Increase in the Amount of Soil Organic Matter and Populations of Microorganisms by Addition of Different Types of Compost for Sustainable Agriculture

Maintaining a positive balance of organic matter in arable land is a fundamental issue for sustain¬able agriculture. Environmentally friendly and cost-effective solutions applicable to large areas and also to small farms are needed. This is especially true for areas affected by environmental processes, leading to deteriorating soil fertility and limiting opportunities for organic farming. Organic fertilization through composting is an effective method of maintaining soil fertility. Due to shortage of traditional organic fertil¬izers, new sources of organic matter are being sought, such as agricultural waste, sewage sludge, household or industrial waste. Identification of waste products and possibilities for their use in compost production with a certain composition was carried out. Physico-chemical characteristics of the starting materials be¬fore composting was carried out. Estimation of their effectiveness as soil improvers on two types of soils - leached cinnamon forest soil from the area of village of Chelopechene, near Sofia, Bulgaria and alluvial meadow soil from the area of Tsalapitsa, Plovdiv region, Bulgaria was accomplished. When composting the ameliorants with the first type of soil, all additives led to positive changes in soil organic matter, while composting ameliorants with the second type of soil, the added organic materials provided a lower degree of storage of organic matter. Therefore, compost addition to leached cinnamon forest soil is more reason¬able, ensuring good stock in the form of humin. Application of compost led to increase in the populations microorganisms, including bacteria and fungi, which is a good indicator of increased soil microbial activity in respective treatments.