Seasonal outlook autumn/ winter 2018

Transcription

1 Seasonal outlook autumn/ winter 2018 Compiled by: Phil Graham, Graham Advisory Matthew Lieschke, Livestock Officer, South East Local Land Services 16 April

2 Table of Contents Executive summary... 3 Points to consider when looking at the graphs... 3 Other factors that should be considered... 4 Background... 4 What drives spring rainfall in southern NSW?... 5 El Nino Southern Oscillation Index... 5 Indian Ocean Dipole... 6 Impacts of ENSO and IOD events... 7 Climate outlook... 7 What might happen to pastures and livestock in the next three months?... 8 Seasonal reports, what do they tell us?... 8 Boorowa Rugby Bigga Bigga low fertility Laggan Taralga Wheeo Wheeo low fertility Bannister Gunning Lake Bathurst Braidwood Further information This seasonal outlook is part of the $25 million of National Landcare Programme investment that Local Land Services is delivering to boost farm gate productivity and improve economical health across NSW. This project is a joint initiative between Local Land Services and Tablelands Farming Systems. Published by Local Land Services. First published April 2018 More information Matthew Lieschke Livestock Officer, South East Local Land Services Goulburn NSW State of New South Wales through Local Land Services, Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing April However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of Local Land Services or the user s independent adviser. 2

3 Executive summary While the Tablelands received good rainfall at the end of February, warm and exceptionally dry conditions that followed meant that by the end of March soil moisture was starting to severely restrict plant growth. However, the patchy nature of the February rainfall also meant that significant variation existed across the region in terms of the amount of green pasture available to livestock and the amount of soil moisture in the profile. Looking ahead, it is the variation in soil moisture that is playing a key role in how the next three months is shaping up. The areas of Gunning, Bigga and Taralga are particularly low in soil moisture and need good rain to drive autumn growth. The outlook for Braidwood is also tight. April rainfall will largely dictate how winter develops. With good April rainfall the amount of pasture available to livestock this winter could end up in the normal range, whereas a dry April is likely to result in unusual measures to improve winter growth. Such measures involve deferred grazing (i.e. supplementary feeding stock in sacrificial paddocks or laneways after the break until pastures reach 500kg DM/ha) or using nitrogen and gibberellic acid to boost pasture growth. The end of April will be an important decision point at these sites. The modelling is indicating that Bookham, Boorowa Rugby, Laggan and Wheeo are sitting in a slightly better position than the previous sites mentioned and there is a high likelihood that the next three months will sit within the normal range (between the historical 25 and 75 percentile band). At these sites it is unlikely that unusual stock decisions will need to be made. Supplementary feeding will be required but that is not unusual for this time of year. Lake Bathurst and Bannister had the most pasture and soil moisture at the start of the projection period. As such, the modelling is indicating that a reasonable winter is likely at these sites and unusual actions related to stock will not be required. Points to consider when looking at the graphs It is the stocking rate run at each site which is important, not the enterprise selected. Most sites are set up on the basis that fertility is good and that the pasture mix is able to respond to moisture in any month of the year. At two sites (Bigga and Wheeo) a low fertility option has also been included. The moisture probe data (rainfall and soil moisture) as of the 25th of March was checked against the model s values to improve accuracy. At most sites there was good agreement. The graphs are reporting green herbage in kg DM/ha for grazed pastures at the stocking rate listed. Any paddocks that you have shut up or grazed at a lower stocking rate will have greater values. The critical thing to look at is how the projected values (solid lines) move compared to the historical values (average of 1963 to 2017and dotted lines). There are 4 projected lines displayed (10%, 25%, 50% and 75%). Given the lack of rain since the runs were completed (26 March) the current likely path would be around the 10% line. The 10% line is giving the projected green value that would be expected in 1 in 10 years given the moisture we had in the soil on the 25 March Look at a number of sites around your location to get a feel for your property. 3

