Abstract:
There are three major climatic zones in Sri Lanka named as wet, intermediate and
dry zones according to the average annual rainfall. Potato has become an essential
food in Sri Lanka and the potato varieties grown in Welimada are also grown in
intermediate zones especially in Badulla district. The intermediate zone’s potato
highly affects the total local potato production. However, the intermediate potato
price is subjected to a price fluctuation within a short period of time and on some
occasions the price variation negatively affects the farmers as well as the customers
and subsequently farmers are unable to cover up their production cost. This study
investigates the factors affecting the variations of production prices of potato grown
at the intermediate zone of Sri Lanka, basically in the Badulla area. To that end, M5P
model tree algorithms were trained to find out the triggering forces behind this
issue and develop a producer price prediction model. Following features are
considered as independent variables for predicting the producer price of potato
grown at the intermediate zone; imported potato wholesale prices (IPW), producer
prices of Nuwara Eliya potato (NPP), rainfall (MxRB), minimum temperature
(MinTB), maximum temperature (MxTB), minimum relative humidity (MinRH) and
maximum relative humidity (MxRH) in Badulla district, extent (ExBP) and
production (PWPMT) of Welimada potato. The data were collected from the
Meteorological Department of Sri Lanka, the Hector Kobbekaduwa Agrarian and
Research Institute and the Census and Statistics Department of Sri Lanka, for the
period from 2005 to 2015. The dataset consists of 574 instances. The data were
preprocessed as there were missing values. Then the M5P models were trained and
tested using 10 fold cross-validation. The prediction quality of the models is
evaluated using the following factors and M5P smoothed model tree gave the best
prediction quality; Correlation coefficient: 0.744, Mean absolute error: 8.2511, Root
mean squared error: 10.7904, Relative absolute error: 62.6481 %, Root relative
squared error: 66.7029 %, out of all the M5P models. The model gave the eleven
(11) rules and according to the rules, it shows that the factors: NPP, MxTB and
MinRH positively affecting and ExBP, PWPMT, IPW, MxRB, MinTB and MxRH factors
negatively affectingthe producer price of intermediate zone’s potato. The outcome
of this study is helpful for the farmers to increase their profit of potato farming at
the intermediate zone by considering these factors for their cultivation planning
and it is able to predict the production price of potato in the intermediate zone in
Sri Lanka.
