Impact of organic amendments from date palm residues on water retention properties of two coarse texture soils

Abstract

The cultivated dryland soils of North Africa present low fertility and productivity due to low organic matter content (Brahim et al., 2021). Date palm residues are an abundant resource in these regions and only a minor part is recovered in oasian agroecosystems. The ISFERALDA project – Improving Soil FERtility in Arid and semi-arid lands using Local organic DAte palm residues – aims at developing the use of organic amendments based on traditional production (composting and slow pyrolysis) as a key tool to improve soil fertility and soil properties.The objective of this study was to quantify the effects of compost and biochar based on date palm residues on soil water retention. Two soils with properties similar to North Africa soils (sandy loam texture, alkaline pH, low organic matter content) were collected in a semi-arid Mediterranean area of southeast Spain. In addition, and in order to test further the influence of soil texture, soil sand content was artificially increased by supplementing the natural soils with washed quartz sand. The different types of organic amendments were tested at a dose of 60 t/ha (Edeh et al., 2020): compost alone, biochar alone and mixture of compost and biochar (50:50 in weight). Water content was measured using pressure membrane apparatus at nine different matric potential (pF), ranging from the saturation to the permanent wilting point.The results showed that water retention was higher in soil with organic amendments regardless of the pF and the soil type. For a specific soil, the addition of biochar alone or in combination with compost to the soil resulted in higher values than compost alone. The improvement in water retention properties was more pronounced for soils amended with sand. Thus, composting and/or pyrolysis of date palm residues is a viable alternative to improve the water retention properties of sandy and loamy soils. Keywords:Date palm – arid and semi-arid lands – organic amendments – soil water retentionReferences :Brahim, N., Karbout, N., Latifa, D., & Bouajila, A. (2021). Global Landscape of Organic Carbon and Total Nitrogen in the Soils of Oasis Ecosystems in Southern Tunisia. Agronomy, 11, 1‑17.Edeh, I. G., Mašek, O., & Buss, W. (2020). A meta-analysis on biochar’s effects on soil water properties—New insights and future research challenges. The Science of the Total Environment, 714, 136857. https://doi.org/10.1016/j.scitotenv.2020.136857