Daniel Jorajuría

Influence of the axle load, tyre size and configuration on the compaction of a freshly tilled clayey soil

Abstract Enhancement of the potential root growth volume is the main objective of farmers when they establish a conventional tillage system. Therefore, the main function of primary tillage is to increase soil’s structural macroporosity. In spite of this, during secondary tillage operations on these freshly tilled soils, the traffic on seedbeds causes significant increases in soil compaction. The aim of this paper was to quantify soil compaction induced by tractor traffic on a recently tilled non consolidated soil, to match ballast and tyre size on the tractors used during secondary tillage. The work was performed in the South of the Rolling Pampa region, Argentina. Secondary tillage traffic was simulated by one pass of a conventional 2WD tractor, using four configurations of bias-ply rear tyres: 18.4×34, 23.1×30, 18.4×38 and 18.4×38 duals, two ballast conditions were used in each configuration. Soil bulk density and cone index in a 0 to 600 mm profile were measured before and after traffic. Topsoil compaction increased as did ground pressure. Subsoil compaction increased as total axle load increased and was independent from ground pressure. At heavy conditions, topsoil levels always showed higher cone index values. From 150 to 450 mm depth, the same tendency was found, but with smaller increases in the cone index parameter, 22 to 48%, averaging 35%. Finally, at the deepest layer considered, 600 mm, differential increases due to the axle load are great enough as to be considered similar to those found in the upper horizon, 36 to 64%, averaging 55%. On the other hand, bulk density tended to be less responsive than cone index to the traffic treatments. Topsoil compaction can be reduced by matching conventional bias-ply tyres with an optimized axle weight.

Sobrecompactación del suelo agricola parte I: influencia diferencial del peso y del número de pasadas

The main objectives of this research were: to determine the responsability of weight, number of passes and independent variables, on the vertical distribution of subsoil compaction and to obtain evidence to decide upon the convenience of matching equipments with light or heavy tractors, according to their differences in passes on the field. Field tests were carried out on grassland, on a typic Argiudol with a soil moisture below, but near to field capacity. The dependent experimental variable was the induced soil compaction and was related to bulk density (assessed with gamma probe), penetration resistance (measured with an electronic cone penetrometer), and remaining grassland yield, six and eight months after traffic treatments were applied. Data from two tests, with two phases of data logging were analysed, totalizing a three year period of assessment pursuit. Results did not show differences between heavy and light treatments in the shallower depth range. Nevertheless, highly significant differences were shown if the deepest range is considered. Decrease in grassland yields ranging from 7 to 25% were measured in out-of-track areas, and 52 to 76% in intrack areas. It was concluded that the number of repeated passes on the same tramlines of a light tractor, can do as much or even greater damage than the heavier tractor with fewer passes. Ten is the critical number of passes, beyond it, advantages taken from the use of a light tractor are lost.

Resistência específica do solo de um pomar frutícola relacionada ao manejo entrelinhas e intensidade de tráfego

Orchard production traffic demands have characteristics that is called controlled traffic. Tractors and its machines, always use the same tracks in each of their passage. Not only this negative condition, but the fact that the irrigation used is usually excessive, it leads to a highly potential condition to enhance over-compaction in Alto Valle region in Argentina. This paper is part of a thesis refered to the possibility of introducing changes in the manner of the phytosanitary applications are done. These changes consist in leaving the fixed calendar method to the one proposed by the Integrated Orchard Production program of the INTA. In an apple orchard field, on two soil conditions, with and without grass, traffic corresponding to a whole year management passages of a tractor and it sprayer were simulated for both systems. Penetration resistance was assessed before and after traffic, and related to induced compaction. Over-compaction values were measured more frequently on non-grassed soil if control plot was considered. Edaphic reology was different for each soil condition after traffic was applied. Traffic decreases due to Integrated Orchard Production management and were of significant importance if a sustainable system is the target.

Comportamento mecânico do solo sob tráfego em dois sistemas de preparo do solo

A former concern related to agricultural soil, under no tillage systems, might be the state of compaction due to farm machinary traffic. Two treatments corresponding to two different tillage systems (disk plowed, LC, and no tillage, SD) included four traffic subtreatmets (0; 80; 160, and 240 Mg km ha-1) on a Typic Hapludert. Cone index (IC) and dry bulk density (DA) were the experimental dependent variables asessed. Soil reology under traffic had a different behaviour in both treatments. In both treatments for the higher traffic intensities (160 and 240 Mg km ha-1) statistical significant difference (P < 0,05) were measured when compared with the control plots, when the IC was considered. Considering LC treatment and the higher traffic intensities, the dry bulk densities values measured arised to 1.83 Mg m-3, the disk plowed, and no tillage under traffic soils reologies are different. If the depth of the maximum response in terms of IC measurements is considered, a direct relationship between traffic intensities and depth, could be stablished.

Compactación inducida por el tráfico de máquinas en suelo forestal

Se realizaron ensayos en campo para evaluar los efectos del trafico de cosecha y extraccion sobre las propiedades fisicas del suelo en una plantacion de alamos (Populus sp.). Fueron evaluadas: a) zonas sin transito vehicular y b) zonas transitadas por maquinaria de cosecha y extraccion. Para ambas situaciones se efectuaron mediciones de resistencia a la penetracion, humedad y densidad aparente. La resistencia a la penetracion en las zonas transitadas resulto significativamente mayor hasta los 150 mm de profundidad, siendo el efecto del transito detectable hasta los 380 mm. A partir de los 150 mm ambos tratamientos superaron valores de 1,5 MPa, que reducirian el crecimiento radicular. La densidad en los sectores con transito resulto significativamente mayores, siendo en los primeros 80 mm significativamente menor respecto a los estratos mas profundos para ambos tratamientos. La presencia de capas de elevada densidad aparente influye en la compactacion superficial.