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You are here: Agriculture » About Agriculture » Publications and Resources » Horticulture » The Use of Soil and Petiole Testing in Wine Grape Viticulture

The Use of Soil and Petiole Testing in Wine Grape Viticulture

March 2008

ISBN 978-1-74199-976-1

Authors:

Megan Hill, Ben Rowbottom and Geoff Kaine
Department of Primary Industries
Ferguson Rd
Tatura, Victoria 3610

Nicole Dimos
Department of Primary Industries
P.O Box 905
Mildura, Victoria 3502

Acknowledgments:

Thanks to the many people we have interviewed for this project. Thanks to GWRDC for funding this project and to Roger Ashburner, Fiona Johnson and Marg Watters for their contributions.

Table of Contents

• Executive Summary
  • Results
  • Market segments
  • Opportunities for research, extension and future work
• Introduction
  • Related Research
    • Adoption of soil testing in vegetable production
    • Adoption of soil moisture monitoring
• Materials and Methods
• Results
  • Market Segments for Soil and Petiole Tests
  • Segment 1 - Pre-planting
  • Segment 2 - Understanding a new vineyard
  • Segment 3 - Evaluate management changes
  • Segment 4 - Problem diagnosis
  • Segment 5 - Problem monitoring
  • Segment 6 - Risk management
  • Segment 7- No tests
• Problems associated with soil tests
  • Analysis of the samples
  • What the test measures
  • Presentation and interpretation of the test results
  • Recommendations arising from test results
• Opportunities to improve soil tests
• Problems associated with petiole tests
• Opportunities to improve petiole tests
• Discussion
• References

Figures

• Figure 1: Market segments based on the benefits sought by growers by soil and/ or petiole testing.

Executive Summary

In this study we identified the benefits growers of wine grapes sought, and the problems they experienced with their use of soil and petiole testing. This knowledge was used to identify research and development opportunities. To collect this information we used methods proposed by Kaine (2004), and interviewed forty-five wine grape growers from nine Australian wine regions, on a range of nutrition-related topics including the use of soil and petiole testing. The results in regard to nutrition were described in Hill et al. (2007).

Result

The majority of wine grape growers interviewed had used, or were using either soil or petiole testing, or both, and regarded these tests as valuable tools to inform their management of soil and vine nutrition. The growers stated they used soil testing to see what nutrients were present in the soil, and petiole testing to see what nutrients the vines were actually taking up. The growers we interviewed were classified into market segments based on commonalities in their reasons for seeking the information obtained from the tests. The market segments were very similar for both soil and petiole tests. An individual grower could be in a number of market segments simultaneously, or could change market segments depending on the stage of their vineyard's development and circumstances in their vineyard.

Market segments

The growers interviewed were using soil tests to:

• Inform their pre-planting nutrition inputs (Segment 1)

Or they were using soil or petiole tests, or both, to:

• Understand a new vineyard (Segment 2)
• Evaluate changes in vineyard conditions or a new management practice (Segment 3)
• Diagnose a vine health problem (Segment 4)
• Monitor a problem in the vineyard (Segment 5)
• Monitoring for early detection of problems in the vineyard (Segment 6)

While most growers were satisfied that the tests provided the information they sought, a number of problems were raised with the testing which resulted in growers ceasing use of the tests and using other agronomic tests or changing service providers. The problems with soil testing related to varying methods of analysis being used, confusing presentation of test results, and inappropriate fertiliser recommendations being made based on the test results. Some growers stated that they had encountered similar problems when using petiole testing. Growers had additional problems with petiole testing, those being the short time frame in which petioles could be sampled (at vine flowering), the variability in test results, petiole test standards not being relevant to Australian conditions, and the length of time until the test results were received. These problems reduced the usefulness and accuracy of the petiole testing.

