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Crop Cover Root Channels May Alleviate Soil Compaction Effects on Soybean Crop

^a Dep. of Natural Resource Sciences and Landscape Architecture, Univ. of Maryland, College Park, MD 20742
^b Dep. of Horticulture, Cornell Univ., Ithaca, NY 14853

View larger version (43K): [in a new window]   Fig. 1. Penetration resistance (kPa) with depth (cm) at Beltsville Agricultural Research Center (BARC) and Wye Research and Education Center (WREC). Average volumetric water content at time of penetration resistance measurement was 0.22 cm3 cm–3 (WREC) and 0.27 cm3 cm–3 (BARC) in the surface soil (0–20 cm) and 0.29 cm3 cm–3 (WREC) and 0.39 cm3 cm–3 (BARC) in the subsoil (20–40 cm).

View larger version (135K): [in a new window]   Fig. 2. Minirhizotron images showing canola roots growing in May (left) and soybean roots observed in July and August (right) following the channels made by the preceding canola cover crop at 38.2 cm (at WREC) (top) and 18 cm (at BARC) (bottom) depth. Bulk density was 1.55 and 1.61 and penetration resistance was 2247 and 2176 kPa for the upper and lower soils, respectively.

View larger version (26K): [in a new window]   Fig. 3. Soil volumetric water content (cm3 cm–3) at the 50-cm depth at Wye Research and Education Center (top) and Beltsville Agricultural Research Center (bottom), May–September 2002. * Denotes days on which differences in soil water content were significant at the 0.05 probability level (Bonferroni). ANOVA performed on soil moisture meter readings.

View larger version (18K): [in a new window]   Fig. 4. Soybean seed yield (kg ha–1) following no-till, no cover; no-till rye; no-till forage radish; or no-till forage radish + rye cover crop treatments at Beltsville Agricultural Research Center (BARC) and Wye Research and Education Center (WREC). Mean separation within each site by LSD at the 0.10 probability level.