Carbon sequestration and phosphorus leaching in pasturelands: A decadal study on the soil health effects of grazing management

Authors: Schantz, Merilynn; Smith, Douglas; Adhikari, Kabindra; OSORIO, LEYTON JAVIER - Texas A&M Agrilife; TOLLESON, DOUGLAS - Texas A&M Agrilife; GOODWIN, JEFFERY - Texas A&M University Institute For Advancing Health Through Agriculture; Thorp, Kelly; Harmel, Robert

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Long-term and large-scale studies are necessary for understanding the effects of grazing management strategies across space and time. A common management strategy on pasturelands is adaptive rotational grazing. While rotationally grazed pastures often have greater plant production, the effects of grazing strategies on soil health have not been comprehensively evaluated. The results demonstrated a strong link between plant production, climate, and soil nutrient abundance. Soil nutrient concentrations of nitrogen, phosphorus, and potassium were low when plant production was high, which commonly occurs in rotationally grazed pastures and cover crops. Soil carbon, alternatively, decreased through time, especially in the rotationally grazed pastures. Lower carbon is likely because of the greater microbial activity associated with adaptive management as CO2 respiration increased through time. Collectively, these results suggest that soil nutrient abundance is tied to plant production as impacted by management strategy and that current pastureland management strategies do not support increased carbon sequestration.

Technical Abstract: Soil health varies spatially due to complex interactions among soil properties, plant production, and management. Maintaining soil quality is crucial to sustaining ecosystem structure and function. A common management strategy on pasturelands is adaptive rotational grazing. While rotationally grazed pastures often have greater plant production, the effects of grazing strategies on soil health have not been comprehensively evaluated. For this second study in our series on the effects of grazing management strategies on integrated crop livestock systems, the objective was to determine how soil health differed between 1) alternative adaptive management strategies of rotationally grazed pastures and no-till cover crops and 2) prevailing methods of continuous year-long pasture and tilled forage oat grazing over a decade timescale. Soil health was evaluated using several soil extractants (i.e., deionized water, H3A, Mehlich 3) and quantified microbial activity via a 24-h CO2 incubation. The results demonstrated a strong link between plant production, climate, and soil nutrient abundance. Soil nutrient concentrations of nitrogen, phosphorus, and potassium were low when plant production was high, which commonly occurs in rotationally grazed pastures and cover crops. Nutrient abundance, however, depended on the extraction method. The strength and pH of the extractants, for example, yielded critical information about the lability of these nutrients and about leaching and runoff potential, an especially important finding for phosphorus as this nutrient was most labile in continuously grazed systems. Soil carbon, alternatively, decreased through time, especially in the rotationally grazed pastures. Lower carbon is likely because of the greater microbial activity associated with adaptive management as CO2 respiration increased through time. Collectively, these results suggest that soil nutrient abundance is tied to plant production as impacted by management strategy and that current pastureland management strategies do not support increased carbon sequestration.