Thickness of Soil Solum as a Parameter of PlantAVAILABLE Water Storage Capacity in Soils Underlain by Carbonate Rocks

摘要

Available water storage capacities were determined by field measurement in limestone-derived soils with a range in depths to carbonate rock of 15 cm to more than 300 cm. Neutron probe access wells were installed and amounts of water were determined throughout two growing seasons. Each soil layer had a characteristic volume of water (called observed field capacity) after recharge by rain periods. At maximum depletions, water approached 15 bar contents. Equations were developed for the prediction of available water (the volume difference between observed field capacity and 15 bar water) from three soil variables; clay content, chert-stone content and depth to carbonate rock. When effects of chert and clay were accounted for the prediction equation was: Total A. W.C.= 0.11 (cm depth - 102). Depths to limestone of less than 61 cm (67 cm A.W.C.) were too shallow to support forest canopies and the natural vegetation was prairie. Forest species survived where depths were greater than 61 cm and some depletion was observed at greater than 250 cm depth. (Author)