Legume plants are environmentally friendly because of the low-cost cultivation costs as well as the good quality of post-harvest residues. The aim of this study was to determine the fertilizer value of post-harvest residues of fenugreek plants grown under various environmental conditions. The value of the aerial parts of fenugreek plants left in the soil after harvest was analyzed in a pot experiment with different seed inoculation treatments (Rhizobium meliloti and not inoculated), different doses of K fertilizer (0.0; 1.25; 2.50; 3.75 g K per pot) and different soil moisture content (50-60% and 30-35%) during the growing season. K fertilization and water stress differentiated the dry weight of the aerial parts of fenugreek plants. Water deficit during the flowering and pod formation phases significantly decreased the dry weight of pericarps, leaves and stems, which was lower by about 17, 3 and 14 %, respectively. An increase in a K dose led to a decrease in the concentrations of N and Ca in pericarps, N, P, Ca and Mg in leaves, and Na, Ca and Mg in stems. Seed inoculation increased N (11.5%) and Ca (7.2%) accumulation in straw. Water stress modified the uptake of minerals by decreasing the accumulation of Mg, Ca and K. Biological N2 fixation was influenced by a dose of K fertilizer and water availability. Biological N2 fixation by R. meliloti root nodule bacteria ranged from 27.96 to 32.08 µg per plant. Nitrogen was most effectively fixed in the treatment supplied with 2.50 g K per pot. Water deficit during flowering and pod formation decreased biological N2 fixation by 4.5%.
Wierzbowska J., Żuk-Gołaszewska K. 2019. The fertilizer value of post-harvest residues of Trigonella foenum-graecum L. J. Elem., 24(1): 331 - 342. DOI: 10.5601/jelem.2018.23.2.1642