Nitrogen partitioning and cycling in barley-soil systems under conventional and zero tillage in central Alberta

Cropping systems which conserve soil, water and nutrients are needed on the Canadian prairies. The objectives of this study were: (1) to assess the effects of urea injection on N partitioning in barley-soil systems under conventional (CT) and zero tillage (ZT); and (2) to measure the dynamics of fertilizer and soil N over the growing season. Twelve microplots were installed in each of CT and ZT plots located on a Black Chernozemic soil and were fertilized (59 kg N ha−1) with 15N urea solution, sown to barley (Hordeum vulgare (L.) 'Empress') and destructively sampled at the fifth leaf, ear emergence, grain filling and ripening growth stages. Distribution of 14N and 15N in shoots, roots, mineral N, microbial N, and soil organic N were measured. The recovery of fertilizer N in the soil-plant system was not different between treatments. Microbial N and non-microbial organic N accounted for > 80% of residual 15N in both treatments. Nitrogen budgets showed that grain removal from CT was 76 kg ha−1 and 56 kg ha−...