2 Introduction
2.1 BACKGROUND
This study forms part of a continuing sequence of projects to develop and test indicators of sustainable agriculture. As part of its goal of facilitating resource management and ensuring sustainable agricultural practices are developed and adopted, MAF policy has set as an operation research goal:
"to provide environmental indicators or reporting systems for monitoring soil quality, water quality, air quality, bio-diversity and energy use".
The benefits of farmers using the indicators and applying the principles of sustainable management are numerous. For farming enterprises to be viable in the long-term, farmers need to address a combination of financial, environmental and social goals. At a practical level, this requires that farmers make the most efficient use of inputs such as soil, fertiliser, agri-chemicals, water, energy, and labour. This will not only ensure the productive capacity of their own land and hence meet and sustain their financial and social goals but also prevent the degradation of the surrounding environment and help meet the social goals of the local community, region and nation.
The Ministry for the Environment is currently establishing a core set of indicators to be used at a national level to give an overview of the state of the environment and the effects of policies and legislation that have an environmental effect. While this national set of environmental indicators provides a guide for indicators at an enterprise level it is not specifically tailored to meet the requirements of an individual farm business. MAF Policy’s programme to develop and test indicators of sustainable agriculture is designed to address this requirement.
To date a number of projects have been undertaken within the MAF Policy operations research framework that deal with indicators of sustainable agriculture. In brief these are:
2.2 Soil Quality Indicators for Sustainable Agriculture
Undertaken by Lincoln Environmental and Lincoln University this project fitted with the MfE soil indicators programme but focused on indicators that could be used at a local level to improve soil quality by changing on-farm management practices.
Indicators of Sustainable Irrigated Agriculture
Undertaken by Lincoln Environmental, this project developed the set of indicators that are the subject of field testing described in this report.
Best Management Guidelines for Sustainable Irrigated Agriculture
Undertaken by Lincoln Environmental this project focused on selecting practical methods that farmers can use to take note of and control the effects of changing irrigation management practices. In particular the purpose of the Best Management Guidelines (BMGs) is to "help farmers obtain the benefits of well-designed and operated irrigation systems". Implementation of these BMGs on trial farms has occurred in parallel with the current report on field testing indicators of sustainable agriculture.
Total Energy Indicators of Agricultural Sustainability
Undertaken by Agriculture New Zealand Ltd this project focussed on developing and testing a set of indicators based on total energy inputs to farming systems.
Financial Indicators of Sustainability for Farming Business and Families
Undertaken by Massey University this project considers economic indicators of farming businesses and how they relate to environmental and social indicators of sustainability
In addition Agriculture New Zealand Ltd and Lincoln Environmental have carried out A Survey of Farmers’ Approaches to and Perceptions about Irrigation Management. This study was designed to collect base information on the extent of different irrigation management practices currently operated in New Zealand as part of the wider research on sustainable irrigated agriculture.
The current project, Field Testing Indicators of Sustainable Irrigated Agriculture, forms a logical next step in the sequence of projects focused on developing and implementing better irrigation design and management practices to ensure the sustainability of New Zealand’s irrigated farms and the best use of New Zealand’s water supply.
2.3 INDICATORS OF SUSTAINABLE IRRIGATION
In response to MAF Policy’s operational research objective on environmental indicators, Lincoln Environmental developed a set of indicators of sustainable irrigated agriculture in 1997. The principal objective of that project was to:
"Identify a series of indicators that farmers can use to measure the sustainability of irrigation as a farming activity."
The output of that project was a set of indicators which:
- reflected the sustainability issues that are important to farmers;
- related to irrigation;
- were (hopefully) measurable by farmers;
- were useful to regional and local councils; and
- were consistent with other New Zealand programmes that have developed indicators of sustainability.
The indicators recommended by that project are summarised in Table 2.1. The criteria by which these indicators were selected were that each indicator should be:
- influenced by irrigation system design and management;
- able to be controlled by farmers;
- readily measurable;
- comparable between farms;
- scientifically valid and repeatable;
- able to measure progress towards goals on a reasonable time scale; and
- could be aggregated for groups of farms.
After selection of an initial set of indicators a workshop of farmers, soil scientists, regional council representatives, and agricultural and irrigation consultants was organised to consider the appropriateness and practicality of the indicators. As a result of comments made at the workshop some changes were made and the final set of recommended indicators emerged.
