Spatial distribution of soil mechanical strength in a controlled traffic farming system as determined by cone index and geostatistical techniques
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Kuupäev
2020
Kättesaadavus
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Abstrakt
Controlled traffic farming (CTF) is a mechanisation system in which all load-bearing
wheels are confined to the least possible area of permanent traffic lanes and where crops are
grown in permanent, non-trafficked beds. In well-designed systems, the area affected by traffic
represents less than 15% of the total field cropped area. The extent and distribution of soil
compaction at locations laterally outboard of the permanent traffic lanes may explain the
performance of the crop on the rows located either side of the wheeling. This compaction is due
to lateral displacement of soil caused by repetitive wheeling, the effect of soil-tyre interaction and
the soil conditions (strength) at the time of traffic. The impact of compaction on crop rows
adjacent to permanent traffic lanes is also dependent on the seasonal effect of weather, because
of changes in soil water availability. This work was conducted to model the spatial distribution
of soil mechanical strength under increasing number of tractor passes to simulate the soil
conditions that may be encountered in CTF systems at locations near-permanent traffic lanes. The
study was conducted on a Typic Argiudoll (26% clay, 72% silt, 2% sand) with four traffic intensities
(0, 6, 12 and 18 passes) using a 120 HP tractor (overall mass: 6.3 Mg). Traffic treatments were
applied to experimental plots using a completely randomized block design with three replications
per treatment. The spatial distribution of soil strength within wheeled and non-wheeled zones was
determined using a cone penetrometer (depth range: 0–300 mm) and geostatistical techniques. In
all treatments, cone index showed a quadratic response with depth, which explained between 67%
and 88% of the variation in soil strength. The number of tractor passes had no effect on the range
of spatial dependence of residuals. No differences were observed in the proportion of grid cells
where penetration resistance was greater than 2 MPa (considered to be the soil strength limit for
root growth of most arable crops) between-traffic treatments, or wheeled and non-wheeled zones,
respectively. The overall mean proportion (± 95% confidence interval) of grid cells (4.9 ± 4.5%)
suggested that this measure has a relatively high variability and therefore may not be a reliable
parameter to be used in the design of future experimental work.
Kirjeldus
Märksõnad
field traffic, soil compaction, soil mechanical properties, soil penetration resistance, articles