TROPICAL PASTURE ESTABLISHMENT .17. PROSPECTS FOR USING WEATHER PREDICTION TO REDUCE PASTURE ESTABLISHMENT RISK

Relationships between Southern Oscillation Index (SOI) phases, that in clude a change of SOI value from month to month, and summer pasture so wing opportunities at a number of locations in northern Australia have been investigated. The number of planting opportunities, date of firs t planting opportunity, number of days to second opportunity and the p robability of obtaining a planting opportunity were all significantly related to the SOI phase for the previous December. The degree of rela tionship varied with the location being analysed. Planting opportuniti es at locations in the more northern and western areas were affected t o a greater degree by the El Nino/Southern Oscillation than those at o ther locations. Low SOI values during December appeared to be related to fewer planting opportunities, higher probability of not receiving a planting opportunity at all, higher probability of not receiving a se cond planting opportunity, and a longer interval between planting oppo rtunities. The relationship between the 30-50 Day Oscillation and plan ting opportunity was investigated. On 50-60% of occasions, passage of the 30-50 Day Oscillation was associated with a planting opportunity w ithin the following 10 days and 30-50 days later.