Effect of dolomite application on available phosphorus status in Tea soils
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Date
2015
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Uva Wellassa University of Sri Lanka
Abstract
Tea (Camellia sinensis L.) is an important economic crop grown on highly weathered Oxisols and
Ultisols in Sri Lanka. Phosphorus (P) is one of the most important macro nutrient that influencing
growth, yield and quality of tea (Zoysa, 1997). Phosphorus deficiency is a concern, and a problem,
in most tea soils. Research shows that over 70% of tea soils are P deficient (Lin et al., 1991). The
availability declines rapidly as the soil pH falls below 5.5 or rises above 7. Therefore, measuring the
soil pH helps the tea grower to adjust soil chemical condition suitable for nutrient uptake and plant
growth (Zoysa, 2008). Dolomite is recommended for amelioration of acidity in tea soils. Present
investigation was carried out to identify the effect of application of Dolomite on soil available
phosphorus status in Tea Growing Soils.
Methodology
Site Description: This field experiment was carried out at field No 17, Midland’s Lower Division,
Ratota. Midlands is an estate(s) and is located in Central Province Matale District of Sri Lanka.
Long term experiment was initiated in 2009. The experiment was carried out by using tea cultivar
TRI 2023.
Experimental Design: Field experiment was laid out in Randomized Complete Block Design
consisting of five treatments in different rate of Dolomite (tons/ha/pruning cycle) namely T1
(Absolutely control), T2 (1), T3 (2), T4 (3), T5 (4). Each treatment replicated thrice.
Soil sampling and Analysis: Soil samples of two depths 0-15 cm and 15-30 cm were collected from
the randomly selected places in each plot as a bulk and sub sample was taken from the bulk after the
mixing. pH of soil suspension was determined by using pH meter(ORION 510A model, USA) with
Ag/AgCl combined electrode. Soil available phosphorous was extracted by Borax solution ( pH 1.5)
and phosphorus was determined by vanadomolybdate blue method (Beater,1949).
Statistical Analysis
The data generated from the study was subjected to Analysis of Variance (ANOVA) and treatment
means were compared least significance difference at probability p< 0.05 using SAS statistical
package version 9.1(SAS Institute, 1999).
Result and Discussion
Effect of application of different rate of Dolomite on soil pH
The effect of different rate of dolomite on pH in soils of 0-15 cm and 15-30 cm depths are presented
in Table 1.Increasing trend in pH was observed with increasing dolomite rates at 0-15cm depth but it
was not significant among treatment means. The highest value of pH was observed in T5 and it
significantly varied from other treatments at 15-30 cm depth. The optimum range of pH for tea is 4.5
to 5.5 (Anon, 2000). Application of different rates of dolomite did not exceed that level. It may be
due to the high buffering capacity of Ukuwela soil series (Liyanage, 2012). Some mechanisms which
affect the soil pH could not be controlled under field trial such as oxidation of applied N fertilizers,
exchangeable acidity, washing out of dissolved cations, leaching of Ca and Mg due to the nature of
the trial in field level. Due to plant uptake of these cations can alter the pH and those affect the
equilibrium of soil pH. When nitrogenous fertilizer of ammonical nature added to soil they are
nitrified and nitric acid is liberated.
Description
Keywords
Agriculture, Export Agriculture, Tea Industrials, Tea Technology, Soil Science, Chemistry