Pasture Conditions in Autumn 2019
Fiona Leech, Senior Agriculture Advisor, Yass
Following the harsh seasonal conditions that we experienced in 2018 including a very short spring, pastures in many instances have had more pressure on them than in other years. During drought pastures are compromised, they are rested less, they are grazed harder and grazed lower than normal. Energy reserves are depleted and the plant is weakened sometimes to the point of death. The worst thing you can do to a pasture during a drought, if a small fall of rain has occurred, enough to promote some green growth, is to continually graze the new green growth. This will deplete the plants energy reserves eventually killing the plant under continued pressure. To ensure survival the plant must be allowed a recovery period, being left to produce a significant amount of leaf to allow it to build up energy reserves prior to being grazed.
The recent March rain received across various districts on the southern tablelands has offered a significant break to the season with pastures responding well. With the amounts of rain that fell and the timing (in excess of 50 mm during the last 2 weeks of March), it is considered an autumn break. Pasture growth occurring at this time of the year will be substantial given the warm daytime air temperatures as well as continuing warm soil temperatures. Given the reduced amount of standing dead dry matter present in many pastures there has been a significant germination of clover across the region. Clover that establishes on an earlier autumn break sets a potential for strong clover content in pastures for the remainder of the year ensuring pasture quality remains high and stock perform well on lower quantities of green feed.
With the rainfall events that have occurred pastures growing on country with improved soil fertility levels will respond quicker than those growing in unfertilized soil. Improving soil phosphorus levels improves plant root development therefore, allowing the plant to better access soil moisture. Under warm and moist soil conditions there is also greater mineralisation of soil nutrients providing plants with a burst of key nutrients for growth.
If you have country with a good fertilizer history this is a year that you may consider to not apply fertilizer. Given the early break that has occurred, a top up of fertilizer is not as important due to good growth still being able to occur before colder winter temperatures set in. In comparison, when the autumn break is late, fertilizer becomes critical in order to encourage growth during the cold winter months. Some properties may have reduced stocking rate which again if you are on a well fertilized place reduces the pressure on pastures.
For some further inland areas of the tablelands region (Yass/Boorowa), historical rainfall records show that April can traditionally be a very dry month. However, given the pasture response we have recently experienced on the March rain and with temperatures lowering and overnight dews forming, pastures will be better able to tolerate a potential dry period should it arise.
Paddocks containing desirable perennial pastures species with good soil fertility should be given a chance to build leaf area as these have the best chance to respond quickly to the rain received. Remember it is important to continue feeding livestock to allow pastures to reach quantities needed to meet livestock requirements.
It is important to not be too hasty with your decision making for pastures that are of concern due to potential loss of perennial grass species over the extended dry period. It is better to spell these pastures now that the autumn break has occurred and see what species regrow. Establishment of a new pasture is an expensive and risky operation and should only occur when you are sure that you do not have enough desirable perennial species still present to work with. Our experience coming out of previous droughts tells us that often there is still enough perennial grass presence in paddocks to build on using various techniques to bring the paddock back to acceptable levels of production.