Actual N Availability from Winter Catch Crops Used for Green Manuring in Maize Cultivation

Field experiments were carried out in Central Italy on several green manure species (pure or mixed) and on succeeding grain maize to find practical relationships for predicting the N effect (N absorbed by maize that derives from the actual gain in soil available N due to green manure). Actually, little information is available for Mediterranean environments, where green manure species and strategies may be other than those of northern-temperate and tropical regions. Relationships were found for maize shooting (Neff = −3.61DW + 29.75N%; R2 = 0.67), flowering (Neff = −1.32DW + 27.47N%; R2 = 0.66) and physiological maturity (Neff = −4.84DW + 50.43N%; R2 = 0.74) (DW = incorporated biomass, N% = N concentration).