Response of Jatropha(Jatropha curcas) to the combination of nitrogen, phosphorus and potassium fertilization and arbuscular mycorrhiza inoculation in four soil types in Samar Provinces [Philippines]

To establish the most advantageous fertilization scheme and soil nutrient management strategies for improved growth and yield of Jatropha curcas in four major soil types in Samar, this study was conducted to determine agronomic response and NPK uptake of Jatropha curcas to different levels of NPK fertilization and mycorrhiza inoculation. The experiment involved four levels of NPK application namely: 0-0-0 kg NPK/ha (T1), 15-15-15 kg NPK + arbuscular mycorrhiza (AM) inoculation (T2), 30-30-30 kg NPK/ha + AM inoculation (T3) and 60-60-60 kg NPK/ha. Jatropha were established and grown for 12 weeks in a pot experiment under open field conditions with all agronomic practices maintained at optimum levels. Results showed that the growth and development of jatropha grown on Catubig clayloam, Bugko sandy loam, Luisiana clay and Libertad clay have been affected by different levels of NPK fertilization and arbuscular mycrorrhiza inoculation. Plant height, number of leaves, number of branches, stem diameter and dry matter yield of jatropha was significantly increased with increasing levels of NPK fertilization. The N and K concentration in plant tissues with its corresponding uptake increased with increasing levels in N and K applied. On the other hand, the P concentration and uptake was higher in AM inoculated plants than those without AM even at higher NPK application rates. Based on the growth performance and the nutritional status of Jatropha grown for 12 weeks under pot culture conditions, a fertilization rate of 15 to 30 kg NPK/ha together with AM inoculation will improve significantly the growth and development of Jatropha grown in these different soil types depending on the inherent soil fertility and soil pH. Furthermore, the results implied that AM has a profound effect on P mobilization and uptake by the Jatropha plant especially in acid upland soils used in this study.