Een onderzoek naar het voorkomen en de oorzaken van de verschijnselen, welke worden aangeduid met den naam "ontginningsziekte"

11 apparently diseased soils gave the same general symptoms of 'reclamation disease' with oats and peas in pot experiments. The number of microbes was smaller and the proportion fungi/microbes was always larger in diseased soils than in similar normal soils. As soil sterilisation brought no cure, the disease could not be ascribed to microbes. The widespread opinion that the disease occurred on a certain black peat (Du. Gliede) was confirmed by pot experiments, also if Gliede was mixed with sand.Two groups of organic substances could be separated by hot ethanolic extraction, one coming out of solution after cooling, the other remaining in solution. From the solution a crystalline substance could be obtained, afterwards called 'Gliedine', causing disease symptoms after application to peas and oats. At minute concentrations it stimulated growth of oats. The residue caused grey speck disease in oats.Fertilizer trials with differently diseased soils showed that only compost or CuSO4 could restore the soil (also in the 2nd year).As 'Gliedine' slowly evaporated at 100 'C diseased soils were heated 3 h per day for 3 days, resulting in restoration of slightly diseased soils, almost cure of moderately diseased soils, and delay of disease symptoms on very diseased soils.The curing effect Of CUS04 must very probably be ascribed to the formation of an insoluble compound with 'Gliedine'