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Soil Cultivation and Seasonal Management

Soil Cultivation and Seasonal Management. Chris Thoreau March 3, 2012. Outline. Introducing Soil Cultivation What is cultivation? Cultivating Machines Hand Tools Cultivation for Small-Scale Farmers Consistency and Plasticity Mycorrhizal fungi

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Soil Cultivation and Seasonal Management

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  1. Soil Cultivation and Seasonal Management Chris Thoreau March 3, 2012

  2. Outline • Introducing Soil Cultivation • What is cultivation? • Cultivating Machines • Hand Tools • Cultivation for Small-Scale Farmers • Consistency and Plasticity • Mycorrhizal fungi • Effect of Cultivation and Loss of Soil Structure • Challenges in Cultivation Reduction • No-till soil management

  3. Soil Cultivation Soil Cultivation: Any intentional mechanical disturbance of the soil using machinery or hands tools With a broad range of implements: • Digging Fork  Broad Fork  Rototiller Plough For a broad range of purposes: • Weeding  Bed Prep.  Cover Crops  Break Ground

  4. Soil Cultivation Soil Cultivation: Any intentional mechanical disturbance of the soil using machinery or hands tools Our Focus: • Soil conditioning implements which • Condition soil for planting • Incorporate cover crops • Alleviate compaction

  5. Soil Cultivation Why Do We Cultivate? • Breaking ground • Incorporate manure, compost, plant residues, amendments • Building soil tilth/structure • Reduce compaction • Seed bed preparation • Weed/vegetation control

  6. Soil Cultivation Cultivation needs change over time and space • Cultivation changes throughout the season • Cultivation changes through the life of a farm • Change in cropping area • Change in crops • Change in growing methods • Cultivation changes with farmer experience

  7. Soil Cultivation Cultivation Considerations • Cultivation is a tool to manage and improve soil conditions • Structure • Drainage • Soil Depth • Cultivation methods need to correspond with sustainability goals • No cultivation activity does just one thing • Cultivation goal: reduce cultivation!

  8. Soil Cultivation Cultivation Considerations • Cultivating for one purpose can be counter productive towards another • Seed bed tillage can increase compaction and affect drainage • All cultivation can increase weed pressure by bringing weed seeds to the soil surface to germinate

  9. Cultivation Methods • Mouldboard/Furrow Plow • Inverts the soil • Discing • Slices/Inverts the soil • Rotovator • Grinds up the soil • Chisel Plow • Deep cultivation • Spading Tool • Gentler cover crop incorporation

  10. Cultivation Methods • These implements require a machine/tractor to power them so choose the implements that are best for your scale of operation • Not sure what is best? Hire someone to do your primary cultivation (breaking ground/incorporating cover crops) for you.

  11. Cultivation Methods • Methods are often used together • Mouldboard Plow Discing • Spading  Rotovator • Mouldboard Plow  Chisel Plow  Disc/Rotovator • Rotavator/Spading  Roller

  12. Cultivation Methods • Small-scale farmers tend to use: • Spading machine on tractor • Rotavator on tractor • Walk behind tractor • Rototiller • Hand tools (e.g., Broadfork) • Often combine machines with hand tools for prepping seed bed • A small tractor is a very versatile machine that can perform a multitude of tasks, but can be pricey and require care! • The rototiller and walk-behind tractor are popular machines for small-scale farmers due to their smaller size and lower cost

  13. Cultivation Methods • Rototiller • Front and rear tine models • Rear tine models preferred for larger scale

  14. Cultivation Methods • Walk-behind Tractor • Larger version of rototiller • But has variety of implement attachments

  15. Cultivation Methods • Hand Tool Cultivation • Low cost soil cultivation solution • Effective but physically demanding • Time consuming • Less impact on soil structure • Less risk of compaction • Only practical on smaller scale

  16. Cultivation Methods • Digging Fork

  17. Cultivation Methods • Broad Fork

  18. Cultivation Methods • Mattock • Great for breaking new ground; compact soil

  19. Cultivation Methods • Considerations when choosing tools/machinery • Budget • Overall farms needs • Physical capability of operator • This changes as you age! • Effect on soil • Effect on environment • Ease/cost of repair and maintenance

  20. Soil Consistency and Plasticity Consistency • Strength with which soil particles are held together • Related to texture and water content Plasticity • Describes the response of a soil to change in moisture content. • Both are very important when considering soil cultivation

  21. Soil Consistency and Plasticity

  22. Soil Consistency and Plasticity • Cultivating soil when too dry • Breaks aggregates into small pieces • De-aggregates • Can result in dust • Very damaging to soil structure • The drier the soil – the more it acts like powder

  23. Soil Consistency and Plasticity • Cultivating soil when too wet • Where to start?! • Compaction • Risk and depth of compaction increases in wet soil

  24. Soil Consistency and Plasticity • Cultivating soil when too wet • The wetter the soil - the more it acts like water

  25. Soil Consistency and Plasticity

  26. Soil Consistency and Plasticity When to Cultivate? Soil moisture needs to be just right • Should be able to handle soil without water dripping out • Should be friable and plastic feeling (if not too sandy) • Soil water levels need to be considered at greater depths • Dry Soil clodding; lost nutrients through dust • Wet Soil  compaction, loss of structure • Decomposition time needs to be considered • Sowing or transplanting to follow?

