Nutrient budgets for Waikato dairy and sheep/beef farms for 1997/98 and 2002/03
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Report: TR 2004/19
Author: Amanda Judge and Stewart Ledgard, Agresearch
Abstract
Nutrient losses from farmland are a contributor to excessive nutrient levels in ground and surface water. Better farm management can be used to reduce the amount of nutrients lost from the farm and into water bodies. A nutrient budget is one way of indicating amounts of nutrients that may be lost from the farm, and whether or not nutrients are accumulating in the soil. A series of nutrient budgets done over time can also indicate whether changing farm practises are having an impact on the amounts of nutrients lost to the environment.
Greenhouse gas emissions are also of interest to environmental issues and reflect aspects of the efficiency of productivity, and energy and nitrogen use on farms (Wheeler et al. 2003).
Nutrient Budgets for Waikato Dairy and Sheep/Beef Farms for 1997/98 and 2002/03
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Table of Contents
| Executive Summary | vii |
| 1 Introduction | 1 |
| 2 Objectives | 1 |
| 3 Methodology | 1 |
| 4 Description of OVERSEER® nutrient budget model | 1 |
| 4.1 Basis of the OVERSEER® nutrient budget model | 1 |
| 4.2 Input requirements for the model | 2 |
| 4.3 Input data sources | 3 |
| 4.4 Assumptions and deficiencies in the input data | 4 |
| 4.5 Greenhouse gases | 4 |
| 5 Results | 4 |
| 5.1 Farm input data | 5 |
| 5.1.1 MAF Monitor sheep and beef farms | 5 |
| 5.1.2 MAF Monitor dairy farms | 5 |
| 5.1.3 Dexcel ProfitWatch dairy farms | 5 |
| 5.2 OVERSEER N and P budget data | 13 |
| 5.2.1 MAF Monitor sheep and beef farms | 13 |
| 5.2.2 MAF Monitor dairy farms | 16 |
| 5.2.3 Dexcel ProfitWatch dairy farms | 16 |
| 5.3 OVERSEER summary data | 23 |
| 5.3.1 MAF Monitor sheep and beef farms | 23 |
| 5.3.2 MAF Monitor dairy farms | 23 |
| 5.3.3 Dexcel ProfitWatch dairy farms | 27 |
| 6 Discussion | 29 |
| 6.1 N leaching and N concentration in drainage | 29 |
| 6.2 P runoff and farm P status | 29 |
| 6.3 Greenhouse gas emissions | 31 |
| 6.4 Caution in data interpretation | 31 |
| References | 32 |