Contribution of fresh-shredded green material to the nitrogen nutrition of oilseed rape (Brassica napus) on a Black Earth Soil (Stagnic Phaeozem)

Recycling of plant waste materials from household, gardening and municipal origin to soils is usually done after an intermediate composting step. In this study, as an alternative to composting, direct application of plant wastes has been evaluated in an on-farm experiment by quantifying the contribution to the nitrogen nutrition of winter oilseed rape and assessing the risk of nitrogen immobilisation in soil. Within experimental field plots receiving non-labeled green material, one-square metre subplots received 7.4 Mg ha⁻¹ of ¹⁵N-labelled fresh-shredded green material corresponding to 60 kg N_t ha⁻¹. After application and incorporation into the soil in autumn, 0.50% of the total green material nitrogen was recovered in oilseed rape plants at harvest. Mulch application in spring resulted in a recovery of 1.62% of the green material nitrogen applied. Determination of the glutamine content in oilseed rape leaves, sampled at flowering, and CaCl₂ extraction of the soil indicated that on the Black Earth Soil there was no temporal nitrogen deficiency of the fertilised crop or nitrogen immobilisation in soil. As a comparison to ¹⁵N uptake, 0.0125 M CaCl₂ extraction of fresh-shredded green material was assessed as an estimation of the nitrogen contribution from green material to the following crop. This estimate was unsatisfactory for spring application, but was acceptable for autumn application. This revised version was published online in June 2006 with corrections to the Cover Date.