ifoam'96 Book of Abstracts 11th IFOAM Scientific Conference 11-15 August 1996, Copenhagen, Denmark

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Potato Fertilization with Biowaste and Manure. P1; 40

University of Helsinki, Lahti Research and Training Centre, FIN-15140 Lahti

Potatoes were fertilized with biowaste compost and horse manure during 1993 and 1994 and the harvests were compared with control plots. The after-effect on potato harvest was observed during 1995. Potato variety was Nicola. Soil type was loam (silty fine sand), with a pH of 5,5, Ca 624, P 15, K 157 and Mg 65 (mg/litre). Soil nutrient status can be described as fair for phosphorus and potassium, but some what poor for other nutrients and pH.
The amount of biowaste compost and horse manure used was 50 tons (120 m3)/ha in 1993 and 60 tons (150 m3) in 1994. The bedding material of horse manure was peat moss. In the composting process the biowaste (kitchen waste) was mixed with birch leaves, wood shavings and peat moss.
The amount of rain was normal (302 mm) in 1993, but the high temperature of May (12.9 C) caused the soils to dry. July was quite dry (35 mm) in 1994 with high temperatures (19.0 C). The year 1995 was very dry, but the harvest was fairly good without irrigation.
The harvests were lower in 1993 than in 1994, because of weather conditions. Horse manure gave a harvest of 25,4 tons/ha and control plots 12.6 tons/ha in 1993. Average harvest of horse manure plots in the year 1994 was 32.2 t/ha, of biowaste compost plots 31.0 t/ha and of unmanured control plots 17.6 t/ha.The effect of fertilization in 1994 was 83% for horse manure and 76% forbiowaste compost in addition to the harvest of control plots. The after effects of horse manure and biowaste compost in the year 1995 were almost identical, horsemanure gave a harvest of 19.9 t/ha and biowaste compost a harvest of 19.8 t/ha. The control plots gave only a harvest of 15.6 t/ha.
Conclusions: By biowaste compost it is possible to gain practically as high harvests as with horse manure. However, it should be examined, is the resulting inner quality of potatoes as good. For example, is the level of nitrates as low as in the case of potatoes fertilized with horse manure.