Soil organic substances positively affect carbon dioxide environment in greenhouse and yield in strawberry

Abstract

Changes in the CO2 concentration were measured, in 15 commercial strawberry green houses where various amounts of organic substances had been applied. With these data, the rate of CO2 evolution and the number of exchanges during the night were estimated for each greenhouse, the effects of the soil organic matters on the CO2 environment in greenhouse, and CO2 assimilation and yield in strawberry were investigated. The soil carbon content was higher in greenhouses, where a large amount of organic substances had been applied over a long period, compared to greenhouses where lesser amounts were applied. The rate of CO2 evolution from the soil was positively related to the total carbon content of the soil; the CO2 in the aerial environment increased with the high rate of CO2 evolution, especially in greenhouses with low ceilings and a small number of atmospheric exchanges. In greenhouses where strawberry plants were grown with nutrient film technique and no organic substance was applied, the rate of CO2 evolution was low. The light conversion efficiency and the net amount of CO2 assimilated in the morning increased with the increases in the rate of CO2 evolution and maximum CO2 concentration before sunrise. There was also a significant correlation between the soil carbon content and commercial yield. To supply plant nutrients and/or to improve soil physical conditions are important functions of soil organic matters; for protected strawberry production, the source of organic carbon for respiratory substrate for soil microorganisms, should be one of the most important functions of organic fertilizers and soil amendments.