your roses to bloom, too.
Animal manure (usually from horses or cows) is such a highly nutritious substance that using it fresh can cause problems — it can ‘burn’ tender plants. And the nutrients in fresh manure are very water soluble, meaning that they can wash away in heavy rain. Ideally, animal manure should be composted before use, until it is ‘well rotted’, safe and stable. Then you can dig it in to your vegetable garden, or use it as a mulch wherever a boost is required.
Poultry manure is slightly different. It has very high levels of nitrogen, but not mulch bulk. It makes a great compost activator if you add it to your compost heap, but you can also dilute it with water to make a liquid feed for leafy vegetables and plants with high nitrogen requirements — like corn.
However, many people (especially in urban areas) have problems finding a reliable source of animal manure. It’s also difficult for organic gardeners to get hold of organic animal manure, that won’t contaminate their gardens with pesticide residues. This summer in the UK, vegetable gardeners have been horrified to learn that the animal manure they’ve used to improve their crops contains a new herbicide — aminopyralid — that takes a long time to break down and is harming vulnerable crops like lettuce and tomatoes. Also, vegetarians may not want to use any animal products in their garden at all.
If you can’t get, or don’t want to use, animal manure then there are other options. The easiest, cheapest and most environmentally friendly option is to compost all your kitchen and garden waste at home, and use home-made compost to improve your soil.
You can also sow special plants, called green manures, for soil improvement. Some green manures have strong roots to break up heavy soils. Others fix nitrogen from the air into the soil, leaving it as fertilizer for the next crop. And still others control weeds, prevent evaporation and soil erosion or provide large amounts of green material for composting or mulching. And you can always choose to plant comfrey, which can be used as mulch material or made into a healthy liquid feed for your tomatoes.