4 Other factors that should be considered Current fat score of your stock this should determine the amount of feeding you need to do to ensure the reproductive performance of your females are maintained. Are your females at typical fat score levels for this time of year or above or below? The current profitability of your enterprises. All livestock enterprises are above profits level which have been experienced in the recent past and so can handle above average autumn feeding. It would be hard/slow to restock if an abnormal amount of destocking was done during this autumn. I believe this is a major factor in decision making for this year. The seasonal forecast from BOM, especially the next month which has the highest accuracy. The latest report for this region sitting in the neutral levels. What does this mean there are no climate drivers forcing the weather to be either wetter or drier, so we back to the random nature of rainfall and late March and April are the driest part of our year. Background During 2016 South East Local Land Services, in conjunction with Tablelands Farming Systems and Monaro Farming Systems established a network of soil moisture probes across the Southern Tablelands and Monaro. As part of this network 20 moisture probes have now been strategically positioned across the landscape to gather real-time information on what s happening to soil moisture under our pastures. Moisture probes have been installed at the following locations: Murrumbateman Yass Bookham Boorowa Bigga Laggan Taralga Bannister Rugby Wheeo Bungonia Gunning Lake Bathurst Braidwood Cooma (x2) Delegate Bombala Sutton Forest Berry Soil moisture information is provided in real-time, with measurements taken at 10cm, 20cm, 40cm, 60cm, 80cm and 100cm. Soil temperature is also recorded at these depths. Each site also has an automatic rain gauge. For further information go to: One of the major benefits of collecting soil moisture data is it gives us an indication of how much moisture we have in the profile at any given time - i.e. is the bucket full, half full or almost empty? Having some understanding of current soil moisture provides an extra piece of valuable information which can be used to increase your confidence with decision making at critical stages of the season. To help guide decision making, the following report presents a three month pasture outlook for 11 probe localities across the Southern Tablelands. Information from the soil moisture probe has been used to help guide the GrassGro outputs contained below (refer to section: What might happen to pastures and livestock in the next three months? ). Information on the major drivers of spring rainfall has also been provided, including a summary of the most recent forecast from the Bureau of Meteorology (BOM). 4

5 Image: Soil moisture logger recording real-time information on an improved pasture at Bannister (M. Lieschke, South East Local Land Services). What drives spring rainfall in southern NSW? The two key drivers of spring rainfall in southern NSW are: 1. El Nino Southern Oscillation (ENSO) 2. Indian Ocean Dipole (IOD) El Nino Southern Oscillation Index The El Nino Southern Oscillation (ENSO) takes place in the Pacific Ocean. Due to its large size and proximity ENSO has a significant influence on rainfall in south eastern Australia during the winter and spring periods. Typically ocean temperatures on the eastern edge of the Pacific (South America) are cooler than those on the Western Pacific (Indonesian Archipelago) creating a temperature and pressure differential which drives south easterly air flow, known as Trades towards Australia. This circulation pattern (known as Walker circulation) can either be enhanced or inhibited by changes in sea surface temperatures. There are three distinct phases of ENSO: 1. Neutral 2. La Nina (wet) 3. El Nino (dry) Neutral This is the most dominant phase, characterised by sea surface temperatures within a ±0.8 C anomaly at the mid-pacific equator. While ENSO sits in the neutral phase for more than half the time, droughts and floods are still possible. La Nina (wet phase) La Nina is characterised by cool sea surface temperature anomalies below -0.8 C at the mid Pacific equator at Nino 3.4. These cooler ocean temperatures enhance the trade winds air flow towards Australia and increase the probability of rainfall over south eastern Australia during winter and spring. 5

