How Does Nitrogen Application Rate Affect Plant Functional Traits and Crop Growth Rate of Perennial Ryegrass-Dominated Permanent Pastures?

Abstract

High doses of nitrogen (N) fertiliser input on permanent pastures are crucial in terms of N surplus and N losses. Quantitative analyses of the response of plant functional traits (PFT) driving crop growth rate (CGR) under low N input are lacking in frequently defoliated pastures. This study aimed to understand the significance of PFTs for productivity and N uptake in permanent grasslands by measuring dynamics in tiller density (TD), tiller weight (TW), leaf weight ratio (LWR), leaf area index (LAI), specific leaf area (SLA), as well as leaf N content per unit mass (LNCm) and per unit area (LNCa) in perennial ryegrass (Lolium perenne)-dominated pastures, in a simulated rotational grazing approach over two consecutive growing seasons. Annual N application rates were 0, 140 and 280 kg N ha−1. The phenological development of perennial ryegrass was the main driver of CGR, N uptake and most PFTs. The effect of N application rate on PFTs varied during the season. N application rate showed the greatest effect on TD, LAI and, to a lesser extent, on SLA and LNCm. The results of this study highlight the importance of TD and its role in driving CGR and N uptake in frequently defoliated permanent pastures.

Effect of slurry application techniques on nitrous oxide emission from temperate grassland under varying soil and climatic conditions

“…In accordance with the German Fertilizer Ordinance (Dü, 2017), the maximum cattle slurry application rate was limited to 170 kg N ha −1 year −1 . As reported by Peters et al (2021), N uptake of a German grassland site was highest between the beginning of the vegetation period and the first cut, and it decreases with further cuttings over time. Thus, in accordance with Peters et al (2021) and in agreement with the recommendations of the regional agricultural extension services, we decided to split the 170 kg N ha −1 year −1 of applicable slurry N into two doses with 100 and 70 kg N ha −1 for the first and second dose, respectively.…”

“…As reported by Peters et al (2021), N uptake of a German grassland site was highest between the beginning of the vegetation period and the first cut, and it decreases with further cuttings over time. Thus, in accordance with Peters et al (2021) and in agreement with the recommendations of the regional agricultural extension services, we decided to split the 170 kg N ha −1 year −1 of applicable slurry N into two doses with 100 and 70 kg N ha −1 for the first and second dose, respectively. Differences between the targeted 170 kg total N ha −1 and the applied amounts of total N with slurry during the first two N applications were the result of a deviation from total slurry N determined in the slurry storages on the farms providing the experimental slurry approximately one month before spreading and the total N determined in the tanks of the experimentally used tanks during slurry application.…”

“…In accordance with the German Fertilizer Ordinance (Dü, 2017), the maximum cattle slurry application rate was limited to 170 kg N ha À1 year À1 . As reported by Peters et al (2021), N uptake of a German grassland site was highest between the beginning of the vegetation period and the first cut, and it decreases with further cuttings over time. Thus, in accordance with Peters et al…”

Species-Enriched Grass-Clover Mixtures Can Promote Bumblebee Abundance Compared with Intensively Managed Conventional Pastures

“…Moreover, in rotational stocking systems, flowering resources can be present on a farm-level from May to September. We could also show that the yields of grass-clover mixtures are similar to intensively managed conventional pastures [74], the forage quality is high in both the binary mixture and the multispecies mixture [55], and grazing of the grass-clover mixtures results in higher yields compared with mechanical harvesting [75]. These all imply that the organic ley system with a grass-clover mixture has the potential to create beneficial effects for the environment while maintaining economic benefits.…”

Can a urease inhibitor improve the efficacy of nitrogen use under perennial ryegrass temperate grazing conditions?

“…This would entail more fertilizer application splits of 8-10 applications compared to 5 applications for cutting regimes across the year. Rotational grazing also consists of a greater number of defoliation events than previous research carried out under cutting regimes, which may encourage greater growth rates (Peters et al, 2021). Actual cattle/sheep grazing, which could impose greater variability and different stresses on the grass through defecation, urination, trampling and defoliation action that could modify or mediate responses to different fertilizer regimes, was also imposed to verify the responses observed under cutting in previous research.…”