Improving Soil Health with Grazing

Transcription

1 Improving Life through Science and Technology Improving Soil Health with Grazing Soil Health Workshop Gatesville, TX 2015 Richard Teague, Texas A&M AgriLife Research, Vernon

2 90% of Soil function is mediated by microbes Microbes depend on plants So how we manage plants is critical

3 Infiltration with Vegetation Composition Thurow 1991

4 The Four Ecosystem Processes 1. Energy flow - Maximize the flow of solar energy through plants and soil. 2. Water cycle - Maximize capture and cycling of water through plants and soil. Reduce export and import. 3. Mineral cycle - Maximize cycling of nutrients through plants and soil. 4. Community dynamics - High ecosystem biodiversity with more complex mixtures and combinations of desirable plant species leads to increased stability and productivity

5 To improve Soil Health Improve soil microbe population by: Keeping the 4 ecosystem processes functioning Improving plant cover Perennial plants rather than annuals Manage for most productive plants Leave adequate plant residue Minimizing bare ground Manage for plant growth for as many days each year as possible

6 Landscape impact of continuous grazing Edwards Plateau Ranch 3-D View w/ GPS Locations 1. 39% area used 2. 41% GPS points on 9% area 3. SR: 21 ac/cow 4. Effective SR: 9 ac/cow

7 Previous research on multi-paddock grazing

8 Many Grass farmers use MP grazing successfully Most conservation award winners use MP grazing

9 Landscape impact of continuous grazing Planned multi-paddock grazing Animals: Graze more of the whole landscape Select a wider variety of plant species Manager can control: How much is grazed The period of grazing, and The length and time of recovery Use livestock to enhance wildlife habitat

10 Restoration using Holistic grazing Noble Foundation, Coffey Ranch Go-back field 18 paddocks + water points Managed to IMPROVE plant species

11 Restoration using multi-paddock grazing Restoration using Holistic grazing Noble Foundation, Coffey Ranch Charles Griffith, Hugh Aljoe, Russell Stevens

12 Managing for Desired Outcomes Match animal numbers to available forage Spread grazing over whole ranch Defoliate moderately in growing season Use short grazing periods Adequate recovery before regrazing Graze again before forage too mature

13 Landscape impact of continuous grazing Planned multi-paddock grazing Ranch road Existing fence Electric fence Water point

14 Influence of multi-paddock grazing on soil and vegetation Jack county Parker county Cooke county

15 Influence of multi-paddock grazing on soil and vegetation Neighbouring ranches in each county: Planned HM heavy SR (± 10 ac/au) Continuous heavy SR (± 10 ac/au) Continuous light SR (± 20 ac/au) Grazing treatment at least 10 years

16 Bare ground (%) Bare Ground a b Heavy Continuous Heavy Heavy Rotation Multi-camp P = b Light Continuous

17 Soil Microbes Parameter Heavy continuous Grazing Management Light continuous Multipaddock Grazing exclosure Total bacteria (g m -2 ) 82a 74a 78a 98a Total fungi (g m -2 ) 97b 98b 174a 105ab Fungi to Bacteria ratio 1.2b 1.1b 3.1a 0.7b

18 Importance of Fungi Fungi provide: Access and transport nutrients Extend root volume and depth Exude glomalin to enhance soil C Increase water and nutrient retention Increase drought resistance Plant growth highest with highest fungal bacterial ratio Killham 1994; Leake et al. 2004; Averill et al. 2014; Johnson 2014

19 Energy (Joules) Penetration Resistance a c P = b Heavy Continuous Heavy Heavy Rotation Light Continuous Multi-camp

20 % Aggregate Stability 120 P = b a ab Heavy Continuous Heavy Heavy Rotation Multi-camp Light Continuous

21 g / m 2 (for 1 hour) Sediment loss 30 P = a ab b 5 0 Heavy Continuous Heavy Multi-camp Rotation Light Continuous

22 Soil Carbon, Nutrients and Water Parameter Heavy Continuous Light Continuous Multipaddock Soil Organic Matter 3.1b 4.4b 4.86a Cation Exchange Capacity 24.6b 23.7b 27.4a Water holding (Gal/acre) 55,700 79,059 87,324

23 Biomass (kg ha -1 ) Tall Grasses a P = b b 0 Heavy Continuous Heavy Heavy Rotation Light Continuous Multi-camp

24 Biomass (kg ha -1 ) Mid Grasses P = ab a b Heavy Continuous Heavy Heavy Rotation Light Continuous Multi-camp

25 Biomass (kg ha -1 ) Annual Forbs a P = b Heavy Continuous Heavy Heavy Rotation Multi-camp b Light Continuous

26 Soil Carbon, Nutrients and Water Parameter Heavy Continuous Light Continuous Multipaddock Soil Organic Matter 3.1b 4.4b 4.86a Cation Exchange Capacity 24.6b 23.7b 27.4a Water holding (Gal/acre) 55,700 79,059 87,324

27 Grazing Management impact on Water Runoff ET Surface runoff Percolation Grazing period Groundwater flow

28 LCA Profit Scenarios (20-year) for HC or LC farms under a CO 2 price of $6 per ton Initial Farm management Practice Change Economic Profit ($ ha -1 ) Carbon Profit ($ ha -1 ) Total Profit ($ ha -1 ) Best Choice HC unchan Initially Practicing HC HC MP HC LC LC unchan Initially Practicing LC LC MP LC HC

29 What we have learnt from ranchers...1 It takes a minimum of 10 paddocks just to stop overgrazing Ranchers with 8 or fewer paddocks are not rotationally grazing, but rotationally overgrazing To support decent animal performance takes paddocks The most rapid range improvement takes 30 paddocks The biggest decrease in workload and greatest improvement has been with > 50 paddocks Dave Pratt, Ranch Management Consultants, rancher survey

30 What we have learnt from ranchers...2 The fastest, cheapest way to create more paddocks is combining herds 1 herd reduces workload a lot; checking 4 herds of 200 animals takes much longer than 1 herd of 800 Productivity per acre is improved without decreasing individual animal performance Carrying capacity and total productivity are greatly increased at low cost Long recovery periods are critical Do not move to the adjacent paddock but to the paddock that has recovered the most Dave Pratt, Ranch Management Consultants, rancher survey

31 High Density Grazing in higher rainfall ecosystems

32 Neil Dennis, SE Saskatchewan

33 Flexible management Temporary electric fence Slew Water

34 High density grazing Low density grazing

35 Earthworm castings and proliferation of forage species

36 Bismarck, ND Cover crop with 25 species

37 Mob grazed

38 Moving to the next paddock Is this wasted forage?

39 8-fold increase in infiltration

40 Jay Fuhrer, NRCS, North Dakota

41 Importance for Ecosystem Function? Regenerative Multi-Paddock grazing can: Build SOC levels and soil microbial function Enhance water infiltration and retention Build soil fertility Control erosion more effectively Enhance watershed hydrological function Improve economic returns while improving the resource base Enhances wildlife and biodiversity Result in grazed soils being a net greenhouse gas sink

42 Conclusions Successful multi-paddocks managers use: Flexible stocking to match forage availability and animal numbers Spread grazing over whole ranch Moderate grazing during growing season Short graze periods Allow recovery before regrazing Graze again before forage too mature Use multiple livestock species

43 To improve pasture soil health Improve soil microbe population by: Perennial plants rather than annuals Manage for most productive plants Leave adequate plant residue Use diverse species mixes and cover crops Eliminate tillage Minimize bare ground Use organic soil amendments Reduce N-fertilizer use Grow plants for maximum days each year Delgado et al 2011; Rodale 2014; Jones, 2014

44 END