6 El Nino (dry phase) The El Nino is characterised by warm sea surface temperatures above +0.8 C at the mid-pacific equator at Nino 3.4. The warmer ocean temperatures reduce the south easterly trade winds air flow, and reduce the probability of rain during winter and spring. El Nino (dry phase) La Nina (wet phase) Source: Bureau of Meteorology (2016) Southern Oscillation Index The Southern Oscillation Index (SOI) gives an indication of the development and intensity of El Nino or La Nina events in the Pacific Ocean. The SOI is calculated using the pressure differences between Tahiti and Darwin. Sustained negative values of the SOI lower than 7 ohen indicate El Nino episodes. Sustained positive values greater than +7 are typical of a La Nina episode. Indian Ocean Dipole The Indian Ocean Dipole (IOD) is a similar ocean-atmosphere phenomenon like ENSO operating in the Indian Ocean at an inter-annual time scale. It appears to impact on rainfall in south eastern Australia from June to November, before fading with the onset of the tropical monsoon. The IOD also has three distinct phases: 1. Positive 2. Neutral 3. Negative Positive IOD (dry phase) The positive phase is characterised by cooler sea surface temperatures in the south eastern equatorial Indian Ocean off the coast of Sumatra and warmer sea surface temperatures in the western Indian Ocean off the coast of Madagascar, Africa. This temperature differential enhances westerly air flows across the Indian Ocean, decreasing the probabilities of rainfall for south eastern Australia during winter and spring period. 6

7 Negative IOD (wet phase) In its negative phase IOD is characterised by warmer sea surface temperatures in the south eastern equatorial Indian Ocean near Australia and cooler sea surface temperatures in the western equatorial Indian Pacific near Africa, increasing the probability of rainfall over south-eastern Australia during winter and spring. Positive IOD mode (dry phase) Negative IOD mode (wet phase) Source: NSW DPI (2011) Impacts of ENSO and IOD events Studies have shown a strong link between rainfall variability in eastern Australia and sea surface temperatures around northern Australia and Indonesia. ENSO and IOD both influence rainfall over south-eastern Australia. Our wettest winter/spring periods occur when a La Nina and negative IOD interact. Our driest winter/spring periods occur when El Nino and positive IOD interact. NSW DPI has developed videos to help explain how the various climate systems work: Climate outlook The Bureau has just released its most recent three-month climate outlook (12 April). The key messages are: The El Niño Southern Oscillation (ENSO) is currently neutral and are expected to remain in neutral territory for the coming months. The Indian Ocean Dipole is also neutral. With both major climate drivers sitting in neutral, there are no strong indicators that we are facing a wetter or drier than average conditions in the coming months. Warmer than average sea surface temperatures remain in the Tasman sea and may provide above average rainfall in the very far south east of Australia. For Southern Tablelands daytime temperatures in the May to June period aren t expected to be much different than the long-term average, however we can expect to see warmer night time temperatures. For further information, including the latest outlook video from BOM go to: Rainfall the chance of above median for Rainfall the chance of at least 25mm for 7

8 May 2018 May 2018 Source: BOM (2018) What might happen to pastures and livestock in the next three months? The outcome is a combination of current soil moisture, pasture mass and stock condition at the assessment date and expectations regarding weather over the future period. Unfortunately no one has a crystal ball, so what other method can be used? CSIRO released a program called GrassGro in the 1990s. This program uses daily weather data, local soil types, relevant pasture species and suitable livestock parameters to model livestock production systems across southern Australia. It has been used extensively in the South East region of NSW for the last 15 years and is accepted by producers as providing robust data to assist farm decision making related to the risk from seasonal variation. Seasonal reports, what do they tell us? The logic behind a seasonal report is too see what the next 3 months could look like by using current conditions (pasture mass, soil moisture, body weights etc.) and then projecting forward using historical weather for the same 3 month period. The historical weather used to create the pasture projections was daily data from 1960 to So, GrassGro essentially creates 57 different potential pasture curves all starting from the conditions on 24 March From this data we can get an estimate/risk of pasture supply for the period examined (i.e. in this case it was from 25 March to 30 June 2018). The tactical runs (projected) are reported against the long term historical data for the same period to give you a feel of how pasture conditions are currently positioned (compared to history) and the potential risk for the future. It is important to note that the pasture curves are not forecasts as they are based on historical weather data for each location. The pasture curves are reported via percentile graphs. The three percentiles used are 25%, 50% and 75%. The 25% line means that in 75% of years (i.e. 42 years) the green pasture supply was better than this line. The 50% line means half the years were above the line and half below. This logic applies to both the historical and projected lines. 8

