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Soil Sampling and Methods of Analysis - Part 5

Chất hữu cơ trong đất là hỗn hợp phức tạp của các hợp chất hữu cơ có nguồn gốc từ phần còn lại đã chết và đang phân hủy của thực vật, động vật, vi sinh vật, và các xác chết và các chất thải trao đổi chất ở các giai đoạn khác nhau của sự phân hủy. Khoáng carbon hữu cơ (C) là chuyển đổi từ hình thức hữu cơ thành các hợp chất vô cơ như là kết quả của phản ứng phân hủy được thực hiện bởi các sinh vật decomposer, phần lớn trong số đó là. | V. SOIL ORGANIC MATTER ANALYSES Section Editors E.G. Gregorich and M.H. Beare 2006 by Taylor Francis Group LLC. 2006 by Taylor Francis Group LLC. Chapter 45 Carbon Mineralization D.W. Hopkins Scottish Crop Research Institute Dundee Scotland United Kingdom 45.1 INTRODUCTION Organic matter in soils is the complex mixture of organic compounds derived from the dead and decaying remains of plants animals and microorganisms and their corpses and metabolic wastes at different stages of decomposition. Mineralization of organic carbon C is the conversion from the organic form to inorganic compounds as a result of decomposition reactions carried out by decomposer organisms the vast majority of which are microorganisms bacteria and fungi Gregorich et al. 2001 . In the process of utilizing soil organic matter heterotrophic soil organisms release CO2 during respiration. The release of CO2 as a metabolic by-product of organic matter decomposition is referred to as C mineralization. Because soil organic matter is a complex mixture of organic compounds of different biological origins and at different stages of decay C mineralization is the result of a complex set of biochemical processes conducted by a wide range of organisms. Despite the fact that it is a simplification of the actual process C mineralization measurements are commonly used in investigations of soils and the data have a wide range of applications in agriculture forestry ecology and the environmental sciences. One reason for this is the relative ease with which CO2 can be measured in the laboratory. There are a wide range of methods for measuring CO2 production in the field and at the landscape scale but this chapter is concerned with measuring C mineralization under controlled laboratory conditions and only limited reference is made to field methods to illustrate some principles. Data on mineralization of soil C may be used in two ways. The rate of C mineralization measured over periods from a few days to a few .