One of the most important natural resources is the soil being the medium on which plants grow. This vital resource produces a bulk of what humans and animals consume as food (statistics have it that plants make up 80% of our food). Hence, it becomes very crucial to save and protect the soil from losing its nutrients.
Cultivators are saddled with the responsibilities of preserving the humus topsoil and maintaining the increase of its organic matter contents. This is necessary to improve the nutrient-providing ability of the soil and promote environment-friendly nutrient management.
To achieve the aforementioned the use of organic fertilizers appears at the forefront as opposed to the excessive use of chemicals considering the environmental impact they pose.
Compost is a cheap, easy to make and very effective material that can be added to the soil to improve crop quality. It is an organic matter (plant and animal residues), which had been decomposed by the actions of bacteria and other organisms, over a period of time.
Many types of organic matter, such as leaves, straws, fruits and vegetable peelings, and manures can be used to make compost. The end product is very different from the original materials, as it is usually dark or brown, crumbly and has a pleasant earthy smell.
Compost is a good fertilizer because it contains nutrients as well as organic matter, although using compost as the only means to maintain soil fertility is possible, a very large quantity would be required for large farms.
Against this backdrop, several other practices such as green manuring, mulching, agroforestry and improved fallowing could accompany composting in order to maintain lasting soil fertility.
Note: Composting animal manure makes it a much-enriched fertilizer.
Compost Making
A good composting process undergoes three stages, which include; the heating phase (fermentation), the cooling down phase, and the maturation phase.
Heating Phase
This is the first stage of composting
also known as fermentation or decomposition which helps to breakdown the
complex and tough fibrous materials in the organic matter contained in the pit.
Some factors that determine the effectiveness of this stage are:
1. The compost heap must be heterogenous – comprise different kinds of organic
materials
2. The right culture/ micro-organisms (bacteria) must be present (the
composting process happens due to the activity of micro-organisms and other
larger organisms like worms and insects)
3. Presence of adequate oxygen and water.
Maximum fermentation process takes place at a temperature of 60 to 70 ˚C in the compost heap. Extremely high temperature may kill the necessary microorganisms which abate decomposition. At appropriate temperature, many pathogenic germs which pose threat to man, animal and plant, are destroyed from the organic material.
Fermentation stage usually begins after four to five days and may take one to two weeks. Micro-organisms are essential to making the best compost and the types of organic material, moisture, air and temperature are critical to the optimal performance of the microbes.
Materials not ideal for
composting
• Plants recently sprayed with chemicals (pesticides or herbicides)
• Diseased plant material
• Persistent perennial weeds.
• Material with hard prickles or thorns
• Non-organic materials such as metal, glass or plastic
• Meat scraps, as these may attract rats and other pests
Note: With the aim of adding more nutrients or to speed up the composting process, some farmers add chemical fertilisers to the heap. Meanwhile, when composting materials are well selected and prepared the compost would have all the necessary nutrients.
Cooling Down Phase
During this period, new types of micro-organisms convert the organic components into humus. The heap remains clammy and hot inside and the temperature drops to about 30˚C.
This stage can be accelerated by regulating the temperature, air and water supply while the time needed for cooling greatly depends on the type of heap, the materials used, the climate and likely the attention given to it. The cooling down period usually takes a few months to sometimes a year (Especially if the condition is not favourable)
Advantages of Turning in Compost
1. It helps to destroy undesirable materials such as weed seeds, insects and disease-causing organisms by exposing them to the lethal temperatures at the centre of the pile.
2. Turning reduces odour problems because offensive odour is an indication that there is an imbalance compost system therefore the pile must be turned at the first sign of bad odour or ammonia smells.
3. Clumping can cause balls/layers in the compost pile where oxygen cannot penetrate; hence, turning helps to break up clumps and layers.
Note: Microbes also need moisture (of between 40 -60%) to thrive, therefore the heap must be kept moist, because the activities of decomposing organisms slowdown in dry piles. Accordingly, it must be noted that it is easier to add water to the heap than to drain it, therefore water should not be added in excess.
Maturation Phase
The temperature drops to match soil temperature in this last phase, depending
on the climate (between 15 to 25 ˚C). Large soil fauna (like earthworms and
termites) are active at this stage feeding strongly on decomposed organic
material, and in this way contribute to decomposition. The compost is ready for
use when it has a dark crumbly appearance and an earthy odour.
Compost versus Chemical Fertilizers
Compost is a better way of feeding plants compared to chemical fertilisers because the latter provide nutrients for plants only without a significant improvement in the structure or quality of the soil; they often improve the yields of crop only for the season they are applied.
Compost is not washed away through the soil like chemical fertilisers, as a result, its beneficial effects last longer.
Plants grown with chemical fertilisers are also said to be more attractive to pests and diseases because they have a greener, juicy growth while those grown with compost are reported to have a slower growth but are full of vigour and would better withstand pest and disease infestations.
For organic cropping systems, compost serves as a primary source of nutrients for the crop while in conventional cropping systems, compost provides a supplementary nitrogen source that compliments fertilizer nitrogen to provide a more sustainable farming system.
Note: In order to quickly supply a crop with the required nutrients, a chemical fertilizer may be necessary for immediate effect.
