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

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

Orlando, Florida

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

ASABE

Controlled traffic farming (CTF) is a mechanization 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. CTF systems require that implement and vehicle operating and track gauge widths are correctly matched. In well-designed systems, the area affected by traffic represents less than 20% of the total cropped area. The extent and distribution of soil compaction at locations laterally outboard of permanent traffic lanes may explain the performance of the crop grown in the rows nearwheel lanes. This compaction is influenced by lateral soil displacement caused by repetitive wheeling, soil conditions (strength), and soil-tire interaction at the time of traffic. The impact of compaction on crop rows adjacent to traffic lanes is also dependent on the seasonal effect of weather. This work was conducted to model the spatial distribution of soil mechanical strength under increasing number of passes of a farm vehicle to simulate the conditions that may be encountered in a CTF system at locations near-permanent traffic lanes. The study used a Typic Argiudoll (Rafaela Series, Argentina) and four traffic intensities (0, 6, 12 and 18 passes of a medium-sized tractor), which were applied to experimental plots using a completely randomized block design with three replications. The spatial distribution of soil strength within the wheeled and non-wheeled zones was determined using a cone penetrometer (depth: 0-300 mm) and geostatistical techniques. In all treatments, cone index showed a quadratic response with depth, which explained 70% of the variation in soil strength. The number of passes with the tractor did not show a significant effect on the range of spatial dependence of residuals. No differences were observed in the proportion of pixels where penetration resistance was >2 MPa (assumed to be the limit value of soil strength for root growth of most arable crops) between-traffic treatments, or wheeled and non-wheeled zones, respectively. The estimated overall mean proportion of pixels (4.86±4.5%) suggests a relatively high variability of this measure, which therefore needs to be considered in the design of future experimental work.