Table 2.1 Recommended Indicators of Sustainable Irrigated Agriculture
Economic |
1. Annual net operating profit after tax ($) |
2. Quantity of crop or product produced per unit of water used for each crop (t/m3) |
3. Profit per unit of water used ($/m3) |
4. Quantity produced per hectare for each crop or product (t/ha) |
5. Quality of produce (% of each crop or product at each grading level) |
6. Annual energy used to operate irrigation systems (kWh) |
7. Energy used per volume of water pumped (kWh/m3) |
8. Labour units per irrigated area (hours/hectare) |
Environmental |
1. Resource consents obtained and complied with |
2. Indicators of soil health |
3. Daily volumes of water flowing onto farm for each crop (m3) |
4. Daily percentage of water flowing onto the farm that is stored in the root zone (derived from soil moisture measurements in and below the root zone) |
5. Daily visual assessment of the amount of ponding or surface water runoff |
6. Maximum water abstraction rate each season (m3/day) |
7. Lysimeter based measurement of nitrogen leaching below the root zone (effluent irrigation only) |
8. Agri-chemicals and fertiliser used per quantity of crop produced (kg/ha or l /ha) |
Social |
1. Record of any abatement notices |
2.4 PURPOSE OF PROJECT
The overall aim of this project has been to test the set of indicators of sustainable irrigated agriculture developed by Lincoln Environmental (Table 2.1). For each indicator, and the set as a whole, the key considerations were to:
- determine the ease of measurement and set protocols (if required);
- determine their usefulness and practicality;
- provide some interpretation of their meaning;
- explore farmers’ perceptions of the methodology;
- discuss possible alternatives; and
- provide an overall value for the set of indicators.
The overall outcome of the project was to be a tested set of practical indicators for sustainable irrigated agriculture that could be used by farmers to benchmark their performance with regard to the efficient and sustainable use of water in agriculture. This is in accord with MAF’s desired key result of ensuring that:
"practical indicators and standards of sustainable agriculture are developed and adopted."1
The project was also expected to yield some benchmark values for the indicators.
2.5 IRRIGATION FACTORS AFFECTING INDICATORS
- Type of irrigation system. This includes the broad categories of surface and spray irrigation as well as more definitive classifications such as wild-flooding, border strips, big guns, travelling irrigators, etc.
- Design of the system. This includes both the hydrological and hydraulic design of the system. The hydrological design is concerned with matching the amount of water applied to the temporal and spatial demand of the plants for water (evapotranspiration) and the water storage capacity of the soil (or other growing media). The hydraulic design is concerned with the correct selection of appropriate engineering devices for the supply (wells, pumps, dams), control (valves, gates), reticulation (pipes, canals) and final distribution (sprinklers, border strips etc) of the water to the root zone with due regard to both the costs (capital and running), topography and climate.
- Operational management of the system. This is concerned with the day-to-day decisions made by farmers about such matters as: when to start and stop irrigation, how much water to apply, and what to do when it rains and how to deal with restrictions on water availability.
- Maintenance of the system. Maintenance, or more correctly lack of maintenance, often leads to deteriorating system performance in terms of increased water usage and energy consumption, and lack of uniformity of application, through leaks, pump impeller wear, stuck valves, collapsed canals, broken sills, etc.
The suite of indicators listed above was selected to provide a broad range of values related to desirable outputs (production and economic performance), inputs (water, energy, labour, agri-chemicals and fertilisers), the natural resource base (water bodies and soil), possible environmental effects (water and air pollution), and social effects. Irrigation will affect these factors either directly or indirectly. Direct effects include factors such as water use, energy consumption and changes in production directly attributable to irrigation, while indirect effects include factors such as profitability, use of other agricultural inputs, and ground and surface water pollution.
Overall, the effects of irrigation result from the interaction of the irrigation system with the rest of agricultural production system. In analysing this relationship it is useful to consider four aspects of an irrigation system.
Ideally, an irrigation system would provide the precise amount of water required for optimum plant growth at the least possible cost. However, even in highly controlled situations such as greenhouses, compromises must be made to arrive at a practical solution. In practice, every irrigation system will be unique, reflecting differences in climate, soils, farm size, shape, subdivision, layout and topography, crops grown, agronomic techniques used, water source, availability of technology, and energy sources. The range of irrigation systems available reflects both the wide range of circumstance encountered and the long historical development of irrigated agriculture over the last few millennia. Thus, when comparing indicators of sustainable irrigated agriculture it is important to bear in mind the type of irrigation system being used, how both the hydrological and hydraulic design were developed around the unique set of pre-existing and agronomic features, and how these may constrain the way in which the system can be operated on a day-to-day basis.
It should also be born in mind that the overall performance or sustainability of irrigated agriculture, as measured by these indicators, may be only weakly affected by the design, operation and maintenance of the irrigation system itself. Management of other agronomic inputs potentially has a greater effect on yield and financial performance, and hence many of these indicators. Therefore, while this study is carried out in isolation, the results should be viewed within the wider context of agricultural sustainability indicators being developed by the other project mentioned in Section 2.1.
1 ‘Strategic directions to the year 2000’, MAF, Wellington.
Contact for Enquiries
MAF Information Services
Pastoral House
25 The Terrace
PO Box 2526
Wellington, NEW ZEALAND
Fax: +64 4 894 0721
Contact this person
