Case studies - Trial sites on seeps trial sites in the Victorian Mallee

Case studies on seeps trial sites in the Victorian Mallee

Contents

03 CASE STUDIES ON SEEPS TRIAL SITES IN THE VICTORIAN MALLEE Introduction

04 CASE STUDY ONE Motts, Murrayville Initial inspection and setup Monitoring and data collection Key take home messages

07 CASE STUDY TWO Marshall, Ouyen Initial inspection and setup Monitoring and data collection Farm Management priorities of grower Key take home messages

09 CASE STUDY THREE Vines, Ouyen Initial inspection and setup Monitoring and data collection Farm Management priorities of grower Key take home messages

11 CASE STUDY FOUR Etherton, Cowangie Initial inspection and setup Monitoring and data collection Farm Management priorities of grower Key take home messages

14 CASE STUDY FOUR Fox, Swan Hill Monitoring and data collection Key take home messages

Introduction

The case studies provide a diverse overview of seeps problems evident in the Victorian Mallee. The case studies highlight the main steps in diagnosing, inspecting and reaching a decision on management of seep areas.

There are five trial sites located in Ouyen, Murrayville, Cowangie and Swan Hill districts.

Rules on seep management are not set in stone and every grower will have a different take on how the problem is approached.

Management Decisions A decision tree on seeps management [insert link to website] guides the grower through a diagnosis and selection of management options process.

The following parameters must be established to use this management tool: 1. Watertable salinity EC Why? Essential for the future management decisions for the arable areas affected 2. Data collection Why? Obtaining data spatial or other to give a better understanding of the site’s dimensions and past productivity.

3. Farm management priorities of the individual grower.

Why? What does the grower want to do? The best course of action for the site may not line up with the goals of the grower.

4. Key take away messages for the site What happened on a practical level and what did we learn?

Motts, Murrayville Farmer questionnaire response. Rohan Mott Our farm covers approx. 14,000ha at Turriff in the central Mallee and the soil type is predominately in the Tempy Land System which is a dune swale formation. We also have some land on the Myall ridge which is quite productive sandy loam. The southern portion merges into Hopetoun Land System which doesn’t have the distinct east west sand dunes but still has some seeps.

About you and the farm.

I have been farming for around 30 yrs with my two brothers Murray and Neil. We employ two full time farm hands and two full time truck drivers. We are 4th generation farmers in our region.

Some detail about your farming system, in particular change to direct drill bar setup, why the change, weed management, moisture retention etc We changed to continuous cropping and no-til in 2002. We sold all our sheep at that time.

We currently use a Bourgalt 86 ft 3320 seeder on 15” row spacing and is 4 row, to better handle trash flow. We have been using VR (Variable Rate) application for around 10 years and vary mainly N and P fertiliser inputs but also have varied seeding rates. We use soil and elevation maps and to a lesser extent cumulative yield maps. Due to extensive frost and large biomass in 2019, 2020 all seeding inputs were applied at a blanket rate across individual paddocks.

Weed management is a combination of herbicide rotation, crop type and hay. We have also windrow burned in the past.

We have had a fairly rigid 3 year rotation of legume/hay, cereal, cereal, sometimes legume, cereal, legume.

Stored soil moisture is critical to us and as a result summer weed spraying is a high priority.

Problem summer weeds are fleabane, skeleton weed, melons and heliotrope.

Winter weeds in cereals are ryegrass, brome grass and barley grass (emerging problem).

Weeds in legumes are radish, milk thistle and to a lesser extent amsinckia.

Seeps management ...so far We have been trialling some deep ripping and the results are looking very promising. We have seen a yield increase of around 30 – 50% We have planted trees above some seeps which after around 7 years we started to see the soil recover and begin to be productive below the trees.

When did the seep start, have and they got worse or always been there?

Some seeps have been there since before we farmed the paddocks.

Others have worsened after what seems to be a number of conditions coinciding. Eliminating or greatly reducing skeleton weed on hills above the seeps, poor establishment of cereal and legume crops above the seeps and wet summers particularly 2010/11. It was after 2010/11 where most of our seeps began to be a problem. Compaction is also likely to be a factor. The soaks are significantly worse in the portion of our farm which is in the Tempy Land System.

Has or how have the seeps changed and or formed over time Some seeps have now formed where we haven’t seen them before.

What is your longer term management plans for them Deep ripping is our main strategy going forward as this is a simple strategy and we are seeing significant results. Lucerne looks very promising also however is currently not compatible with our farming system without sheep or fences so we are yet to do this. Also given that our seeps comprise less than 1% of our farm we don’t give them the focus we perhaps should.

