Milking the Weather - June 2010 Edition
Seasonal Preparation
Greg O’Brien, DPI Ellinbank and Tom Farran, DPI Tatura
Current settings
For most Victorian dairy farms, this has been the best start to the season for a long time. Rainfall has been good, resulting in handy pasture growth, successful early establishment of pastures and crops plus improved irrigation water availability.
At the time of writing, strong signals for next season milk price are coming through with Fonterra announcing an opening milk price of an average of $4.36kg/MS. This announcement was made with additional comments, stating that this was a conservative opening milk price and there was an expectation of some step-ups throughout the season. The current Dairy Australia situation analysis is positive for farm gate milk prices.
The major Victorian grain growing regions have also had a good start with nearly all crops sown and growing well on the back of some good rain in late May. Comments coming out of most of these regions are that they will have adequate moisture to get through until spring. However, once again the fate of these crops will depend on what spring delivers.
At present all the major components needed to make up a good season seem to be taking shape. Current seasonal conditions are good in most regions and the seasonal forecast indicates a likely chance of a La Niña for 2010, which can result in above average rainfall for south eastern Australia in winter/spring (but not always). Milk price is looking reasonable and hay and grain supplies/prices are looking economical from a dairy perspective.
With all these elements looking more positive than previous years, forward decision making should be more enjoyable for many as we progress into the season. Although some may be feeling more confident, it is still important to consider each plan and decision with care. The level of planning required will be dependent on your individual situation and risk profile. While the current climate indicators and other externalities look more favourable there is still no 100 per cent certainty in the forecasted conditions or external pricing influences.
Last season’s Wimmera crop is an example of this. The crop at the end of October looked like it was across the line after a reasonably good season and many farmers were expecting above average yields come harvest time. Then, nearing the end of the race, extremely high temperatures in November were recorded at the critical grain fill period. In a matter of a fortnight the excellent season had come undone with many of crops yielding below average with poor quality.
How can this climate information be used to make decisions on my farm?
Now into winter, decisions of what to sow for the autumn are in the past, lending our decision making to managing winter feed and spring planning. This can be assisted by looking at the short-term weather forecasts and taking into consideration the likelihood of different outcomes associated with the longer range three month outlook. As we head into the winter, the skill of the three month outlook increases for south eastern Australia compared to autumn. Also, the influence of the El Nino Southern Oscillation (La Niña/ El Niño) becomes more influential heading into winter and spring. So watch this climate driver over the next two months to see how it sets up and how it may influence our winter/spring rainfall in Victoria.
Although it is too late to change what you have sown, it may be helpful for future planning to note down what has worked and what hasn’t for you this autumn . Given the current climate indicators and seasonal conditions in your area, it is time to focus on what decisions can be made now.
Some of the elements to consider now are:
- Management of pastures/crops
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- Grazing management
- Fertiliser decisions
- Weed and pest management;
- Feed purchasing (including forward contracts);
- Stock agistment; and
- Carry-over water (northern irrigation farmers)
Grazing Management
Scientific research and the practical findings of farmers have proven that ryegrass dominant pastures should be rotationally grazed based on leaf stage. To maximise production and provide a high quality product, grazing at the three leaf stage is the way to achieve this during winter. However canopy closure (where the ground can no longer be seen) can override this guide if closure occurs before the three leaves have fully emerged, as this will cause quality to decline and the bottom leaves to decay. Once the fourth leaf begins to grow the first one begins to die and decay resulting in poorer quality and slower net growth rates.
However, while grazing at the three leaf stage will result in you growing the most feed for the year it can be risky. In winter, paddocks ready to graze at the three leaf stage may become unavailable for a period of time in wet conditions. Another issue that may arise is if you run into a true surplus of feed while drying off cows in winter, meaning that feed cannot effectively be conserved. Under these circumstances some farmers will speed up the rotation length and graze at around the 2.5 leaf stage to avoid the risk of being unable to graze if wet and then will be able to graze the pasture again before it goes past the three leaf stage. Grazing past the three leaf stage will see the pasture decline in quality, particularly in the bottom section of the plant. This can make it difficult for the cows to eat down to the desired residual without having to make them hungry, resulting in valuable feed being wasted.
So, based on what the forecast weather is, combined with what the current seasonal conditions are (wet/dry), can be used to help you decide if you should speed up your rotation length or slow it down. If it is forecast to be wet and the soil is already moist then you may choose to speed up the rotation because some paddocks might become ungrazeable for a period of time, and if already out at three leafs, it may become rank before you can get back on it. If the rotation is sped up then you will have more time before it goes rank, but may not grow as much feed for the year.
Fertiliser
Fertiliser decisions are based on a number of factors. For the purpose of this article I will just focus on nitrogen and how the forecast weather can help you with nitrogen fertiliser decisions.
Firstly, to get a good response from nitrogen fertiliser it needs to be the main limiting factor affecting plant growth. If another factor, such as available moisture is the main factor affecting plant growth it is unlikely that you will achieve a good response after applying nitrogen.
