borderline significantp<0.08
A multifactorial model using analysis of variance (ANOVA) was used, with N fertilization level, year (with “on”/”off” nesting) and plot as predictor variables, For trend determination, a five-level contrast analysis was performed ( Rosenthal et al., 2000 ), and presented with its significance value, also when the trend was borderline significant (p<0.08), including its type (either linear (P L ) or quadratic (P Q )), and the trendline itself.