Effects of water absorbent polymers on early growth performance of Eucalyptus grandis X urophylla clones in Kiboga district

Abstract

This study assessed the soil chemical properties at different planting sites, examined effects of amending different planting sites with hydrogel brands on growth of Eucalyptus grandis x Urophylla (GU) clonal seedlings and determined the optimum amount of hydrogel amendments that support field growth of GU clonal seedlings in Kiboga district. A 3 by 3 factorial Randomized Complete Block Design with three treatments and a control, and four replications was used to collect the data at two planting sites. Sixty sub soil samples were randomly collected from the planting sites at 30cm soil depth. Ten composite samples from two sites were taken to the laboratory for analysis of chemical properties. Soils at the planting sites were amended with different hydrogel brands (Prisma SPA and Altretgel) and GU clonal seedlings planted in soil amended with 0 g, 2 g, 4 g and 6 g hydrogel. Survival percentage, root collar diameter, height, number of leaves and branches were recorded after three months of planting. The study was conducted from November 2024 to February 2025. Data were subjected to analysis of variance and regression in R studio. Results showed that site A and site B had high base saturation (>80%). Site A had sandy clay loam soils while site B had clay loam soils with high Cation Exchange Capacity (20.9%). Ca, pH and ECE, showed significant linear relationship with survival percentage and number of leaves of GU clonal seedlings. GU clonal seedlings planted in soil amended with hydrogels registered higher survival (>65%) than seedlings planted in soils not amended with hydrogels. Hydrogel brands showed significant differences in growth of GU seedlings (p<0.05). Prisma hydrogel performed better than Altretgel in root collar diameter, height, number of leaves and number of branches. Treatment levels showed significant differences in growth parameters of GU seedlings (p<0.001). GU clonal Seedlings in soils amended with 4 g of Prisma hydrogel showed higher growth of GU seedlings at both planting sites. Overall, GU clonal seedlings planted in soil amended with hydrogels grew better than those planted in soil without hydrogel amendments (controls). Water absorbent polymers can enhance growth of GU clonal seedlings and improve overall above ground biomass (root collar diameter, height, number of leaves and number of branches) in semi-arid (Northern region) and dry subhumid (Central region) areas of Uganda. The study recommends Prisma hydrogel to be applied to enhance establishment of commercial plantation forests and On-farm tree growing. Soils should be amended with 4 g of Prisma hydrogel to enhance growth of GU clonal seedlings.