COMPARISON OF TILLAGE AND DIRECT DRILLING FOR ITALIAN RYEGRASS ON THE PROPERTIES OF A FINE SANDY LOAM SOIL

Abstract

The soil physical, biological, and chemical condition was assessed under cultivated and direct-drilled systems for the annual establishment of Italian ryegrass (Lolium multiflorum Lam.) on Prince Edward Island. After 3 yr, the degree of tillage-induced soil compaction and change in soil biological and chemical properties were determined over the 0- to 24-cm soil depth, and compared with the soil structure under a permanent timothy (Phleum pratense L.) pasture. The study was conducted at two sites on a Charlottetown fine sandy loam, an Orthic Humo-Ferric Podzol (Haplorthod). Although the tillage comparisons produced significant changes in soil porosity, pore-size distribution, pore continuity, aggregation and soil strength, the range in physical properties was within the range considered optimum for soil structure. Soil strength was shown to exhibit marked temporal variation over the growing season. Changes in the distribution of soil microbial biomass C and N, percent organic C, pH and plant nutrients were evident between the establishment methods. Generally, soil chemical and biological conditions under direct-drilling were similar to those under permanent pasture. Comparison of the actual with the estimated maximum bulk density down the soil profile indicated that the propensity for soil consolidation or compaction was the same under the direct-drilling and cultivated systems and similar to that measured under permanent pasture. The annual establishment of Italian ryegrass, for 3 yr, by direct-drilling did not adversely affect soil structure or increase soil compaction. Key words: Direct-drilling, Italian ryegrass, soil structure, soil biological properties, tillage