Land Use

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GUEST OBSERVATION
Microplastics in the ocean, pieces of plastic less than 5mm in size, have shot to infamy in the last few years. Governments and businesses targeted microbeads in cosmetics, some were banned, and the world felt a little better.
Dealing with microbeads in cosmetics is a positive first step, but the reality is that they are just a drop in the ocean (less than a billionth of the world’s ocean).
Microplastics in soil may be a far greater problem. Norwegian research estimates that in Europe and North America, between 110,000 and 730,000 tonnes of microplastic are transferred to agricultural soils each year.
Here lies the issue: we know almost nothing about microplastics in global soils, and even less in Australian soils. In this article we take a look at what we do know, and some questions we need to answer.
How microplastics get into agricultural soil
Sewage sludge and plastic mulch are the two biggest known contributors of microplastics to agricultural soil. Australia produces about 320,000 dry tonnes of biosolids each year, 55% of which is applied to agricultural land. Biosolids, while controversial, are an excellent source of nutrients for farmland. Of the essential plant nutrients, we can only manufacture nitrogen. The rest we must either mine or recycle.
Sewage treatment plants receive water from households, industry, and stormwater, each adding to the load of plastics. Technical clothing such as sportswear and quick-dry fabrics often contain polyesters and polyamides that break off when clothes are washed. Tyre debris and plastic films wash in with the stormwater. Treatment plants filter microplastics out of the water, retaining them in the sludge that is then trucked away and spread over agricultural land.
In agriculture, plastic mulch suppresses weeds, keeps the soil warm and damp to assist germination, and improves yield. Over time, these mulches break down, and some fragment into smaller pieces.
Biodegradable bioplastic mulches are designed to break down into carbon dioxide, water, and various “natural substances”. Environmentally friendly plastics are often more expensive, raising the question of whether businesses will be able to afford them.
Other potential sources of plastics in agricultural soil include polymer sealants on fertilisers and pesticides, and industrial compost. Unsold food is often sent to the composting facility still in plastic packaging, and with plastic stickers on every apple and kiwi fruit.
The Australian Standard for composts tacitly recognises that microplastics are likely to be present in these products by having acceptable levels of “visible contamination”. Anyone who has bought compost or garden loam from a landscaping supplier may have noticed pieces of plastic in the mix.
In horticulture, particularly as green walls and green roofs grace more buildings, polystyrenes are used deliberately to make lightweight ‘soil’.
There might be other pathways we don’t know about yet.
What happens once microplastics are in the soil?
Here we stand at the edge of the cavernous knowledge gap, because we don’t know the effect of microplastics in our soil. The overarching question, physically and biologically, is where do microplastics go?
How plastics fragment and degrade in the soil depends on the type of plastic and soil conditions. Compostable, PET, and various degradable plastics will behave differently, having different effects on soil physics and biology.
Fragments could move through soil cracks and pores. Larger soil fauna might disperse fragments vertically and laterally, while agricultural practices such as tillage could push plastics deeper into the soil. Some fragmented plastics can absorb agrochemicals.
Soil microbes can break down some plastics, but what are the byproducts and what are their effects? Newer, biodegradable bioplastics theoretically have limited impact as they break down into inert substances. But how long do they take to break down in different soil and climatic conditions, and what proportion in the soil are non-degradable PET plastics?
Both the main form of carbon in soil and polythene (the most common type of plastic) are carbon-based polymers. Could the two integrate? If they did, would this prevent plastics from moving deeper into the soil, but would it also stop them breaking down?
Could plastics be a hidden source of soil carbon storage?
Bioaccumulation
Bioaccumulation is when something builds up in a food chain.
Research into microplastic accumulation on land is sparse at best. A 2017 study in Mexico found microplastics in chicken gizzards. In the study area, waste management is poor and most plastics were ingested directly from the soil surface as opposed to having bioaccumulated.
Nematodes can take up polystyrene beads suggesting some potential for bioaccumulation, however earthworms have reduced growth rate and increased mortality when they ingest microbeads.
Larger microplastics are unlikely to cross plant cell membranes, but it’s possible that plants can absorb the chemicals formed when plastic degrades. Plants have natural mechanisms to keep contaminants out of their fruiting bodies – pieces of plastic in apples or berries is highly unlikely – but root vegetables and leafy greens are a different story.
Metals can accumulate in leafy greens and the skin of root vegetables – could plastics or their byproducts do the same?
This is before we even get to nanoplastics, which are 1-100 nanometres wide. Can plant roots can absorb nanoplastics, and can they pass through an animal’s gut membrane?
Where to now?
The first step is to quantify how much plastic is currently in the soil, where it is, and how much more to expect. This is more difficult in land than water, as it’s easier to filter plastics out the ocean than to separate them from soil samples. The smaller the plastics are, the harder they’ll be to track and identify – which is why research must start now.
Research needs to address the different types of plastics, including beads and other synthetic fibres. Each is likely to act differently in the soil and terrestrial ecosystems.
Understanding how these plastics react will inform the next obvious questions: at what quantity do they become hazardous to soil, plant and animal life, and how can we mitigate this impact?
<img src="https://counter.theconversation.com/content/96858/count.gif?distributor=republish-lightbox-basic" alt="The Conversation" width="1" height="1">Plastics in soil represent artefacts of human civilisation. Soils are full of human artefacts; if this was not the case then there would be no field archaeology. However, the effects of microplastic may persist far longer than our own civilisation. We must fill in our knowledge gaps swiftly.
Alisa Bryce, Research Affiliate, University of Sydney
Alex McBratney, Professor of Digital Agriculture &amp; Soil Science; Director, Sydney Institute of Agriculture, University of Sydney
Budiman Minasny, Professor in Soil-Landscape Modelling, University of Sydney
Damien Field, Associate professor, University of Sydney
Stephen Cattle, Associate professor, University of Sydney
This article was originally published on <a href="http://theconversation.com" target="_blank">The Conversation</a>. Read the <a href="https://theconversation.com/we-have-no-idea-how-much-microplastic-is-in-australias-soil-but-it-could-be-a-lot-96858" target="_blank">original article</a>.
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j.ballantyne1990-6AQqhLzZaK

