2 Summary of 1997/98 Project
2.1 METHODOLOGY
The methodology used for the 1997/98 project to test the irrigation Best management Guidelines was to:
- identify and select three trial farms;
- install flow and soil moisture measuring equipment;
- carry out design audits to ensure that the irrigation systems were capable of being operated at the required performance level;
- aided by the flow and soil moisture information, to have farmers use the Guidelines to manage their irrigation systems, and
- provide on-going liaison in use of the Guidelines.
The following farms were selected:
- Andrew Mulholland of Bankside, a dairy farmer using border strip
- Bruce Rolls, of Te Pirita, a dairy farmer using spray irrigation (centre-pivot);
- Jos Van De Klundert of Darfield, a cropping farmer using spray irrigation (rotating boom).
In the 1997/98 season, design audits of the three systems had been carried out, and flow measuring equipment installed on the two dairy farms. Data collection and analysis was carried out on the two farms for part of the season, and key indicators calculated for the two dairy farms.
2.2 DIFFICULTIES ENCOUNTERED
Delays in delivery of flow measurement and soil moisture measurement equipment resulted in a very late start to implementation of the programme in 1997/98. Although some useful results were obtained in the latter part of the season, the worksheets used for data recording and calculation of indicators were difficult to use. On top of that, the summer was exceptionally hot and dry. Further details are given below.
2.2.1 Measuring Flow and Depths Applied
During the 1997/98 season, finding suitable flow measuring equipment for installing on irrigation machines at acceptable cost was found to be very difficult. A prototype flow meter was developed in June 1998, and tested in July and August on a frost protection scheme. This flow meter was available for installation on the centre-pivot irrigator in October.
2.2.2 Providing Regular Soil Moisture Data to Farmers
In 1997/98, all soil moisture data recorded by the Aquaflex™ meters was downloaded and interpreted by Lincoln Environmental staff, and then faxed to the farmers with instructions for subsequent irrigation. Although the method proved to be extremely good for providing information for best irrigation practices, it did not allow farmers to take the measurements and interpret the data themselves. As one of the requirements of the project was that farmers should manage their irrigation systems themselves, an improvement to the system was required.
2.2.3 Unsuitable Worksheets
The worksheets provided with the Best Management Guidelines were found to be unsuitable. Although all three farmers in the study had computers, the worksheets were not easy to use and to interpret. They were heavily focussed on on-going calculation of indicators, and the amount of paper work involved was not acceptable to the farmers involved in the project. This needed to be made more user-friendly and useful in terms of helping farmers make good irrigation management decisions and providing the information needed to calculate indicators.
2.2.4 A Summer of Extremes
The 1997/98 summer was extremely hot and dry. Daytime temperatures and evapotranspiration figures were much higher than normal, and rainfall was much lower than normal.
Because of limited irrigation system capacities, the extremely hot and dry conditions resulted in very few irrigation management decisions being required in 1996/97. For most of the season, farmers were simply trying to ‘keep up’, and the main irrigation decision required was when to stop at the end of the season.
These conditions were unusual, and it was hoped that more ‘normal’ conditions would prevail in 1998/99.
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