Soil Conductivity as a Measure of Soil and Crop Status—A Four‐Year Summary

Abstract

Animal manure can be an important resource providing soil available N for plant needs, but determining the nutrient availability resulting from such amendments is difficult. A study was conducted to examine changes in electromagnetic induction (EMI) soil conductivity and available N levels during four growing seasons in relation to manure or compost application and use of a green winter cover crop. With simultaneous soil samples, a series of soil conductivity maps of a research cornfield were generated using a global positioning system (GPS) and EMI methods. The Clay Center, NE, site was treated during a 10-yr period with a winter wheat (Secale cereale L.) winter cover crop (1CC) and no-cover crop (2CC). The site was split for subtreatments of manure and compost at rates matching either the P or the N requirements of silage corn (Zea mays L.). Differences between the 1CC and 2CC treatments for values of NO 3 -N and water-filled pore space (WFPS), as estimated by apparent electrical conductivity (EC a ), were compared for each year. Differences in profile weighted soil conductivity explained 79.5, 98.0, 93.4, and 98.4% of the variability due to NO 3 -N differences, and only 20.5, 2.0, 6.6, and 1.6% of the variability due to WFPS differences for years 2000, 2001, 2002, and 2003, respectively. Sequential measurement of profile-weighted soil electrical conductivity (EC a ) was effective in identifying the dynamic changes in plant-available soil N, as affected by animal manure and anhydrous ammonia fertilizer treatments during four corn growing seasons.S USTAINABLE AGRICULTURE requires innovative and practical tools to optimize farm economics, conserve soil organic matter, and minimize negative environmental impacts (Johnson et al., 2003). Electromagnetic induction soil conductivity sensors may provide one such tool. Profile weighted EC a can provide an indirect measure of important soil properties (Davis et al., 1997). The EMI instrument is sensitive to factors that influence soil conductivity, including (i) soil moisture content, (ii) amount and type of salts in solution, and (iii) the amount and type of clays present (Brune and Doolittle, 1990). Electromagnetic techniques are well suited for mapping soil conductivity to depths useful for agriculturalists (McNeill, 1990). Electromagnetic induction soil conductivity has been shown to be a very useful tool in locating seepage from animal waste lagoons (Ranjan et al., 1995); Eigenberg and Nienaber (2003) found values to correlate well with salt levels at an abandoned composting site. Sudduth and Kitchen (1993) used EMI methods to estimate clay pan depth in soil. Electromagnetic methods have been used to map soil salinity hazards (Williams and Baker, 1982;Corwin and Rhoades, 1982). Electrical conductivity methods have been shown to be sensitive to high nutrient levels (Eigenberg et al., , 2000 and have been used to detect ionic concentrations on or near the soil surface resulting from field application of cattle feedlot manure. Electrical conductivity has gene...

Electromagnetic Induction Sensor Data to Identify Areas of Manure Accumulation on a Feedlot Surface

“…Th ese methods have been used to correlate EC a values with salts contained in animal manure (Eigenberg et al, 2002(Eigenberg et al, , 2005Eigenberg and Nienaber, 2003). Traditional methods for using covariate information to estimate the spatial distribution of specifi c ionic constituents use techniques like cokriging (Isaaks and Srivastava, 1989) or kriging with external drift (Wackernagel, 1998).…”

“…Specifi c details on the EMI equipment and techniques used for this study are described in Eigenberg et al (2005Eigenberg et al ( , 2008. Briefl y, a Dualem-1S meter (Dualem Inc., Milton, ON, Canada) was used to collect EC a data from the feedlot surface.…”

Runoff Water Quality Characteristics Following Swine Slurry Application under Broadcast and Injected Conditions

“…The increase in soil NO 3 -N content may have contributed to larger EC measurements. Eigenberg et al (2006) reported that sequential measurement of profileweighted soil EC could be used to identify dynamic changes in plant-available soil N. No significant differences in WSP, BKP, NH 4 -N, or pH values were found between test dates on the control plots.…”

Grazing Management, Season, and Drought Contributions to Near-Surface Soil Property Dynamics in Semiarid Rangeland

“…As a relative measure of the total quantity of ions in soil solution, electrical conductivity has been proposed as an integrative assessment for monitoring coupling/decoupling of nutrient cycles (Patriquin et al 1993). Positive associations between electrical conductivity and extractable N in nonsaline and noncalcareous soils are well established (Smith and Doran 1996;Eigenberg et al 2006), and highlight the potential role of electrical conductivity as surrogate for available N, which, in turn, affects key metabolic processes contributing to greenhouse gas flux (Robertson and Vitousek 2009). Given the relative ease of in-situ assessments of electrical conductivity (Johnson et al 2001;Arnold et al 2005), extension of nearsurface electrical conductivity findings toward relative categorizations of greenhouse gas ''hot spots'' (e.g., field areas associated with former watering sites or bale grazing) may serve to facilitate spatially strategic management practices aimed at reducing N loss from grazing lands.…”