Abstract:
Site specific management of soil pH and nutrients is important for the effective
use of soil inputs to obtain a higher yield at a minimum cost. This study was
conducted to explore the variability of surface soil pH and subsequent
delineation of potential management zones in an intensively cultivated vegetable
field in the Wet Zone of Sri Lanka. The experimental site was located in the
Doragala area which covers Kandy, Galigamuwa Lithosols complex. Thirty one
topsoil (0–30cm) samples were taken by employing a stratified random
sampling scheme. Soil pH was measured using 1:2.5 soil to 1M KCl.
Descriptive statistics of the soil pH were calculated using SPSS 18 statistical
software. The experimental variogram for soil pH was calculated and a
theoretical model was fitted using variowin software. A map of soil pH was
developed using the ordinary kriging interpolation technique. The fuzzy k means technique was used to establish the management zones. The soil pH
showed a normal distribution with a skewness of 0.231. Soil pH of the field was
in the range of 5.80 to 7.05, with a mean value of 6.41.The spherical model
fitted to the experimental variogram of soil pH showed a sill variance of 0.11
and a range value of 23.3 m. The ordinary kriged map showed a strong spatial
variation of the soil pH within the field. The fuzzyk-means classification
procedure revealed that the field can be divided into two potential management
zones. Moreover, the average soil pH values were significantly different across
these potential management zones (pH=6.1 and 6.7, respectively). This study
revealed that the within-field variability of soil pH in the selected field is
significant and this variability is sufficiently structured to identify two potential
management zones to support nutrient management. However, further studies
are needed to assess the production and economic benefits.
