Briefly about: Improving soil with compost

An option for improvement of elaborated peat-free soil conditioner formula can be adding composted material. But what is compost?

A mixture of different organic minerals (organic residues, soil organic residues) which are modified by organism action is called compost. It can be stacked, moistened, limed, organic or mineral fertilizers and biological preparations, etc. additives that promote biological processes and decomposition of organic compounds can be added to it. Composting is a human-regulated biological process in which organic matter (also different waste) is converted into humus-like material. Composting not only reduces the amount of waste, but also reduces the use of mineral fertilizers. Good compost improves soil structure and provides plants with the necessary nutrients, it is used to improve soil properties, as a fertilizer, as well as as a substrate in horticulture.

What is being composted?

Different materials with different chemical composition are used to make compost. Straw, plant residues, weeds, farm waste, unusable fodder, manure, poultry manure, slurry, sawdust, wood processing residues, tree leaves, peat, etc. organic materials are used for composting in agriculture. It is useful to compost materials whose direct use is not efficient, handy or desirable. For example, peat itself decomposes slowly, because of that it is not useful to compost it alone therefore it is composted with manure, slurry, bedless manure, mineral fertilizers.

Garden plant residues and waste can be used for composting in the garden, as about 40% of human waste are compostable. Following non-structured materials can be composted: garden waste (flowers, leaves, weeds, moss, fallen fruit and old vegetables, cut grass, needles); sawdust, pet manure, manure, kitchen waste (fruit/vegetable residues and peel, food residues, eggshells, coffee grounds, tea grounds). And the following structural materials can be used: garden waste (straw, hedge, tree and shrub cuttings, branches and shoots, straw, reeds, tall grass); paper (cardboard, paper towels, paper bags, newsprint).

What is needed for composting

Due to the different materials used for composting, its preparation technologies may differ, but the basic principles are similar. It should be noted that composting is not just stacking of different materials and keeping them a certain period of time, there are things that need to be taken into account when composting is done, so that the micro-organisms that break down the compost can live and decompose the compost.

Composting is influenced by factors such as sufficient nitrogen (nitrogen to carbon ratio is important, so for example, pure straw decomposes faster when the slurry is added; and for example, cut grass and kitchen waste contains nitrogen); temperature (in winter composting practically does not take place, because the temperature is too low for the living organisms); moisture (when making compost it is recommended to mix drier and wetter material; dry piles need to be watered); air supply (mixing of the compost pile could be required); as well as environmental reaction (optimal pH 6-7).

One of the compost materials must be one that decomposes slowly in the soil (straw, hay, grass, well-decomposed peat, tree leaves, sawdust) and the other material that decomposes quickly (slurry, fresh manure, poultry manure, farm waste). In other sources it is mentioned that it is important to use a mixture of structural and non-structural materials, that provide air spaces and air access to the compost pile; structural materials are usually those which decompose more slowly and contain more carbon.

If the necessary factors are provided for composting, there is no need for compost starters, additional microorganisms or fertilizer. Some microorganisms multiply very rapidly in compost under suitable composting conditions (theoretically 562,940,000,000,000 bacteria can be formed from 1 bacterium in 24 hours).

Simply creating a compost pile

The recommended compost pile size, for example for peat-manure compost, is 3-4 m in width and 2 m in height. A 40-50 cm thick carpet layer of peat is placed at the bottom, a 25-30 cm thick layer of manure is placed on top of it, the layering is continued to a height of 1.5 m and the pile is closed with a 40-50 cm thick layer of peat so that it does not dry out and decomposing processes can take place inside.

A garden compost pile is formed by piling branches, shoots, etc. structure-material 20 cm in height and 1.5×1.5 in width, thus providing an air-permeable layer at the bottom of the compost pile. Then, by mixing wetter and drier, finer and coarser material, it is piled on top until the height of the compost pile has reached 1-1.5 m. Kitchen waste and weeds should be placed in the middle of the compost pile, as in the centre of the compost pile will be the highest temperatures. When stacking the pile, it is possible to scatter a bit of semi-finished compost or a bit of clay soil in a layer after every 30 cm compost layer. When the height of the compost pile is reached, it is covered with a soil layer, to prevent it from drying out.

If all the material is thrown together in a pile, it will break down and decompose over time, however, due to the lack of air, the inner side of the pile will rot and therefore stink, and the decomposition will take place slower. It is necessary to build the compost pile on the ground and not on a surface, such as concrete, because then all the necessary organisms, such as earthworms, will not be able to get into it. It is also not recommended to make compost in a hole as there will not be enough air to decompose properly. Properly composted garden compost does not stink!

When is the compost ready?

Depending on the material to be composted, moisture and air access, composting technology, composting on average takes 6-12 months. The composting process is started by microorganisms, and then the temperature in the compost pile can reach 60 °C. As the temperature begins to drop, also visible organisms, such as earthworms, occur. When the compost is ready, it is loose, easily spreadable, does not contain sprouting weed seeds, has lost unpleasant odours. The state of the compost can be determined by a C:N ratio test and the absence of undesirable organisms and compounds. To make sure that the compost is ready it is possible to perform a cress test – by sowing cress in a small sample of the decomposed compost mass, if the compost is ready, a green cress carpet will form.

What should not be composted or towards what should be paid more attention?

Coloured printed and glossy papers should not be composted as they may contain heavy metals neither plastic-coated cardboard can be composted. The peels of various southern plants, such as citrus fruits, can be composted in small quantities, but should not be composted in large quantities, as these fruits are highly sprayed with pesticides. Wood ash is well suited for composting, but lignite and charcoal ash should not be used as it usually contains heavy metals. Plants with fungal or bacterial diseases need to be composted at 45 ° C for at least 4 weeks, and weeds need to be composted in the centre of the pile where higher temperatures are so that their seeds are not able to germinate. It is also possible to compost human excrement (dry toilet contents, sewage sludge), but then it is necessary to ensure certain conditions, for example, high temperatures.

Other composts

From the practice of permaculture, hillbeds (hugelbets) are becoming more and more popular, in the bottom of it garden materials (branches, grass, leaves, manure, weeds that compost) are stacked and a thick layer of soil covers the top. In apartment buildings, kitchen waste can be composted, for example, by placing a special container on the balcony, which also has holes to allow air access, paper or other structural materials and earthworms (Eisenia foetida) must be added to the kitchen waste. Controlled composting of sewage sludge is provided in special areas. Various digestates are also added to composts.