MEASUREMENT OF SOIL ELECTRICAL PROPERTIES FOR THE CLASSIFICATION OF MANAGEMENT VARIANTS T. TÓTH 1, A. RISTOLAINEN 2,V. NAGY 3,D. KOVÁCS 1,CS. FARKAS 1 1 RISSAC, 2 MTT, 3 Institute of Hydrology Slovak Academy of Sciences 5 th Alps-Adria Scientific Workshop 7 March 2006, Opatija, Croatia

Scheme of this presentation -Objectives -Research transects -Instruments -Analysis of differences between management variants -Analysis of correlation between field values and laboratory data -Conclusions

Objectives Comparison of five field instruments, which are used as indirect techniques for the characterization of soil electrical properties, in order to distinguish classes of soil salinity, texture, vegetation and soil management. First question: are the instruments useful or not? The answer is given by ANOVA between management variants. Second question: what do the instruments tell us? The answer is given by correlation analysis between instrumental readings and laboratory measured values.

Data collection Data collection - Field measurements: EC a - electrical conductivity  - volumetric water content through  - 1 m interval - Soil sampling for analysing soil physical and chemical 5 m interval Site description Site description - Kiskunság Region, Hungarian Plain: mosaic-like soil cover - Three 70 m long transects on 10 Nov 2004

Rhoades et al.1999 Arrangement Amount/ratio of soil constituents: water, charged particles, ions, ConductivityEM & capacitance

EM= EMRC- 120 M_ec= Martek SCT CF_ec=Con- ductivity fork P_ec&P_ per= Plak percometer P_ec&P_ per= Plak percometer Volw= BR-30 Opera- tion principle Electro- magnetic induction Resistivity /conductivity Resistivity /conductivity Capa- citance Opera- tion fre- quency aprox. 10 kHz Hz500 Hz 75 kHz for EC=P_ec 50 MHz for wat.content= P_per 30 MHz Specifi- cations Coil spacing 1 m Dipole configuration, 0.90m el. spacing Wenner array, 0.48 m el. spacing Opera- tion depth m with vertical coil ~0.45 m~0.25 m0.20 m0.10 m Technical parameters of instruments

OPERATION PRINCIPLE OF EM & ECa METERS + variants of heights

CF_ec P_ec & P_per CF_ec CF_ec P_ecand P_per Instruments 1 -CF_ec (Conductivity fork, Geological Survey of Finland) -P_ec and P_per (cond/capac probe “Percometer”, Adek ltd., Est)

EM M_ec Volw M_ec Instruments 2 -M_ec (4 electrode resistivity sensor, Martek Instruments, US) EM -EM (EMRC-120 instrument, Hungary) Volw -Volw (capacitance probe “BR-30, RISSAC, Hungary)

Transect studies and differences between management variants

Non saline highest spot Slightly saline spot Saline lowest spot Transect 2 – salt-affected grassland with small shift in texture and big change in elevation

Low lying extreme saline spot

Extreme saline spot

Wheat in the lowest & least sandy spot Forest in highest & most sandy spot Transect 3 – across border of forest and wheat field with large shift in texture and big change in elevation

Transect EC (mS m-1) ForestHeadlandWheat significant differences between the 2 categories!!

Pasture Maize fallow Wheat Transect 1 – different soil management and crops, no changes in texture and elevation

Correlations

Correlation coefficients between different instrument readings in three transects (n=210). Values in Bold are statistically significant (p<0.01)

Correlations between field measured and laboratory values

Correlation between soil parameters sampled in the 3 transects at the depth of m and soil electrical conductivity (n=45). Values in Bold are statistically significant (p<0.01)

Conclusions Soil salinity, textural differences and also management variants can be distinguished with decreasing statistical significance The methods show close correlation between instrumental readings and with the laboratory standard methods