Effects of forage species and sward-lifting on compacted soil

Using shallow tillage (e.g. direct drilling) is one approach farmers could use to reduce establishment costs within dairy systems but soils are often compacted by machinery during field operations. Research has shown that different forage species may alter the physical properties of soil. An experiment investigating the effects of forage species established by direct drilling, either with or without sward-lifting, on soil compaction was established on a previously compacted area of silt loam at Trawscoed, Aberystwyth University. Treatments consisted of perennial ryegrass (Lolium perenne), white clover (Trifolium repens) or lucerne (Medicago sativa) established by direct drilling compared to ryegrass established by ploughing, with each of these treatments set up either with or without prior sward-lifting. The existing ryegrass sward was used as a control. Triplicate plots (17 x 3 m) of each treatment were sown on 17 July. Sward lifting reduced soil penetration resistance for all treatments in all soil layers between 7.5 and 37.5 cm but increased resistance in the 0 - 7.5 cm layer. Ploughing reduced soil penetration resistance in the top 22.5cm of soil. Soil penetration resistance within the 0 - 7.5 cm layer of soil was lower in existing ryegrass plots than lucerne plots during early establishment.