Influence of harvest managements of festulolium and tall fescue on biomass nutrient concentrations and export from a nutrient-rich peatland

- Biomass nutrient concentrations dropped sharply during spring-summer growth.
- Annual removals ranged from 240 to 315 kg N, 42-53 kg P and 172-252 kg K ha−1.
- On average, the grasses removed ∼80 kg more N and 30 kg more P ha−1 yr−1 than the amounts applied as fertilizers.

This study was designed to show the effects of harvest time and frequency on biomass nutrient concentrations (total ash, N, P, K, Ca, Mg, Fe, Mn, Cu and Zn) as well as total nutrient removal potential by festulolium and tall fescue cultivated on a nutrient-rich fen peatland. The harvest managements included a three-cut (3C) and three two-cut (2C) systems which differed by two-week delays of first cut as: 2C-early, 2C-mid and 2C-late, representing phenological stages of pre-heading, inflorescence emergence, and flowering, respectively. In the study year, the grasses received 80-16-60 kg N-P-K ha−1 in spring and 80-0-100 kg N-P-K ha−1 after each harvest (except final). Nutrient concentrations and total ash content in the biomass dropped sharply during spring-summer growth. Concentrations of Ca, Mg and Mn were significantly higher in tall fescue biomass during spring-summer growth, but for other nutrients, there were no consistent differences between the two grasses. Total ash in the biomass from 3C managements (1.1 Mg ha−1) was ∼28% higher than in the biomass removed by 2C managements (0.8 Mg ha−1). Similarly, mean annual N removal by 3C (315 kg N ha−1) was 31% higher than by 2C (240 kg N ha−1) managements, but net removals (removed minus applied N) from both managements were similar (75-80 kg ha−1). Net P-removal by 3C (37 kg P ha−1) was higher than by 2C (26 kg P ha−1) managements, whereas total K removals in all managements were close to the applied K amount (i.e., net removals were close to zero). Whereas all crop/management combinations extracted more N and P than applied, the 2C-late approach is recommended since the biomass yield was higher than for the other 2C approaches, and it required less fertilizer and management inputs than the 3C approach.