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Long-term agroecosystem research on northern Great Plains mixed-grass prairie near Mandan, North Dakota

Sanderson, M. A., Liebig, M. A., Hendrickson, J. R., Kronberg, S. L., Toledo, D., Derner, J. D., Reeves, J. L.
Canadian journal of plant science 2015 v.95 no.6 pp. 1101-1116
agroecosystems, beef cattle, body weight, carbon, climate change, drought, drought tolerance, fertilizer application, fertilizers, grazing, greenhouse gas emissions, indigenous species, invasive species, pastures, remote sensing, soil productivity, soil quality, soil water, steers, stocking rate, vegetation, yearlings, Great Plains region, North Dakota
In 1915, a stocking rate experiment was started on 101 ha of native mixed-grass prairie at the Northern Great Plains Research Laboratory (NGPRL) near Mandan, ND (100.9132 N 46.7710 W). Here, we document the origin, evolution, and scientific outcomes from this long-term experiment. Four pastures of 12.1, 20.2, 28.3, and 40.5 ha were laid out and stocked continuously from May until October with two-year-old or yearling beef steers at four rates (average of 85, 102, 134, and 255 kg liveweight ha-1). Results after 30-years of grazing indicated that a moderate stocking rate of 1 two-year-old steer per 2.8 ha or 1 yearling steer per 2.2 ha sustained livestock gains and vegetation. The experiment generated some of the first information on the grazing and drought resilience of native vegetation and relationships of livestock productivity to soil moisture for predictive purposes. After 1945 the experiment was reduced to the light and heavy stocking rate pastures only, which have been managed and grazed in approximately the same manner to the present day. The pastures were used to assess responses of vegetation to fertilizer in the 1950s and 1960s, develop grazing readiness tools in the 1990s, and assess remote sensing technologies in the 2000s. The long-term pastures currently serve as a unique resource to address contemporary questions dealing with drought, soil quality, carbon dynamics, greenhouse gas emissions, invasive species, and climate change as part of the Long-Term Agroecosystem Research (LTAR) Network and National Ecological Observatory Network (NEON).