Seasonal changes in the structure of clay soils in relation to soil management and crop type. II. Effects of cultivation and cropping at Compton Beauchamp

Abstract

SUMMARY The effects of direct drilling and ploughing on the structure and macroporosity of a clay soil at Compton Beauchamp, Oxfordshire, growing winter wheat, were studied using large thin sections (10 * 5 * 3.5 cm) and image analysis of photographs of fluorescent resin impregnated soil blocks. Composite coarse angular to subangular blocky and medium to fine granular aggregates were present in the top 3 cm of the direct drilled soil and in the top 10 cm of the ploughed soil. Settling of the soil and coalescing of these aggregates took place throughout the year under both treatments, but was most marked in the ploughed soil. In the subsoil (20 to 30 cm) most of the structural changes could be attributed to changes in the soil water content. Swelling in the winter led to the closure of the most macropores and shrinking in the spring and summer led initially to the development of vertical planar macropores and then to large cracks. Freezing and thawing in the winter created many very small subcuboidial aggregates at the soil surface which later coalesced as a result of raindrop impact.

Effect of Tillage Systems on Spatial Variation in Soil Chemical Properties and Winter Wheat (Triticum aestivum L.) Performance in Small Fields

“…Since the CT plots had been tilled for the last time 11 months before soil sampling, settling occurred in the soil profile and reduced the spatial variation. Mackie-Dawson et al [51] found that, after a tillage operation, structural changes due to settling occur between planting and harvesting, especially near the soil surface, whereas, Kader et al [52] found that tillage management (reduced tillage vs. CT) had limited influence on organic matter fractions in the surface layer of silt soils under cereal-root crop rotations in the Belgian loess belt. However, Perfect and Caron [53] identified a statistically significantly higher soil spatial variability (p < 0.05) in the contents of water and C tot in the upper 10 cm of soil in long-term NT compared to CT; possibly, their sampling time, which took place immediately after tillage operations in the CT plots contributed to the large difference between NT and CT.…”

Comparison of porosity in a Chernozemic clay loam soil under long-term conventional tillage and no-till

“…Most studies have generally reported a higher total porosity (surface soils) for CT than NT (Pagliai et al 1983(Pagliai et al , 1984Shipitalo and Protz 1987;Mackie-Dawson 1989;Pikul et al 1990;Drees et al 1994). Some studies, however, have reported greater porosity in NT than CT (Moran et al 1988) or no difference in total porosity (Singh et al 1991;Pagliai et al 1995).…”

“…Pores under NT are dominantly biopores (Francis et al 1988) or craze planes (Boone et al 1976), and are oriented parallel to the soil surface (Shipitalo and Protz 1987). More abundant biopores in NT than CT have been attributed to earthworm burrows (Boone et al 1976;Shipitalo and Protz 1987;Mackie-Dawson et al 1989;Drees et al 1994).…”

Application of Micromorphology to Study Manuring Practices: A Case Study from Bronze Age in Cornwall, UK

“…The cases-studies regarding prehistoric manuring practices from Northern Isles of Scotland and England demonstrate that midden heaps were not only ploughed insitu, but it was also intentionally disbursed over the fields during Neolithic, Bronze and Iron Age. The examples of the Neolithic midden cultivations in UK are from Pool, Sanday, Orkney [36], Tofts Ness or Old Scatness, Shetland, Skara Brae [14], Noltland, Westray [37], and Hazleton North, Gloucestershire [38]. It is suggested that the Neolithic farmers did not only cultivated earlier midden, probably created during the Mesolithic period, but they have also used those from their own creations [39].…”