Management-Intensive & Multiple-Species Grazing

Transcription

1 Management-Intensive & Multiple-Species Grazing Tipton D. Hudson Washington State University Extension Rangeland & livestock management specialist

2 3 keys to grazing success 1. Match animal demand to forage availability 2. Defoliate preferred species moderately 3. Ensure adequate recovery period after grazing

3 April 21, 2011 Overgrazed?

4 June 21, 2011 Overgrazed?

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6 Assumptions in this presentation Healthy agro-ecosystems are considerably more productive, stable and resilient than those in poor condition. Ranch livelihoods depend on healthy ecosystems. The value of ecosystem services to society is worth more to society than agricultural earnings. From Richard Teague, Texas A&M

7 90% of Soil function is mediated by microbes Microbes depend on plants So how we manage plants s critical Teague

8 Improving soil health Requires improving soil microbe population (diversity & quantity) 1. Improve plant cover Perennial v. annual Yield is important Residual plant material is critical 2. Reduce bare ground Grow plants for as much of the year as possible

9 Measurable indicators of ecosystem health community dynamics Species composition & richness Age class distribution Woody plants Ground cover

10 Indicators of ecosystem health water cycle Infiltration Cover on interspaces Plant spacing Soil density Erosion Litter incorporation

11 Indicators of ecosystem health mineral cycle Litter decomposition Evidence of biological activity Multiple rooting depths (plant diversity, functional class diversity) Nitrogen deficiency evident in plants (-)

12 Indicators of ecosystem health energy flow Species composition Plant spacing Period of active plant growth Warm- and cool-season grasses Rapid growth for prolonged period

13 Plant response to grazing % Leaf Volume Removed % Root Growth Stoppage 10% 20% 30% 40% 50% 60% 70% 80% 90% 0% 0% 0% 0% 2 4% 50% 78% 100% 100%

14 Grazing management principles Match animals to forage base Ensure animal distribution (at all spatial scales) Defoliate primary forage species moderately Apply short grazing periods Aim for higher animal density to put litter down Observe adequate recovery period before grazing again, then move to paddock with longest recovery Respond adaptively to dynamic conditions

15 Grazing ecology grammar Stocking rate Carrying capacity Stock density AUM Rotational grazing MiG SDHD Savory method Adaptive management

16 Causes of poor results Too many animals Re-grazing too soon / inadequate recovery period Insufficient stockwater system Failing to adapt to changing conditions Grazing too severely during active growth period Unreasonable expectations under physical limits to greater forage productivity

17 General grazing factors to manipulate Timing Duration Frequency Intensity These factors drive vegetation composition and health. Severity of grazing is a combination of duration and intensity.

18 Historical perspective on grazing management

19 Sustainable grazing strategies High stock density, many paddocks, short grazing periods Or Very conservative stocking rate, light utilization, animal distribution tools applied

20 Bare ground by management strategy Bare ground (%) a P = b b Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011

21 Infiltration by vegetation composition Thurow 1991

22 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 Teague et al. 2011

23 Importance of Fungi Fungi: access and transport nutrients extend root volume and depth enhance soil carbon increase water and nutrient retention increase drought resistance Plant growth rates & yield are highest with highest fungi:bacteria ratio Killham 1994; Leake et al. 2004; Averill et al. 2014; Johnson 2014

24 Soil Compaction (Penetration Resistance) 300 a P = Energy (Joules) c b 0 Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011

25 Tall Grasses a P = Biomass (kg ha -1 ) b b Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011

26 Mid Grasses P = ab a Biomass (kg ha -1 ) b Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011

27 Annual Forbs a P = Biomass (kg ha -1 ) b b 0 Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011

28 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

29 Grazing for ecosystem function Build soil carbon Enhance microbial populations and function Enhance water infiltration and retention Build soil fertility Reduce erosion Enhance hydrologic function Improve profitability Enhance wildlife habitat & biodiversity

30 Next steps / for more information... Tipton D. Hudson Extension range & livestock extension specialist Washington State University hudsont@wsu.edu