Penetapan kalender tanam padi berdasarkan fenomena enso (El Niño Southern Oscillation) dan IOD (Indian Ocean Dipole) di wilayah Monsunal dan Equatorial

Abstract

Increasing fluctuation and more frequent climate anomaly in the last decade due to ENSO and IOD phenomena has severe implications on food crops. Therefore, a sound planting season adaptation strategy is needed in the efforts to enhance sustainable food security. Research has been conducted in West Java (Monsoon rainfall pattern) and West Sumatera (Equatorial rainfall pattern)province. Analysis of the correlation between ENSO and the IOD with rainfall has been carried out to find the relationship between ENSO and the IOD with rainfall in the period from December to February, March to May, June to August, and September to November. Water Satisfaction Index and irrigation rice-field water balance was used to obtain optimal planting time. Artificial Neural Network was used to rainfall prediction for improvement of cropping pattern planning. Interviews with farmers to study the adaptation measures of farmers against the impact of drought. The spatial distribution of partial correlations between rainfalls with ENSO and IOD over West Sumatera and West Java indicated a significant impact on rainfall anomalies along the period of September – November. The ENSO and IOD events had a wider impact in West Java, which was known as a monsoon rainfall pattern especially over northern part of West Java. On the other hand, there was only a little impact of the ENSO and IOD on rainfall anomalies in the south-western West Sumatera. In the period of June-November the impact to rice- field in West Sumatera was only about 20% while, the impact in West Java could reach up to 80%. In the region affected by strong ENSO and IOD like Indramayu, impact of ENSO and IOD has delayed the peak of early planting by more than 6 dekads. The peak of early planting occurred in November III/ December I could reach up 30% due to ENSO and 35% due to IOD. The period-stratified ENSO variability had delayed planting time by 2 to 5 dekads in monsoon rainfall pattern (West Java) and 1 dekads in equatorial pattern (West Sumatera). Meanwhile, the period-stratified IOD variability in West Sumatera and West Java had delayed planting time by 1 to 2 dekads. Result of the prediction showed that the period of September 2010 to February 2011 was above normal. Wet conditions resulted in the potential of planting time 1 dekads earlier on rain-fed land and 2 dekads earlier on irrigated land than in normal conditions. Adaptation by farmers to climate anomalies was more apparent in a monsoon rainfall pattern area with various efforts in the utilization of water resources, i.e. pumping technology, the adjustment of planting time by 2-3 dekads and changing crop rotation from paddy-paddy-palawija into paddy-palawija.