Soil Compressibility under Irrigated Perennial and Annual Crops in a Semi-Arid Environment

Abstract

ABSTRACT:In irrigated soils, a continuous state of high moisture reduces resistance of the soil to applied external forces, favouring compaction. The aim of this study was to evaluate the susceptibility to compaction of developed calcareous soils in irrigated annual and perennial cropping systems of the Apodi Plateau, located in the Brazilian semi-arid region. Four areas of irrigated crops were evaluated: banana after two (B2) and 15 (B15) years cultivation, pasture (P), and a corn and beans succession (MB), as well as the reference areas for soil quality and corresponding natural vegetation (NVB2, NVB15, NVP and NVMB). Samples were collected at layers of 0.00-0.10 and 0.20-0.30 m; and for B2 and B15, samples were collected in the row and inter-row spaces. The following properties were determined: degree of compactness (DC), preconsolidation pressure (σ p ), compression index (Cc), maximum density (ρ max ), critical water content (WC crit ), total organic carbon (TOC) and carbon of light organic matter (C lom ). Mean values were compared by the t-test at 5, 10, 15 and 20 % probability. An increase was seen in DC at a layer of 0.20-0.30 m in MB (p<0.15), showing the deleterious effects of preparing the soil by ploughing and chiselling, together with the cumulative traffic of heavy machinery. The TOC had a greater influence on ρ max than the stocks of C lom . Irrigation caused a reduction in Cc, and there was no effect on σ p at field capacity. The planting rows showed different behaviour for Cc, ρ max , and WC crit, , and in general the physical properties displayed better conditions than the inter-row spaces. Values for σ p and Cc showed that agricultural soils display greater load-bearing capacity and are less susceptible to compaction in relation to soils under natural vegetation.

Load-bearing capacity and critical water content of the coffee plantation soil with management in full sun and shaded

“…Load-bearing capacity is important in studies of soil compaction, sustainability of productive systems, evaluation of different agricultural management systems and traffic of machines and animals. In this regard, Tassinari et al (2015), Watanabe et al (2017) and Sousa et al (2019) are some examples of the soil LBC theory applied in agriculture. The capacity of a soil to support load depends on several factors, such as the drying and wetting processes of the soil, texture and mineralogy, soil bulk density, use and management adopted in the agricultural area, structure and soil water content, being these last two parameters of great contribution (Dias Junior et al, 2019).…”