Mitigation of ammonia and methane emissions with manure amendments during storage of cattle slurry

This study aimed at assessing the efficacy of manure amendments in abating ammonia (NH3) and methane (CH4) emissions during storage. Two experiments were carried out. Experiment 1 was conducted using 20 L of slurry for 98 days. Treatments were: aluminium sulphate (alum), lactogypsum, zeolite, actiglene, ammonium thiosulphate, biochar, dairy processing waste, Digest-IT and control (without amendment). Experiment 2 was conducted using 660 L of slurry in underground storage tanks for 77 days. Treatments were: sulphuric acid, gypsum, biochar and control (without amendment). NH3 measurements for experiment 1 and experiment 2 were conducted using the photoacoustic gas monitor and dynamic chamber techniques, respectively. CH4 was measured using the static chamber technique in both experiments. The effect of amendments on slurry composition was determined at the end of the experiments. Experiment 1 showed a significant reduction in NH3 emissions in the alum (82%), lactogypsum (46%) and zeolite (32%) treatments relative to the control (100.3% total ammoniacal nitrogen (TAN)). CH4 was reduced significantly in the alum (87%), ammonium thiosulphate (64%) and lactogypsum (67%) relative to the control (291.9 g m-2). Experiment 2 showed a significant reduction (32%) in NH3 emissions in the sulphuric acid relative to the control (4.4% TAN). CH4 was reduced significantly in the sulphuric acid (46%), gypsum (39%) and biochar (15%) treatments relative to the control (291.9 g m-2). In general, amendments altered slurry composition such as dry matter, volatile solids, carbon and nitrogen contents at the end of storage. Lactogypsum, alum and sulphuric acid were effective in abating both NH3 and CH4 emissions and can contribute to improving air quality.