Initial inspection and setup Initial works by the land manager began on the site in 2012, with a row of red gum trees established on the visual seep line to prevent further salinisation of the area below. Rohan was interested in undertaking further work in this area and was very willing to help with the project. Bores were established in June 2019 and sites surveyed from high to low elevation. Four bores were hand augered and monitoring of these piezometers for both depth and salinity of the seep water commenced. Three pits were also dug by Michael Moodie, for soil characterisation at the seep site also based on elevation.

This seepage area is also one of the main Seeps Research Sites being studied by Michael Moodie (Frontier Farming Systems).

Monitoring and data collection

Picture 1) Rohan Mott site 2018

Table 1) Initial EC from Watertable

Picture 2) Mott site installation of piezometers

Total Area Included = 125 ha Total scalded Area A = 4.625 ha Area B = 1.024 ha Area C = 2.7 ha

B

A C

Picture 3) Michael Moodie producing soil classification data with bore in

Picture 4) Google Earth image of area of seep site attributed to grower

Picture 4 highlights the areas that are visually scalded within the vicinity of the research site. By quickly mapping the area on Google earth we can account for the total area affected and apply rational costs for management and the potential impact of no action.

Picture 5a) (NDVI) Normalised Difference Vegetation Index

Picture 5b) (NDVI) Normalised Difference Vegetation Index

The NDVI image highlighted by picture 5b) has given a reasonable account of the area impacted by the seep with very low vegetative biomass (red colour). The low biomass is also attributed to sand and poor establishment of the crop or herbicide damage.

Picture 6) Elevation m Rohan Motts site

Picture 7) Current tree plantings

Picture 8) New area of management established and tree line proposal

Key take home messages 6 year old trees at Site A are beginning to impact upon the water table levels indicated by a significant lowering above the tree line at Bore 1C. 30 year old trees at Site C have completely dried the area below them but need to be extended further to the east to utilise all seepage water from the dune above.

Marshall, Ouyen Farmer questionnaire response. Joe Marshall About you and the farm .....

Our family operate a 6000 ha farm located between Ouyen and Kulwin. My brother Daniel and I crop 4000ha annually. My father Andrew and Uncle Ian run sheep on the remainder.

Some detail about your farming system, in particular change to Direct drill bar setup why the change weed management moisture retention etc.

We moved to direct drill about 11 years ago. The main reason was to maintain cover on the sandy areas of the farm, build soil health, retain moisture and ultimately build a more profitable business model. We run a rotation of Wheat, Barley and Legumes along with some Vetch and Oaten hay.

Seeps Management ...so far Seeps on our property were always attributed to seepage from the channel system as far back as I can remember. Since the Northern Mallee pipe line was completed in 2004 and the channel system decommissioned, some of these areas have recovered, but some remain seemingly fed by unused water from the sand hills. This excess moisture combined with sub soil constraints cause the seeps.

Many of these areas which have now formed into seeps were highly productive and would often yield significantly more than the paddock average for many years. The legume phase of the rotation can seemingly tip things over the edge and nothing will grow. With little cover the topsoil blows away then it's very hard to establish crops.

When did the seep start have and they got worse or always been there?

Since the huge rain events of 2010/11 we have seen new seeps emerge in areas not seen before. All of our seeps are on blocks that have been continuously cropped for at least 10 years. Over this time we have seen a large reduction in weed populations through improved weed management over summer, especially weeds like skeleton weed with large tap roots. These weeds would have previously used a lot of excess moisture deep in the profile over summer.

Has or how have the seeps changed and or formed over time.

Things we have tried on the farm in no particular order are deep ripping of sands, which we have found to not be a miracle cure after 2 seasons. Ripping does alleviate some moisture levels around the seeps and we hope to see some longer term benefits of this.

Also ripping the seep itself reduced the standing water after a rain and produced clod formation which had the subsequent effects of better germination in the coming season. Also it was seen as having potential to encourage some salt leaching.

Covering the seeps and affected areas with straw did improve germination in the scaled area but long term benefits of this are questionable with the salt already breaching the surface.

What is your longer term management plans for them We plan to plant cover crops of both puccinella and tall wheat grass noting that both species have been hard to germinate in the past.

Initial inspection and setup Joe Marshalls site was established in March 2019.

4 bores (piezometers) were installed for future watertable depth and salinity measurements.

Joe was keen to establish the site due to his observation that the scalded area was becoming more saline in sections and also getting larger. Joe has a solid farming background with accurate records to help with the GIS (geographical information systems) to assist with the monitoring and also the development of this site.

