The Importance of Spatial Soil Variability – Chilean Soil Types, Technology and Testing

It is of fundamental importance that management practices seek a more efficient use of available resources such as water and nutrients, and with less environmental impact. Unlike agriculture in other parts of the world, where most soil studies are carried out, Chile has mostly volcanic soils in agricultural production, so we need to expand the available local data.

Today, at the Institute of Agricultural and Soil Engineering (IIAS) [English:Institute of Agricultural Engineering and Soil] of the Faculty of Agricultural Sciences of the Austral University of Chile, the studies are funded by the DID-UACH project aimed at defining this variability with simpler and lower cost tools. The preliminary results of this project show that variables such as extractable aluminum and pH in sodium fluoride (NaF) are good tools to define different areas within the same series of soils. This has been validated in different soils of the Araucanía, Los Ríos and Los Lagos regions. Ultimately, the idea is to implement this type of analysis so that farmers can define areas within their farms and thus make more efficient use of their resources.

The evaluation of soil quality is a matter of absolute concern for the Institute, since several projects are currently being carried out among IIAS researchers to provide practical tools for farmers who seek to have higher soil quality standards.

Most of Chile’s soils in agricultural and forestry use (60%) are made of volcanic materials. They are called trumaos and nadi (Andisols) and reddish-brown clays (Ultisols). These floors have a series of unique characteristics that differentiate them from floors created by other materials. Less than 1% of the world’s soils are of this constitution, and they are highly productive. These unique properties are its low density (<0.9 g cm-3), alta retención de P (> 85%), high content of organic matter (> 10%), Fe and Al.

Much of the world’s soil studies are conducted with non-volcanic soils, for which the parameters are inconsistent with Andisoil soils. An example: apparent density, where values ​​around 1.6g/cm3 present serious problems for root growth in crops. However, Chilean soils have a classification of 0.3 to 0.75 g/cm3, presenting a considerable difference. Therefore it is essential to obtain local ranges of values ​​and critical thresholds of soil parameters – to know if the soil is of poor quality, or if it has lost quality. Analyze its functionality. Is it capable of retaining water, of draining? Its nutrient composition. Is it capable of filtering contaminants, etc.?

The Fondecyt de Iniciación project (11110238), under the direction of the Institute (IIAS), aims to counteract the lack of comparative data on soil quality in Chile. The idea, ultimately, is to give farmers these assessment tools with which they can better analyze whether the land should be used for crops, pasture or forestry, and whether the soil is losing, gaining or maintaining its quality over time.