The Secrets of Making Healthy Compost

Following on from the previous two articles on 'Unlocking the Secrets of Sand, Clay and Silt Soils' and 'The Secrets of Plant Nutrients', this article is going discuss how to make beautiful compost that smells sweet, is lovely to touch and full of nutrients for your plants. This end product of composting is called humus. Compost that ends up smelly and sludgy is not broken down properly. This article will help you correct that problem. It is all about oxygen and getting the Carbon:Nitrogen ratio correct.

Compost is important for several reasons:-

It improves soil structure can increase or decrease soil pH it encourages micro-organisms and worms it holds water, preventing the water leaching through the soil profile it improves the pore spaces between the particles of clay soil it cools soil temperatures during summer it contains nutrients if you make your own, you control what goes into it reduces the demand for landfill tips

However, you do need to be aware of the pitfalls:-the quality of the compost depends entirely on what you put into it it can be expensive if you have to buy in the ingredients weeds such as Couch grass if growing near-by can grow into it if it hasn't heated up to over 60C, the bad micro-organisms and weed seeds haven't been destroyed if there is too much nitrogen and not enough oxygen in it, it smells disgusting large pieces such as sticks don't break down; pieces need to be very small and insects and critters can live in it as it is such a good source of food

Another aspect you need to be aware of is, inadvertently building up the soil level. Over the years of adding compost and mulches, the original soil level increases to the point where it is several inches or centimetres higher. This can cause problems because the plant roots are no longer at the surface of the soil and aren't getting as much oxygen as they once did. All plant roots need oxygen and if it is not available all plants die. This happens more with mulches but you still need to be aware of it with compost.

Overall, the good points outweight the bad ones.

C:N Ratio C:N stands for Carbon:Nitrogen ratio. This ratio needs to be balanced otherwise the compost won't decompose. The reason why composts smell is because there is too much nitrogen (kitchen scraps, grass clippings) and not enough carbon and oxygen. This causes a build up of ammonia and this is what causes the smell. To rectify this problem more carbon needs to be added in the form of paper or leaves. The ratio is usually 30:1, this means 30 parts of carbon to 1 part nitrogen.

Methods of Composting There are two main ways of making compost: The Hot Method (fast) and the Cold Method (slow). The fast method brings the temperature of the heap to over 60C and this kills the harmful bacteria. For the fast method to work, the compost heap needs to be in a warm and sunny spot and turned regularly ie. 3-4 times per week. The cold method is usually compost made in the green compost bins. The bins need to be in a warm place that receives morning sun and afternoon shade. It can take up to 6 months for the compost to be ready.

Principles of Composting A compost heap can be compared to a party for micro-organisms where they consume a huge amount of food in the process of this get really hot doing it.Like all parties, there needs to be some preparation and the party goers (micro-organisms) need the right conditions. If the conditions are right the micro-organisms will multiply break down the organic matter.

Ingredients Needed The main ingredient is organic matter. Carbon can be identified as all the brown products such as saw dust and nitrogen can be identified as all the green products such as lawn clipping. Below is a list of all the things you can put into your compost heap. leaves, pea straw, sugar cane grass clippings kitchen waste (not meat or fats and oils) old potting mix the muck from the gutters saw dust dust from the vacuum cleaner shredded twigs and branches discarded annuals perennial flower stalks dog and cat hair human hair shredded paper products - not the glossy coloured pages

Construction of Composting Bays You need an area at least 1.5m X 3m for it to work This gives you plenty of room for turning your compost Walls are constructed from corrugated iron, or steel mesh, held in place using steel stakes,Star pickets or concrete -re-enforcing rods cut to length. Timber stakes rot too quickly. Form 3 bays that are open fronted 1 Bay is for putting material in to break down, 1 bay for spreading on the garden and the last bay is allowed to turn into compost. Turn using a fork on a weekly basis. Adds some nitrogen fertiliser - about 3 to 4 handfuls, blood and bone as it contains a high percentage of nitrogen. As micro-organisms break down the material in the heap they rely heavily on nitrogen present and quickly use it up. Adding blood and bone fertiliser replaces nitrogen used by micro-organisms.

Compost Bins This method of composting is best suited to those who have a plastic compost bin are in no hurry for having compost. This method can take up to 6 months. You can hurry up the process by regularly turning the compost at least 3 times a week. The extra oxygen allows the micro-organisms to break down the material more quickly. You don't need to buy worms for your compost bins, they will come naturally if the conditions are right for them. Don't build your compost heaps on bricks or concrete. The worms need to be able to escape into the soil if it is to hot or to wet. Then simply add all the kitchen and garden waste listed previously and over a period of time the worms will gradually eat their way through whatever you feed them. Micro- organisms will also be present in the bin and assist the breakdown process. These bins are especially good for smaller gardens. Watch the moisture content - they can be come too wet. Drill holes in the side to allow oxygen into the bin. Keep in a cool shady spot - Worms don't like the heat. Don't put citrus or onions in the compost.

Temperature The hotter the air temperature, the faster the compost breaks down. In winter compost takes several months longer to break down as the air temperature is colder.

Moisture The compost heap must contain some moisture for the micro-organisms to function effectively. The heap must be moisture but not too wet. The compost should have the same feeling as a squeezed kitchen sponge; it feels damp but not soggy. This is about 50% moisture content and is perfect for composting. The best time to add moisture to the heap is during the turning procedure where water can be applied to all areas of the heap and then mixed through.

Compost is ready to use when the inside temperature of the heap is the same as the outside air temperature. The length of time this takes depends on all of the factors that have been discussed ie. type of materials used, moisture content, frequency of turning etc.

Applying Compost to the Soil Compost can be applied to the soil in two ways:

1.By spreading it on top of the existing garden beds and letting the worms move it down into the soil or mixing it with the existing soil by digging it through. Care must be taken that roots of existing trees and shrub are not disturbed. Digging it in to a spades depth is ideal for a vegetable patch, annual or perennial beds.

2.Using the compost as a mulch and simply spreading it over the surface of the garden to a depth of about 4 centimetres. But be careful, it can become compacted because of the small particles if you put it too thickly on and then can become water resistant.

Compost Accelerators Products marketed to assist the breaking down process don't work so don't buy them. If you want to try and hurry up the breaking down process you can add herbs such as comfrey or borage.

Compost is a wonderful resource with many benefits. It is a fantastic way to use up garden and kitchen wastes and reduce landfill. It also has the added benefit of improving the water holding capacity of the soil and reducing run off. The quality of the final product - the humus - depends on how much effort you put into it and what you put into it. The secret of good healthy compost is oxygen.