Fertilization of Alfalfa Crop in Order to Develop Sustainable Management Systems

Understanding the complex relationships between soil fertility, crop productivity, and management systems in agriculture would contribute to developing sustainable management systems. The paper analyzed the possibility production systems with reduced fertilization by comparing traditional mineral fertilizer application systems and no-fertilizer systems. The field experiment was carried out in 2017-2019 in central Serbia on eutric cambisol. The experiment with the alfalfa variety K-28 was set up according to a completely randomized block system in 3 replications. The following fertilization variants were applied: A1 (unfertilized - control), A2 (N30:P30:K30 kg ha-1 in autumn), A3 (N30:P30:K30 kg ha-1 in autumn and 30 kg ha-1 N in spring), A4 (N45:P45:K45 kg ha-1 in autumn), A5 (N45:P45:K45 kg ha-1 in autumn and 15 kg ha-1 N in spring), A6 (15 kg ha-1 N in spring) and A7 (30 kg ha-1 N in spring). Variants of application of complex mineral fertilizers in autumn A2, A3, A4, and A5 did not lead to a significantly higher alfalfa forage yield compared to fertilization systems when nitrogen was applied in smaller amounts in spring. Satisfactory alfalfa yields were achieved when nitrogen was applied in the spring in the amount of 15 kg ha-1 (A6), especially in conditions of sufficient water supply to the plants. All varieties of fertilization influenced the increase in the proportion of weeds. The use of low rates of nitrogen fertilizers with the application of moderate irrigation can be a good management practice that can reduce environmental pollution without greatly alfalfa forage yield reduction.