The soil N and ammonium (NH4) content was determined using the Kjeldahl method (Pro-Nitro A, model
4002430). All plots were also fertilized before planting with phosphorus (P) (65 kg P ha1 year1) and potassium (K) (207 kg K ha1 year1) to avoid mineral deficits. The elemental plot dimensions were 15 11m(with 15e16 rows per plot) and were arranged in a randomized block design with three replicates