Opportunities for research, extension and future work

The problems growers had experienced with soil and petiole tests could provide opportunities for research and extension to improve the relevance and value to growers of soil and petiole tests in particular, and plant tissue tests generally. Specifically, there are opportunities for research and extension to improve:

• the relevance of petiole test standards to Australian conditions,
• the clarity and presentation of soil and petiole test results,
• the reliability of recommendations arising from soil and petiole tests,
• identify tissue tests that overcome the limited opportunities for conducting petiole tests

Further research could be conducted to estimate the size of the market segments we identified for soil and petiole tests and to determine why the use of tissue tests, such as sap tests and blade (leaf) analysis, is not more widespread.

Our findings also suggest that there may be common patterns in the reasons for using tools such as soil and petiole tests across horticultural industries. Therefore research and extension strategies used in relation to these tools in other industries may provide insights for the wine grape industry.

Introduction

Hill et al. (2007) found that soil and petiole tests were widely used by wine grape growers, and were considered to be valuable tools to assist in nutrition management. Yet some of these growers also stated that there were problems associated with the tests. In this study we investigated how and why these tests are used, and identified research and extension opportunities for improvement of the tests and their use. Other methods of agronomic testing,such as sap tests, were not within the scope of this study.

When conducting a soil test the grower or agronomist collects a number of soil samples at various depths and locations within the block, and sends them to a laboratory for analysis. The samples are analysed for micro-, macro-nutrients, pH, salt levels and possibly other characteristics, such as organic matter content, depending on the service provider and service purchased. The test results supplied to the grower contains information on these soil characteristics, and often information on the optimal ranges for these characteristics and recommendations on fertiliser applications,again depending on the service provided.

Petiole tests are conducted by collecting petioles (leaf stems) from the vines commonly at flowering. These petioles are then analysed to determine micro- and macro-nutrients levels present in the vine petioles. Again the results that are supplied to the grower usually include a range showing normal nutrient levels, and sometimes may include recommendations for fertiliser application.

Related Research

There have been a very few studies reporting on the adoption of soil testing in livestock and cropping industries¹ and none on the adoption of soil or petiole testing by viticulturists orhorticulturalists in particular. However, Kaine (2004) has been applied to understand the adoption of soil testing in vegetable production (Bewsell and Kaine, 2001), soil moisture monitoring and sustainable practices in viticulture(Kaine and Bewsell 2001a, 2001b, 2002, Bewsell and Kaine, 2003), and soil moisture monitoring in pome and stone fruit (Kaine et al.2005). We will discuss these studies briefly as they are all related to technologies that test soil properties, and they are illustrating the use of Kaine's concepts (Kaine, 2004)in a range of horticultural industries.

Adoption of soil testing in vegetable production

As part of a study on the adoption of soil monitoring and irrigation scheduling practices in the Victorian vegetable industry, Bewsell and Kaine (2001) found that most vegetable growers in the regions they studied regularly used soil testing to determine the nutrient status of their soil so they could tailor their crop's fertiliser program. Bewsell and Kaine (2001) also found that these growers used soil testing when they had experienced, or anticipated that they may encounter a nutrition problem in a block.  Bewsell and Kaine (2001) also found that the growers usually conducted soil tests when they were growing vegetables on a block new to them.

Adoption of soil moisture monitoring

Kaine and Bewsell (2001a,2001b, and 2002) investigated the adoption of irrigation and soil moisture monitoring technologies in six Australian grape-growing regions, and developed recommendations for extension programs, again using a similar methodology tot his study.

They found that soil moisture monitoring provided the most benefit to grape growers with pressurised systems who used it to tailor their irrigation inputs to meet their grape quality objectives.  In particular growers with systems that applied smaller volumes of water, such as micro-spray and drip systems, had a greater need to monitor soil moisture than other grape growers. Growers also needed access to water on demand to be able to use soil moisture monitoring to meet grape quality objectives.  The main benefits soil moisture monitoring provided to growers were in irrigation scheduling and controlling quality or vine vigour.  Interestingly Kaine and Bewsell (2001a, 2001b, and 2002) did not identify water saving as a major factor motivating the adoption of soil moisture monitoring at that time.

