Influence of compost amendment rate and level of compaction on the hydraulic functioning of soils

Abstract

There has been widespread interest in using compost to improve the hydrologic functions of degraded soils at construction sites for reducing runoff and increasing infiltration. The objective of this study was to determine the effects of compost amendment rate on saturated hydraulic conductivity (Ks) and water retention in order to identify target compost rates for enhancing soil hydrologic functions. Samples were prepared with three soil textures (sandy loam, silt loam, and sandy clay loam), amended with compost at 0%, 10%, 20%, 30%, 40%, and 50%. All soils were tested at a porosity of 0.5 m3/m3, and the sandy loam was further tested at high (0.55 m3/m3) and low (0.4 m3/m3) porosities. The Ks and water retention data were then used to model infiltration with HYDRUS‐1D. With increasing compost amendment rate, Ks and water retention of the mixtures generally increased at the medium porosity level, with more compost needed in heavier soils. As porosity decreased in the sandy loam soil, the amount of compost needed to improve Ks rose from 20% to 50%. Water distribution in pore fractions (gravitational, plant‐available, and unavailable water) depended on texture, with only the highest compost rates increasing plant‐available water in one soil. Results suggest soil texture should be taken into consideration when choosing a compost rate in order to achieve soil improvement goals. Hydrologic benefits may be limited even at a high rate of compost amendment if soil is compacted.

Wildflowers and compost amendment can improve infiltration in soils impacted by construction

“…Finally, compost appeared to be more effecive in fine‐textured soils than course‐textured soils, similar to other studies (Aggelides & Londra, 2000; Kranz et al., 2022, 2023; Mohammadshirazi et al., 2017). Kranz et al.…”

“…Finally, compost appeared to be more effecive in fine-textured soils than course-textured soils, similar to other studies (Aggelides & Londra, 2000;Kranz et al, 2022Kranz et al, , 2023Mohammadshirazi et al, 2017). Kranz et al (2023) found that 20%-50% compost by volume was needed to increase infiltration depending on the soil texture. Compost application needs to be optimized to site-specific soil characteristics to be an effective soil amendment for post-contruction soil restoration.…”

“…Kranz et al. (2023) found that 20%–50% compost by volume was needed to increase infiltration depending on the soil texture. Compost application needs to be optimized to site‐specific soil characteristics to be an effective soil amendment for post‐contruction soil restoration.…”

Challenges in Sustainable Agriculture—The Role of Organic Amendments

“…Although compost can increase WHC due to its high organic matter content, its application does not necessarily affect PAW. Moreover, Kranz et al [84] reported that when sandy and silt loam soils with medium porosity were amended with high levels of compost, in some cases they would show NE on PAW. Also, they showed that a significant increase in PAW can occur after applying compost to sandy clay loam and high-porosity sandy loam soils.…”