Innovative greenhouse cultivation in compost barn

Abstract

This paper describes a new method in Norway for composting and its use for cultivation of plants in greenhouse. The composting is performed in a combined stable and greenhouse directly in the deep litter which is a mixture of cow manure and wood chips – a compost barn. This method is known in USA, Israel and the Netherlands. A newly constructed compost barn with 18 suckle cows was followed by four visits and samplings during 2017 and 2018. The focus was on compost quality for growth media and the plant growth performance. During summertime, when cattle were outdoors, tomato Lycopersicum esculentum, pumpkin Cucurbita maxima and squash Cucurbita pepo were cultivated. Compost was analysed for nutrients at the beginning and the end of season. Compost maturity was evaluated using different standards and methods such as sprout inhibitions, the Solvita®method and sensory assessment. The results showed a high compost pH. The compost C:N ratio was reasonable for plant cultivation but, it could be lower by letting the compost mature for more time. The temperature in the compost during the composting process was lower than expected. The evaluation of compost maturity indicated stable and mature compost. The challenge of cultivation directly in the compost seems achievable. During the first growing season, the compost seemed too moist and consequently there was a sciarid Sciaridae spp. flie plague. During the second season, the compost seemed too dry and consequently attracted mould. According to the farmers, the management of cattle using this system was comparable to conventional management in terms of the time and effort required. Animal welfare was no issue. A suggestion to improve compost quality is to add more woodchips from broadleaved trees to reduce the compost pH. It was concluded that using compost barns as greenhouses is promising and could be implemented in agroecological systems.