  27. Mycorrhizal Fungi • Hyphal soil fungi • Forms symbiotic relationships with plant roots • 80-90% of terrestrial plants • Improves plant uptake of phosphorus and water in return for sugars • Acts as expansion of plant root zone • Contribute to soil aggregation and improved soil structure

  28. Cultivation and Mycorrhizal Fungi • Cultivation destroys hyphal networks • Some species are killed by tillage • Redistribution of fungal spores to lower soil profiles reduces root infection • And…

  29. Cultivation and Mycorrhizal Fungi • The loss of soil structure limits regrowth of the fungi • Reduction pore space • Fungi require air and water • Reduced pore space limits air and water movement • Compaction makes hyphal regrowth difficult

  30. Fungal Loss and Plant Growth • Fungal loss = • Disadvantage for plants • Less P uptake • Less water uptake • Reduced Disease immunity • Loss of microbial diversity • Reduces aggregation

  31. What to do? What to do? • Remember: goal is to reduce cultivation over time • Reducing cultivation is difficult • Difficult to manage large areas; especially organically • Most low-till systems herbicide dependent • Disease pressure can be higher in some no-till systems

  32. What to do? What to do? Strategies to Reduce Cultivation Impact on Soil • Choose methods carefully! • Use spader over rotovator for cover crops • Slow down rotation speed on rotovator • Separate growing beds and paths • Reduces compaction risk in growing areas • Tractor wheels can go in pathways • Design beds around tractor width

  33. What to do? What to do? Strategies to Reduce Cultivation Impact on Soil • Stay on top of weeds • Reduces temptation to cultivate • Reduces weed pressure  less weed seeds Incorporate no-till methods into your system • Easier to do at smaller scale

  34. No-till Soil Management Strategies No-till goals: • Maintain overall integrity of soil • Reduce risk of compaction • Reduce risk of structure damage • Promote sustained biological presence • Reduce use of machinery • Mimicking natural soil processes

  35. No-till Soil Management Strategies No-till goals in relation to why we cultivate : Why Do We Cultivate? • Improve soil tilth/structure • Weed control • Reduce compaction

  36. Looking Forward with No-till • Rodale Institute developed crimping method • Effective for cover crops • Perennial wheat • Use of winter killed cover crops • No-till is a viable small-scale option

  37. Cultivation through the Season • Most cultivation happens early in season • Often gives instant results • Main cultivation uses: • Breaking ground • Add amendments at this time • Follow with cover crop • Incorporating cover crops • Weed/vegetation control • Effcieitn vegetation control • Seed Bed Prep • Ensures fine soil texture for ease of seeding

  38. Cultivation through the Season Early Season • Most cultivation happens early • Incorporating winter cover crops • Prepping seed beds • Be patient! Watch soil water levels • Season length depends on soil and location • Assess need for cultivation • Can you utilize no till methods? • Transplanting into winter killed stubble • If using no till methods get an early start

  39. Cultivation through the Season Mid-Season • Cultivation more about weed control • Could be incorporating cover crops • Could be incorporating amendments for later crops • Good time for no-till cover crop management • Warm weather = rapid decomposition

  40. Cultivation through the Season Late Season • Cash crop growing usually priority • Cover crops can be more easily sown into less-than-ideal conditions – no cultivation needed • If no cover crop being sowed, or it’s too late to sow, beds should be mulched • Makes early season prep easier • Remove mulch, add compost, sow or transplant

  41. Cultivation through the Season No Till Cropping Sequence – Small Scale Starting with: • Fall Rye cover crop – well established due to early sowing

  42. Cultivation through the Season No Till Cropping Sequence – Small Scale 1. Cover crop cut in mid-late February 2. Mulched… • Heavily with organic material • Synthetic material • Mulch smothers the crop – reducing light, encouraging biological activity

  43. Cultivation through the Season No Till Cropping Sequence – Small Scale 3. Mulch removed in April - May • Cover crop absent • Area now ready to plant 4. Top with compost, transplant: • Tomatoes • Long season – in ground until September • Undersow with legume

  44. Cultivation through the Season No Till Cropping Sequence – Small Scale 5. Tomatoes removed in September/October • Manage weeds carefully to keep soil clean • Mulch lightly in summer to reduce evaporation 6. Amend bed with compost – plant garlic • Mulch garlic heavily with straw/leaves • If planted early may be able to interplant Asian greens

  45. Cultivation through the Season No Till Cropping Sequence – Small Scale 7. Harvest garlic in following July • Remove mulch and amend with compost 8. Transplant overwintering broccoli and mulch 9. Harvest broccoli in early spring

  46. Cultivation through the Season No Till Cropping Sequence – Small Scale 10. Summer cover crop – buckwheat, phacelia, legume

  47. In Closing • Cultivation can both improve and damage soil • Soil water is indictor of when to till • Using appropriate method • Like all human activity: Tillage does more than just one thing • No-till is feasible on smaller scales • Limited examples of sustainable, large-scale, no-till systems • Though reduced tillage is possible • New no-till methods need to be developed • Perennial crop development and expansion reduces soil impact

  48. The future or the past?

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