Kaine and Bewsell (2001a, 2001b, and 2002) found some growers had adopted soil moisture monitoring but then ceased using the technology and concluded that these growers had used soil moisture monitoring to provide them with information while they were becoming familiar and confident with their new irrigation system. Once this was achieved growers no longer perceived that they needed to test soil moisture.

Bewsell and Kaine (2003) studied the adoption of sustainable pest and irrigation management practices, and the adoption of soil moisture monitoring in viticulture in New Zealand.  Their findings regarding soil moisture monitoring adoption in New Zealand were similar to the findings for Australia. Soil type and the ability to control vinifera and grape quality using irrigation were the main factors influencing adoption of water monitoring technology in New Zealand.

A study of the adoption of soil moisture monitoring techniques in the GoulburnValley stone and pome fruit industry, found similar reasons for adoption to those found in New Zealand and other Australian industries(Kaine et al. 2005).  Growers with pressurised irrigation systems and water on demand were found to be the highest adopters of soil moisture monitoring. The main benefits gained by growers of using soils moisture monitoring were controlling tree vigour, high water tables, salinity, or managing dwarf rootstocks (Kaine et al. 2005).

In short, these studies indicate that growers adopt techniques for testing soil characteristics when these created benefits by assisting:

• to solve problems in production (salinity, tree or vine vigour),
• in the management of constraints on production(limited water),
• in improving product quality (grape quality),
• in implementing new technologies or practices(changing irrigation systems).

Materials and Methods

This study consisted of four parts. These were:

1. Data collection to identify the factors that influenced the adoption of soil and petiole testing;
2. Data collection to identify problems associated with soil and petiole testing;
3. Analysis and interpretation of data to enable market segments to be identified based on the benefits growers were seeking from the tests; and
4. Identification of opportunities for research and extension in regard to soil and petiole testing

The theory and methods used in this study are reported in detail in Hill et al. (2007).

Results

Most of the growers interviewed had used soil and petiole testing at least once, and stated that they had found them a valuable tool when making decisions about vine nutrition. Growers offered a range of reasons for using the tests. The frequency of testing varied depending on the reason for testing. The growers we interviewed were classified into seven segments based on their reasons for using soil and petiole testing (see Figure 1).  

Growers were initially partitioned into those that used testing and those that had not (segment 7). Growers that had used testing were first partitioned depending on whether they used soil tests to guide soil preparation prior to planting vines (segment 1). Those that were not using tests for pre-planting were then partitioned depending on whether they used testing to identify conditions in a new vineyard (segment 2). Growers were then sub-divided depending on whether they had changed management practices (segment3), or had experienced a problem with vine health. The latter were partitioned into two segments depending on whether testing had been successfully used to diagnose and resolve the problem (segment 4) or testing was used to regularly monitor conditions in the vineyard to assist in the management of the problem (segment 5). The last segment consisted of growers that employed testing as a strategy to ensure early detection and correction of nutrition-related problems with vines (segment 6).

Individual growers may be members of two or more segments at the same time depending on their circumstances. For example, a grower could be a member of segment 1 (soil test pre-planting) while establishing a new block in their vineyard, and in segment 6 (petiole test annually to monitor nutrition) for established blocks in their vineyard.

Figure 1: Market segments based on the benefits sought by growers by soil and/ or petiole testing.

Market Segments for Soil and Petiole Tests

Segment 1 – Pre-planting

Growers in this segment tested soil to determine the type and amount of inputs such as fertiliser, gypsum and lime they should incorporate, often by deep ripping, into the soil before planting new vines.  The benefits growers in this segment sought from soil testing were to obtain information to plan their pre-planting nutrition program so as to maximise vine establishment and minimise nutrition problems in the future. Almost all of the growers we interviewed conducted soil tests at this stage, even if some of them conducted no further soil or petiole testing.

Laura, a grower from the Strathbogie Ranges said

"I had the whole vineyard site soil tested before I planted. I wanted to make sure that I got the right amounts of lime, gypsum and super phosphate down the rip lines to give the vines a strong start. If you miss that chance you will run into problems later, and are always trying to fix something up that you should have taken care of before."

