THE INFLUENCE OF ORGANIC AND MINERAL FERTILISATION ON VEGETABLE GROWTH AND N AVAILABILITY IN SOIL: PRELIMINARY RESULTS
Soil samples taken from 0–30 cm, 30–60 cm and occasionally 60–90 cm, were analyzed for mineral N content several times during the growing season. Treatments with NPK application had the highest soil mineral N content throughout the experiment and the N uptake was closely related to the cabbage yield (R2=94%). Plants grown under mineral fertilisers were higher, heavier and larger than organically grown plants. The highest yield (8500 kg dry matter ha-1) was obtained with mineral fertilisation where N was supplied twice (before transplanting and during head formation), followed by mineral fertilisation in which the whole amount of N was added at transplanting time (7900 kg d.m.ha-1), then the treatment fertilised with FYM (6000 kg d.m.ha-1), compost (4200 kg d.m.ha-1) and, finally, the control (3700 kg d.m.ha-1).
Compost induced N immobilization during cabbage and spinach cultivation, despite its relatively low C/N ratio (C/N=17). However, spinach that was sown in September 1997 on the same field showed better emergence on the organically manured plots and, although the survival rate during winter was better on the NPK treatment, the yield (821 kg d.m.ha-1) was not significantly higher.