Contribution of fresh-shredded green material to the nitrogen nutrition ofoilseed 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 t his study, as an alternative to composting, direct application of plant was tes has been evaluated in an on-farm experiment by quantifying the contribu tion to the nitrogen nutrition of winter oilseed rape and assessing the ris k of nitrogen immobilisation in soil. Within experimental field plots recei ving non-labeled green material, one-square metre subplots received 7.4 Mg ha(-1) of N-15-labelled fresh-shredded green material corresponding to 60 k g Nt ha(-1). After application and incorporation into the soil in autumn, 0 .50% of the total green material nitrogen was recovered in oilseed rape pla nts at harvest. Mulch application in spring resulted in a recovery of 1.62% of the green material nitrogen applied. Determination of the glutamine con tent in oilseed rape leaves, sampled at flowering, and CaCl2 extraction of the soil indicated that on the Black Earth Soil there was no temporal nitro gen deficiency of the fertilised crop or nitrogen immobilisation in soil. A s a comparison to N-15 uptake, 0.0125 M CaCl2 extraction of fresh-shredded green material was assessed as an estimation of the nitrogen contribution f rom green material to the following crop. This estimate was unsatisfactory for spring application, but was acceptable for autumn application.