Problems of abandoned fields
Department of Field Crop Husbandry, Estonian Agricultural University, Kreutzwaldi 64, 510014 Tartu, Estonia; e-mail: email@example.com
The study was based on data gathered in 1995–2002 in areas where plant cultivation was discontinued for various reasons and at various times. The objective of the study was to track changes in plant community, biomass production and soil weed seedbank in the abandoned fields.
The discontinuation of cultivation resulted in the emergence of plant communities, which were characterized for the first 1–2 years by a considerable proportion of annual species. The length of the period with annual species having a large representation in a community depended in many cases on the spread of Elytrigia repens in the abandoned fields. In land left idle for 5–6 years, perennial species supplanted annual species. Apart from E. repens, aggressive species turned out to be Cirsium arvense and Artemisia vulgaris (predominantly scattered all over the field). Weed seed density in the ploughed layer (30 cm) of abandoned fields amounted 157,000 to 666,000 seeds m-2, with the upper 10-cm layer accommodating up to 51% of the total seedbank. The biomass produced by plants depended on the texture of the soil and the age of the plant community, being 32.6 t ha-1 at the maximum. The accumulation of organic matter on and in the soil is a positive development in abandoned fields. Abundant residue contributes to an improvement of the physical and mechanical properties of the topsoil layer, reducing soil bulk density and decelerating soil compaction. The surface residue is a favorable environment for soil fauna.