Use of geophysical survey as a predictor of the edaphic properties variability in soils used for livestock production

Nahuel R Peralta,Jose L Costa,Maria A Marino,Jose R Marques Da Silva,Pablo L Cicore

doi:10.5424/sjar/2015134-8032

Abstract

The spatial variability in soils used for livestock production (i.e. Natraquoll and Natraqualf) at farm and paddock scale is usually very high. Understanding this spatial variation within a field is the first step for site-specific crop management. For this reason, we evaluated whether apparent electrical conductivity (ECa), a widely used proximal soil sensing technology, is a potential estimator of the edaphic variability in these types of soils. ECa and elevation data were collected in a paddock of 16 ha. Elevation was negatively associated with ECa. Geo-referenced soil samples were collected and analyzed for soil organic matter (OM) content, pH, the saturation extract electrical conductivity (ECext), available phosphorous (P), and anaerobically incubated Nitrogen (Nan). Relationships between soil properties and ECa were analyzed using regression analysis, principal components analysis (PCA), and stepwise regression. Principal components (PC) and the PC-stepwise were used to determine which soil properties have an important influence on ECa. In this experiment elevation was negatively associated with ECa. The data showed that pH, OM, and ECext exhibited a high correlation with ECa (R2=0.76; 0.70 and 0.65, respectively). Whereas P and Nan showed a lower correlation (R2=0.54 and 0.11 respectively). The model resulting from the PC-stepwise regression analysis explained slightly more than 69% of the total variation of the measured ECa, only retaining PC1. Therefore, ECext, pH and OM were considered key latent variables because they substantially influence the relationship between the PC1 and the ECa (loading factors&gt;0.4). Results showed that ECa is associated with the spatial distribution of some important soil properties. Thus, ECa can be used as a support tool to implement site-specific management in soils for livestock use.

Highlights

The Argentinean pampas is a vast plain region of about 50 Mha and it is considered one of the most suitable areas for grain crop production in the world (Satorre & Slafer, 1999)
Principal components (PC) and the PC-stepwise were used to determine which soil properties have an important influence on electrical conductivity (ECa)
The model resulting from the PC-stepwise regression analysis explained slightly more than 69% of the total variation of the measured ECa, only retaining PC1

Summary

Introduction

The Argentinean pampas is a vast plain region of about 50 Mha and it is considered one of the most suitable areas for grain crop production in the world (Satorre & Slafer, 1999). On its southern portion (Flooting Pampas), the predominant soils of the region belong to the great group Natraquoll and Natraqualf (Soil Survey Staff, 2010). These soils exhibit a distinctive characteristic, which is the presence of a natric horizon (Btn), locally called ‘‘sodic’’ (Soil Survey Staff, 2010). They have a poorly developed drainage system, normally situated in flat landscapes, with a strong textural contrast between horizons and with halomorphism and hidromorphism processes (Taboada, 2006). A way to improve this type of management could be based on site specific agriculture technologies, improving soil-plant interactions knowledge and efficient production factors usage at farm and paddock level (Serrano et al, 2013)

Objectives

Methods

Results