Effects of plantain in pasture on nitrous oxide emissions from cattle urine patches, as affected by urine deposition timing and soil type

Abstract

Two lysimeter experiments were conducted to quantify the effect of including plantain in pasture on nitrous oxide (N₂O) emissions from cattle urine patches, as affected by urine deposition timing and soil type. In experiment one, two pasture types were tested: (i) perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) (PRG/WC), and (ii) perennial ryegrass/white clover/plantain (Plantago lanceolata) (PRG/WC/P) pastures, under four urine application dates (late summer, early autumn, mid-autumn, and late autumn). In experiment two, two pasture types were tested: (i) PRG/WC and (ii) PRG/WC/P on two soil types (Balmoral shallow stony silt loam and Templeton deep stone-less silt loam). Both experiments applied cow urine (700 kg N ha⁻¹) and collected gas samples using a closed chamber method. In experiment one and two, the addition of plantain to pasture had no significant effect on N₂O-N emissions. Soil type had no significant effect on N₂O-N emissions. However, urine application timing had a significant effect, with February having the highest average N₂O-N emissions (9.0 kg N₂O-N ha⁻¹), followed by March (3.0 kg N₂O-N ha⁻¹), April (2.7 kg N₂O-N ha⁻¹) and May (1.7 kg N₂O-N ha⁻¹). This change in N₂O-N emissions is attributed to cooler conditions reducing microbial activity, subsequently reducing nitrification and denitrification rates.