Effect of Plantago lanceolata L. cultivar on nitrous oxide emissions from simulated cattle urine patches

Abstract

Narrow-leaved plantain (Plantago lanceolata L.) has potential to reduce N₂O emissions from pastoral livestock systems. This study aimed to 1) compare N₂O emissions between plantain and ryegrass (R) swards, and 2) determine if N₂O emissions differed between three plantain cultivars with differing biological nitrification inhibition (BNI) potential (High (H), Medium (M), and Low (L)). Experiments were performed in two locations of New Zealand (Waikato and Southland) with differing soil types, latitude, and climate. Swards were established in a split-plot randomised block design with dairy cow urine (U) and non-urine (NoU) treatments. For the U treatments, cumulative N₂O emissions in Waikato were similar between all plantain cultivars and ryegrass (1588 ± 108 g N ha‾¹). However, in Southland, cumulative N₂O emissions from plantain swards were ∼50 % less than from ryegrass (mean 501 cf. 979 g N ha‾¹), with emissions differing by up to 212 g N ha⁻¹ between cultivars P < 0.05). For the NoU treatments, plantain reduced cumulative N₂O emissions compared with ryegrass by an average of 60 % (Waikato) and 53 % (Southland), with no differences among plantain cultivars. Urine N₂O emission factors (EF₃) were 0.20 % (H, L) and 0.23 % (M, R) in Waikato (P = 0.893), and 0.05 % (M, L), 0.07 % (H), and 0.11 % (R) in Southland (P < 0.001). The observed differences between sites and cultivars may relate to variation in management practices, soil type and physicochemical properties, localised climate, and plant traits. While plantain can reduce N₂O emissions compared to ryegrass swards, the magnitude of this reduction varies between cultivars and is environment specific.