| Summary: | The objectives of study were 1) to determine the effects of soil physical and chemical
properties to the oil palm productivity, and 2) to determine the physical and chemical properties
of the soil that becomes the limiting factor of oil palm productivity. The experiment was
conducted in oil palm plantations belonging to the Asian Agri Group, namely Bahilang (North
Sumatra), Aek Kuo (North Sumatra), Topaz (Riau) and Badang (Jambi), by collecting secondary
data in each research site since 2008 to 2012.
The research was conducted in nested design, and tested factor was the level of soil
fertility. Soil fertility levels were nested at each research site, while the blocks were nested at
each soil fertility level. Secondary data collected were physical and chemical properties of soil,
productivity of oil palm, oil extraction rate (OER) and the content of free fatty acids (FFA).
While the primary data collected from research sites were the content of chlorophyll a, b, and
total, nitrate reductase activity (ANR), as well as the content of proline in the leaf tissues of oil
palm. Data were analyzed with Analysis of Variance (ANOVA) at 5% levels, and continued with
the correlation and regression analysis to determine the pattern of the relationships between
physical and chemical properties of soil with leaf tissue analysis results, oil palm productivity,
and the contents of FFA as well as OER.
The results showed that four oil palm plantations that became the objects of research
have the optimal soil physical properties, especially from the side of the proportion of sand, dust
and clay fractions, so that it was not the limiting factor of oil palm productivity. The soil pH as
well as P and K contents in the soil were the main limiting factor of oil palm productivity in the
research sites. The contents of N, Mg and Ca in the soils of all research sites were already high
so that the dosage application of N, Mg and Ca were reduced in the future fertilization program.
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