Nitrogén-, foszfor- és kálium-ellátottság hatása a lóbabra (Vicia faba L.) | Effect of N, P and K supplies on faba bean (Vicia faba L.)

The aim of the research was to study the effect of N, P and K supplies on the nutritional status of faba bean in a long-term mineral fertilisation experiment and to determine the nutrient concentrations and nutrient ratios associated with satisfactory nutritional status. The long-term fertilisation experiment was set up in 1989 on chernozem meadow soil calcareous in the deeper layers, with all possible combinations of four levels each of N, P and K supplies, giving a total of 64 treatments. The present paper discusses the results obtained in 2001 and 2002, which can be summarised as follows: In all the years the seed yield of faba bean exhibited a significant increase of 9% when the NO ₃-N content of the 0–60 cm soil layer prior to sowing rose to 76–85 kg ha ⁻¹, which could be achieved in most years at the 80 kg ha ⁻¹ N fertiliser rate. P fertiliser significantly increased the seed yield up to a soil AL-P ₂O ₅ content of 176–183 mg kg ⁻¹. The K supplies had no significant effect on the seed yield when the soil AL-K ₂O content was in the 230–465 mg kg ⁻¹ range. Excessive N supplies (160, 240 kg N ha ⁻¹) increased the N and Mn contents of faba bean leaves, while reducing the Fe, Zn and Cu contents. When the AL-P ₂O ₅ content of the ploughed layer was 120–339 mg kg ⁻¹, greater P supplies induced a higher Ca concentration in the leaves. P–Cu and P–Zn antagonism could be detected at AL-P ₂O ₅ contents of 176 mg kg ⁻¹ or more, and became more pronounced as the P supply level increased. A significant decline in the Fe content could be detected at soil AL-P ₂O ₅ contents of 195 and 339 mg kg ⁻¹. When the AL-K ₂O content of the ploughed layer was in the 229–465 mg kg ⁻¹ range, increasing K supplies were associated with higher N and K concentrations. Excessive K supplies resulted in a substantial decline in the Na, Mg and Zn contents of the leaves. Leaf analysis at the beginning of flowering can be recommended for judging the nutritional status of faba beans. In this phenophase, satisfactory nutritional status is indicated by the following nutrient concentrations in young, fully developed leaves: N 5.3-6.0%, P 0.35–0.45%, K 2.0–3.5%, Na 0.3–1.0%, Ca 0.8–1.3%, Mg 0.35–0.50%, Fe 250–400 mg kg ⁻¹, Mn 60–120 mg kg ⁻¹, Zn 30–60 mg kg ⁻¹ and Cu 3–7 mg kg ⁻¹.