Sau khi hệ thống thoát nước, đất hữu cơ thay đổi chức năng cơ bản của họ từ bồn hấp thụ cácbon tự nhiên và hồ chứa nước với các nguồn khí gây hiệu ứng nhà kính và các cơ quan thiếu nước. Tự nhiên của quá trình hấp thụ các-bon là paludification, thoát nước và sục khí, đất hữu cơ trải qua quá trình moorsh hình thành không thể đảo ngược (MFP). | CHAPTER 2 Irreversible Loss of Organic Soil Functions after Reclamation Piotr Ilnicki and Jutta Zeitz CONTENTS Abstract I. Introduction II. Morphological Classification of Genetic Soil Horizons III. Changes in Physical Properties A. Peat Shrinkage B. Peat Density C. Peat Porosity D. Hydraulic Conductivity IV. Changes in Chemical Properties V. Changes in Biological Properties VI. Soil Degradation Symptoms and Prevention VII. Conclusion References ABSTRACT After drainage organic soils change their basic functions from natural carbon sinks and water reservoir to sources of greenhouse gases and water-deficient bodies. The natural process of carbon sequestration is paludification with drainage and aeration the organic soil undergoes the irreversible moorsh-forming process MFP . The intensity of MFP is shown by morphological and structural transformations enrichment in humic substances changes in mineral composition as well as shifts in microbial populations mesofauna and earthworm species. The climatic impact 2003 by CRC Press LLC factor CO2 CH4 NOx of organic soil cultivation would be between and Mg CO2ha-1 yr-1. Maximum CO2 production is associated with arable farming and 90-cm deep water table level. The easily mineralizable N pool makes up to of total N in the 0-20 cm layer supplying 77 to 493 kg N ha-1 yr-1 as mineral N depending on moorsh stage. Optimum volumetric air content for N mineralization is 20-30 . There is 20 more N mineralized under arable farming compared with grassland. The NO3-N to NH4-N ratio increases with MFP thus enhancing N leaching and denitrification in anaerobic microsites. Addition of N-bearing fertilizers increases N pollution hazards. Organic soil quality as monitored by MFP attributes is best maintained under grassland farming with high groundwater level. I. INTRODUCTION Drainage must increase volumetric air content to at least 6-8 in the upper layer of organic soils used as grassland Okruszko 1993 . Air contents up to .
