Phytomass formation and carbon amount returned to soil depending on green manure crop
¹ Department of Field Crops and Grasslands, Institute of Agricultural and EnvironmentalSciences, Estonian University of Life Sciences, Tartu, Estonia; e-mail: email@example.com
² Department of Soil Science and Agrochemistry, Institute of Agricultural and EnvironmentalSciences, Estonian University of Life Sciences, Tartu, Estonia
The trials were carried out during the 2004–2006 growing seasons at the Department of Field Crop and Grassland Husbandry of the Estonian University of Life Sciences. Various green manures and ensuing cereals were studied in respect of phytomass formation and quantity of C returned to soil. The highest amount of organic matter was applied by red clover (8.91 Mg ha–1) and lucerne (8.41 Mg ha–1), and the lowest by unfertilized barley. The total phytomass of pure sowings of barley ranged, depending on the nitrogen fertilizer norm, from 6.55 to 11.54 Mg of dry matter per hectare, of which the grain yield constituted 37.3–43.2%. Sowings of lucerne and red clover added 3.44–3.82 Mg C ha–1 to soil, while sowing of bird’s-foot trefoil supplemented 1.99 Mg C ha–1. Preceding crop determined the phytomass of ensuing crops and the amount of C returned to soil. The amount of C of the oats grown after clover was 5.32 Mg C ha–1, whereas 3.28 Mg C ha–1 was returned to soil. Lucerne pure sowing resulted in 3.17 Mg C ha–1 returned to soil. When oats were preceded by barley (without manure), 2.53 Mg C ha–1 was returned to soil.