Field pea response to liming of an acid soil under two tillage systems

There is an increased use of no-tillage (NT) methods in soils of the Peace River region of Alberta-British Columbia where a good proportion of acid soils exist. There is little information, however, on how crops, soils, and weeds respond to liming under different tillage intensities. A Hythe clay loam (Gray Luvisol; initial pH in CaCl2 approximate to 5) was limed (7.5 t ha(-1)) in May 1991. Field pea (Pisum sativum L.) yield, soil properties, and weed populations under conventional tillage (CT) and NT were monitored during three growing seasons (1993-1995). The pH of limed soil in the 0-10 cm layer ranged from 6.0 to 6.3. Liming slightly increased NO3-N, P and bulk density of soil, lowered exchangeable Al concentration and wet aggregate stability, and had no effect on NH4-N and penetration resistance. Liming increased the grain yield by 0.50 (22%) t ha(-1) yr(-1) in CT and by 0.55 (18%) t ha(-1) yr(-1) in NT. Aboveground dry matter (DM) increase of 1.37 (27%) t ha(-1) yr(-1) in CT and 1.72 (25%) t ha(-1) yr(-1) in NT was obtained due to liming. Populations of annual broadleaf, annual grass and perennial weeds were not affected by either liming or tillage. Reduced soil acidity and exchangeable Al in conjunction with increased NO3-N and P contributed to increased crop yield by liming under both CT and NT. Higher soil moisture in the NT contributed to increased yield in comparison to CT system, as other soil properties and weed population were not significantly affected by tillage.