Dr Peter Wylie

Horizon Rural Management, Dalby

There is a lot farmers can do to manage climate better. But climate forecasts are only a small part of the potential improvements to be made. Forecasts need to be integrated with other practices, rather than being treated in isolation.

For seasonal forecasts to make much impact on farmers bottom line, we need better forecasts, with one-month lead time and there is a need to help farmers understand them better.

Good management of climate risks is vital for making a profit and surviving in the business of farming. Farm business failure often follows a succession of problems, such as drought, waterlogging or frost, which haven't been managed well.

Farmers mostly say there is nothing they can do to manage climate risks, but good managers adjust their management according to the season, rather than doing the same thing each year. There is no doubt that managing climate makes more money.

But seasonal forecasts are a small part of the decision making process on managing climate. There is a need to integrate seasonal forecasts in a management package with other ways in which we can manage climate risk.

Seasonal forecasts are not yet accepted by many farmers, particularly in southern Australia. There is a need for better forecasts, and a need to understand the probabilistic nature of forecasts.

If we take any of the major climate problems, such as drought or waterlogging, then there is much that can be done on grain farms to minimise loss from these events.

It is important then to relate the use of seasonal forecasts with these other practices and fine-tune the whole management plan. In some cases there is no further improvement possible using a forecast, while in other instances it can help a great deal.

One example of an important way to manage drought in the summer rainfall grain growing areas is the decision not to plant.

When the SOI during April-May is negative, there is a high chance of poor wheat yields and negative profits. But sorghum in the summer following a negative SOI in April-May may be quite profitable.

Farmers at Roma found sorghum was more profitable than wheat during the El Nino years of the 1990’s and a cut back in wheat area in these years was quite profitable.

In the example for Roma in Table 1 there is a large difference in the wheat yield in years with positive and minus Apr-May SOI, but little change in the yield of sorghum in the following summer. Because the price of sorghum is often higher in an El Nino year, sorghum could actually be more profitable in El Nino years than in La Nina years.

A lot has been said (and modelled) in the past about adjusting fertiliser rates and other agronomic inputs. But in general terms, the effect of changes in these decisions is small when we consider the unreliability of the forecasts and the outcome of the seasons.

Sometimes the forecast will be right but the decision ends up wrong. This happened in 1998, when there was a classic case for post-planting application of nitrogen fertiliser on wheat in northern Australia. But the season was so wet and leaf disease so bad, that extra nitrogen had a negative effect on crop yield.

Despite this experience, there is scope for forecasts to help minimise the impact diseases such as yellowspot. Severe outbreaks of this and other diseases, such as leaf rust and take-all are more likely in La Nina years. In these situations it may pay to increase rotation and the use of disease resistant varieties.

An important way to use seasonal forecasts is for making decisions on double cropping in those areas where summer rainfall allows farmers to grow both winter and summer crop. Adjusting crop frequency, this will not only help to produce more grain in seasons of above average rainfall, it will also reduce soil erosion and salinity. By using more of the water in seasons of above average rainfall and reducing the water which runs off (causing erosion) or percolates through the soil causing salinity.

In the Liverpool plains area of NSW, long fallowing practices have contributed to salinity. Farmers are now using an opportunity cropping program, which by planting a double crop when the soil profile is full, will reduce the amount of drainage, which occurs in wet seasons.

The decision to plant wheat as a double crop after cotton or chickpea after sorghum will be improved if it based on the amount of subsoil moisture and the seasonal forecast. If the SOI is rising or positive and subsoil moisture is good, then there is a chance of a reasonable crop.

Grain prices are just as important as yield for profit. The chance of higher prices due to a domestic shortfall of feed grain or quality wheat is likely to be much higher in an El Nino year. This has implications for marketing and whether to sell prior to harvest or wait and see whether prices will rise.

The El Nino weather patterns appear to have an effect on world grain prices. When there is an El Nino, important grain producing regions in the Northern Hemisphere, in India, China and the U.S.A tend to have better than normal rainfall. But when we have a La Nina, some of these parts of the world, have drier than normal weather.

During two significant La Nina events, in 1974-5 and 1988, the world wheat prices doubled due to reduced grain supply. Several major droughts in the US, such as the last one in 1988, coincided with major La Nina events. During the last five La Nina events, the yield of corn in the US has been calculated at 19% below the average. Such reductions can have a big impact on prices.

During the most recent La Nina event there has been some drought in the USA, but it did not extend far enough into the Corn Belt or the spring wheat area to affect grain supplies. It has, however, had a major effect on cotton prices.

The major problem with forecasts for grain farming in Australia, is that they come too late to be useful in the major decisions. Winter crop is mostly planted in May, with decisions on crop choice and fertiliser made during April and May. A seasonal forecast for the winter season, which comes at the end of May leaves us with only a few minor options to tidy up.

Even a one month lead time, predicting SOI from sea surface temperatures or some other way, could allow decisions on winter crop planting to be made in April, rather than late May.

The credibility of forecasts would be improved if we helped farmers understand when they are most useful and when they are telling us nothing. Even for April-May, when the forecasts are most useful, there are not strong indicators in most years.