Sustainable Soil Field Days

The Making Good Better project held two field days last week to showcase the work that has been done during the project. The days were also used to launch the Soil Quality website for Tasmania. This website can be used by farmers for benchmarking their soil data. It also has a series of factsheets covering soil issues including soil structure, water logging, cation exchange capacity, and calculators which can be used to calculate the cost of growing green manure or retaining stubble or applying different types of lime. Andrew Wherrett and Dan Murphy from the Soil Quality program in WA came over for the days and gave us some insights both into the website and soil issues in WA.

David Rowlings from Queensland University of Technology gave us a very detailed overview of the soil carbon and nitrogen cycles and how closely linked the two are. He had some excellent tips for improving the efficiency of N fertiliser use - leaks have environmental impacts as well as costing dollars. Bill Cotching reviewed the soil survey and trial results from the MGB projects and we also heard from some of the farmers involved in the MGB project. The weather was reasonably kind at Bothwell and we were able to visit Llanberis (Richard Hallett) and Dennistoun (Tom Edgell) where we looked at the soils being farmed in the area and some of the field testing techniques for assessing soil quality. Richard also gave an overview of the Variable Rate Irrigation technology that is being used on some of his centre pivot irrigators. Unfortunately at Dairy Plains the rain got the better of us, but we did have a quick trip out to Juniper Lea (Rob Terry) where we were able to play with some dirt and hear about some of Rob's farming operation.
For a look at the presentations from the field days click on the link to the Macquarie Franklin website. The Mac Frank website also has a copy of the MGB Demo Trial Booklet available for download, plus other information from the project, including farmer case studies.

For more information about the soil quality program go to the Soil Quality website

Variable Rate Irrigation

Earlier in December the Bothwell Making Good Better focus group had a session looking at Variable Rate Irrigation (VRI). We visited Richard Hallett's property Llanberis, where Richard has two different systems installed, on two of his centre pivots. Along with Richard, Will Burden (Roberts Irrigation) and Reuben Wells (AgLogic) gave the group an excellent overview on how the VRI works, what is involved, etc. VRI uses GPS technology to control individual sprinklers and/or the speed of the wheels to increase or decrease the amount of water applied to particular sections of paddock. There is a GPS node installed at a control unit at the centre point and at the end of the machine. Soil maps are used as a base to program the machine (maps can be created a number of ways - simply by reveiwing aerial photos of the paddock, by detailed soil surveying on the ground or by EM survey). Once the map is created different programs can be produced for different areas - for example a drainage line may be an avoidance area (no water applied), a wet hollow may get 20% of the rate applied to the rest of the paddock and a sandy bank may get 110% of the standard rate. The programs can be altered as the season progresses, and saved, so they are on file for future years. It is important to put the time in at the start of the season to do the mappng and set up your programs so that it all runs smoothly when you need it to.

A key benefit of VRI is that it can be used to keep water off wet areas, prevent waterlogging, bogging and runoff as well as being able to adjust amounts of water for different soil types. With huge variation in soil types in pivot circles on Llanberis (from sands to black cracking clays), Richard is very happy with his system, which is enabling him to get yields off areas that would never grow anything in the past. However VRI is expensive and not a silver bullet for all problems, so make sure you've got everything else right with your irrigation system first (sprinklers, drainage, etc), and then look carefully at likely returns/payback time.

Soil health - linking it all together

Declan McDonald from DPI in Victoria recently visited our Making Good Better north and north western groups for discussion group meetings on soil health.
The northern group went first to Phil Spencer's property Sand Park where Phil gave us an overview of his farm management, which is focussed on improving soil health. Phil uses significant amounts of compost on his paddocks each year (usually 2.5-3t/ha), as well as a fish/seaweed soil drench. Whenever he applies N fertiliser it is mixed with compost first. He now has two paddocks set aside as areas where he is trialling no use of synthetic fertilisers (this year they are in peas and grass seed) at all - these areas received 7t compost/ha over two applications. Declan felt that Phil was approaching his farming in a very holistic way - that by managing for soil biology as well as nutrients, that he is ensuring that his soils will be "finely tuned and running on all cylinders". There was a lot of discussion about compost - in Victoria many farmers are now producing their own, with local compost turners for hire. We then went to Eastfield with Sam Bond, where we had a look at how Sam manages breaks in his cropping rotation to maintain soil health - a clover seed crop is the final "cash" crop in the rotation before ryegrass is drilled in. The circles are then fenced into quarters and used as irrigated fattening paddocks for lambs for 3-4 years. A saline area was also visited where Declan suggested using a thick layer of mulch as a trial to rehabilitate the saline area.