9 The seasonal forecast from BOM can be used to assist with deciding which percentile data is the most relevant for the current year. If the BOM forecast for the next month was a 70 per cent chance of below median rainfall then you might only look at the projection lines below 50 per cent. The 75 per cent line is from a favourable period for rainfall and temperature and this does not match with the current BOM forecast There is no process that can provide a precise forecast. We need to use all available information to improve our confidence in making farm management decisions. Bookham Self replacing merino flock, 10.8 DSE Kg DM/Ha GREEN Bookham - pasture outlook Historical (25%) Historical (50%) Historical (75%) Projected (25%) Projected (50%) The projections are indicating that there is a high likelihood that the next 3 months will sit within what we would regard as a normal range. It is unlikely that unusual stock decisions will need to be made. Some supplementary feeding might be required but that is not unusual for this time of year. Bookham assumptions Self-replacing Merino flock lambing late July/ early Aug 10.8 DSE Native perennials, sub clover and annual grasses 500 m 9

10 Boorowa Self replacing merino flock, 10.8 DSE Due to the good rainfall in late February this site starts the projection period slightly above the 50% historical level of green feed (dotted blue line), however moisture levels at the end of March were starting to severely restrict plant growth. This is evident by the early separation of the solid lines. The projections are indicating that there is a high likelihood that the next 3 months will sit within what we would regard as a normal range, however April rainfall will determine how difficult winter will be. It is unlikely that unusual stock decisions will need to be made. Some supplementary feeding might be required but that is not unusual for this time of year. Boorowa assumptions Self-replacing Merino flock lambing late July/ early Aug 10.8 DSE Phalaris, sub clover and annual grasses 488 m 10

11 Rugby Prime lamb enterprise, 13.8 DSE The seasonal projection is tracking along normal lines with pasture production expected to be within the normal range (slightly below the long-term average) It is unlikely that unusual stock decisions will need to be made. Some supplementary feeding might be required but that is not unusual for this time of year. It is worth noting that this site does not have a functioning probe so this is unadjusted model data. Rugby assumptions 1 st Cross ewes producing 2 nd Cross lambs, lambing late May 13.8 DSE Phalaris, sub clover and annual grasses 610 m 11

12 Bigga Self replacing merino flock, 11.5 DSE This site is currently low in soil moisture and needs good rain to drive autumn growth. April rainfall will control how winter develops, it could end up in the normal range or be in a range where extending feeding in sacrifice areas will be required. The end of April will be an important decision point. If good rains come the speed with which pasture can recover is shown by the slope of the green and blue solid lines. Bigga assumptions Self-replacing Merino flock lambing mid August 11.5 DSE Perennial grass, annual grass, sub clover 644 m 12

13 Bigga low fertility Self replacing merino flock, 7.4 DSE Low fertility paddocks would not have used as much soil moisture (compared to the previous graph) due to lower growth from the summer rain. As such, the low fertility site has carried a bit more moisture into autumn, hence the slightly better performance when compared to history. However, it s also important to note that the slope of the green and blue solid lines aren t as steep and hence indicating that pastures will be slower to recover once there is adequate moisture in the system (compared to the previous graph). Also note that all three solid lines are indicating less pasture available during winter, which suggests that supplementary feeding will be higher on lower fertility country, despite running a lower stocking rate. Bigga assumptions Self-replacing Merino flock lambing mid August 7.4 DSE Perennial grass, annual grass, sub clover 644 m 13

14 Laggan Self replacing merino flock, 7.3 DSE Due to the good rainfall in late February this site starts the projection period around the 50% historical level of green feed (dotted blue line) The projections are indicating that there is a high likelihood that the next 3 months will sit within what we would regard as a normal range. Laggan assumptions Self-replacing Merino flock lambing in August 7.3 DSE Microlaena, sub clover and annual grasses 887 m 14

