ORBi: Destain Marie-France - On-the-go georeferenced measurements of soil mechanical strength and differenciation of soil structure.

Reference : On-the-go georeferenced measurements of soil mechanical strength and differenciation of ...


	Document type :	Scientific congresses and symposiums : Paper published in a journal
	Discipline(s) :	Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
	To cite this reference:	http://hdl.handle.net/2268/80086

Title :	On-the-go georeferenced measurements of soil mechanical strength and differenciation of soil structure.
Language :	English
Author, co-author :	Destain, Marie-France [Université de Liège - ULg > > Gembloux Agro-Bio Tech >]
	Sirjacobs, Damien [Université de Liège - ULg > Département des sciences de la vie > Algologie, mycologie et systématique expérimentale >]
	Hanquet, Bernard [ > > ]
	Leemans, Vincent [Université de Liège - ULg > > Gembloux Agro-Bio Tech >]
	Verbrugge, Jean-Claude [Université de Liège - ULg > > Gembloux Agro-Bio Tech >]
Publication date :	2008
Journal title :	Geophysical Research Abstracts
Publisher :	European Geophysical Society
Pages :	EGU2008-A-07400
Peer reviewed :	Yes
On invitation :	No
Audience :	International
ISSN :	1029-7006
e-ISSN :	1607-7962
City :	Katlenburg-Lindau
Country :	Germany
Event name :	5th EGU General Assembly, 2008
Event date :	13-18 April 2008
Event organizer :	European Geosciences Union
Event place (city) :	Vienna
Event country :	Austria
Keywords :	[en] soil strength ; on-line ; mapping ; granulometry ; cohesion ; dry bulk density ; water content ; friction angle ; pF ; canonical variables
Abstract :	[en] Soil strength is defined as the resistance which as to be overcome to obtain a given soil deformation. Amongst the numerous methods developed to measure soil strength, two are classically used. On one hand, a laboratory method based on triaxial tests of undisturbed soil samples allows the estimation of cohesion and internal friction angle by the Mohr-Coulomb equation. On the other hand, measuring soil penetration resistance by pushing a cone into a soil is a widely used technique. Both techniques deliver discontinuous field information and are not suited to produce digital soil mapping. The objectives of this paper are to present a sensor able to continuously measure soil strength variations. The sensor was constituted of a thin blade pulled in the soil at a constant depth and speed and a beam which transferred the soil-blade forces to a transducer fixed on a vehicle. The transducer measures the draft force Fx, the vertical force Fz and the moment My thanks to an octagonal ring dynamometer. A measurement chain was developed to acquire simultaneously the signals provides by the soil strength sensor and those of a DGPS. Signal processing was notably based on geostatistics and allows soil mapping [1]. Four fields representative of the soils used in silty areas for arable production in Belgium were selected. The measurements were repeated several times during 1999-2003. Targeted test plots were chosen in each field to perform reference measurements, namely granulometry, cohesion, friction angle, pF, water content, dry bulk density, and cone index. The within-field studies revealed high variability caused by texture, history, traffic, etc., and showed a correlation between the sensor signals and physical parameters, such as cone index and soil moisture, as long as no over-consolidation of the soil occurred [2]. To assess the similarity of soil strength between the fields, the data Fx, Fz and My were classified by using canonical variates (CV). The two first CV represented 95.9 % of the variability, which means that two main variables contain the essential part of the information. In a plane (Fz, Fx), three clusters could be distinguished. The first one (trials 1 and 5), characterized by a low draft and a high Fz, corresponded to trials performed in March on soils ploughed during the winter, naked or covered with small vegetation, and characterized by small values of cone index. The second one (trials 2, 3, 4, 7) with high values of Fx and Fz grouped measurements done just after wheat harvest in August. The third cluster (trials 6) corresponded to measurements performed during wheat growth. It may be concluded that the signals from the sensor treated by suited statistical analysis have the potential to differentiate soil structures at a field scale. REFERENCES [1] Sirjacobs D., Hanquet B., Lebeau F., Destain M.-F. (2002). On-line mechanical resistance mapping and correlation with soil physical properties for precision agriculture. Soil and Tillage Research 64, 231-242. [2] Hanquet B., Sirjacobs D., Destain M.-F., Frankinet M., Verbrugge J.-C. (2004). Analysis of soil variability measured with a soil strength sensor. Precision Agriculture, 5, 227-246.
Research units :	Gembloux Agrobiotech - labo mécanique agricole
Funders :	Ministère de l'agriculture - Belgium
Name of the research project :	Agriculture de Précision
Target :	Researchers ; Professionals ; Students
Permalink :	http://hdl.handle.net/2268/80086
Other URL :	http://www.geophysical-research-abstracts.net/volumes.html

File(s) associated to this reference

Fulltext file(s):

	File	Commentary	Version	Size	Access
Open access	EGU2008-A-07400_Destain et al.pdf		Publisher postprint	9.31 kB	View/Open

All documents in ORBi are protected by a user license.

Dspace v1.5