Similarly, a grower of super premium Merlot, Shiraz and Sauvignon Blanc in the Yarra Valley said

"I had a soil test done before planting the vines. I wanted to know if I had to add anything to the soil, or if I was going to run into problems. This land was under orchard before I planted vines. The test showed that there were no pH problems or nutrient deficiencies. I have dug an occasional hole to look at worm activity since, but I haven't done any more testing. If I saw a problem, I would do both soil and petiole tests"

Most of the growers interviewed said that they were satisfied that the soil tests provided them with the information they needed in this regard. A few growers reported that they had problems with preplanting though they indicated these were because of the misinterpretation of test results or incorrect recommendations they received based on the test results, rather than because of problems with the test itself.

The members of this segment correspond with the members of first segment in Hill et al. (2007).

Segment 2 - Understanding a new vineyard

Some of the growers we interviewed used soil and petiole testing for a few years "to get a handle on things", that is, to obtain information about the conditions in a vineyard that was new or unfamiliar to them.

The growers in this segment tended to use soil and petiole tests for three to five years, after which they said they understood the nutritional requirements of the vineyard and how the soil and vines responded to the fertilisers and products they were using. Testing over this period gave the growers the confidence that their nutrition program was working and they were not going to run into serious nutrition problems in the future.

Michael, a Bendigo grower managed a vineyard with Shiraz, Cabernet Sauvignon, Semillon and Riesling varieties. Michael used petiole testing while he was new to the vineyard:

"I've done petiole analysis in the past. It definitely helped us set our fertiliser program. We have got a handle on it now though, we were getting the same results all the time and the site has fairly well balanced vines, so it's not worth testing anymore".

Tony is a Sunraysia grower, with vineyards on three different properties. Tony said

"I used to monitor the water and do soil and petiole testing. It gives you the information to make sound, informed decisions. But with falling grape prices and rising costs I don't do it anymore. The soil tests always came up good, and never identified any problems. I kept doing petiole tests until I saw the trends, until I got a good handle on it. You need to combine science with experience to be successful".

The growers in this segment said that testing provided them with the information they needed.

Segment 3 - Evaluate management changes

Growers in this segment used soil and petiole testing for a limited period to evaluate and understand the impact of management changes they had made in their vineyard, either on the soil characteristics (soil test), the vines nutrition status (petiole testing), or both (soil and petiole test). Examples of the management changes that were evaluated were; using a new nutrition product, changing the fertiliser rate, mulching the vineyard or installing drip irrigation. These growers used the tests for a few years until they felt that they "had a handle on things" and understood the implications of the changes they had made, then they ceased testing.

For example Bill, a grower in Sunraysia with wine grapes, told us

"When I installed drippers I had soil pits dug and the soil tested. I wanted to know if the new irrigation system would affect the nutrient availability of my soil. It turned out I've got uniform soils and the change to drippers didn't have enough effect (on nutrient availability) for me to need to change my fertiliser program".

Hayden manages vineyards in the Coonawarra region for a medium sized wine producer. In recent years organic sprays, mulches and manures have been included in his nutrition program and he was interested to know if these changes had improved soil health and nutrient status. Hayden said

"We are trying to go for softer options now, conventional (fertilisers) are not as good for soil, they kill off the bacteria and fungi in soil, which damages the soil structure and reduces nutrient uptake. I will do a soil test this year which will include a biological test because I haven't done one for a while and I want to know if these (organic) products are helping".

The growers in this segment said that they had not experienced any problems with soil and petiole testing.

Segment 4 – Problem diagnosis

Growers in this segment used the tests to try to determine why vines were looking unhealthy or weak, for example if vine growth was sparse or the leaves were discoloured. The growers said that when they found unhealthy vines, they first checked the vines roots for damage and then conducted soil and petiole tests to determine if the cause was nutrient or soil related. The growers conducted soil tests if they believed the cause was most likely soil related and petiole tests if they believed the cause was most likely related to the vines current nutritional status.

