Soil Macronutrient Responses in Diverse Landscapes of Southern Tallgrass to Two Stocking Methods.
Northup, B. K., Starks, P. J., & Turner, K. E. . 2019.
Abstract
Macronutrient (N, P, S, K, Ca, and Mg) availability and distribution in soils of grassland
ecosystems are affected by diverse factors, including landscape position, climate, and forms of
management. This study examined flux in plant-available macronutrients in production-scale
(60 to 80 ha) paddocks of southern tallgrass prairie of central Oklahoma, United States, managed
(2009-15) under two contrasting stocking methods (continuous yearlong; rotational stocking among
10 sub-paddocks). Macronutrient availability within the 0- 7.5 cm and 7.5- 15 cm soil depths were
determined with sets of anion-cation exchange membrane probes at 16 locations within paddocks,
oriented along transects from water sources to far corners. No clear overall effect related to stocking
method was recorded for all macronutrient distributions. The only significant stocking method ×
location interaction occurred for K (p = 0.01). All other macronutrients displayed significant (p < 0.08)
location effects that were common across stocking methods. Effects relatable to stocking method
occurred in interactions with soil depth or time of year (p < 0.10), but responses of macronutrient
flux to stocking method in these interactions varied. Higher flux occurred in available S, Ca, and
Mg in proximity (<24 m) to water sources, which may be related to grazing, but local features of
the landscape may also have been involved. More attention to landscape features included within
paddocks, and standardized organization of water and other features within paddocks, would
improve the potential to define grazing effects on macronutrient distribution.
Key Words
exchange membranes; grazing management; soil macronutrients