The next day Rachel took Declan to visit Mark Wadley's farm at Deloraine to discuss options for using effluent pond crust as a soil conditioner. As part of Mark's MGB activities, he has undertaken earth works so that the crust can be easily removed with an excavator and then stock piled for use as a soil amendment. Declan felt that the stock piled crust would make a good soil conditioner 'as is' but that biological activity could be improved with composting. Declan and Mark discussed options for a small scale composting trial - Declan advised that measuring the temperature profile is very important. Compost thermometers are around $300 and can also be used for measuring haystack temperatures. While in the area, Declan also visited Tim Schmidt's property to look at soil management in a difficult paddock. We then had a kitchen table chat with Colin and Liz Chaplin at Moriarty about the cost/benefits of incorporating composts and soil amendments. It was very interesting to hear Declan's long term perspective on soil biology. On the way to the airport, we discussed the 'tipping point' of NW ferrosol structural decline - both Decland and Pete Aird from Serve-Ag feel that when these soils get below 3% OC then there are negative feedback in terms of soil structure and management.

We got the real dirt on soil carbon

Our recent field day held at Kinburn Cressy on 1 November had an excellent turnout of farmers, especially considering what a busy time of year it is. The day was led by Dr Bill Cotching from TIAR, who showed us that soil carbon can help turn our farms into multi-million dollar assets...or can it? While Bill had a lot of evidence that soil carbon is an important part of our farming system, the jury is out on whether easy dollars can be made from it through the Carbon Farming Initiative. Bill gave an excellent overview of the potential of different soil types (clays vs sands) to store carbon, and of the different pools that carbon is found in (humus, particulate, recalcitrant (charcoal)). Sam Rees (Macquarie Franklin) and Craig Newman (AgVita) gave an overview of measuring soil carbon - field sampling and bulk density (BD is covered in a previous blog), while Craig talked about analysis of soil carbon in the lab - total carbon is analysed using a combustion method, which burns off all the carbon in the sample. Organic carbon is analysed using the Walkley Black method which is a chemical digestion.
Bill gave an overview of the influence of management on soil carbon. While temperature and moisture (rainfall) are the biggest factors influencing soil carbon management does also have a strong influence. Bill showed some results from long term (150 year!) trials at Rotham in England which demonstrated that cropping does deplete soil carbon (compared to pasture). It also showed that soil carbon can be increased by adding organic amendments (such as manures) however these additions must be continued to maintain soil carbon. Bill also showed a ranking of management practices and their influence on soil carbon. Bare fallows are the worst thing that you can do for soil carbon - growing pasture is one of the best. Tillage has its place and doesn't appear to be as bad as we have thought. Following on from Bill, we had a series of short presentations by farmers and agronomists on specific management activities that they have had experience in. Peter Aird (Serve-Ag) gave an overview of drainage and the importance that this has for encouraging good plant growth and healthy soils. Bill Chilvers (Oakdene) spoke about his experiences with a long term (5 year) Southern Farming Systems stubble trial, where they found that retaining stubble significantly reduced compaction (and increased infiltration) of soils. Stubble also had positive effects on critters both good and bad (earthworms and slugs). Bill concluded that effectively managing stubble requires a long term view and good attention to detail - and there is a place for burning in some situations. Wheat stubble was highlighted as being one of the more difficult to manage (both in terms of amount of material and slowness in breaking down). Rob Bradley (Woollen Park) gave an overview of his Nuffield scholarship, in which he was interested in researching the sustinability of our cropping systems, where has has found inputs and efforts are on an upwards trend to keep producing the same yields. As he travelled the world, Rob found that integrated livestock and cropping systems (like ours in Tassie) are actually quite rare and "old fashioned”. Instead, the trend of overseas commercial farms is increasingly to separate livestock and cropping as the system intensifies. He ventured into the organic sphere where integration is still practised and an important part of the nutrient cycle. Rob concluded that livestock (and pastures) are a critical component of ensuring the sustainability of his cropping program. The morning wrapped up with a presentation by Ian Smith (Crystal Brook) on his recent experiences with compost teas. Ian runs a vegi farm and is running a trial this year to look at the effects of compost tea on onions. Results so far are very encouraging, with much better root development and lower weed pressure on the area treated with compost tea (interestingly the onions on this side were innoculated with micorrhizal fungi and were not drilled with any fertiliser - other than that they have been treated exactly the same).  Ian gave us a lot of information on the practicalities of preparing compost tea, and on the importance of using good quality compost (composts ain't composts!).
After lunch Bill, Darrel Wise (manager at Kinburn) and Peter Aird took us on a tour of the farm, where we looked at four paddocks with similar soil types but very different management histories. Bill demonstrated the use of his rating system for soil structure (where 10 is excellent structure and 1 is very poor) - the variation in soil structure across the paddocks was very clear.
The afternoon was broken up by the running of the Melbourne Cup where John Rees (having Dunaden in the sweep) was the winner of the soil testing prize (valued at $278) donated by AgVita Analytical. We then broke into small groups for the final test of the day  - matching 4 different soils with their paddock histories. This allowed the groups to put into practice a lot fot he theory that had been covered throughout the day - and they got to do a "bucket chemistry" labile (active) carbon analysis of the soils using potassium permanganate. All groups did an excellent job of working out which soil belonged where and the prize had to be settled by random draw.

