Estimating the chemical composition of the soil solution of glasshouse soil. 1. Compositions of soil solution and aqueous extracts.

Abstract

Press extracts, saturation extracts and 1:5 by-weight extracts obtained from 75 glasshouse soils were analysed for EC and K, Na, Ca, Mg, NO3, Cl, SO4, HCO3 and P. The analytical data are discussed, with the exception of the HCO3 and P contents of press extracts, as these were much lower than the HCO3 and P contents of equilibrium solutions of the soils. The water-saturated soil pastes from which the saturation extracts were obtained were prepared from both field-moist and air-dry soil. They stood overnight at 25 degrees C before filtration. This overnight storage was unsatisfactory for NO3, as it induced denitrification in the saturated pastes prepared from air-dry soil. Hence, for the determination of NO3, saturation extracts were prepared from air-dry soil, with pastes standing only two hours before filtration. The suspensions from which the 1:5 by-weight extracts were obtained were prepared from air-dry soil and stood overnight at 25 degrees C before filtration. Again overnight storage proved unsatisfactory because of denitrification. Thus, for the determination of NO3, 1:5 suspensions were prepared, this time with a storage period of only two hours. (Abstract retrieved from CAB Abstracts by CABI’s permission)