Changes in soil chemical properties and crop yields with long-term cropping system and nitrogen fertilization

Information is needed on the long-term impact of cropping system and N fertilization on dryland soil health and crop yields. We studied the 13-yr effect of cropping system and N fertilization rate on soil chemical properties at the 0- to 60-cm depth and related them to annualized crop yield in the northern Great Plains. Cropping systems were conventional tillage barley (Hordeum vulgare L.)/spring wheat (Triticum aestivum L)-fallow (CTB/WF), no-tillage barley/spring wheat-fallow (NTB/WF), no-tillage barley/spring wheat-pea (Pisum sativum L) (NTB/WP), and no-tillage continuous barley/spring wheat (NTCB/W). Nitrogen fertilization rates were 0, 40, 80, and 120 kg N ha(-1) to barley planted from 2006 to 2011 and 0, 50, 100, and 150 kg N ha(-1) to spring wheat planted from 2012 to 2018. At 0 to 5 cm, soil pH and CEC were greater with NTB/WP than NTCB/W and CTB/WF, and soil organic matter (SOM) and Olsen-P were greater with NTCB/W than CTB/WF. Increased N rate reduced soil pH, K, Ca, Mg, and CEC at most soil depths. Annualized crop yield was greater with NTCB/W and NTB/WP than NTB/WF and CTB/WF and maximized at 80-100 kg N ha(-1). Most soil chemical properties induced by N fertilization were negatively correlated, but Mg concentration at 30-60 cm induced by cropping system was positively correlated with annualized crop yield. No-till barley/spring wheat-pea rotation with 80-100 kg N ha(-1) can sustain dryland soil chemical properties and barley and spring wheat yields in the northern Great Plains.