The presentations from the day are available on the Macquarie Franklin website...www.macquariefranklin.com.au/resources.html

Getting the dirt on soil carbon

We are running a soil carbon field day as part of the Making Good Better project.
It will be held on Tuesday 1 November from 9.15am to 4.15pm at "Kinburn" 918 Cressy Main Rd Cressy
Cone along if you're interested in learning more about:

• the basics of soil carbon
• how to measure it
• how to manage it

The day will be a practical day with both expert and farmer speakers, and will include a farm tour (and a Melbourne Cup sweep!). Morning and afternoon tea will be provided and lunch will be available for purchase from Longford Rotary Club.
Our main speaker will be Bill Cotching from TIAR. Bill is a preeminent soil scientist, and also has a wealth of practical experience after working with Tasmanian farmers for many years. Other speakers will include Sam Rees (Macquarie Franklin), Craig Newman (Agvita), Bill Chilvers (Oakdene), Ian Smith (Crystal Brook), Rob Bradley (Bradley Agriculture) and Peter Aird (Serve-Ag).
The day is being sponsored by Agvita Analytical, in addition to the Australian Government through their Caring for our Country initiative.

For more information or to RSVP please contact Mel Rae at mrae@macfrank.com.au

Soil - a weighty issue

Do you truly know how much carbon is in your soils? Isn’t this supplied on your soil test result? While a standard soil test usually does supply a value for carbon (either Organic C or Total C) this is not enough to calculate the amount of carbon per hectare (t C/ha). As the soil test value is expressed as a percentage, it actually is telling you how much carbon there is for a known weight of soil. Therefore, the weight of soil per hectare is also needed to fully understand how much carbon there is.
So how do you know how much soil there is per hectare?
To do this you just need to know the weight of soil for the volume sampled (otherwise known as bulk density). Sound simple? Well, while it is simple in theory, in practice measuring the tonnes of soil per hectare can be a bit fraught for the unwary...
The most common method is to carefully collect a sample of soil using a metal cylinder of known volume. This sample is then dried in an oven (to remove the water) before being weighed. The end result is a weight of soil per volume which then can be converted to tonnes of soil per hectare.
So if bulk density is needed to get a true value of t C/ha, why isn’t this done with the regular soil test sampling?

The simple answer is time and cost. To get an accurate value for bulk density careful collection is needed. Small changes in soil weight can have large changes when converted to tonnes per hectare. Multiple samples should also be taken to account for any variability across a paddock. Taking meaningful samples for bulk density is therefore a time consuming process and takes a lot longer than normal soil sampling.