Soil and agricultural land
The vulnerability of soils to climate change is strongly linked to the type of soil and its inherent characteristics, but is ultimately determined by land use and management.
The focus for adaptation in this region is on understanding the issues for agricultural land managers in order to develop adaptation options that have benefits for soils and agricultural production. There is significant variability in land type and geology in the East Gippsland region. Soils in the eastern part of the East Gippsland region are well structured and fertile with high organic matter content, whilst in the west of the region soils are generally low in organic matter content, are lightly textured and prone to erosion (EGCMA, 2013).
The major agricultural commodities in East Gippsland are vegetables, livestock and livestock products (meat, milk, and wool), crops, and hay. Agricultural production in the region is concentrated on the Gippsland Plains, the Mitchell and Tambo river valleys and the Monaro Tablelands, where the original open grassy woodland lent itself to grazing, and where rich alluvial soil has supported the development of intensive agriculture. In general, the lowland soils associated with the Red Gum Plains and fertile river valleys have the potential for increased agricultural production in the future (EGCMA, 2013).
A key challenge for the management of grazing land relates to varying stocking rates in response to seasonal conditions. The onset of dry seasonal conditions and transition to longer-term drought is often subtle and the ability to adaptively adjust stocking rates is a constant challenge, but when done successfully maintains ground cover and reduces the need for hand feeding of animals. Strategic use of stock-containment areas is also very effective in protecting pasture and soils, with benefits in both drought and excessively wet years.
Asset vulnerability
Compared to other parts of Victoria, the projected changes in temperature and rainfall by 2050 in East Gippsland will be more moderate. As a consequence, there may be more opportunities for adaptation and development of new enterprises in primary production than in other parts of Victoria and potential for increased production due to shifts in crops to Gippsland from other production areas.
The vulnerability of soils to climate change is strongly linked to the inherent properties of the soil as described by the soil type and the level of ground cover. In East Gippsland, soils were assessed as having a lower overall potential vulnerability to climate change compared with the other asset classes. The soils, on freehold land, with the highest potential vulnerability were: dark clays, pale sands, yellow duplex soils, red friable earths, grey clays and grey sands. (Spatial Vision & Natural Decisions, 2014).
Table 1. Highest potential vulnerability for soil classes that have a freehold land interface in East Gippsland (Spatial Vision & Natural Decisions, 2014).
Asset name |
East Gippsland RCS Landscape Area |
Red friable earths |
East Coast Gippsland Lakes & Hinterlands Far East Catchments
|
Pale sands, Yellow duplex soils |
East Coast Gippsland Lakes & Hinterlands |
Grey clays, Grey sands |
Far East Catchments East Coast Gippsland Lakes & Hinterlands Gippsland Lakes Upper Catchment |
Dark clays |
East Coast |
Potential adaptation options
Potential adaptation options for agricultural land and soil are set out in Table 2 below and have formed the basis of analysis for development of this Plan. Options have been identified in response to key climate change variables.
It is important to note that the options outlined below relate to individual practices, rather than whole farming systems. For agricultural land managers, profitability is the underlying driver to be considered when adaptation options are being assessed. Adaptation in farming systems is unlikely to happen practice by practice, rather through incremental changes that enhance the long-term financial viability of enterprises. Market forces remain a key influence on the operation of farming enterprises and set the context for adaptation. The potential adaptation options described below will require careful evaluation of both short-term and long-term financial performance, feasibility and risk, and support through farm-scale extension and agronomic advice.
Table 2. Potential adaptation options for agricultural enterprises in East Gippsland.
Climate Change Variables: |
||||
---|---|---|---|---|
Reduced and more variable rainfall |
Increased temperatures and extreme heat |
Increased intensity and frequency of rainfall events (including flooding) |
Increased frequency of fire |
Storm surge and sea level rise |
Agricultural land – grazing (beef, dairy and sheep) |
||||
Soil management practices to reduce compaction, tillage, and retaining stubble; these reduce potential for nitrous oxide loss and increase soil carbon, while also improving productivity
Optimise feed use efficiency through improved breeding programs that improve growth rates and weaning times
Use flexible grazing techniques based on the pasture and animal requirements to maintain productivity and improve ground cover
Match fertiliser program to pasture/crop requirements including industry tools that draw on soil/plant testing, seasonal forecasting, soil nutrient reserve and fertiliser type
Increase diversity of farm water options
|
Provide shelter and shade from extreme heat, through vegetation establishment or use of shade structures
Provision of sheltered watering points
Trial of new pasture and crop varieties
Increase ground cover through grazing management
Change to milking times to avoid hottest part of day
Consider calving/lambing times in the context of potential heat stress and feed availability
Use of summer active perennials in pasture systems
|
Improve and increase flood-warning systems
Maintain groundcover to mitigate against erosion
Adoption of alternative grazing strategies
Consider timing of planned burns and risk of rainfall events / flooding to reduce downstream impacts |
Consider on-farm strategies to protect assets in high fire risk areas
Additional insurance
Property level fire management plan
Increased effort on invasive plant and animal control after fires |
Identify alternate varieties and breeds that can deal with increased salinity
Urban development may move away from the coast to high agriculture and natural asset areas
|
Agricultural land – horticulture |
||||
Increase on-farm water storage capacity
Increase irrigation efficiency and re-use where applicable
Spread production over a range of areas within the region to different irrigation or rainfall zones
New/alternate varieties more tolerant of water stress and reduced rainfall
Change crops to more water efficient varieties |
Trial new/alternate varieties more tolerant of increased temperature
Shift timing of planting, change crops
Use protective structures
Irrigation and water management to mitigate heat effects
For perennial crops optimise canopy growth and shading to prevent damage to fruit (sun, fungal and pest attack)
|
Use alternative bed preparation techniques that reduce cultivation
Inter row plantings of pliable plant species
Shift production out of floodplain and/or spread production across multiple locations
Early detection programs to address new diseases and pests
Schedule planting to avoid planting during flood prone times
Use ground cover crops to protect paddocks at flood risk during time of year when floods most likely |
Additional insurance
Farm based fire management plan
Consider placement of key infrastructure to enable better protection during fire event.
