Effects Of Iron Fertilizer And Rice Varieties On Methane Emission From Paddy Fields

As a major greenhouse gas after carbon dioxide,methane's contribution to global warming accounted for 20% and methane from paddy field is the main anthropogenic source. Then, the respiratory process of iron oxide on root surface iron film formed by rice root system can inhibit the production of methane effectively, so applying ferrihydrite with high redox potential is beneficial to methane emission reduction. For exploring efficient measures for methane emission reduction and low emissions-high yield rice varieties, this study used ten common Oryza sativa L as the materials and adopt the method of pycnometer and DCB to measure root porosity and root iron plaque by means of water culture and iron stress for 24 hours in order to screen some varieties with large porosity of root and high content of iron plaque on root surfaces per gram dry root. The second was planting one-season rice with the varieties which had been selected in a field plot experiment under soil submergence applied Fe fertilizer or not and measured methane emission of rice, methane production rate of soil and root, iron content in different valence of different soil system, soil pore water methane and Fe (?) concentration, root porosity and iron plaque on root surfaces and other biogeochemistry parameters.The results show: 1. The four varieties with large porosity of root and thick root iron plaque selected by water culture are Bo I You 26, Qionghui 115, Japonica 326,Indica rice CHCS06. 2. The amount and average rate of methane emission of the four varieties after applying Fe fertilizer all have reduced. The emission reduction of Indica rice CHCS06, Bo I You 26, Qionghui 115 are very obvious, especially Indica rice CHCS06 whose effective value reaches up to -38.40%. 3. Applying Fe fertilizer has different degrees of adverse effect on methane production rate in rhizosphere soil and non-rhizosphere soil, especially after the first-earing phase, but has no evident effect on methane production rate of rice root except for Qionghui 115 which has significant inhibition. 4. The Fe (?) concentration in soil increases after applying Fe fertilizer, but the variation trend in the Fe (?) concentration of different varieties is not conspicuous. 5. Except for some individual period of the rice, it can reduce methane production rate through applying Fe fertilizer. 6. The variation of rice root porosity presents ruleless and root iron plaque of different varieties all has raised during different period other than Bo I You 26. And there has no prominent correlation between root porosity and root iron plaque. In short, it's beneficial to decrease the amount and average rate of methane emission, inhibit methane production rate in soil and reduce methane production rate by applying Fe fertilizer which is a kind of effective measure. From the results we can know the effect of methane emission for Bo I You 26 and Indica rice CHCS06 is most obvious.