| Summary: | Knowledge about the biomass productivity of trees planted in a rainwater harvesting structure, i.e., a trench (<i>T</i>), relative to a normal pit (<i>P</i>) on degraded land is scarce. The objective of this research paper is to compare the effect of <i>T</i> with <i>P</i> on the growth and biomass production of the <i>Acacia saligna</i> and <i>Casuarina equisetifolia</i> which were planted on degraded land. All the individual stems of both species in the <i>T</i> and <i>P</i>, their diameters at breast height (DBH) and heights in 2016 and 2020 were measured. Species-specific allometric equations were used to quantify the biomass production of the studied species. The <i>t</i>-tests were used for data analysis; both <i>A. saligna</i> and <i>C. equisetifolia</i> individuals planted in the <i>T</i> had higher DBH and height increment as compared with <i>A. saligna</i> and <i>C. equisetifolia</i> that were planted and grown in a <i>P</i>. The results also revealed significant differences on the mean DBH and height of <i>A. saligna</i> and <i>C. equisetifolia</i> planted in a <i>T</i> and <i>P</i> (<i>p</i> < 0.05). Between 2016 and 2020, the total biomass (TB) of <i>A. saligna</i> planted in a <i>T</i> and in a <i>P</i> increased significantly (<i>p</i> < 0.05) on average by 25.5 kg/tree and 7.7 kg/tree, respectively (<i>p</i> < 0.05). Similarly, the mean TB values of the <i>C. equisetifolia</i> planted in a <i>T</i> and a <i>P</i> between 2016 and 2020 increased significantly (<i>p</i> < 0.05) by 28.9 kg/tree and 13.1 kg/tree, respectively. Finally, establishing trenches to restore degraded lands was shown to facilitate growth and biomass production of planted species on degraded land.
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