Abstract
Spatial variability of soil properties at the field scale can determine the extent of agricultural yields and specific research in this area is needed. The general objective of this study was to investigate the relationships between soil physical and hydraulic properties and wheat yield at the field scale and test the BEST-procedure for the spatialization of soil hydraulic properties. A simplified version of the BEST-procedure, to estimate some capacitive indicators from the soil water retention curve (air capacity, ACe, relative field capacity, RFCe, plant available water capacity, PAWCe), was applied and coupled to estimates of structure stability index (SSI), determinations of soil texture and measurements of bulk density (BD), soil organic carbon (TOC) and saturated hydraulic conductivity (Ks). Variables under study were spatialized to investigate correlations with observed medium-high levels of wheat yields. Soil physical quality assessment and correlations analysis highlighted some inconsistencies (i.e., a negative correlation between PAWCe and crop yield), and only five variables (i.e., clay + silt fraction, BD, TOC, SSI and PAWCe) were spatially structured. Therefore, for the soil–crop system studied, application of the simplified BEST-procedure did not return completely reliable results. Results highlighted that (i) BD was the only variable selected by stepwise analysis as a function of crop yield, (ii) BD showed a spatial distribution in agreement with that detected for crop yield, and (iii) the cross-correlation analysis showed a significant positive relationship between BD and wheat yield up to a distance of approximately 25 m. Such results have implications for Mediterranean agro-environments management. In any case, the reliability of simplified measurement methods for estimating soil hydraulic properties needs to be further verified by adopting denser measurements grids in order to better capture the soil spatial variability. In addition, the temporal stability of observed spatial relationships, i.e., between BD or soil texture and crop yields, needs to be investigated along a larger time interval in order to properly use this information for improving agronomic management.
Highlights
Soil physical and hydraulic properties can change drastically over space [1] and time [2] and their evaluation is essential for a rational soil management and, for increasing crop yieldsWater 2019, 11, 1434; doi:10.3390/w11071434 www.mdpi.com/journal/waterWater 2019, 11, 1434 performance [3]
Results highlighted that (i) bulk density (BD) was the only variable selected by stepwise analysis as a function of crop yield, (ii) BD showed a spatial distribution in agreement with that detected for crop yield, and (iii) the cross-correlation analysis showed a significant positive relationship between BD and wheat yield up to a distance of approximately 25 m
They dynamically affect water balance components and crop yields by relating soil hydraulic functioning to climate patterns and crop water requirements [4,5]. Soil properties, such as saturated hydraulic conductivity, total organic carbon content, structure stability index, dry bulk density, as well as capacitive indicators obtained from the soil water retention curve were widely and successfully applied to investigate soil management effects on soil physical and hydraulic properties [3,6,7,8]
Summary
Soil physical and hydraulic properties can change drastically over space [1] and time [2] and their evaluation is essential for a rational soil management and, for increasing crop yieldsWater 2019, 11, 1434; doi:10.3390/w11071434 www.mdpi.com/journal/waterWater 2019, 11, 1434 performance [3]. They dynamically affect water balance components and crop yields by relating soil hydraulic functioning to climate patterns and crop water requirements [4,5] Soil properties, such as saturated hydraulic conductivity, total organic carbon content, structure stability index, dry bulk density, as well as capacitive indicators obtained from the soil water retention curve (i.e., plant available water capacity, relative field capacity, air capacity) were widely and successfully applied to investigate soil management effects on soil physical and hydraulic properties [3,6,7,8]. Investigations addressed at evaluating new experimental procedures for soil hydraulic characterization, and at establishing the usefulness and sensitivity of soil properties as predictors for crop yield, are needed This is a current issue in Mediterranean agro-environments, where water resources are scarce and need to be optimally managed [12]
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