Spatial distribution of soil mechanical strength within a controlled traffic farming system as determined by cone index and geostatistical techniques

ALESSO, C.A.; CIPRIOTTI, P.A.; IMHOFF, S.C.; LINGUETTI, C.G.; MASOLA, M.J.

Orlando, Florida

Congreso; ASABE 2016 - Annual International Meeting of American Society of Agricultural and Biological Engineers; 2016

ASABE

Controlledtraffic farming (CTF) is a mechanization system in which all load-bearingwheels are confined to the least possible area of permanent traffic lanes andcrop is grown in permanent, non-trafficked, beds. CTF practices require the system to beorganized so that implement and vehicle operating and track gauge widths arecorrectly matched. In well-designed systems, the area affected by trafficrepresents less than 15% of the total cropped area. The extent and distributionof soil compaction at locations laterally outboard of permanent traffic lanesare useful to understandthe response of the crop to such a compaction. This compaction is influenced by lateral soildisplacement caused by repetitive wheeling, soil conditions (strength) andsoil-tire interaction at the time of traffic. Therefore, the impact ofcompaction on crop rows adjacent to traffic lanes is also dependent on theseasonal effect of weather. This work was conducted to model the spatial distribution of soilmechanical strength (penetration resistance) under increasing number of passes of a tractor to simulate the conditions that may be encountered in a CTF system. The study used a Typic Argiudoll (Santa Fe, Argentina) and four traffic intensities (0, 6, 12 and 18 passes of amedium-sizedtractor,which wereapplied to experimental plots using a completely randomized block design with three replications. Thespatial distribution of soil strength within the wheeled and non-wheeled zones was determinedusing acone penetrometer (depth:0-300 mm)and geostatisticaltechniques. In all treatments, cone index showed a quadratic response with depth,which explained approximately 70%of thevariation insoil strength. The number of passes withthe tractor did not show a significant effect on the range of spatial dependence of residuals. Nodifferences were observed inthe proportion of pixels where penetration resistance was >2MPa (assumed to be the threshold for root growth)between-traffic treatments, or wheeled and non-wheeled zones, respectively. The mean proportion was4.86% (± 4.5%). These results showed the high variability of this measure whichshould be taken into account to design further experiments