In natural settings, like forests, a harmonious cycle unfolds, where nutrients extracted from the soil by plants are seamlessly returned to nurture the Earth. Leaves, twigs, trees, and fruits falling to the ground provide sustenance for macro- and microorganisms, which decompose over time. Plants and fruits consumed by birds, deer, and other animals find their way back through manure, rich in essential nutrients like phosphorus. This natural process maintains a delicate balance in the soil, fostering an environment conducive to healthy plant growth.

As humans engage in agriculture, plants utilize nutrients to fuel growth and yield abundant harvests. However, if these nutrients aren't replenished, the soil gradually loses fertility. 

But what is soil fertility?

Soil fertility is the capacity of soil to retain, cycle and supply essential nutrients for optimal plant growth. Fertile soil can provide all essential plant nutrients i. e. nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, zinc, copper, boron, molybdenum, and nickel in amounts needed to produce yields with high quantity and quality.

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Although inappropriate use of chemical fertilizers can effectively boost harvests and provide these nutrients, they come with detrimental consequences, including increased costs, reduced soil microbial life, and groundwater pollution, ultimately leading to soil exhaustion. Declining soil fertility threatens the sustainability of the existing farming systems. Therefore, it is high time to promote  agroecological practices that focus on soil and water conservation adapted to local conditions.

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Composting as a Sustainable Solution

Recognizing the need for an alternative, composting emerges as a sustainable solution to replenish soil nutrients while addressing waste management challenges. Unlike chemical fertilizers, composting mimics the natural decomposition process, albeit at an accelerated pace, without the adverse side effects. This eco-friendly method aligns with the principles of agroecology, promoting a holistic and sustainable approach to agriculture. 

Composting proves to be a cost-effective and waste-reducing alternative to conventional practices. Instead of burning residues from yards, farms, or kitchens, these organic materials can be transformed into valuable compost, adding nutrients back to the soil. The process enriches the soil and contributes to a healthier ecosystem by preserving microbial diversity.

Preparation of Compost

Compost is a mixture of ingredients used as plant fertilizer to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plants, food waste, recycling organic materials and manure.

Factors to consider during the preparation of compost.

• Moisture content - The recommended moisture content of compost ranges between  40% to 60%; too high or too low will affect aerobic microbial activities. The moisture content could be measured using a compost moisture meter. Alternatively, visual check and hand feel could be used. If the pile is too dry, it will lack heat, and there will be little evidence of organic material breakdown. If the compost is too wet, it appears slimy and smells terrible.
• Temperature - Temperature is the result of microbial activities that determine the materials' interactions. Temperatures between 30-50 °C and 55-60 °C are conducive to mesospheric and thermophilic bacteria, respectively. Temperatures affect microbial growth and activities, hence the rate at which the raw materials decompose. Higher temperatures result in faster organic material breakdown, destroying weed seeds and killing pathogens. However, excessively high temperatures (>70˚C) can inhibit microbial activity. Temperature regulation is accomplished by turning the pile.
• Degree of Acidity - The material's acidity impacts the entire composting process. Too low an acidity level of the organic materials inhibits carbon dioxide and heat generation. A high acidity can cause excessive ammonia volatilization, leading to nitrogen loss. Turning or aerating your compost to improve air circulation and foster aerobic bacteria is the best way to reduce acidity. Also, be sure that there is plenty of “brown” material in the compost. Some folks say adding wood ash to compost will aid in neutralizing it. Add several layers of ash every 18 inches (46 cm.)‍
• Ventilation and oxygen supply - Air, especially oxygen is necessary for the multiplication of microbes involved in decomposing organic materials. Turn the compost regularly to ensure proper air circulation, which speeds the decomposition process by encouraging beneficial bacteria and fungi growth. Adequate ventilation and oxygen supply can reduce nitrogen loss and odour production and reduce the moisture of the compost products, making them easy to store.

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Advantages of composting

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1. Ensures nutrient recycling.
2. Reduces environmental pollution risks through proper handling and practices.
3. Increases the amount of organic matter in the soil.
4. Improves soil air circulation and water holding capacity.
5. Provides food for soil microorganisms and increase biodiversity, hence soil health.
6. Improves soil structure.

‍SAT Training Courses on Composting

Sustainable Agriculture Tanzania (SAT) offers hands-on training courses at the Farmers Training Center (FTC), guiding farmers and enthusiasts in composting and waste management. Our courses, such as Sustainable Waste Management and Composting, Conservation Agriculture, and Organic Agriculture Intermediate and Advanced, empower individuals to learn practical skills, providing valuable insights into creating compost and giving waste added value. 

Check out our training schedule at FTC for further information on available courses. Join us in embracing a sustainable and nature-inspired approach to soil fertility and waste utilization.