Conversion from a sycamore biomass crop to a no-till corn system: effects on soils.

Agricultural lands may be used to produce short-rotation woody crops (SRWCs) for fuel or fiber, but the effects of SRWCs on soils are poorly understood. In this study, a SRWC was integrated with an annual row crop system in a row crop-SRWC-row crop rotation. The objective was to document the effects of the woody crop on soil total C, N, inorganic N, and aggregate stability after the site was returned to row crop production. Soybean [Glycine max (L.) Merr.] was followed by 4- and 5-yr rotations of American sycamore (Platanus occidentalis L.), followed by no-till corn (Zea mays L.) (SY4C and SY5C, respectively). Continuous row crops (soybean converted to corn) served as a control (SBC). Four rates of broadcast NH 4 NO 3 were applied to corn. The study was in southwestern Tennessee on a Memphis-Loring silt loam intergrade (fine-silty, mixed, active, thermic Typic Hapludalfs-fine-silty, mixed, active, thermic Oxyaquic Fragiudalfs). During 3 yr of post-sycamore corn production, increases in soil total C concentration below a 2.5-cm depth were attributed to the sycamore crop. After fertilization of first-year corn at 73 and 146 kg N ha -1 , soil inorganic N concentrations were lower in the SY4C than the SBC system from 0 to 2.5 cm. Mean weight diameter (MWD) of water-stable soil aggregates at depths of 2.5 to 15 cm was greater for the SY4C than the SBC system. Four- and 5-yr sycamore rotations significantly affected chemical and physical properties of an agricultural soil.