Rules of thumb for minimizing subsoil compaction

Abstract

Subsoil compaction is persistent and can affect important soil functions including soil productivity. The aim of this study was to develop recommendations on how to avoid subsoil compaction for soils exposed to traffic by machinery at field capacity. We measured the vertical stress in the tyre–soil contact area for two traction tyres at ca. 30‐ and 60‐kN wheel loads on a loamy sand at field capacity. Data on resulting stress distributions were combined with those from the literature for five implement tyres tested at a range of inflation pressures and wheel loads. The vertical stress in the soil profile was then predicted using the Söhne model for all tests in the combined data set. The predicted stress at 20 cm depth correlated with the maximum stress in the contact area, tyre inflation pressure, tyre–soil contact area and mean ground pressure. At 100 cm depth, the predicted vertical stress was primarily determined by wheel load, but an effect of the other factors was also detected. Based on published recommendations for allowable stresses in the soil profile, we propose the ‘50‐50 rule’: At water contents around field capacity, traffic on agricultural soil should not exert vertical stresses in excess of 50 kPa at depths >50 cm. Our combined data provide the basis for the ‘8‐8 rule’: The depth of the 50‐kPa stress isobar increases by 8 cm for each additional tonne increase in wheel load and by 8 cm for each doubling of the tyre inflation pressure. We suggest that farmers use this simple rule for evaluating the sustainability of any planned traffic over moist soil.

Seasonal dynamics in wheel load‐carrying capacity of a loam soil in the Swiss Plateau

“…We are fully aware that an evaluation at the 0.35 m depth does not necessarily imply zero compaction risk at deeper subsoil layers, as σ v could be larger than σ pc at another depth. Especially machinery with high wheel loads transmits high stresses also to greater depths (Schjønning et al ., ). Although having a higher regeneration potential, compaction of the topsoil should not be neglected either.…”

Retrieval of Sediment Fill Factor by Inversion of a Modified Hapke Model Applied to Sampled HCRF from Airborne and Satellite Imagery

“…Researchers have recognized soil compaction as an environmental degradation process which hinders the maintenance of soil quality [8][9][10]. The mapping of soil compaction plays a significant role in agriculture, specifically in improving crop production [8,10] and in other environmental and geophysical applications [9,[11][12][13][14]. Soil compaction can be quantified by measuring the bulk density or porosity [15].…”

Soil structure and microbial activity dynamics in 20‐month field‐incubated organic‐amended soils

“…A large change in BD (scaled with the initial BD) in this case indicates a reduced compressive strength and vice versa . These stress ranges were used because pressures exerted on topsoil by tyres of agricultural machinery range from 70 to 375 kPa, with an average of 200 kPa (Schjønning et al , ). Hence any stress range less than this average was considered to be small and vice versa .…”