tailieunhanh - AGRICULTURAL NONPOINT SOURCE POLLUTION: Watershed Management and Hydrology - Chapter 4

Phốt pho (P) là một chất dinh dưỡng chính mà có nhiều vai trò quan trọng và ảnh hưởng sản xuất nông nghiệp và các hệ sinh thái tự nhiên. Đó là điều cần thiết cho tất cả các hình thức của sự sống và không có tác dụng độc hại. Phốt pho là một yếu tố cần thiết cho sự phát triển của thực vật, và đầu vào của nó đã được công nhận là cần thiết để duy trì sản xuất cây trồng có lợi nhuận. Là một trong các chất dinh dưỡng cây trồng chính, theo yêu cầu của tất cả. | 4 Phosphorus and Water Quality Impacts Kenneth L. Campbell and Dwayne R. Edwards TABLE OF CONTENTS Introduction Phosphorus Sources Sinks and Characterization Introduction of Phosphorus into the Environment Phosphorus Dynamics in Crop Soil Water Systems Factors Influencing P Transformations and Processes Adsorption Desorption Precipitation Dissolution Mineralization Immobilization Plant Uptake Phosphorus Loadings to Aquatic Systems Factors Influencing P Transport Processes Surface Transport Subsurface Transport Impacts of P Loadings to Aquatic Systems Managing Phosphorus for Water Quality Availability-Based Approaches Transport-Based Approaches References INTRODUCTION Phosphorus P is a major nutrient that has many important roles and influences in production agriculture and natural ecosystems. It is essential to all forms of life and does not have toxic effects. Phosphorus is an essential element for plant growth and its input has long been recognized as necessary to maintain profitable crop production. As one of the major plant nutrients it is required by all plants in varying amounts for optimum growth and production. Phosphorus also is an important nutrient in the diet of animals and contributes to animal growth maintenance and production. For these reasons it is often necessary to supplement the native P in the soil and in animals diets with additional P Even under good management practices this 2001 by CRC Press LLC can result in excess P available to move from agricultural production areas especially in areas where animal wastes are being used as In addition to these important roles in production agriculture P has an important influence on the growth and makeup of both upland and wetland natural ecosystems. Different plants need P in different amounts so the P concentration in an ecosystem affects the makeup of the ecosystem in both uplands and