Soil water under conventional and alternative cropping systems in cryoboreal subhumid central Alberta

Abstract

Soil water limits plant growth in the Canadian Prairie Provinces. Efficient use of soil water is, therefore, paramount in crop production. Two 2-yr field studies were conducted (i) to determine the effects of crop selection and cropping practice on the temporal and spatial distribution of soil water and (ii) to quantify water use and water-use efficiencies (WUE) of alternative crop/cropping systems for a subhumid region of Alberta. The first study was at the Ellerslie Research Station on an Orthic Black Chernozemic and the second at the University of Alberta Breton Plots on an Orthic Gray Luvisol. At each site three annual crops/cropping systems [barley (Hordeum vulgare L.), barley intercropped with field pea (Pisum sativum L.), and faba bean (Vicia faba L.)] and a perennial forage [creeping red fescue (Festuca rubra)] were grown in 1987 and in 1988. At Ellerslie, tillage methods to grow annual crops were conventional and zero tillage. At Breton, the two tillage methods used were: (i) conventional and (ii) deep tillage (to enrich the surface horizon with clay from the subsoil). The experimental design used was a split plot with four replications. Soil water was measured by neutron attenuation. Evapotranspiration was calculated as the change in soil water to 0.80-m depth plus precipitation. Soil water changes were more closely associated with the kind of crop grown than with the method of tillage used. The barley/field pea intercrop exhibited a pattern of water use similar to barley. Greater water-use efficiency measured in the intercrop system was attributed to differences in canopy structure and plant biomass production. Faba bean and red fescue had lower WUE than barley and the intercrop. The water requirement by faba bean was close to that of red fescue and related to leaf area development. Small tillage effects on soil water were observed during 1988. Soil water under zero tillage was greater than under conventional tillage. Faba bean and red fescue are likely to succeed more in agro-ecological regions such as Breton. Further studies are required to improve our understanding of the effects of these cropping systems on water resources when they are used in rotational-production systems. Key words: Barley, field pea, faba bean, creeping red fescue, conventiional tillage, zero tillage, deep tillage, water-use efficiency