Soil structure and Field Traffic Management. Tim Chamen CTF Europe

Transcription

1 Soil structure and Field Traffic Management Tim Chamen CTF Europe

2 What are the physics of a good soil structure? A diverse mix of solids, air and water with a continuous network of pores that allow free movement of air, water and roots the economics of creating and maintaining this have to work as well!

3 SOIL STRUCTURE

4 Examples of good & poor soil structure Reasonably good Very poor

5 Examples of good & poor structure Good Poor

6 How can we improve soil structure? Increase organic matter levels Maximise level and duration of green or other cover Avoid stresses on the soil: compaction tillage bare fallows at any time raindrop impact

7 The importance of SOM! Without soil organic matter (SOM), soils have no structure or life SOM is the primary food source for all soil living animals and micro-organisms Don t starve them! they create aggregation and thus porosity

8 The dynamics of SOM Plants add SOM Soil micro-organisms break it down - Addition or loss of SOM is the balance of these two processes Inappropriate tillage increases loss by exposing more of the soil to microbes

9 High yielding crops Manures Addition of SOM Composts

10 Addition of SOM Cover crops with large vigorous roots as much growth and over as long a time period as possible must be compatible with cash crops

11 Loss of SOM Vigorous tillage in poor soil conditions

12 Whole crop removal Loss of SOM only cover cropping has any chance of maintaining status quo in this situation

13 Cover cropping with maize? Cornwall in mid May can we avoid these bare soils? by growing this over-winter and using strip tillage to plant?

14 SOIL COMPACTION

15 Causes of soil compaction Machines pressure and weight under tyres or tracks pressure dominates effects in topsoil weight dominates effects in subsoil Livestock high pressure, low weight effects mostly confined to topsoil W P P/2 D = W Rule of thumb for tyres pressure (P) at the surface reduces to half its value at a depth equivalent to the width of the tyre

16 Dynamics of soil compaction Effect of increasing weight at same surface pressure Effect of soil moisture content From:

17 Predicted pressure at 0.5 m depth, bar Causes of soil compaction increasing weight It s load that does damage at depth 2.5 t vehicle 21 t vehicle Timeline from the 1930s to the present day 850 kg Horse R /70 R /65R /50R32

18 Causes of soil compaction Tillage thin bands at tillage depth caused by poorly set or maintained machines magnitude of effect much less than traffic and livestock Rainfall impact surface layer recognised as crusting

19 Outcomes of compaction - it stops water getting into soils After: Chyba, 2012

20 Outcome of water not getting in! Soil, chemical and nutrient losses

21 Effect of water not getting in - phosphate loss to waterways Most phosphate is held on soil particles as phosphate in solution is increased through fertiliser addition, more is adsorbed onto soil particles

22 Effect of water not getting in - phosphate loss to waterways Medium to heavy soils large adsorbing capacity large polluting potential if eroded but less at risk of erosion

23 Lighter soils Effect of water not getting in - phosphate loss to waterways low adsorbing capacity less polluting potential if eroded but at greater risk of erosion

24 Outcomes of compaction Yield of Grass in Wheel Tracks as % of Yield in Untracked Area, No Traffic 1 Pass 3 Passes Sig. First Harvest *** Second Harvest NS Third Harvest NS Total *** Source: AFBI Hillsborough

25 Other outcomes of compaction it makes soils stronger! First video, random traffic no-till for 3 years Second video, zero traffic no-till for 3 years

26 Compaction makes soil management more difficult and costly Energy to loosen. Energy to re-compact Loss of moisture Random traffic Uneven germination and growth Non-trafficked soil Timeliness effects on subsequent chemical applications

27 Compaction management Livestock

28 Grassland Case Study Acknowledging Farmers Weekly Academy 180 ha organic dairy farm, West Yorkshire 260 cows on grass for 10 months of year paddock grazing mostly leaf with 27% protein 3000 ft of concrete sleepers gets cows to paddocks electric fenced to keep cows on track Close eye on sward first signs of damage, brought back onto hard standing 4 hours grazing sufficient, 12 h max on paddocks

29 Restricting access time to pasture Access for 48 cows Full (22 h) 2 x 5 h 2 x 3 h Alternating Full/2x3 Result: No difference in milk or milk solids yields 13.2 and 1.15 kg/cow/day respectively Cows learnt to graze more aggressively After Dr Emer Kennedy, Teagasc, Moorepark

30 Grassland Case Study Aerator used in autumn and spring conditions must be right not too dry or wet removes water from surface

31 Sward lifter only for deeper compaction

32 No treatment Sward lifted Spike aerated Slide thanks to: George Fisher Consulting Cheshire

33 Compaction management Machinery

34 Addressing the principles Choosing and using tyres correctly Learn the principles manufacturer s literature and training workshops tyre data book or pdf lowest inflation pressure for load and speed

35 Choosing the right tyres Axiobib - 20% more load at same pressure Xeobib 40% more load at same pressure

36 Tyres have very different characteristics

37 What can be achieved Combine on standard tyres

38 What can be achieved Same day, same combine but on low pressure tyres

39 Setting up machinery combinations properly Mounted cultivators correct ballasting 3-point hitch geometry top link position should ensure weight transfer onto rear wheels Trailed cultivators correct ballasting particularly important with single tracks

40 Keep an eye on weight Take time to remove excess weight Not always easy or appropriate and can remove too much!

41 Another approach Controlled Traffic Farming - CTF any system that confines all tracks to least possible area of permanent traffic lanes CT is NOT prescriptive about tillage CT is NOT just about keeping tramlines in the same place Commitment to continual improvement

42 CTF can turn tracking on its head! CTF: 85% not tracked Tracked areas: Traditional 85% Min till 65% No till 45%

43 Match as many track gauges as possible CTF how? Match implement widths Introduce a Global Navigation Satellite System (GNSS) with RTK correction Rover Base station Radio aerials GPS receivers

44 Matching track and implement gauges OutTrac CTF system Cereal harvesting Grain auger Cultivator/drill Trailer Chemical application Harvester e.g. 2.8 m Other vehicles e.g. 2 m

45 Example of OutTrac for maize OutTrac CTF System 3.35 m harvester track gauge 6 m, 9 row maize planter, 0.67 m rows 2.01 m tractor track gauge

46 Grassland system based on 4.8 m Front and side mounted mowers

47 CTF benefits Higher crop yields Simpler lower cost farming Improved water management 4 x better water infiltration less run-off and erosion less risk of fertilizer loss This rather than this or this

48 CTF benefits Less intensive tillage & better crop establishment Large fuel savings Lower operating and capital costs Improved soil health lower greenhouse gas emissions more soil-living animals

49 but CTF also has some drawbacks It needs careful planning and attention to detail matching track gauges matching implement widths Cereal harvesting Grain auger Trailer Chemical application Cultivator/drill It requires investment in auto-steer It introduces an element of inflexibility Needs a change in agronomy less and shallower tillage different soil structure

50 Take home messages Good structure is enhanced by: increasing soil organic matter high yielding crops residue retention perennial crops cover crops to fill a seasonal gap less tillage particularly rigorous tillage in poor conditions reducing compaction low ground pressure controlled traffic

51 Smart Agri-Systems Platform for information on soils, precision farming & CTF