Maintenance of soil fertility on organic farm by modeling of crop rotation with participation alfalfa

Abstract

The aim of this paper is to maintain soil fertility on an organic farm without livestock production by using alfalfa green biomass. The research was carried out on the farm of Mokrin PP company, by modeling and sizing of crop rotation with alfalfa (Medicago sativa L.) on the non-carbonate humoglay. To ensure a cost-effective technical solution, alfalfa seed production was organized. In the autumn of 2015 alfalfa sowing was carried out in a field of 5 ha. Green biomass of the first and third cuttings, as well as crop residue after harvesting of seeds in the second cutting, were mowed and chopped by harvester for low silage and stored in the silage-pit. After nine months, a mature alfalfa compost was obtained with optimum values of total nitrogen (5.04%), organic matter (42.56%), C/N, pH, humidity, and EC. Two-year alfalfa utilization is the recommended time in this research because to the following benefits: in crop rotation, alfalfa field is provided with nitrogen by symbiotic ni­trogen fixation and the alfalfa is cultivated every five years in the same field, while in the middle of that period the field is fertilized with compost produced on the farm. The amount of compost obtained by crop rotation (2016 - 48.80 t; 2017 - 62.30 t) is enough for about 20% of the arable area per year. Thus, the fields are fertilized every fourth year with 10 t ha-1 of compost. Thanks to alfalfa biomass and seed and also nitrogen fixation, maintaining soil fertility is resolved in a sustainable and natural way.