Improving water and fertiliser use efficiencySwan Coastal PlainBY VO THE TRUYEN
UNIFORMITY assessment on water distribution in a vegetables field in North Perth in 2019 by DPIRD.
The main vegetable production region in Western Australia is the South West, including the Swan Coastal Plain from Gingin (100km north of Perth) to Myalup (100km south of Perth). Within this area, about 67 per cent of the total value1 of the State’s vegetables are produced.
There are opportunities for vegetables growers to improve their profitability.
 3-years report on benchmarking of WA vegetables production business efficiency
THE pest monitoring will focus on establishment, thresholds, beneficial insect interactions and damage.
vegetablesWA project on improving water and fertiliser use efficiency
There is a great source of available knowledge that can be introduced to vegetable growers to induce practice changes in terms of improving water and fertiliser use efficiency.

This knowledge could enhance grower understanding of soil characteristics, the regional soil map, how water filters through the soil profile, nutritional demands of different crop types
and growth stages and irrigation techniques.

While high initial investment costs of irrigation systems hardware or technology may place barriers on adoption of irrigation innovations, the assessment of irrigation system efficiency carried out by DPIRD, in collaboration with vegetablesWA and a private consultant in 2019, showed all participating farm properties achieved acceptable to good levels of efficiency. It’s believed that the improvement of irrigation and fertiliser application practices and technology could bring 
significantly positive outcomes, including higher yield and elevated profitability, to growers.

In line with the enhanced focus on productivity improvement, environmental sustainability and business profitability, the central objective of the project is ‘more profitable and productive use of water and fertiliser’. The key indicator of success is a 10 per cent reduction in net fertiliser costs and a 10–25 per cent reduction in irrigation volumes for participating growers.
Benefits of bridging the practice gap
The three-year benchmarking report, produced by vegetablesWA in partnership with PlanFarm, shows average fertiliser, irrigation and power costs are $3,999, $218 and $1,530 respectively; with a large portion being used for irrigation pumping.

A 10 per cent reduction of fertiliser and irrigation costs would result in a benefit of $570/ha/crop. This is a significant improvement to grower profits, since the average profit before tax for the WA vegetables industry is $6,200/ha/year. 
Project strategy
The project is designed to help grower participants go through a 5-stage process that includes:

  1.  Knowledge (expose growers to water and fertiliser use efficiency concepts and assist them in understanding the benefits).
  2. Persuasion (the forming of a favourable attitude to it).
  3. Decision (commitment to its adoption).
  4. Implementation (putting it to use).
  5. Confirmation (reinforcement based on positive outcomes from it).
Enhancing grower decision making in relation to water and fertiliser application practices
Over a series of workshops the project will introduce growers to knowledge and information relative to soil types, water demand pattern of crops and soil water movement by using tools as local soil maps, soil dye test images, content of ‘free fertiliser’ in bore water analysis and crop nutrition demands etc. A core group of four to six growers will then be encouraged to try changes in water and fertiliser application using this recently introduced knowledge.

Improved irrigation scheduling and management
Trials will be conducted with a 10 per cent reduction in fertiliser and water applications, based on soil type, crop type and growth stage in anticipation of providing benefit cost analysis case studies for growers. Information sessions on the aspects of improving scheduling and management of irrigation, including the benefits from the trials, will be discussed with growers in regard to the
advantages and disadvantages, with the aim of gaining ‘lessons learned’ in support of wider adoption of on farm best practice.
Benchmarking the benefit of practice change
Grower participants will be assisted in fine tuning any changed practices to see the relative advantages (the degree to which it is perceived to be better than what it supersedes); compatibility (consistency with existing values, past experiences and needs) and; observability (the visibility of results) that have resulted.

Work that will support Growers in this stage will include:

  • Developing hand-out materials to visually illustrate the established knowledge, such as posters of root zones growing over time and the dynamics of water movement in soil over time in drip irrigation etc.
  • Continue assessing data on yield and/or return improvements and working with growers to highlight the ‘relative advantage’ by comparing old and new data.
  • Disseminating results from demonstrations and organising field days to encourage growers to learn from results of research.
  • Workshops to inform growers about the achievements.
Evaluation and success
This strategy is designed to capture the learnings and impacts of intensive practice-change in relation to new and improved irrigation/fertigation systems choices and improved scheduling of irrigation/fertigation management to optimise water and fertiliser use and general business profitability.
Evaluation and successFor more information or to offer your assistance with this project, please contact vegetablesWA Regional Development Officer, Vo The Truyen on 0457 457 559 or email