NITROGEN RESIDUES OF FIELD BEANS (VICIA-F ABA L) .1. NITROGEN ACCUMULATION AND NITROGEN RESIDUES

The objectives of the study were the variability of nitrogen accumulat ion and nitrogen residues of field beans (Vicia faba L.) as dependant on growing conditions. Moreover, the relations between the seed yield production and the nitrogen residues of field beans were investigated. Factorial field experiments were conducted in 1990 at one location in cluding two cultivars (Alfred, Mythos) and in 1991 at two locations in cluding one cultivar (Mythos) but two different row distances (20/25 c m, 40 cm) at identical planting densities. At maturity the dry weights of the plants (dt/ha), the N-content (%), the N-amounts (kg N/ha) acc umulated in vegetative plant fractions and the seeds separately, and t he N(min)-residues (kg NO3-N/ha) in the soil were measured. The accumu lated amounts of nitrogen and the nitrogen residues of comparable trea tments differed as dependent on growing conditions up to 225 and 90 kg N/ha, respectively and as dependant on row distances up to 90 and 65 kg N/ha, respectively. The residues were composed of quantitatively di fferent fractions of very different N-contents and C: N-relations. The N-residues in vegetative fractions were positively correlated with th e seed yields.