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)