We have no idea how much microplastic is in Australia's soil (but it could be a lot)

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Land use zoning is a tool used by local governments to define the types of land use permitted or prohibited in each zone.
Simply put, zoning is a framework to decide what can and what cannot be built in specific areas.
Zoning differs from state to state in Australia, but land under the control of the Commonwealth (federal) government is not subject to state planning controls.
Although zoning differs from state to state, zones are generally classified into these broad categories: Residential, Commercial, Industrial, Agricultural and Mixed-Use. Within these are sub-categories, with zones typically identified by a colour on a map.
When considering investing in commercial property, it pays to check with the local council about the zoning of the land to avoid running afoul of the law and nasty surprises later.
Listed below is the zoning for states and the ACT.
Australian Capital Territory
The ACT has commercial zones from CZ1 through to CZ6, with CZ5 for mixed-use, while CZ6 is a leisure and accommodation zone.
New South Wales
NSW has a Standard Instrument Local Environment Plan in place with that covers residential, commercial and mixed use among others. Listed is the zoning for commercial: 
B1 Neighbourhood Centre
B2 Local Centre
B3 Commercial Core
B4 Mixed Use
B5 Business Development
B6 Enterprise Corridor
B7 Business Park
B8 Metropolitan Centre
Northern Territory
The NT has a long list of codes, with commercial zones divided into the following:
CB Central Business
C Commercial
SC Service Commercial
TC Tourist Commercial
The residential goes from single dwelling to high density.
Queensland
The Queensland Planning Provisions (QPP) document provides a format and structure for local governments to prepare their planning schemes while allowing the flexibility to address each local government's circumstances. Zoning is controlled by individual councils and differ from council to council across the state.
South Australia
In SA, zoning differs from council to council across the state.
Tasmania
Tasmania has 23 different zones, and all its 29 councils each have a planning scheme within the guidelines of the Tasmania Planning Commission , with the exception of the Hobart City Council which has two.
Victoria
All land in Victoria has a zone, specifying particular purposes for land, such as residential growth, low density residential or commercial 1. The framework is managed by the Victoria Department of Transport, Planning and Local Infrastructure.
Western Australia
Local councils in Western Australia set their own planning schemes, which are controlled by the Western Australian Planning Commission.
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prateek24-ezbwHMbNAk

