Nitrogen and carbon release during decomposition of roots and shoots of leguminous green manure crops

L. Talgre¹*, H. Roostalu², E. Mäeorg¹ and E. Lauringson¹

¹Department of Field Crop and Grassland Husbandry, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, EE51014 Tartu, Estonia
²Department of Soil Science and Agrochemistry, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, EE51014 Tartu, Estonia
*Correspondence: liina.talgre@emu.ee

Abstract:

In Nordic conditions, soils are frozen during winter, affecting the decomposition rates of crop residues. Hence, the decomposition rates of above- and underground biomass and the dynamics of the N and C released into the soil were studied in trials focused on green manure crops. The decomposition of the residue and N release from the residue varied among the five species of legume tested. There was a marked difference in decomposition rates between shoots and roots, which may also be explained by the differences in the chemical composition of the residue. The shoot residue decomposes rapidly and it serves as a source of N for the subsequent crop. The root residue decomposes more slowly and this had a positive effect in a crop rotation in the second year.

Key words:

The effects of green manures on yields and yield quality of spring wheat

L. Talgre¹, E. Lauringson¹, H. Roostalu² and A. Astover²

¹Department of Field Crops and Grasslands, Institute of Agricultural and Environmental
Sciences, Estonian University of Life Sciences, Tartu, Estonia
²Department of Soil Science and Agrochemistry, Institute of Agricultural and Environmental
Sciences, Estonian University of Life Sciences, Tartu, Estonia
E-mail: liina.talgre@emu.ee

Abstract:

A field experiment was conducted in the period of 2004–2006 to investigate the effect of green manure treatments on the yield and yield quality of spring wheat. In the experiment, different green manure crops were compared for amounts of N, C and organic matter applied into soil and their effect on the yield and yield quality of succeeding cereals. The amount of organic matter applied into soil was dependent on the cultivated crop. The highest amount of organic matter was applied with hybrid lucerne, the lowest, with unfertilised oats. With sowings of red clover, lucerne and hybrid lucerne, 4.91–7.70 Mg C ha-1 and 341.9–379.1 kg N ha-1 were added to soil with green material and roots. The yield of spring wheat on unfertilised soil was 2.12 Mg ha-1, but the treatment with hybrid lucerne as a preceding crop gave an extra yield of 1.45 Mg ha-1. Green manure crops did not have a unilateral effect on the quality of spring wheat. Grain yield grew with the increased norm of mineral nitrogen, but there was no significant improvement in quality indicators.

Key words:

biomass, crude protein, gluten index, grain yield, green manure crops, nitrogen, spring wheat