Effect of different types of fertilizer application on the fertility of oil palm reclamation soil under polyculture system

Due to high demand in food production, farmers have been applying high level of synthetic fertilizer in farm that often led to degradation of soil quality. Thus, application of fertilizer in a sustainable way will help to improve the soil quality. To evaluate the effect of different fertilizer application on soil fertility under polyculture cropping system (okra, water spinach and yard long bean), an open field experiment was conducted in the oil palm reclamation soil at the research farm in Innovation Centre in Agritechnology for Advanced Bioprocessing (ICA) UTM-Pagoh. The experiment was carried out with randomized complete block design (RCBD) with three replications for each treatment. There were five treatments involved which were: (T1) no fertilizer, (T2) organic fertilizer, (T3) inorganic fertilizer, (T4) organic-inorganic compound fertilizer and (T5) organic + inorganic fertilizer. The initial and final soil samples were collected to study the effect of different types of commercial fertilizer application on soil pH,electrical conductivity(EC), moisture content, bulk density, C/N ratio and nutrients (P and K) contents in the soil surface layer (0–15 cm) of the experimented site for 14 weeks. This study was conducted at an oil palm reclamation land consists of sandy loam soil. Results showed that the soil pH was lowest with an average of 6.05 units in T5 and was significantly higher in T1 (8.23 units). The EC value in T5 is highest with 172.4 ds/m and lowest in T1 with an average of 25.5 ds/m. T5 showed the highest soil moisture with 15.81%. Bulk density showed no significant different among all the treatment with the highest value was in T4 (1.22g/cm3) and lowest in T3(1.05g/cm3). The average amounts of C/N ratio ranged from 11.11 to 13.60 between all treatments with the highest ratio in T4 (13.6). The average P and K contents were highest in T5 (1564.7 mg/kg and 1056.2 mg/kg).Thus, it showed that the application with the mixture of organic and inorganic fertilizer (T5) able to improve the soil fertility which previously showed lower moisture and nutrient contents.