Monitoring and data collection Water Table Salinities.

Initial EC readings from watertable in four bores

Picture 1) Marshall Site

Picture 2) Marshall Site installation of bores (Ryan fox & Ashley Wright)

Picture 3) Google Earth image of area of seep site attributed to grower * Shaded area in yellow indicates scalded zone - Total Area Included = 200ha

Picture 4) (NDVI) Normalised Difference Vegetation Index August 2019

Picture 5) Elevation m

Farm management priorities of grower Tall wheat grass and puccinellia were sown in July 2019.

This was sown late but seed was not available until this period. Usual timing of this operation would be late March to early April. The seed was sown on the scalded area and also upon the visual inception zones. Unfortunately this did not take with any real success and was a hindrance on the cropping operations being implemented. Weeds were also an issue with this approach especially considering the normal operations conducted around the site and also the lack of establishment.

In subsequent discussions with Joe, it has been decided to establish a line of salt tolerant trees above the break of slope of the bare salt-pan.

Trees will be 20 metres apart and have an individual sheep-proof guard around them. The guard will consist of a length of sheep mesh 6 m x 900 high, formed into a circle. Each tree and guard will cost $60. It is proposed that 10 trees will be required. After 5 years the guards could be moved onto another site.

Key take home messages Timely sowing of salt tolerant grass species is vital to achieve success in re-establishing groundcover on affected areas.

Trees planted 20 metres apart and individually guarded are likely to be successful in preventing expansion of the seepage area at this site.

Picture 6) Elevation and proposed tree line for future prevention

Vines, Ouyen In December 2018 a site was selected and established on the Vines family farm east of Ouyen. The site was established to enable the assessment of water drainage into a localised seep from a sand rise. The development of investigative methods for data collation and applied management strategies were discussed and a breakdown of this is listed below.

Initial inspection and setup The site already had some Tall Wheat Grass established with some success. The total area of successful establishment accounted for 0.75 Ha. We decided to try and determine if this area had created a buffer great enough for managing the recharge.

Picture 1) Area of established Tall Wheat Grass and Google Earth Image of seep site and Tall Wheat grass area

Monitoring and data collection Watertable salinity EC Initial EC from watertable and depth (m)

Total Area Included =26ha

Figure 1) Google Earth image of area of seep site attributed to grower

Figure 2) (NDVI) Normalised Difference Vegetation Index

Figure 3) EM 38 Image Vines

Figure 4) Elevation m

The data sets provided above give some clarification on the area involved in the seeps direct entry and recharge points.

Both the elevation and also NDVI have some relevant data for the soil type and also the spatial properties. The EM 38 clarifies the water table rising on the southern flat of the rise with some large numbers showing up in surface salt.

Farm management priorities of grower Geoff discussed that his son was keen to realign the fences to better suit the soil types and a new placement is seen in Figure 1, that will enclose 26 Ha. Sturdy individual tree-guards would be utilised on the single row of trees spaced at 20 metres.

Figure 5) New area of Management established and tree line proposal 3.7 Ha

Picture 2) Puccinellia established July 2019.

The more salt tolerant perennial grass Puccinellia was sown into areas where Tall Wheat Grass had failed. Temporary fencing highlighting the importance of stock exclusion.

Key take home messages On this site the short term treatment has been to establish salt tolerant grasses; aiming to both utilise seepage inflows and create groundcover to minimise evaporation and resultant salinisation.

Long term treatment will be the establishment of a single row of strategically placed salt-tolerant trees above the seep. At 20 metre spacing and straight rows positioned to fit current farming practices, these will replace the need for other works to remain in the future. Individual guards of sheep mesh (900x6000) will be used and relocated to new sites every 4 to 5 years.

The potential for the salinised affected area to be fenced and used as permanent pasture for stock has also been discussed with the cost of this being significantly higher.

Etherton, Cowangie Brian Etherton’s dune seepage site, Cowangie 2020 In 1981 two seriously affected bare dune seepage saltpans of about 8 ha each were sown to Tall Wheat Grass (TWG) and Puccinellia, and were fenced to exclude stock.

The saltpan near the road (Saltpan 3) was fenced with more traditional post and wire construction, where-as the one in the centre of the paddock (Saltpan 1) a relatively new 5 wire electric fence (consisted of 3 hot wires and 2 return earths) was trialled.

In 1981 a series of shallow and some deeper piezometers (20 metres deep) were installed to monitor watertable levels and salinities. The deeper piezometers were installed to assist our understanding of these seepage processes in relation to the highly saline (Parilla Sand) regional groundwater that underlies the Victorian Mallee region.

