Book of Abstracts
11th IFOAM Scientific Conference
11-15 August 1996, Copenhagen, Denmark
1Norwegian Crop Research Institute (NCRI), Plant Protection Centre. Fellesbygget, N-1432 Ås. 2NCRI, Apelsvoll Research Centre, Landvik, N-4890 Grimstad
Research in organic vegetable production has been very limited in Norway although problems with weeds, pests and diseases sometimes are considerable. Likewise, nutrient supply, in particular N, is a major obstacle to achieving sufficient yield of good quality. Field trials (split plot, 3 blocks) are carried out in an experimental stockless farming system with the following rotation: 1. Spring wheat with undersown grass and clover 2. First year grass or clover seed production 3. Second year grass or clover seed production 4. Potato 5. Cabbage 6. Carrot. Each of the years 1994-96 one experiment is carried out in carrot and one in cabbage. Weed control strategies in cabbage and carrots. Living mulch of spring sown white clover in cabbage showed considerable yield depression. This strategy is not possible without measures to reduce competition from the white clover. Mulching in carrots did not reduce handweeding. Stale seed bed preparation considerably reduced the number of germinating seeds after sowing or planting and also reduced time needed fore hand weeding both in carrot and cabbage.
Reduction of pest attack. The cabbage plots with living mulch had fewer cabbage root fly or turnip fly eggs, and less damage from thrips. In one season with extremely high populations of diamondback moth, there were no differences in damage rates with or without mulch. There was no increase in damage from snails with living mulch. Attacks by other cabbage pests were too low to evaluate the effect of living mulch. The effect of nematodes as a biological control was negligible. Mulching in carrots gave higher yield and better quality one of the seasons because of greatly reduced damage from the carrot psyllid. Attacks by other carrot pests (carrot fly or cutworms) were too low too evaluate the effect of mulching or biological control by nematodes.
Diseases. Both treatment with Trichoderma harzianum and living mulch slightly reduced the clubroot attack (not statistically significant). In 1994, a significant interaction between T. harzianum treatment and living mulch in reducing club root was observed. Mulching in carrots did not influence the incidence of post harvest diseases. Cavity spot has not been observed in the experiment.
Fertilising with composted household wastes (CHW). Increasing amounts of CHW to cabbage resulted in a significant increase in total and standard I yield; the highest level giving significantly more loose and cracked heads in the field and more rotting during storage. The same yield effects of increasing levels of CHW were obtained in carrots, however no difference in market quality was observed. Medium amounts of CHW gave the significantly highest fresh and dry matter yield in potatoes. The different levels did not influence the distribution in size fractions nor the different market quality characteristics observed.
Sensory analysis, to examine the effect of increasing amounts of CHW and washing on the sensory quality of carrots, was carried out by a trained sensory panel. Different levels of fertiliser influenced the crispness and juiciness; the lowest level of fertiliser giving the best sensory quality. Unwashed carrot material showed a significantly less bitter taste than washed carrot material.