Management-Intensive & Multiple-Species Grazing Tipton D. Hudson Washington State University Extension Rangeland & livestock management specialist
3 keys to grazing success 1. Match animal demand to forage availability 2. Defoliate preferred species moderately 3. Ensure adequate recovery period after grazing
April 21, 2011 Overgrazed?
June 21, 2011 Overgrazed?
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
90% of Soil function is mediated by microbes Microbes depend on plants So how we manage plants s critical Teague
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
Measurable indicators of ecosystem health community dynamics Species composition & richness Age class distribution Woody plants Ground cover
Indicators of ecosystem health water cycle Infiltration Cover on interspaces Plant spacing Soil density Erosion Litter incorporation
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 (-)
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
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%
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
Grazing ecology grammar Stocking rate Carrying capacity Stock density AUM Rotational grazing MiG SDHD Savory method Adaptive management
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
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.
Historical perspective on grazing management
Sustainable grazing strategies High stock density, many paddocks, short grazing periods Or Very conservative stocking rate, light utilization, animal distribution tools applied
Bare ground by management strategy Bare ground (%) 40 35 30 25 20 15 10 5 0 a P = 0.0006 b b Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011
Infiltration by vegetation composition Thurow 1991
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
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
Soil Compaction (Penetration Resistance) 300 a P = 0.0005 Energy (Joules) 250 200 150 100 50 c b 0 Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011
3000 2500 Tall Grasses a P = 0.003 Biomass (kg ha -1 ) 2000 1500 1000 500 0 b b Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011
Mid Grasses 2500 2000 P = 0.188 ab a Biomass (kg ha -1 ) 1500 1000 500 0 b Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011
Annual Forbs 600 500 a P = 0.014 Biomass (kg ha -1 ) 400 300 200 100 b b 0 Heavy Continuous Heavy Rotation Light Continuous Teague et al. 2011
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
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
Next steps / for more information... Tipton D. Hudson Extension range & livestock extension specialist Washington State University 509-962-7507 hudsont@wsu.edu