Hydroxylamine Content And Its Relationship With N₂O Production In Selected Soils

The global N₂O emissions from natural and cultivated soils account for about 70%of global N₂O emissions.Nitrification and denitrification are the main processes for N₂O production.Hydroxylamine?NH₂OH?is an intermediate product of the nitrification process and an important participant in the formation of N₂O.Because of its difficulty in detection,international research on soil NH₂OH content and its potential role in soil N₂O emissions is extremely limited.In response to this problem,this study used a recently proposed NH₂OH content detection method to study the granite parent material,the quaternary red clay parent material,the sediment parent material of the late pleistocene century,and rivers collected from the three provinces of Hunan,Hubei and Henan.Under several utilization methods of alluvial parent soil,the content of NH₂OH and its relationship with the physical and chemical properties of the soil,the effect of NH₂OH on soil N₂O emission,and the NH₂OH conversion coefficient R_NH2OH-N2O and the physical and chemical properties of soil.The main results obtained are as follows:?1?The type and utilization of soil parent material have a significant effect on soil NH₂OH content.The NH₂OH content of the 30 soil samples collected in this study mainly varied between 0.10-8.30 ng N/g,with an average value of 3.12 ng N/g.The NH₂OH content of the soil with different parent materials is ranked as follows:granite?4.54 ng N/g?>quaternary red clay?3.74 ng N/g?>late pleistocene sediments?2.85 ng N/g?>river alluvium?0.80 ng N/g?g).From the distribution of sampling locations,the NH₂OH content showed a downward trend from south to north.Under different land use methods,the soil NH₂OH content is different.Generally,the NH₂OH content in paddy fields is higher and the forest land is lower.?2?The higher the value of soil water content,NH₄⁺-N content and C/N,the more stable NH₂OH;and the higher the value of p H,total iron,total manganese,TDN content increases the soil NH₂OH content.?3?The R_NH2OH-N2O of the soil varies between 40-50%,which means that about half of the NH₂OH present in the soil can be converted into N₂O.The large amount of total manganese and active manganese in the soil will promote the conversion of NH₂OH to N₂O.R_NH2OH-N2O is related to the type of soil parent material:the main factor affecting the R_NH2OH-N2O of the soil for the development of the granite parent material is total manganese,which has a maximum direct effect on R_NH2OH-N2O of 1.121?direct path coefficient?,and its indirect effect on R_NH2OH-N2O through active manganese is also at most 0.159?connected diameter coefficient?;the main factor affecting the R_NH2OH-N2O of the red clay parent material development soil in the fourth season is TDN,and its direct effect on R_NH2OH-N2O is at most 0.828?direct path coefficient?.