Kajian Status Hara Tanah di Bawah Tegakan Sistem Agroforestri Berbasis Karet di Kecamatan Bahorok, Kabupaten Langkat

Abstract

This research aims to examine the soil nutrient status in rubber agroforestry systems in Bahorok subdistrict, Langkat Regency affected by species combinations (rubber monoculture, rubber-Durio zibethitus, rubber-Elaeis guineensis, rubber-Garcinia atroviridis, rubber-Aquilaria malaccensis, rubber-Arenga pinnata agroforestry) and soil depths (0-20 cm, 30-60 cm). The survey method was based on the concept of Ex-post facto and designed by Factorial Randomized Block Design. The observed parameters were N-total, P-available, and exchangeable cations of K, Ca, Mg, and Na. Soil samples were taken by purposive sampling technique, and the data analysis was done by ANOVA followed by Duncan’s Multiple Range Test at 5%. This research was done on soil with the same texture class so that variations in the soil nutrient concentrations were not affected by the different soil characteristics but by the effect of different agroforestry types. The results demonstrated that the best rubber agroforestry system was rubber-Garcinia atroviridis agroforestry where the concentrations of N, K, Ca, and Mg were the highest, except the P-available. However, the rubber agroforestry systems were not significant to Na. The best soil depth on rubber agroforestry systems was 0-20 cm, which showed the highest concentrations of N and K compared to 30-60 cm, but the soil depths were not significant in P, Ca, Mg, and Na concentrations. The interactions between species combinations and soil depths in rubber agroforestry systems were not significant in all observed parameters.