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Nông nghiệp trong bối cảnh năm, khái niệm về các phức tạp xung quanh tính bền vững và khó của việc xem xét di chuyển từ lý thuyết định nghĩa hành động thực tiễn Cung cấp Hiện nay vấn đề quan trọng cho năm Các nhà nghiên cứu (Fresco và Krooneneberg năm 1992; Park và Seaton 1995, Moffatt và al, 1999) Khi Kiểm tra Tiêu chuẩn liên quan đến tính bền vững, có là xem xét hỗ trợ cho Cơ sở sinh thái của hệ thống sản xuất Điều đó tương tác với môi trường tự nhiên (Hạ, 1990). Điều này có liên quan với quan điểm. | 920103_CRC20_0904_CH16 1 13 01 11 16 AM Page 335 CHAPTER 16 Changing Soil Biological Health in Agroecosystems Julian Park CONTENTS Introduction.335 Agroecosystem Sustainability and Soil Health.336 Organic Carbon and Its Distribution in Soils.339 Organic Carbon as an Indicator of Biological Health in Agroecosystems.341 The Quality and Quantity of Crop Debris Returned to the Soil . . . 343 The Growth and Turnover of Plant Roots.343 Cultivation .344 Managing Soil Biological Health .345 Acknowledgments.347 References.347 INTRODUCTION In an agricultural context the complexity surrounding the concept of sustainability and the difficulty of moving from consideration of theoretical definitions to practical action currently provide an important issue for researchers Fresco and Krooneneberg 1992 Park and Seaton 1995 Moffatt et al. 1999 . When examining criteria associated with sustainability there is support for considering the ecological underpinning of production systems that interact with the natural environment Lowerance 1990 . This is associated with the view that it is desirable for ecosystems to be able to sustain function and thus maintain a given level of productivity into the future. 0-8493-0904-2 01 0.00 .50 2001 by CRC Press LLC 335 920103_CRC20_0904_CH16 1 13 01 11 16 AM Page 336 336 STRUCTURE AND FUNCTION IN AGROECOSYSTEMS DESIGN AND MANAGEMENT In most agroecosystems the degree of intervention is usually larger and more frequent than natural disturbance rates with the primary objective being to maintain productive output. Some degradation is both inevitable and acceptable in these systems with different soil types and climate zones being able to withstand varying levels of intervention Burke et al. 1995 . In ecosystems such intervention is related to resistance the ability of a community to avoid displacement in the face of disturbance and resilience the speed with which a community returns to its former state after it has been disturbed and displaced . This .