Soil solution nitrate concentration ([NO3−]) measured lysimetrically at 30 cm depth is presented in Fig. 1. GC treatment increased [NO3−] up to 47mgL−1 in September of year 3 (Fig. 1A). Seasonal soil solution pH varied (Fig. 1B). GC-treated plots had a greater seasonal soil organic matter (OM) at a depth of 0–10 cm during the most months of the three year study (Fig. 2). Although GC plots had a greater seasonal soil OM in the subsoil fraction during some months, a narrower range of soil OM was observed in the deeper fraction (Fig. 2B).