BIODEGRADABLE AGRICULTURAL MULCH (“Biologisk nedbrytbart jorddekke”)

SUMMARY The physical qualities and properties of the EcoCover™ paper mulch were investigated in the Nordic climate with focussing on paper biodegradation and durability, soil microclimate, plant growth and yield. The excperiments were performed by comparing the paper mulch with commercially available plastic- and starch-based mulches, which are commonly applied in row cultivation of single-season and perennial crops. In addition to winter trials with EcoCover test plots without any plant cultivation in the period from 2005 to 2006, summer tests were performed in 2006 using two crop plants, strawberries (cv. ’Korona’) and iceberg lettuce, which were studied in field trials to evaluate the effect of the biodegradable EcoCover paper mulch on biomass production. Climatic Data – Similar day and night temperatures under the EcoCover mulch could be observed when comparing paper mulch and test plots without any cover. When temperatures raised above 5 ºC in spring time and the following summer, day temperatures under the mulch were significantly lower (occassionally decreased by >10 ºC), compared to the black plastic and maize starch-based mulches, while lower temperatures under paper mulch at night did not exceed more than 5 ºC. The paper mulch showed very good properties in preserving soil humidity Biodegradation – Weight loss and degradation of the EcoCover paper mulch were studied in winter (2005/2006) and summer trials (2006) in order to evaluate its persistance. Dry matter of the paper mulch was decreased by an average of 12 % during the 6-months winter trial, and a faster, 13 % decrease during the 4-months summer trial as an effect of biodegradation. Weed Control – Both EcoCover paper mulch and plastic mulch showed similar effects of suppression of weed growth. In contrast, the rather poor strength of the maize mulch led to cover damage and resulted in increased weed growth in July and August. Plant Growth & Yield – Flowering and strawberry development showed similar progresssion for all studied mulch types. Most flowers were observed of the end of June, and most berries recorded of the end of July. Vegetative biomass production of aerial plant parts of both strawberry and iceberg lettuce was distinctly reduced as an effect of changes in microclimate, especially under-mulch temperatures during day time throughout the summer season. Leaf growth of strawberry plants grown on EcoCover paper mulch was 40-55 % lower than the control plants, and iceberg lettuce growth was reduced by even 60 % compared to the other mulches. The decreased production is probably due to light reflexion of the white paper mulch compared to the black plastic and maize-starch mulches. It is expected that under the plastic- and starch-based mulch a higher root/soil temperature would be obtained, and thus, would favour plant establishment after planting, growth and development when compared to EcoCover paper mulch.