The study sought to determine the effects of fertilizer on growth performance of Para rubber (Hevea brasiliensis) saplings planted in NGP-Agroforestry site in Dumabel, Aglipay, Quirino, Philippines. The growth performance was observed using the following parameters: height and diameter increments, crown diameter and number of leaves.

The statistical analysis indicated that there were significant differences in height and diameter increments. Direct influences of fertilizer on crown expansion and leaf production are unclear. In light of agroforestry system influences, the inherent biophysical factors in the agroforestry site may have contributed to the performance of the rubber saplings. However, the condition of the study area is still at its incipient stages and so the effect of vegetation, soil changes and microclimate are yet to be quantified better. In all, the results of the study reflect those fertilizers are essential input to growing rubber trees in once-degraded areas.

Lastly, Treatment 6, N₂PK (8 grams of Urea, plus 12 grams of Superphosphate and 6 grams of Potassium Chloride) is the optimum fertilizer treatment for the Para rubber saplings which gives the highest diameter and height increment of 2.1 cm and 0.85 m respectively, within six (6) months period.

Thesis (Master of Science in Forestry - Forest Resources Management)

Includes appendix and bibliographical references.