Coordinated recovery programs to assist landholders to respond. |
Identify alternate varieties that can deal with increased salinity
Provide buffer between crop and area likely to be impacted by storm surge and increased salinity
|
Mitigation Options
On a global scale soil is estimated to contain three times as much carbon as the atmosphere and nearly four times as much as contained in living matter (Lal, 2002). However, the carbon content of many agricultural soils has declined over time and there are some estimates of significant opportunities for carbon sequestration through changes to land use and land management (Lal, 2002). The amount of additional carbon sequestered when a new management practice is adopted depends on the initial carbon content, the practice, soil type and climate.
In East Gippsland, the soils underlying agricultural land are variable in their type, fertility and condition. There are various forms of soil degradation in the region including erosion, acidification, structure decline, waterlogging and salinisation. These threats to soil health and productivity have been the focus of a range of initiatives including mapping of erosion risk, soil testing as well as extension and implementation of recommended management practices by farmers. Adoption of management practices that aim to address these threats can have flow-on benefits in the form of soil carbon accumulation, but carbon itself may not be a primary driver for the management practices of many farmers.
Improving soil carbon stocks on agricultural land in East Gippsland is strongly linked to management practices; such strategies that optimise fertiliser use, stock management and groundcover retention in grazing systems, and reduced tillage in cropping and horticultural systems or in grazing systems.
Soil carbon can be stored in grazing systems by increasing the amount of organic matter in agricultural soils. This occurs when management practices either increase the amount of biomass (such as plant material) that is incorporated into the soil and/or reduce the amount of organic matter that is released from soils (for example, by reducing soil disturbance) (Department of Environment, 2014). Soil carbon is inherently unstable and prolonged drought can remove much of the stored carbon.
An increase in soil carbon has benefits to farming through improved soil structure, water holding capacity and nutrient retention. Soil carbon will accumulate where there is extra, sustained pasture growth. The practices that are likely to increase soil carbon through the production of extra growth are the use of fertilizer, some rotational grazing systems and the introduction of perennial pasture species. The benefit to producers will be primarily from utilising the extra feed generated from the activities undertaken, rather than any direct benefit from increased carbon content. Any strategies to improve soil carbon levels must consider the economic justification for undertaking the specific activity.
There is much uncertainty and debate, particularly within Australia, around the role of soils in carbon sequestration. This includes issues such as: the total potential of agricultural soils to store additional carbon, the rate at which soils can accumulate carbon, the permanence of the stored carbon, and how best to monitor changes in soil carbon stocks (Sanderman et al, 2010).
The Emissions Reduction Fund allows farmers and other landholders to earn carbon credits by reducing greenhouse gas emissions or storing carbon on the land. Participants can earn carbon credits by setting up a project under an approved ERF method, which sets out the rules for implementing and monitoring the activity (see Appendix 5 for further explanation).
It is important to note that many of the options available to primary producers to increase soil carbon, for example stubble/biomass retention in cropping and grazing systems, are seen more generally as key strategies in the development of more profitable and sustainable farming systems. The adoption of these practices is not currently being driven by a motivation to participate in initiatives such as the Emissions Reduction Fund (ERF), but rather as a means of achieving long-term farm viability. The biomass from which the organic matter (soil carbon) is derived is expensive to produce and, at current pricing, commercial sequestration provides a much smaller return than using the feed for livestock. In addition there are restrictions on future land use.
Within broad parameters, landholders will have a choice of which land management activities to implement to build soil carbon. Activities must include at least one new management activity. Some activities, such as permanent destocking, are not eligible. Types of activities that could potentially be implemented include, but are not limited to, converting cropland to permanent pasture, rejuvenating pastures, or changing grazing patterns.
Site specific factors such as soil type, climate and management history all influence the potential for soil carbon sequestration (the increase in soil carbon stocks over time). There is no guarantee that any one or more of the eligible activities chosen by landholders will build soil carbon at any particular project site. Project proponents should seek expert advice on the management actions that will best suit their project area.
Landholders must measure the soil carbon stocks at the project site at regular intervals during the project to estimate carbon sequestration. Emissions from other sources that have changed as a result of the project, such as emissions from livestock, tillage events and applications of lime or synthetic fertiliser, must be calculated to find the net abatement from the project.
For more information about climate change pressures on soil and agricultural land, please see East Gippsland Regional Catchment Strategy: Climate Change Adaptation and Mitigation Plan.