Location: Dale Bumpers Small Farms Research CenterTitle: A vertical profile imaging method for quantifying rock fragments in gravelly soil
|JIANG, ZHOUDONG - Shenyang Agricultural University
|WANG, QUIBING - Shenyang Agricultural University
|ADHIKARI, KABINDRA - University Of Arkansas
|BRYE, KRISTOPHER - University Of Arkansas
|SUN, ZHONGXIU - Shenyang Agricultural University
|SUN, FUJUN - Shenyang Agricultural University
Submitted to: Catena
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2020
Publication Date: 5/1/2020
Citation: Jiang, Z., Wang, Q., Adhikari, K., Brye, K.R., Sun, Z., Sun, F., Owens, P.R. 2020. A vertical profile imaging method for quantifying rock fragments in gravelly soil. Catena. 193:104590. https://doi.org/10.1016/j.catena.2020.104590.
Interpretive Summary: It remains a challenge to quickly and accurately estimate rock fragment (RF) concentrations in a vertically exposure soil profile, which is important for field soil investigation. With increasing rock fragments in soils, there is a decrease in water holding capacity, soil organic carbon stocks, cultivation potential. Determining the quantity of rocks in soil takes time and significant expense so there is a need to develop rapid assessment tools to determine this important soil property. This paper describes an efficient, alternative method to evaluate a soil profile using photographs based on digital soil morphometrics. The procedure worked very well when compared to the traditional method of collection and measuring in the laboratory. This method is suitable for identifying and quantifying RF concentrations and distribution in a single photograph of a vertically exposed, alluvial soil profile with low-contrast and abundant rocks.
Technical Abstract: Rock fragments (RFs) play an important role in soils that can influence land use and management decisions. Rock fragment concentrations most often are visually estimated (VE) in the field, for which accuracy strongly depends on experience and practice of soil classifiers. The direct measurement (DM) method is more accurate, but is costly and labor-intensive. Due to its importance, a simple and inexpensive method for estimating RF concentrations without destructive soil sampling is necessary. The development of camera technology and digital image processing provide an opportunity for soil descriptions and quantitative analyses using an alternative soil profile imaging (PI) method. Therefore, the objective of this study was to explore the potential for RF concentration estimation using a PI method as compared to the VE and DM methods. Apart from VE and DM, different image processing procedures inside the PI method were compared in a stony, alluvial profile (Entisol) with low contrast among RFs in order to develop an alternative and efficient RF quantification method. Results showed that the hue-saturation-value (HSV) color model performed better than the red-green-blue color model for identifying RFs. The proposed profile imaging method accurately segmented 84.9% of the RFs from the soil matrix. The PI had a greater correlation with DM (r = 0.81) compared to the VE method (r = 0.78). Results showed that the alternative PI method could be used to accurately and efficiently estimate RF concentrations in a naturally stony soil profile with low contrast among RFs.