Property 101: Get in the zone on commercial property 

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GUEST OBSERVER
Cities and mine sites are complex spaces, which frequently change at a fine scale. This makes them hard to monitor. It is now possible, though, to adapt digital aerial photography to monitor changes as small as 10-20cm in both land use and vegetation in three dimensions.
Interested? Wondering whether that’s feasible? Here’s how you can do it cost-effectively.
Monitoring changes in land cover including vegetation has been routine since digital satellite imagery became available in the 1970s and 1980s. However, satellite images have traditionally been too coarse to monitor complex environments such as cities and mine sites, so aerial data is often acquired. In addition to needing sub-metre resolution, city buildings, mine pits and spoil dumps present challenges for automatically tracking change.
Analogue (film) imagery has been used for aerial monitoring long after digital photographers replaced film in hand-held cameras. This is partly because changing large programs with multiple users is risky.
About ten years ago the authors started working with Landgate, the Western Australian government agency responsible for photographing Greater Perth. Our aim was to see if the advantages of satellite monitoring could be incorporated into Landgate’s annual aerial photograph capture to detect changes in land use and vegetation condition at the sub-metre level.
<h2>How is it done?</h2>
As well as recording red, green and blue bands of light, a near infra-red band was included because vegetation health is best measured at this wavelength. The elevation of the ground, buildings and trees is estimated each time, with a similar resolution as the pixel size making the imagery three-dimensional. Being digital, it is easy to count pixels to quantify changes.
Digital data allows changes over time to be measured with much greater accuracy and efficiency than when comparing film images.
It requires, though, that the images be captured using a standard approach. Standardised images ensure that a change in digital reflectance represents a real change and not a change in the atmosphere, sun angle, camera type or a shadow. Each image also needs to be very accurately aligned.
Reflectance targets were placed on the ground to ensure images were standardised during the acquisition as well as between years.
After trials in 2006 and 2007, summer images were chosen. This was because these met most of the requirements of the consortium of 13 government agencies and non-government organisations that guided the transition from analogue to digital.
Summer is a time when un-irrigated plants are most stressed. This enables monitoring of soil water deficits, groundwater-dependent vegetation and an assessment of irrigation efficiency at the individual-sprinkler scale. There is also less cloud and the impact of recent rainfall is less evident, given that the capture can take several weeks. To limit shadows, capture times were restricted to two hours each side of solar noon.
The area covered by the digital aerial photography each summer (see figure at right) extends beyond that needed to update street directories. It includes groundwater catchments, pine plantations and peri-urban horticulture. This coverage also enabled us to monitor disease impacts on native trees of interest to the consortium.
Technical details can be found in an article in the International Journal of Digital Earth and on the Urban Monitor websit<a href="https://urbanmonitor-beta.landgate.wa.gov.au/project.php">e</a>. The website includes a beta test site of vegetation products maintained by Landgate.
<h2>Many uses, and counting…</h2>
The method has been applied to:
1) Monitoring tree canopy cover in the Greater Perth region for state and local government planners to assess habitat loss and an increase in the urban heat island.
<a href="/images/2016/01/28/image04.png" target="_blank">Click to enlarge</a>
<img src="/images/2016/01/28/image04.png" alt="">
2) Identifying tall trees (even those in low-elevation areas) of importance to roosting birds such as the endangered Carnaby Cockatoos for the Perth Peel Regional<a href="https://www.environment.gov.au/resource/urban-monitor-enabling-effective-monitoring-and-management-urban-and-coastal-environments"> </a>Sustainability Plan. In the image below, tree heights are shown in increasingly “hot” colours, displayed with a sun-shaded elevation model in grey for unvegetated areas. 
<a href="/images/2016/01/28/image-20160121-9746-1tx05wv.jpg" target="_blank">Click to enlarge</a>
<img src="/images/2016/01/28/image-20160121-9746-1tx05wv.jpg" alt="">
 
3) Tree and bush decline in native vegetation in urban areas. The image below shows vegetation losses in red, growth in green and no change in yellow. Non-vegetated areas are uncoloured.
<a href="/images/2016/01/28/image-20160121-9725-zngwfw.png" target="_blank">Click to enlarge</a>
<img src="/images/2016/01/28/image-20160121-9725-zngwfw.png" alt="">
4) Estimating the effect of urbanisation on urban water balances, especially runoff and recharge. Being three-dimensional, the images can identify where water will flow in new urban catchments.
5) The identification of blocks of land that have been built upon for urban infill planning (shown as red blocks in the image below).
<a href="/images/2016/01/28/image-20160121-9769-1wfyfg4.jpg" target="_blank">Click to enlarge</a>
<img src="/images/2016/01/28/image-20160121-9769-1wfyfg4.jpg" alt="">
6) Drying of groundwater-fed wetlands in the Perth Peel region.
7) The impact of mine or coal seam gas developments on vegetation and runoff. The example below shows predicted flow paths and accumulations of water in a rural landscape after development of coal seam gas sites.
<a href="/images/2016/01/28/image-20160121-9763-1cfenec.png" target="_blank">Click to enlarge</a>
<img src="/images/2016/01/28/image-20160121-9763-1cfenec.png" alt="">
 
The scale of the imagery is especially suited to local government and mining companies reporting to regulators, as it can help separate mine impacts from climate, fire, grazing or other disturbances.
Readers will probably identify further uses for the method – something that we have experienced whenever we give talks on its application.
In the Greater Perth region, digital acquisition using monitoring standards has replaced analogue capture, so it is routine with limited additional costs for acquisition. Not all datasets have been fully processed but they are archived for later reference as funds and needs arise. The data are expected to become increasingly valuable over time because they cannot be acquired retrospectively.
In time it is anticipated that Urban Monitor products similar to Land Monitor will be made available on the Landgate website. Land Monitor has used interpreted satellite imagery to provide change products to West Australian natural resource management agencies for more than 15 years for an annual cost of about $80,000.
This shows that good monitoring need not be expensive if thoughtful acquisition methods are used and products are developed to meet multiple user needs.
 
Don McFarlane is research scientist; Groundwater Hydrology Team Leader, CSIRO and can be contacted <a href="https://theconversation.com/profiles/don-mcfarlane-2324" target="_blank">here</a>.
Peter Caccetta is research scientist, CSIRO, and can be contacted <a href="https://theconversation.com/profiles/peter-caccetta-221621" target="_blank">here</a>. 
Both are authors for The Conversation.
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