Soil NO3--N showed the largest relative annual range in values, which was the result of a
very low mean NO3--N level (6 mg N kg-1 soil) in 2010 (Table 8). All cover crop treatments (including monoculture hairy vetch) had low soil NO3--N in 2010, indicating that low NO3- in
2010 was not related to stand composition (cover crop x year interaction) (Fig 4d).