15 Taralga Prime lamb enterprise, 17.2 DSE Due to the high stocking rate at this site the initial herbage mass has a major impact on the decision you might make. If the amount of green pasture available in late March was closer to the 50% historical value (i.e. 400kg.DM/ha) that would push the projection into the 25% to 50% historical range, meaning a hard winter is ahead but one that can be managed with supplementary feeding. If the graph is accurate then unusual measures will be needed when it rains to improved winter growth. This could entail deferred grazing (i.e. supplementary feeding stock in sacrificial paddocks or laneways after the break until pastures reach 500kg DM/ha), using nitrogen and gibberellic acid to boost pasture growth etc. Taralga assumptions 1 st Cross ewes producing 2 nd cross lambs, lambing late August 17.2 DSE Phalaris, sub clover and annual grasses 965 m 15

16 Wheeo Self replacing merino enterprise, 13 DSE Due to very good rain in late February this site is slightly above the 50% historical level of green feed for this time of year. The pasture projections are within normal ranges and radical action is unlikely. Wheeo assumptions Self-replacing Merino flock lambing late August 13 DSE Perennial grass, sub clover and annual grasses 880 m 16

17 Wheeo low fertility Self replacing merino enterprise, 7.4 DSE Due to low soil fertility the amount of pasture grown is less but it is still behaving in a similar pattern compared to historical levels as the Wheeo graph above. Lower soil fertility means you grow less pasture for the same amount of rainfall. The pasture projections are within normal ranges and radical action is unlikely. Wheeo assumptions Self-replacing Merino flock lambing late August 7.4 DSE Perennial grass, sub clover and annual grasses 880 m 17

18 Bannister Beef breeding operation, 11.9 DSE Bannister site starts the projection period above the 50% historical level of green feed (dotted blue line), thanks to good rainfall in late February and ability of this soil to take in and store moisture. The starting pasture mass and current soil moisture is indicating a reasonable winter is likely at this site. Bannister assumptions Breeding cows calving mid July 11.9 DSE Perennial grass, sub clover and annual grasses 890 m 18

19 Gunning Self replacing merino flock, 12 DSE This site is currently low in soil moisture and needs good rain to drive autumn growth. Like the other drier sites, April rainfall will determine how difficult this winter will be. The end of April will be a key decision point. Gunning assumptions Self-replacing Merino flock lambing mid August 12 DSE Microlaena, sub clover and annual grasses 590m 19

20 Lake Bathurst Merino x Terminal flock, 12.1 DSE Due to very good rain in late February this site is above the 50% historical level of green feed for this time of year. This site has the soil moisture to handle the current dry period and the projections are indicating that unusual actions related to stock will not be required. Lake Bathurst assumptions Merino x Terminal flock, lambing mid August 12 DSE Perennial grass, sub clover and annual grasses 685 m 20

21 Braidwood Self-replacing beef enterprise, 11.5 DSE Hot and dry conditions in March means that the starting position (in terms of green pasture available) is well below the long term average, sitting around the 25 percentile. The model projections are indicating that a hard winter is ahead but one that can be managed with supplementary feeding. If the graph is accurate then measures will be needed when it rains to improve winter growth. This could entail deferred grazing (i.e. supplementary feeding stock in sacrificial paddocks or areas after the break until pastures reach 500kg DM/ha) using nitrogen and gibberellic acid to boost pasture growth etc. Braidwood assumptions Self-replacing beef enterprise, August calving 11.5 DSE Phalaris, cocksfoot and sub clover pasture 665 m 21

22 Further information For further information on weather forecasting and climate drivers see: NSW DPI fact sheet Drivers of Climate Variability in the Murray Darling Basin data/assets/pdf_file/0005/402863/climate-variability-drivers-in-mdb.pdf Tablelands Farming Systems fact sheet Weather forecasting explained _weather-forecasting-explained.pdf Bureau of Meteorology ENSO wrap up: Bureau of Meteorology Climate Outlook: 22