Validation of a critical nitrogen dilution curve for hybrid ryegrasses

Abstract

One of the challenges of modern grassland systems is to minimize nitrogen (N) fertilization without negatively affecting the forage yield. Therefore, critical N dilution curves (Nc = ac W−b) have been developed in different species to improve N fertilization management. The aim of this study was to validate a critical N dilution curve for hybrid ryegrasses. Two field experiments were conducted in southern Chile. Treatments were the factorial combination of two hybrid ryegrasses (Shogun and Trojan cultivars) and seven N fertilization rates (0, 50, 100, 200, 350, 525 and 700 kg N/ha). Factors were arranged in a split‐plot design, where forage species were assigned to main plots and N rates to subplots that were randomized into four blocks. A wide range in forage yield and plant N concentration was observed (yield: 0.16 and 3.9 Mg DM/ha and N: 1.6% and 5.1%). The variations in these traits were principally explained by the N levels and harvest times. Relative yield responses of both cultivars were significantly (p < 0.001, R2 = 0.81–0.87) related to the nitrogen nutrition index (NNI) calculated with different critical N dilution curves. However, the NNI calculated with N dilution curves from annual ryegrass best described the relative yield response of hybrid ryegrass. Therefore, this validated critical N dilution curve (%Nc = 4.1W−0.38) will serve as a useful diagnosis tool for improving the N fertilization management of grazing systems for hybrid ryegrasses.

Effects of Phosphorus Fertilizer Solubility on Pastures Yield and Quality in Andisols

“…The study presented here showed a wide range of forage yields of pastures grown under rainfed conditions, mainly affected by P levels and harvest times. Forage yields observed here are in line with those previously reported for southern Chile under rainfed conditions (Demanet et al 2015;Loaiza et al 2016;Sandaña et al 2019) with production ranging from < 1 to < 5 Mg DM ha −1 per cutting time. The differences in yield between experimental sites can be attributed to differences in chemical properties of Andisols.…”

The Effect of Drying Methods on Water-Soluble Carbohydrates and Crude Protein Concentrations and Their Ratio in Two Perennial Ryegrass Cultivars

“…Crude protein concentration followed the seasonal pattern of greater CP concentration in the winter and lower in the spring [45,46]. Previous studies comparing perennial ryegrass found CP concentrations of between 60-61 and 340-353 g kg −1 DM, with a mean of 180-229 g kg −1 DM [47,48].…”

Editorial: Grass and Forage Science – 75 years of impact and service to the science of grasslands

“…Whilst a major emphasis of early papers was on the improvement and productivity of grasslands, there has been an increased emphasis on the ecosystem services that grasslands provide across the globe (D’Ottavio et al, 2018) and the ecological and societal pressures on grassland agriculture. Therefore, we have seen papers submitted that seek to understand nitrogen responses in terms of efficiency of plant responses (Sandaña et al, 2019) and the farming system implications of the role of nitrogen on forage quality and productivity, animal production and nitrogen leaching (O’Connor et al, 2019) including a revisitation of the role of legumes in this context (Guy et al, 2018; Niderkorn et al, 2019; Woods et al, 2018).…”