So what has this got to do with the weather forecast? Moisture (too much or too little), temperature and day length have the biggest impact on plant growth. For example if the ground is already on the dry side and the forecast indicates that you will have a greater chance of a dry couple of months ahead, it is likely that moisture is going to be a more limiting factor than nitrogen so there is a chance you may not achieve a profitable response. Another scenario is that moisture may be adequate, but the three-month outlook indicates that it will be very dry for the next few months. This will mean that using nitrogen may get a good response in the short-term, but will use up available moisture quickly, resulting in slowed plant growth (by running out of moisture) sooner than if no nitrogen had been applied. Therefore, you would need to weigh up when the growth is the most important to you. If wet conditions are more likely, this may prevent nitrogen applications for environmental reasons. Slightly earlier applications may be applied (before it comes in wet) to fill an anticipated feed shortage.
Weeds and Pests
Generally for pests, the weather forecast can be an advantage to start to predict their behaviour. Many pests of pasture will often cause the greatest problem when the pasture is under stress. Often this is caused by problems such as lack of or too much moisture, as well as cold temperatures (frosts and cold spells without sun). Certain pests require different conditions to thrive. A current example in northern Victoria is that the late summer/early autumn rain and warm autumn has assisted the locusts survival. Favourable spring conditions would mean that there is a chance that locusts will hatch out in plague numbers. So keeping an eye on what the forecast is, heading into spring, should assist farmers in areas that are likely to be affected to assess the level of threat of this occurring and to plan out appropriate management strategies.
An integrated approach to weed management will be the most successful approach. This means that multiple control and management options need to be considered. So just using chemical to control weeds isn’t always the most successful approach. Other options like crop rotation/pasture renovation, grazing management, strategic use of hay/silage making and fertiliser decisions, can all help to control weeds in crops and pastures.
Understanding the strengths and weaknesses of the weed you’re dealing with and taking into consideration the potential outcomes associated with the long-term forecast will help decide on the most appropriate weed management response. For example, barley grass will germinate quickly on adequate moisture when the soil temperature is in its preferred range (10-15 degrees). It is believed that at least 95 per cent of the seed bank will germinate within seven days under these conditions. It will establish quickly and early quality of the plant is okay. As it reaches the reproductive stage of its lifecycle in late winter (which varies depending on what part of Victoria you live in) the quality becomes poor to the point that stock don’t want to graze it. It then sets a large amount of seed normally in mid spring. This seed is a soft seed, meaning that nearly all of it will germinate the following year and unfortunately there aren’t any desired in crop chemical options for barley grass. Barley grass is undesirable because of the poor quality of feed that it produces in late winter/spring. This means there are two periods of time to look at control options. The first and most popular option is to give it a chance to germinate in the autumn and spray it out and then sow the pasture or crop. The second, is to spray the barley grass in early spring to stop it setting seed.
So if you have missed the autumn chance to clean up barley grass and you can see that it is going to cause problems in the spring, using the weather forecasts (both short-term and longer term outcomes) may assist your decisions to have a go at sowing a spring/summer crop in the paddock to try and control the problem.
For example, if it looks like a good spring coming up, doing nothing would mean that you won’t be able to capitalise on the good spring as the barley grass will take over. So you may decide to spray the paddock out in the late winter/early spring and put a summer crop in because if the conditions are good you will at least be growing some good quality feed and helping to fix the problem for next year.
Feed purchasing
Linking climate information to feeding your cows—the portfolio approach
A portfolio approach to feeding basically describes the need to have multiple options for filling the herd’s feed requirements. The farm portfolio of feeds will change over time. Adaptation of the feedbase has a large bearing of the viability of the business.
The feed portfolio is presented in the diagram below. The feedbase typically consists of perennial ryegrass (but may be a different species on some farms), other home grown pastures and crops, conserved fodder reserves plus purchased feed.
What impact can the climate have on your feed portfolio?
Have you ever tried to estimate seasonal fluctuation by the amount of home grown feed you have grown?
Having a greater understanding of the seasonal influences can help with risk management on farm.
A shortfall in home grown feed can be offset by purchasing feed but may not be cost effective. You might wish to offset some of this with home grown fodder reserves (silage pits). Maybe part of the shortfall can be buffered through the use of nitrogen fertiliser or strategic use of forage crops. Perhaps you have an out paddock that has some untapped potential to grow more if need be. Agistment is another option.
Experience has proven time and time again that it is not a good idea to solve a feed problem through reduced feeding per cow as it usually ends up being less profitable, impacting on reproduction and cow condition in the long run. If you are going to keep the cow, then plan on feeding it.
Thinking of your feed as a portfolio may help with management decisions. In the example below, we have estimated the impact of a poor season on the home grown feed portfolio.
A cow producing 500 kg MS per year will eat ~ five tonne of good quality dry matter. A 200 cow herd would eat about 1000 tonne. If pasture consumption was seven tonne per ha and the farm was 100 ha, then 700 tonne comes from home grown feed and 300 tonne from off-farm feed. If seasonal conditions resulted in 20 per cent less growth, this would require an extra 140 tonne of pasture quality feed to be found to maintain milk production. This 140 tonnes would either need to be purchased, grown with extra nitrogen use, or the amount of feed required would need to be reduced. This can be done through agistment, selling cows or young stock and parking cows. Some of these options can have long-term impacts on the business and need careful consideration.
So what does your feed portfolio look like? What is the impact of the forecast season on your feed portfolio? How do you plan to manage the impact of seasonal variability?
Planning changes to your feed portfolio needs to include a recognition that rainfall has been through wetter and drier than average periods over the longer term record. While the long term trend under climate change is for a drier and hotter climate compared to the long term average, there is still the likelihood that wetter than average years will occur within this longer term trend. Therefore managing seasonal variability becomes key.
