To determine the effects of soil amendments (lime or ammonium-sorbed zeolite) on emissions of nitrous oxide (N2O) and dinitrogen (N2) gases from pasture and wetland soils, a 90-day incubation experiment was conducted under controlled moisture and temperature conditions. Soil samples (0–0.10 m soil depth) collected from pasture and adjacent wetland sites were treated with 2 nitrogen (N) sources (cow urine or urea) at 200 kg N/ha with and without added soil amendments using 10-L plastic containers and then incubated at 25°C. Subsoil samples were taken out at different intervals to measure gaseous emissions of N2O and N2 using the acetylene (C2H2) inhibition method, ammonium (NH4+), nitrate (NO3–), soluble organic C, and pH. The anaerobic conditions (81% water-filled pore space) in wetland soils precluded nitrification, and therefore no increase in NO3–, N2O, or N2 was observed during the 90-day incubation period. In the pasture soil, the application of urine, urea, and soil amendments significantly affected daily and total N2O and N2 emissions and their ratios over a 90-day incubation period. Total N2O emission from urea-treated soil (48 kg N2O-N/ha) was significantly higher than from urine-treated soil (39 kg N2O-N/ha) and the control soil (4.5 kg N2O-N/ha). The application of zeolite significantly reduced N2O emissions from urea and urine-treated soils by 45% and 33%, respectively, due to the sorption of NH4+ by zeolite. Liming had minor effect on N2O emission. However, when lime was applied with zeolite, a significant reduction in N2O emission was observed. Lime application alone was found to increase N2 emissions in urine and urea treated soils by 46% and 35%, respectively, and thereby lower N2O : N2 ratios. The results indicate that zeolite reduced N2O emission while lime increased N2 emissions and lowered N2O : N2 ratios, and warranting further attention for mitigation of N2O.

Seagrass ( Zostera muelleri Irmisch ex. Aschers) was historically prolific in Whangarei Harbour, New Zealand, but has since declined. Over two years we compared the survival of mid‐intertidal zone transplants (18 × 0.25 m ² plots) from a remnant meadow to a former site using three methods: (1) intact ‘sods’, (2) unanchored ‘sprigs’ and (3) sprigs amongst ‘mats’ of artificial plants. Before and after transplant, we quantified plant cover in all plots, and in transects across the wider intertidal zone. We also measured plant biomass, irradiance and water quality at each site. We found that sods and sprigs were equally effective with plant cover increased from <1 to 63%, but mats were ultimately not successful. Cover across the wider transplant site increased from 10% to 46% (biomass from 58 to 321 g m ⁻² ). Donor plots regenerated within 9 months. This study shows that Z. muelleri can be rehabilitated by transplant upon reinstatement of suitable growing conditions at former sites.