Comparison of Conventional and Alternative Nursery Field Management Systems: Soil Physical Properties

Abstract

Abstract Effects of five nursery field management systems on the physical properties of a Waukegan silt loam soil were investigated: cultivation, herbicide management (oxadiazon), legume companion crop—‘Norcen’ bird's-foot trefoil (Lotus corniculatus ‘Norcen’), winter cereal cover crop/mulch—‘Wheeler’ winter rye (Secale cereale ‘Wheeler’), and mixed grass sod—80% ‘Eton’ perennial ryegrass (Lolium perenne ‘Eton’) and 20% ‘Ruby’ red fescue (Festuca rubra ‘Ruby’). Six tree species were included in the study: Fraxinus pennsylvanica ‘Marshall Seedless’, Malus ‘Red Splendor’, Gleditsia triacanthos var. inermis ‘Skyline’, Acer rubrum ‘Northwood’, Thuja occidentalis ‘Techny’ and Picea glauca var. densata. Field management treatment effects on soil water infiltration capacity, aggregation, bulk density, and temperature were quantified. Significant treatment differences were observed for all soil characteristics investigated. Bare soil treatments (cultivation and herbicide management) generally reduced water infiltration, soil aggregation, and winter soil temperatures and increased bulk density and summer soil temperatures compared to cover crop treatments. After seven years, water infiltration was increased 2 to 4 times for the bird's-foot trefoil companion crop, 3 to 6 times for the rye cover crop/mulch, and 4 to 9 times for the grass companion crop compared to cultivated and herbicide management treatments. Under herbicide management, bulk density of surface soil was increased by 19.7% compared to cultivation. Bulk densities of compacted soil layers just below the depth of cultivation were reduced by 6.6% when maintained with rye and grass cover/companion crops for seven years. Soil aggregation was dramatically reduced by herbicide management and increased for soil maintained under grass sod; only 17.1% of soil aggregates measured 2.0 mm while 72.7% measured 0.5 mm for herbicide managed plots compared to 77.0% and 15.5% for soil maintained with a grass companion crop, respectively. Herbicide management was most often associated with negative effects on soil characteristics important to longterm productivity while grass sod and the rye cover crop/mulch system were most beneficial. The effects of cultivation and the bird's-foot trefoil companion crop on soil physical characteristics were intermediate. The bird's-foot trefoil treatment was difficult to manage and tree growth was reduced sufficiently for the trefoil and grass sod treatments to disqualify them as possible alternatives to cultivation or herbicide management. Implications of soil physical characteristics, as influenced by field management practice, regarding plant performance and soil management are discussed.