Abstract
Degradation of soils, including salt accumulation, is one of the serious problems in agricultural production, particularly greenhouse culture for vegetables and flowers in Japan. This problem still remains as one of the major subjects in horticulture to be solved.
In this paper, we firstly analyzed some chemical components of the soils collected from three types of greenhouses with different periods of use ranging from 9 to 24 years.
The pH of shallowest layers of top-soils in the houses was 4.0 to 4.4, and the EC of the same layers ranged from 1 to 3.2mS cm-1. These are signigficant evidences to present the salt accumulation in the soils. From the analytical results with the ion chromatography, the contents of water soluble SO4-, NO3-, Cl- and Ca2+ in the greenhouse-soils tended to be higher in shallower layers, and with increasing the periods of use. The yearly increase rate of EC and ionic contents were calculated, and then, the range of production limits for greenhouse soils was estimated from the experimental results to be about 30 years.