In this district the highly saline regional groundwater’s upper level is at approximately 40 m AHD. (Australian Height Datum). Examples where the watertable discharges naturally at the surface include the Pink Lakes near Underbool and the Cowangie Plains.

Initial inspection and setup.

Brian was concerned about the rapid expansion of seepage salting on his property in 1981 that had resulted following the very wet years of the mid 1970’s.

The Soil Conservation Authority, Ouyen, in April 1981, gave assistance towards the establishment of salt tolerant grasses and the new idea of a cheaper protective fencing using electricity. A number of field days were held attracting large numbers. The fencing proved difficult to maintain with wind-blown weeds causing havoc, and sheep in full wool not respecting its shocking potential!

The fence only lasted some 4 years but that was enough for the tall wheat grass and puccinellia to establish over 50% of the less saline areas.

Monitoring and data collection Installation of piezometers In 1982 a series of both shallow and deep bores were drilled to assist in our understanding of the site.

Regular monitoring of their relative levels, salinities and occasionally pH has assisted greatly towards this understanding.

Watertable salinities Water table salinities of Saltpan 1 are presented in Table 1. These have always been relatively high ranging from 27,000 to 41,000 EC. The more detailed monitoring that happened in the 1980’s indicated fluctuating water levels responding to wetter and drier months with an overall trend downwards as the years passed.

Recent recommencement of watertable monitoring for this project has reinforced that downwards trend. This in in sharp contrast to all adjoining properties that are reporting the expansion of existing historic saltpans and the emergence of new seepage areas over the past 10 years.

Picture 1) B Etherton Sites (The central site, Site 1. is being monitored)

It is important to note that due to all watertable salinities being significantly above the tolerance levels of even salttolerant pastures, the main thrust of all remedial works were to minimise the expansion of the pans. This property remains one of the very few that still operates on a two year rotation, not all that dissimilar to 40 years ago. This is in contrast to the almost continuous cropping practices of neighbours.

After 40 years of Brian’s current management these areas are very stable. They still have some bare areas too saline to re-establish ground cover; but overall have a good amount of a mixture of perennial native grasses, native salt bush and samphire and even an occasional tall wheat grass plant. There is no sign of expansion and watertable levels are all from 1 to 2 metres lower than in the same month in 1981.

Initial EC from watertable

Total Area Included = 200ha Multiple sites with different historical management Figure 1) Google Earth Image of Area of seep site attributed to grower

Figure 2) (NDVI) Normalised Difference Vegetation Index Site 1 2 and 3 at the Etherton site

Farm management priorities of grower Site 1 On April 6th 1981 SCA Ouyen used combine equipment to sow 8.4ha of saltpan on Site 1 as indicated in Figure 5 below. A mixture of 5kg/ha of tall wheat grass and 1 kg/ha of puccinellia mixed with 200kg/ha 2:1 fertiliser was used. The salt pan had been cultivated before the sowing commenced and both seed and fertiliser was dropped from the fertiliser box and lightly incorporated with discs.

The site was fenced in 1981 with a five wire electric fence and was powered purely by battery for 3 years to assist in the establishment of the site.

A a

Figure 6) Management Site 3

Figure 3) Elevation m

Figure 5) Management Site 1 (8.4 ha)

Site 3 (9.8 ha) is shown to the left in Figure 6 with the original site represented by A and was sown on the 6th of April 1981. A mixture of 5kg/ha of tall wheat grass and 1 kg/ha of Puccinellia mixed with 200kg/ha 2:1 fertiliser was used. The remaining area of this Site, (3.8 ha) was untreated and represented in Figure 6.

Even by just not cultivating nor controlling weeds has allowed this additional area to stabilise over some 30 years.

Site 2 This area surrounding the saltpan was planted to trees six years ago

by Brian and a neighbour( 25.6 Ha).

At Site 2 above, the two adjoining land managers combined and established a protective fence and planted all rising land well above the seepage affected area to trees. These are growing well. To the east another land manager didn’t get involved and the affected area to seepage continues to expand into his paddocks. We plan to monitor the effect of both the treatment and the varying land management decisions.

Figure 7) Management Area of Site 2

Key take home messages With very saline watertables (above 15,000EC) it is critical to understand that remedial actions must aim to prevent salt pan expansion and create surface cover enough to prevent erosion.

It is also critical to eliminate all cropping practices from such seepage affected areas and livestock exclusion is ideal.

