ENERGETIC EVALUATION OF GREEN MANURE PREPARATION FOR ORGANIC FARMS

Organic agriculture should be based on living agro-ecological systems and cycles, where biodiversity plays an important role. Perennial legumes are often planted to supply nitrogen, enhance nutrient cycling and availability to other crops in the rotation. Legume aboveground mass is often used as green manure in crop production farms. However, in the case of large green manure and nitrogen content incorporation, it is not always possible to control the intensity of organic matter mineralization processes. It can have a deleterious effect on soil and water quality or climate change (due to N2O and NH3 losses). Therefore, there is a need for such green manure preparation methods, which could accumulate mobile nitrogen in biomass. The aim of the study is to assess preparation techniques of red clover (Trifolium pratense L.) aboveground mass as green manure, namely mulching, ensiling and composting in terms of productivity (output rate), fuel and energy costs, and the production cost. In accordance with the decreasing amount of energy used, green manures lined up as: green manure-straw compost > green manure silage > fresh green manure (mulching). Preparation methods affect green manure quantity and quality. The cost evaluation of green manure preparation methods revealed that ensiling of red clover mass is more expedient compared with composting.