Tall fescue management and environmental influences on soil, surface residue, and forage properties

Authors: Franzluebbers, Alan; POORE, MATTHEW - North Carolina State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2020
Publication Date: 5/19/2021
Citation: Franzluebbers, A.J., Poore, M.H. 2021. Tall fescue management and environmental influences on soil, surface residue, and forage properties. Agronomy Journal. 113:2029-2043.

Interpretive Summary: Pasture management is an important land use mixed within cropping, forestry, and urban uses throughout the southeastern US. Limited information is available on how various pasture management approaches might affect soil health and functioning. A scientist from USDA-Agricultural Research Service in Raleigh NC collaborated with a ruminant livestock specialist from North Carolina State University to evaluate how management and environmental characteristics affected soil and forage nutritive values on 92 farm fields in North Carolina and surrounding states. Rotational stocking of pastures led to greater surface residue carbon content than continuous stocking of pastures. Managed grazing of pastures led to greater soil organic carbon content and soil microbial activity than hayed fields due to return of feces to the pasture. Older pastures were of equal or greater forage nutritive value than younger pastures, and these older pastures often had greater soil biological activity and nitrogen mineralization potential. Elevation gradient from the Coastal Plain to the Blue Ridge led to greater forage nutritive values and greater soil organic carbon and nitrogen contents. Fall-stockpiled tall fescue forage responded to nitrogen fertilization more in soils with lower soil-test biological activity, but many pastures had sufficient nitrogen in soil due to cycling through organic matter. These results will be useful to farmers, farm advisors, and nutrient management specialists to make more effective soil management decisions on pastureland in the southeastern US.

Technical Abstract: Environmental characteristics within a region often result in site-specific agro-ecological responses to management. Evaluating the effects of management on soil and plant responses within a region with known environmental gradients, therefore requires sampling across a diversity of locations. We conducted a series of 92 field trials on soil N availability in fall-stockpiled tall fescue in North Carolina and surrounding states. Soil properties at 0-10-cm depth, surface residue C and N contents, and forage mass and nutritive values were evaluated for differences in response when partitioned into several broad farm characterizations. Surface residue C content was only greater with rotational than with continuous stocking (2333 vs 1573 kg/ha, respectively; p=0.05). Total, particulate, and mineralizable C and N were greater when pastures (1) were grazed than when frequently or exclusively hayed, (2) had wild rather than novel endophyte, (3) were older (>10 years), (4) were at higher elevation in the Blue Ridge than lower in the Coastal Plain, and (5) were grown on finer than coarser-textured soils. Magnitude of forage mass and nutritive value responses to N fertilization was greater when pastures were hayed, had novel endophyte association, and were younger stands. These N responses coincided inversely with soil organic C and N fractions. We conclude that soil texture and physiographic region exerted strong environmental effects on soil properties, but management factors of harvest type, endophyte association, and pasture age were important in modifying soil organic C and N fractions to sustain forage productivity without large quantities of additional N fertilizer.