Effect of Biochar on NH3 Volatilization and N2O Emission in Brown Soil

In this study, we investigated the effect of biochar on NH3volatilization and N2O emission in brown soil by using enclosed acid absorbing method and static chamber-gas chromatograph method. The results showed that without fertilizing, there was no significant effect of biochar effect on NH3volatilization and N2O emissions but if biochar was combined with urea, a dramatic mitigation of which could be found. Biochar application was supposed to regulate urea-N transformation more easily than soil nitrogen. Under the conditions of this experiment, both NB20 (20 t·hm-2of biochar and conventional nitrogen fertilizer applied) and NB40 (40 t·hm-2of biochar and conventional nitrogen fertilizer applied) treatments reduced NH3volatilization and N2O emissions significantly. By contrast of NB0 (single urea), the accumulated NH3volatilization and N2O emissions of NB20 and NB40 decreased by 15.6% and 24.4% and by 21.76% and 19.56% respectively. Under conventional fertilization conditions (NB0), 10.35% of nitrogen in fertilizer was lost in the form of NH3and N2O, and compared with NB0, NB20 and NB40 reduced nitrogen gaseous loss from fertilizer by 2.76% and 4.12% respectively.

Transformation of Nitrogen Fertilizers in Greenhouse Experiments

The primary (1 st year) and the after-effects (2 nd , 3 rd year) of N fertilizers (KNO 3 , NH 4 Cl) on the soil-plant-atmosphere system were studied in a three-year greenhouse pot experiment with and without maize plants. The two- and three-year balances of the fertilizer N uptake and gaseous N losses were also analyzed. The cumulative values of the gaseous losses showed a similar trend in all years, significant differences were not obtained. On the basis of the three-year balance, the gaseous loss in the planted and unplanted pots was 18-22% and about 37-39%, respectively. Consequently, there was a 50% decrease in denitrificated gaseous losses of fertilizer N due to plant N uptake. The cumulative gaseous loss, calculated by the difference method, was significantly higher in cases of KNO 3 applications than in NH 4 Cl treatments, as an assumed consequence of the intensive denitrification. It was found that the gaseous loss was not influenced by soil moisture. In contrast to the gaseous losses, the values of plant N uptake and soil mineral N content showed significant differences in the years studied, as a result of the quick transformation of mineral N to organic N, the non-complete homogenization of the total soil amount, the seasonal climatic differences in the greenhouse during the years studied, and consequently the different microbiological activity. The plant N uptake was found to depend significantly on the fertilizer N form. Results obtained by the difference method and the 15 N-tracer technique were very similar. In the case of KNO 3 treatment and higher soil moisture (WHC = 80%) plant N uptake was more intensive, ranging between 48-57% (calculated by the difference method), and 35-51% (calculated by the 15 N- tracer method) in the first year (1993). It can be concluded that 60-100% of the fertilizer N was used from the soil by plant uptake and gaseous losses, which depends mainly on the treatments and the soil moisture during the first year. These values changed between 7-17% in the 1 st year after-effect and between 1-5% in the 2 nd year after-effect.

Effect of feed type on methane produced by sheep

The loss of digestible energy from ruminant feeds as methane gas is often assumed to be about 0.08 of gross energy (GE) intake. This represents a significant loss of feed energy and recently concern has been expressed about the importance of methane as a gas which contributes to global warming. As methane is a gaseous loss, its measurement requires specialised equipment. Therefore the metabolisable energy (ME) content of many feedstuffs is estimated using a predicted methane energy loss.