Effect of Hydrogel soil amendment on survival and growth of Melia volkensii under field conditions in Nakasongola District
Hydrogels are known to aid early seedling establishment in water-stressed environments. However, inadequate information on the amount of hydrogel required for different species under varying aridity regimes limits their wide application. This study examined the optimal quantity of hydrogel required for soil amendment to maximize survival and growth of Melia volkensii one of the most resilient tree species suitable for small-scale, large-scale commercial planting and utilisation in semi-arid areas. To assess this potential, three-month-old seedlings of M. volkensii were planted in the field in a Randomized Complete Block Design (RCBD) with three replicates. The treatments included four levels of hydrogel concentration (0g (Control), 5g, 10g and 15g). Seedling Survival and Root Collar Diameter (RCD) were measured once every month for six months. Height increment was stopped at four months after the plant tips were damaged by wild animals while soil moisture content was measured once at the end of six months. One-way Analysis of Variance (ANOVA) was used to analyse the data with repeated-measures. Results indicate that application of hydrogel increased survival from 50 to 90% (Mean= 40%±SE). Height and root-collar diameter increased significantly almost two fold higher in hydrogel-amended soils compared to the control. The optimum quantity of hydrogel for M. volkensii was found to be 5g per planting hole. Results further showed increased tree survival, following hydrogel application to sandy loam soils under moisture-stress environments. Thus, hydrogel use can be a promising technology for improving the productivity of sandy soils in drought prone areas such as the cattle corridor of Uganda. Therefore, it is recommended that for field application aimed at ensuring tree seedling survival, establishment and growth, hydrogel should be applied in five (5) grams per planting hole.