Interaction between soil health, forage quality/quantity, and livestock production

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1 Interaction between soil health, forage quality/quantity, and livestock production John Derek Scasta Ecosystem Science and Management University of Wyoming

2 Soil Forage Livestock Linkage Very few studies (< 5) have linked all three mechanistically on rangeland Critical because rangeland production of forage supports livestock production Knowing if soil health is declining, stable, or increasing is starting point Is soil health of rangelands changeable in a realistic time frame? Soil health, also referred to as soil quality, is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans.

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4 Rancher Quote Paraphrased Quote from a Rancher I have taken soil samples from my range before and sent them for analyses. The results have never resulted in a management action or management change How do we make soil health apply to range forage and livestock production?

5 What do we know about soil, forage, and livestock Soil fertility, soil water holding capacity, infiltration, and soil microbiology all have a potential positive benefit for increasing forage productivity Increased forage productivity enhances livestock carrying capacity Muir et al Sala et al Lipiec, J., & Stepniewski 1995

6 Wilson Wilson et al. 2009

7 But we are constrained by our environment to some degree Many of the WY range sites I work on only produce 100 to 1,000 lbs/ac Sala et al. 1988

8 Soil Health and Range The Challenge Many soil health concepts developed in the row crop world Different than range Deeper and more fertile soils Minimizing or eliminating tillage Maximizing litter retention Use of cover crops for multiple objectives We all know soils are critical BUT Range soils often function in a black-box and row crop methods may not apply How do the physical, chemical, and biological features of soil affect forage quality/quantity and livestock production?

9 MT site Needle and thread Blue grama Threadleaf sedge Authors Conclusions Individual properties explained a slight ( 10%) amount of variation in plant biomass. There may not be one or even several soil properties that consistently predict appreciable variation in peak grassland biomass, especially variation within an ecosystem independent of precipitation.

10 Need to be careful about grandiose claims Claim that it was the application of management intensive grazing BUT was probably the effect of taking it out of row crop agriculture and being put into perennial forage

11 Need to recognize cost/reality of inputs in studies

12 Soil Organic Matter & Grazing - DECREASE Soil organic C and N for 24 Great Plains grasslands soils Soil texture was a major control over organic matter dynamics Impact of grazing showed steady-state soil C and N levels were sensitivity to grazing with soil C and N levels decreasing with increased grazing rates Regionally SOM can be accurately predicted with four parameters: 1. Temperature 2. Moisture 3. Soil Texture 4. Plant Lignin Content**

13 Soil Organic Matter & Grazing Increase Cheyenne, WY study 11 years of grazing versus grazing exclusion Top 30 cm of soil had: Greater soil N and soil C in grazed pastures

14 Grazing effects in a different environment Multi-paddock grazing had: Higher soil aggregate stability than high-continuous but not light-continuous and ungrazed Lower soil penetrations resistance (similar to ungrazed) No difference in soil bulk density or infiltration rate Higher SOM and CEC (similar to ungrazed) Higher fungal/bacterial ratio Limitations Tallgrass prairie Needs empirical assessment

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16 Questions Do you have baseline soil, forage, and livestock data? Are you in a maintenance or recovery situation? What is even possible on high, cold, arid/semi-arid WY rangelands? Do other results transfer? Can changes to soil health make appreciable or detectable changes in the 3 critical forage metrics? 1. Forage composition 2. Forage quality (i.e., protein, palatability, nutrient) 3. Forage quantity (i.e., energy, TDN) and total carrying capacity