Click on image to view larger version.



Fig. 2. Grain yield of winter wheat (WW) after summer fallow (one crop every 2 yr) compared with continuous annual no-till hard red spring wheat (HRSW) during 6 yr in the Horse Heaven Hills, Washington. {dagger} = WW yield in 1997 is the average from several neighboring fields, not from replicated plots, and thus statistical analysis is not possible in 1997. {ddagger} = HRSW grain yield is from replicated plots during all 6 yr. § = statistical comparison of average grain yield is for 5 yr (1998 to 2002). Grain yield of WW after summer fallow was significantly (P < 0.05) greater than grain yield of annual HRSW each year and when averaged over the 5 yr.