Nutrients Use Efficiency and Uptake Characteristics of Panicum virgatum for Fodder Production

Panicum virgatum could produce cattle feed with lower costs due to the low input requirements and its perennial nature. Dry biomass yield vs. N-P-K nutrient uptake relations as well as the N-mineralization and the N-fertilization recovery fraction for Panicum virgatum (cv. Alamo) were determined under field conditions for four N-fertilization (0, 80, 160 and 240 kg ha-1) and two irrigation levels (0 and 250 mm), οn two soils in central Greece with rather different moisture status. It was found that the dry fodder yield on the aquic soil may reach 14 t ha-1 using supplemental irrigation; while on the xeric soil a lower yield of 9-10 t ha-1 may be produced only under supplemental irrigation. Moreover, the average N, P and K concentration was 1.3%, 0.14% and 1.3% in leaves, and 0.5%, 0.85%, and 1.5% in stems, respectively, showing the very low crop requirements. Furthermore, linear biomass yield-nutrient uptake relationships were found with high R2, pointing to nutrient use efficiency of 132 and 75 kg kg-1, for N and K respectively. The base N-uptake ranged from 71-74 kg ha-1 on the aquic to 60 kg ha-1 or less on the xeric soil. Finally, it was found that N-recovery fraction was 20% on the aquic soil and lower on the xeric. Therefore, it could be conclude that Panicum virgatum seems to be a very promising crop for fodder production and its introduction in land use systems (especially οn aquic soils of similar environments) should be taken into consideration.