Time series analysis of wheat moisture content variations for grain storage systems

Abstract

The Philippines is one of the many countries that consume and produce wheat grains. Despite having agricultural resources, the country still struggles to supply wheat and continues to import tons of wheat from different countries. Moreover, being a tropical country, the weather conditions exacerbate the parameters in defining grain quality, and thus, impact the preservation of grains in bulk storage systems. This study aims to understand the fluctuations of moisture content over time and its impact on grain quality and identify trends to utilize in optimizing storage systems management practices. Furthermore, this study investigated the moisture content variations, analyzed the temporal dynamics, and forecasted future trends using the ARIMA model, which can effectively handle time series data and has been applied in several agricultural applications. From the correlation patterns from lag intervals of the correlogram, there is a total of 24 ARIMA models generated with varying (p, d, q) values. These models were then evaluated using log-likelihood, AIC, RMSE, and MAE to select the best-performing and most appropriate model for forecasting wheat moisture content data. Out of these 24 models, Models (4,0,3), (4,0,4), and (1,0,0) are the top performing models, however, Model (4,0,3) emerged as a strong forecasting model in predicting wheat moisture content trends for the forthcoming two-year horizon. Its evaluation performance resulted in a log-likelihood of −69.38384, AIC of 156.7677, RMSE of 0.4248, and MAE of 0.30427, having the least values in three of the validation methods. When used in forecasting, the trend of the moisture content continues to consistently fall within the lower end of the accepted range. The distribution of the predicted values also shows a perfectly normal distribution, showing its effectiveness of the model for forecasting. These findings will serve as a guide towards enhancing operational efficiencies and sustainable growth within the flour milling landscape.