IMPROVEMENTS IN SOIL TILTH AND RAPESEED EMERGENCE BY LIME APPLICATIONS ON ACID SOILS IN THE PEACE RIVER REGION

Abstract

The tilth of two acid soils, a Gray Luvisol and a Gleysol, was assessed in field experiments in which CaCO3 was applied 5–6 yr previously and fertilizer applied annually. The CaCO3 caused a major shift in distribution of dry aggregates towards coarser fractions in the Gray Luvisol and a smaller shift in the Gleysol, indicating that the CaCO3 increased the resistance of these soils to pulverization by preceding cultivations. Also, the CaCO3 increased soil moisture in one instance and increased rapeseed (Brassica campestris L.) plant emergence in general. Both CaCO3 and Ca(OH)2 in this and other field experiments darkened the soil color and altered soil cracks, even as quickly as over winter. In contrast the fertilizer applications did not affect soil appearance, dry aggregates, soil mositure or emergence of rapeseed. In a second set of field experiments, Ca(OH)2 applied 9 yr previously shifted dry aggregates to coarser sizes and increased rapeseed emergence for the Gleysol, and it tended to increase rapeseed emergence on three of four other soils. Organic matter in the soils was decreased by the Ca(OH)2. The direct improvement in tilth by these liming materials is strongly indicated, even though the soils had low ESP and normal exchangeable Mg/Ca ratios. The apparently rapid, though long-lasting improvement in tilth by lime may have important agronomic significance.