Determining Soil Hydraulic Properties Using Infiltrometer Techniques: An Assessment of Temporal Variability in a Long-Term Experiment under Minimum- and No-Tillage Soil Management

Mirko Castellini,Giorgio Baiamonte,Alessandro Vittorio Vonella,Domenico Ventrella,Michele Rinaldi

doi:10.3390/su12125019

Mirko Castellini, Giorgio Baiamonte + Show 3 more

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https://doi.org/10.3390/su12125019

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Abstract

Conservation agriculture is increasingly accepted by farmers, but the modeling studies on agro-environmental processes that characterize these agricultural systems require accurate information on the temporal variability of the soil’s main physical and hydraulic properties. Therefore, specific investigations carried out in long-term experiments can increase our knowledge on the pros and cons of different measurement techniques. In this work, the simplified falling head (SFH) technique and the Beerkan Estimation of Soil Transfer (BEST) procedure were applied to investigate the temporal variability of some main soil physical and hydraulic properties, including bulk density (BD), field saturated hydraulic conductivity (Kfs), macroporosity (Pmac), air capacity (AC), plant available water capacity (PAWC), and relative field capacity (RFC). For this purpose, a long-term experiment was selected, and the experimental information obtained was used to verify the long-term impact (fifteen years) determined by two alternative forms of soil management, minimum tillage (MT) and no tillage (NT), for the cultivation of durum wheat. The main results of the comparison between MT and NT showed: (i) A comparable temporal variability in Kfs values when SFH was considered, given that in 75% of considered cases, the same result (i.e., significant or not significant) was obtained; (ii) a comparable temporal variability in Kfs values under MT (but not under NT) when both SFH and BEST were used, as a result of a possible Kfs,SFH overestimation under NT; (iii) differences in Kfs estimations by a factor of 6 or 7 (Kfs,SFH > Kfs,BEST) when comparable soil conditions (moisture and soil density) were considered; (iv) a comparable temporal variability when other soil indicators (BD, Pmac, AC, PAWC, and RFC) were simultaneously considered. After about fifteen years of field experiments characterized by continuous soil management and conducted with the methodological rigor typical of experimental farms, the SFH- and BEST-derived experimental information showed a substantial equivalence between MT and NT for the fine-textured soil investigated.

Highlights

The soil hydraulic properties are key information in many fields of agro-environmental research works, since they are necessary, for example, for simulating a few agro-environmental processes [1,2,3], for establishing agronomic adaptation strategies under climate change [4,5,6], and for quantifying economic and environmental impacts of alternative soil management [7,8,9,10].Many techniques are available in the literature for obtaining the hydraulic soil properties that differ in accuracy, specific skills for their application, and experimental efforts
Higher bulk density (BD) values were observed under no tillage (NT) than minimum tillage (MT), as, on average, they varied in the range of 0.98–1.19 g cm−3 under MT and 1.19–1.32 g cm−3 under NT
The temporal variability of some hydraulic soil properties was investigated over two years by applying the simplified falling head (SFH) and Beerkan Estimation of Soil Transfer (BEST) techniques in a long-term field experiment for wheat cultivation under minimum tillage and no-tillage soil management

Summary

Introduction

The soil hydraulic properties (i.e., water retention and hydraulic conductivity) are key information in many fields of agro-environmental research works, since they are necessary, for example, for simulating a few agro-environmental processes [1,2,3], for establishing agronomic adaptation strategies under climate change [4,5,6], and for quantifying economic and environmental impacts of alternative soil management [7,8,9,10].Many techniques are available in the literature for obtaining the hydraulic soil properties that differ in accuracy, specific skills for their application, and experimental efforts (costs and execution times). The evaporation method is widely used because it provides accurate estimations of soil hydraulic properties [11], but requires sampling of undisturbed soil cores and relatively laborious and time-consuming lab procedures. The simplified falling head (SFH) technique by Bagarello et al [12] allows the estimation of the field saturated hydraulic conductivity (Kfs) in a sufficiently accurate and repeatable way with relatively limited experimental effort. For these potentialities, it has been widely used to obtain Kfs in specific agro-environmental investigations on both herbaceous [13] and arboreal [14] agronomic crops. A literature review revealed that the SFH technique was successfully applied to investigate the influence of soil compaction on water infiltration rate due to cattle hooves or tractors [15], to assess soil hydraulic quality factors and develop a comprehensive soil quality index under different cropping systems [16], to study the soil physical quality response to sugarcane expansion in Brazil [17], and to investigate the impact of herbicide glyphosate on compost-amended soils [18]

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