Spatial Variability of Saturated Hydraulic Conductivity and its Links with other Soil Properties at the Commune Scale

Abstract

Saturated hydraulic conductivity (SHC) is a key property for evaluating soil water movement and quality. Most studies on spatial variability of SHC have been performed soil at a field or smaller scale. Therefore, the aim of this work was to assess (quantify) the spatial distribution of SHC at the commune scale and its relationship with other soil properties, including intrinsic sand, silt, and clay contents, relatively stable organic carbon, cation exchange capacity (CEC), dynamic water content (WC), total porosity (FI), and dry bulk density (BD) in the surface layer (0–20 cm). The spatial relationships were assessed using a semivariogram and a cross-semivariogram. The studied commune (140 km2) with predominantly permeable sandy soils with low fertility and productivity is located in the south-eastern part of Poland (Podlasie region). The mean sand and organic carbon contents are 74 andobablyctknąć, czy o to chodzid mniej znacznie mniejszed? ? 0.86 and their ranges (in %) are 45-95 and 0.002-3.75, respectively. The number of individual samples varied from 216–228 (for SHC, WC, BD, FI) to 691 for the other soil properties. The best fitting models were adjusted to the empirical semivariogram (exponential) and the cross-semivariogram (exponential, Gaussian, or linear) used to draw maps with kriging. The results showed that, among the soil properties studied, SHC was most variable (coefficient of variation 77.3%) and significantly (p <0.05) positively correlated with total porosity (r = 0.300) and negatively correlated with soil bulk density (r = –0.283). The mean SHC was 2.597 m day–1 and ranged from 0.01 up to 11.54 m day–1. The spatial autocorrelation (range) of SHC in the single (direct) semivariograms was 0.081° (8.1 km), while it favourably increased up to 0.149–0.81° (14.9–81 km) in the cross-semivariograms using the OC contents, textural fractions, and CEC as auxiliary variables. The generated spatial maps allowed outlining two sub-areas with predominantly high SHC above 3.0 m day–1 in the northern sandier (sand content >74%) and less silty (silt content <22%) part and, with lower SHC in the southern part of the commune. Generally, the spatial distribution of the SHC values in the commune area depended on the share of individual intrinsic textural fractions. On the other hand, the ranges of the spatial relationship between SHC and the intrinsic and relatively stable soil properties were much larger (from ~15 to 81 km) than between SHC and the dynamic soil properties (0.3-0.9 km). This knowledge is supportive for making decisions related to land management aimed at reduction of hydraulic conductivity and chemical leaching and improvement of soil water resources and crop productivity.

Preparing Maps of the Distribution of Organic Matter and Calcium Carbonate in Northern Iraq

“…The study of the spatial distribution of soil chemical, physical, and fertility characteristics is of great importance in the management and successful use of the land, as indicated by [6]. [7] stated that the differences between soil series and inter-soil relationships are an important rule for inferring differences in the morphological characteristics of soil pedon and that recognizing the spatial variation IOP Publishing doi:10.1088/1755-1315/1262/8/082069 2 of soil and plant characteristics in agricultural fields allows for estimating plant growth conditions, making recommendations for fertilizers required for the agricultural area, and applying a management system. Good for the area, and this leads to the economy in time, effort, and money.…”