Protective fencing or creating a physical barrier when treating saline seeps with watertable salinities greater than 15,000EC: observing the results from more than 20 seepage affected areas over 40 years has highlighted the importance of creating a physical barrier to normal paddock operations for success. size of the seep affected area also has relevance, the larger areas affected without a physical barrier generally escape damage from misadventure however small affected areas without the physical barrier of either a permanent fence and / or trees being established and maintained have over time, invariably failed. this is due mainly to either changing managers that don’t appreciate the underlying issue, and / or contractors that fail to get the information to exclude the area from normal paddock operations.

Costing for Site 1 + 3 Salt tolerant pasture establishment per ha is: seed, $60; fertiliser, $40; and sowing, $35; a total of $135/ha Protective fencing of approx. $6 /m would initially be required to exclude stock and to create a physical barrier to deter normal paddock operations from the treatment.

Costing -Site 2 Perimeter fencing, $6 /m. Trees, individual guards and watering in at $5/ unit; with 100 trees per hectare ($500/ha) Costing -Site 2 Perimeter fencing, $6 /m. Trees, individual guards and watering in at $5/ unit; with 100 trees per hectare ($500/ha)

Fox, Swan Hill Farmer questionnaire response Dylan Fox About you and the farm .....

We are a fourth generation family farm located 20 km south of Swan Hill. We have a mixed farming operation growing grain crops, oaten hay and prime lambs. Soil types consist mainly of a sandy-loam to clay-loam.

Some detail about your farming system, in particular change to Direct drill, bar setup , why the change, weed management moisture retention etc We switched to a direct drilling seeding system in 2008, using minimum till for the first few seasons. In 2014 a Gason hydra-max bar was purchased to deep band higher rates of fertiliser at sowing. We decided to go to a direct drilling system of cropping to minimize soil erosion, retain moisture from summer rain, improve efficiency of the farm (do more acres with less labour) and to control weeds with a broader range of pre-emergent herbicides.

Seeps Management ...so far Currently the only management change we have tried to reduce the seeps area is deep ripping prior to sowing the winter crop. Last year (2020) you could visually see the rip lines and the crop was growing better all season, have ripped more area this season (2021) and with closer rip lines.

When did the seep start have and they got worse or always been there?

The seeps have been getting noticeably worse since 2010-11 season when there was a large amount of summer rain.

Also, the paddock was winter fallowed in 2014 which also worsened the main seep in this paddock and started up smaller seeps as well. Good summer weed control has also increased moisture conservation causing the water table to rise in the centre of the soak.

What is your longer term management plans for them In the future I would like to plant trees or species of summer growing grasses along the top side of the seep as a permanent moisture drawing tool.

Monitoring and data collection Watertable level EC reading

As shown to the left in Figure 1 we have the visual area of concern mapped from Google earth. It is quite accurate in terms of the scalded area and gives a good idea on the scope of the problem, especially where it has been occurring for a number of years. The images also highlight an old channel system that used to run on the right hand side of the scald.

Figure 1) Google Earth Image of Area of seep site attributed to grower Total Area Included = .821ha

Figure 2) (NDVI) Normalised Difference Vegetation Index Fox site

Figure 3) Elevation m 1000ha

Figure 2 also highlights the scalded area well but must be well ground truthed with the sandy areas in this image also showing low biomass. The scalded area is well below the average of the paddock and highlights salinity issues. This is the inverse of what is seen over summer on the emerging seep with summer weeds feeding off the available water on the breech of the seep.

The elevation data in Figure 3 gives an account for the immediate area and also further around the seep. It places the site in the middle of a large reduction in elevation from east to west. It is not known if these large differences feed this or other seeps in the area but as more data becomes available with time and knowledge it will be interesting to discover.

Figure 4 gives a good account of the Fox farm seep with the elevation contour produced accounting for the region the seep is highlighted by the NDVI over summer.

Figure 4) Elevation m Site location high and low point in proximity to seep

Picture 6) Pentrometer used on site for ripping assessment.

Picture 5) Installation of piezometer with Tony and Dylan Fox at Goshen

Picture 7) Ripped site right up to the scalded area

Selective ripping took place on this site based on the potential for seep management and also the pentrometer reading across the elevated sand. The dry seasons have not given a true indication of the effects of the ripping in relation to the seep.

Extensive work has been performed for the betterment of specific commodities in these areas and have shown promising results for greater production and water use.

Key take home messages Both Tony and Dylan agree that the best long term action would be for trees to be planted but in a manner which has limited impact on their operation.

A seeder path-width is the most acceptable width for both water interception and limited operational impact. The spray pass will have to be managed independently but given the area will only be in between the trees as seen below in picture 8.

Picture 8) Trees arranged for seeder pass and along the seep line high enough for interception