School of Agriculture, Food and Ecosystem Sciences - Theses

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Start date: 2020 × End date: 2022 × Type: Masters Research thesis × Author: SONG, YUMENG ×

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    The effect of in vitro manure nitrogen composition and lignite application on dairy cattle manure ammonia emission
    SONG, YUMENG ( 2022-09)
    The major objectives of the master study were to estimate the urinary nitrogen (UN) to faecal nitrogen (FN) ratio from sampled dairy cattle, to quantify the effectiveness of lignite application on reducing ammonia (NH3) emission and to establish the relationships between dairy cattle manure NH3 emission, nitrogen (N) isotope fractionation (delta-15N), the N to phosphorus (P) and N to potassium (K) ratios in diverse manure property and environmental conditions. The in vitro manure incubation system was conducted to explore the manure daily changes, daily NH3 emission and the effect of lignite application on reducing NH3 emission. The UN to FN ratios were approximately 1 to 1, calculated via the N balance study. Total 600 g reconstructed manure was put into each incubation system to achieve a manure UN to FN ratio of 1 to 1 for CT and CT+L, and 2 to 1 for 2U1F and 2U1F+L. Further, 250 g lignite powder was added into CT+L and 2U1F+L and mixed with manure. Acid traps were settled to collect emitted NH3 emission. A total of 15 g manure sample and 15 mL of acid sample were collected daily from each incubation system and stored frozen (-20 degrees centigrade). The daily NH3 emission in the non-lignite group decreased with incubation days while it increased with days in the lignite group. The major NH3 emission occurred in the first 7 days in the non-lignite group and in the last 10 days in the lignite group. There was a weak relationship between temperature and daily NH3-N emission (R2 = 0.30, P <= 0.05). The cumulative NH3-N emission of 2 UN to 1 FN ratio (2U1F) treatment was 45.8% higher than control (CT) treatment in non-lignite groups, while it of 2U1F with lignite application (2U1F + L) was 100% higher than CT with lignite application (CT + L). The lignite application reduced the cumulative NH3-N emission by 87.5% compared to CT and CT + L treatments and 82.9% compared to 2U1F and 2U1F + L treatments. The manure delta-15N from the CT and 2U1F treatments increased with incubation days (R2 = 0.85 and 0.91, respectively; P <= 0.001). However, there was no relationship between manure delta-15N from the CT + L, 2U1F + L treatments and incubation day (R2 = 0.07 and 0.08, respectively; P <= 0.001). The manure N to P ratio decreased with incubation days (R2 = 0.81, 0.73, 0.81, and 0.84 in CT, 2U1F, CT + L, and 2U1F + L treatment, respectively; P <= 0.001). There was a weak relationship between manure N to K ratio and incubation days found in CT treatment (R2 = 0.28, P <= 0.001), while manure N to K ratio decreased with incubation days in the other three treatments (R2 = 0.70, 0.79, and 0.90 in 2U1F, CT + L, and 2U1F + L treatment, respectively; P <= 0.001). Overall, the master studies showed that manure delta-15N could not be used as an accurate biomarker to estimate NH3 emission in relatively low NH3 concentrations (R2 = 0.02, P <= 0.001) while the N to P ratio was better to use (R2 = 0.85, P <= 0.001). The manure delta-15N outperformed to be the best biomarker to estimate NH3 emission in relatively high NH3 concentrations (R2 = 0.83, P <= 0.001). The lignite application was an effective method to reduce NH3 emissions. However, further study is required to investigate the maximum absorption ability of lignite for improving the application in livestock industries.