Rotational horse grazing and dry weather maximize infiltration into soil macropores

Laura B. Kenny, Daniel Giménez, Joshua S. Caplan, Ali Al-Sarraji, Mohson AlHello, Mark G. Robson, William Meyer, Carey A. Williams

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Growing livestock populations have intensified the potential for detrimental effects of grazing on grassland soils globally. Grazing management techniques can mitigate these effects but they are livestock-specific and studies on horse grazing are rare. The objective of this work was to compare the effects of rotational grazing (i.e., livestock graze sub-sections of a pasture in sequence) with the continuous approach to grazing on (1) rates of water infiltration (i) at slightly negative pressure potentials (h, −15, −10, −5, −3.5, −1 hPa), (2) saturated hydraulic conductivity (Ksat), and (3) bulk density (BD). At a site in New Jersey, USA, one pair of pastures was managed with rotational grazing while another pair experienced continuous grazing. Twelve Standardbred mares were grazed for two years at a stocking rate of 0.52 horses ha−1. Over that period, i (n = 79, each at 5 h values) and BD (n = 154, from depth ranges 0–10 and 30–40 cm) were measured multiple times and Ksat values were derived from infiltration measurements. Also, the standardized precipitation-evapotranspiration index (SPEI) was calculated with meteorological data from a nearby weather station. We found that: (1) i values inclusive of the largest pores tested (h = −1 hPa) were greater in rotationally- vs. continuously-grazed fields (geometric means ± GSE were 80.2 ± 1.15 and 42.3 ± 1.13 cm d−1, respectively), (2) Ksat values were consistent with those of infiltration at h = −1 hPa but were too variable to isolate the effect of pasture management, and (3) near-surface BD was similar under rotational and continuous grazing (arithmetic means ± SE were 1.32 ± 0.02 and 1.37 ± 0.02 Mg m−3, respectively). Further, during periods of water surplus (i.e., when SPEI was positive), infiltration was strongly reduced in the smaller soil pores (h = −10 and −15 hPa) of the rotationally-grazed fields. This reduction was likely the result of pore colonization and blockage by pasture grass roots growing in these fields. This study suggests that rotational management allows for a larger macropore system than continuous grazing, which could lead to a reduction of water deficits and contribute to the sustainability of grazed ecosystems, with positive effects accruing through time.

Original languageEnglish (US)
Article number105539
JournalSoil and Tillage Research
StatePublished - Jan 2023

All Science Journal Classification (ASJC) codes

  • Agronomy and Crop Science
  • Soil Science
  • Earth-Surface Processes


  • Drought
  • Pasture management
  • Soil fertility
  • Tension infiltrometer
  • Water balance


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