Analysis of climatic risk and coping strategies in two major corn-growing areas in the Philippines

Climate and weather are crop growth and yield defining factors since the fluctuations in weather and variability in climate affect productivity and crucial aspects of crop production system. Farm-level decisions and activities in crop production such as planting date, dose and timing of fertilizer, irrigation water, interventions to control pests and diseases are dependent on climate variability. Climate or the average weather for along period of time, determines the crop growing season during which the crop is expected to experience minimal environmental stresses such as inadequate water from rainfall, and extreme temperature, and therefore will give reasonable yield levels. Moreover, different crop physiological process (e.g. transpiration, photosynthesis, respiration, etc.) are highly influenced by climate variability and weather. Moreover, the build-up, spread, and the biological cycles of different crop pests and diseases, which are also reducing factors for crop survival and productivity are also largely climate-related. Thus, planting time or growing season for the crop is synchronized with the period with reasonable likelihood of receiving adequate rainfall. Use of climatic and agro-meteorological information to determine the planting calendar ensures successful crop production. Recent research studies on climate change and climate variability have provided empirical and observational data-based evidences that there had been a disproportionate increase in the mean level and variability of most weather and climatic variables in various locations. This has resulted in the rainy season in an area, and the more frequent occurrence of extreme climate events which were experienced in many parts of the country especially in the major crop growing areas in the Philippines. Thus, the optimal crop growing season has also been modified, and now has to be determined in the light of climate change and climate variability. Planting dates should be optimized considering the confidence on medium-term weather forecasts and seasonal climate outlook for the production areas such as corn growing areas whenever they are available. Thus, a study was conducted to determine the optimal planting period in two major corn growing areas (provinces) in the Philippines, namely, Isabela and Bukidnon, considering climate variability. Corn is second most important crop in the Philippines. Isabela and Bukidnon are the top two corn provinces provinces in the Philippines. They also have different types. An assessment of the effects of climate variability in corn productivity in these two representative areas provides an objective evaluation of the vulnerability of corn production due to climate risk. Since the spatial and temporal distributions of hydrologic processes have been altered as evident in the changes in rainfall patterns, the optimal planting window has to be determined. The study used the eco-physiological or process based crop simulation model (CERES-Maize model) to determine corn yields in the two provinces given the observe as well as synthetic weather data obtained using a weather data generator (SIMMETEO) for the specified climate scenarios. The crop model is parametized using the crop genetic coefficients for IPB 911 corn variety. Analysis of historical and synthetic sequences of weather variables for each of the two provinces shows they are statistically the same. Thus, these data sets are used as inputs to the crop model to simulate crop yields of corn for various increments of planting dates, and under different climate scenarios. Corn yield estimated for different planting dates during the possible growing seasons provide information to determine the optimal planting window which represents the date or duration with the high yield and minimal variance of crop yields.