For instance Chas, who grows vines in the Goulburn  Valley, said

"I had a soil test done because I had a problem in the vineyard and was trying to rule out a number of possibilities. I'd looked at the roots, water, soil and weeds, but there was no problem with these so I thought I'd better look at nutrition. I tested an area of healthy and an area of sick vines and the tests results all looked the same. This made me realise it may be a pest issue. It turned out that the sick vines were infested with phylloxera".

Dave grows red wine varieties in the Barossa Valley, Dave said

"If I see an issue with my vines I get a petiole test done. I tested some Shiraz five years ago, the test showed the vines had a boron deficiency. I had a feeling that was the problem because the vines looked so ordinary. The test confirmed that that was the problem".

The benefit growers in this segment sought from soil and petiole testing was identification of the cause of their vine health problem. If the problem was related to nutrition they wanted to know which nutrients would best solve the problem, in regard to the best fertiliser or soil treatment to apply.

The benefits this segment sought from soil or petiole testing were not realised if:

• There was more than one factor causing the problem with vines
• The cause was related to nutrition but the vines were not flowering, so petiole testing could not be conducted
• The test recommendations were inaccurate, incorrect or not suited to the site

Segment 5- Problem monitoring

Growers in this segment regularly used soil and petiole tests to monitor a problem they were experiencing such as soil salinity or nutrient deficiencies, or a situation they believed could develop into a problem such as acidity levels.  The growers in this segment indicated that they had identified the source of the nutrient imbalance, hence they were not members of Segment 4, and while they may be adjusting their fertiliser program to address the nutrient imbalance they were not planning major management changes (Segment 3).

An example of a grower in this segment was Sarah who manages vines for a corporate Coonawarra vineyard. Sarah said

"We are worried about our soil salinity levels, so we soil test regularly. We also use soil tests in problem areas to confirm petiole test results, which we conduct every year. We use petiole tests mostly because they have standards and they give us a better indication of what the plant has taken up, rather than what is there (in soil) but not available. We just want to make sure things are not getting out of hand".

Ken manages a large vineyard in the Strathbogie region. Ken said

"I have variable soils, with some of the patches of sandy loam being a bit acidic. I have had the soil tested in the past and am due to do it again this year. I also petiole test different blocks each year, especially targeting the problem areas. One of the reasons I got soil tests done was because I just wasn't getting enough yield and vigour in the vineyard. Some of this is probably due to the dry years, but not all of it. The soil tests showed increased acid levels, which decreases the nutrient availability. So I have stopped using urea and super phosphate, and have used chook manure, lime, rock phosphate and mulch for the last two years to improve soil health".

Segment 6 – Risk management

Growers in this segment have tests done regularly to monitor conditions in their vineyard, even though they do not have any significant soil or nutrition-related problems. These growers indicated that they like to have tests conducted regularly as this gives them peace of mind that their vines nutrition needs are being met, desired production goals (yield and quality) will be achieved, and that problems will not emerge that will catch them unprepared. Other growers in this segment used soil and petiole test results when liaising with vineyard owners, chief viticulturists, finance managers or wineries about grape quality, vineyard planning or management or budgets. Essentially an unexpected nutrition problem poses a major risk for these growers and this risk can be easily and inexpensively managed by soil or petiole testing.

Kingsley runs a Managed Investment Scheme vineyard in Heathcote. Kingsley told us

"We base our rate of fertiliser application on soil and petiole tests, testing nine out of seventeen blocks each year. In April we soil test and put out any necessary ameliorations we need to meet our production targets. The tests help me to convince the finance people we're doing the right thing, and we need the test results to get the fertiliser allowance we need".

Francis manages a vineyard in the Yarra Valley that sells most of its fruit to local wineries to make ultra-premium wines. Francis said

"Since the initial work (pre-planting lime and gypsum) I haven't done anything in regard to nutrition. This block was under pasture for beef cattle before it was developed as a vineyard, so it had been top dressed annually and has plenty of residual fertiliser. I soil and petiole test alternative blocks yearly. I'm building up a reference data bank because I want to make sound decisions about fertiliser applications based on information. Everything seems to be in the ideal ranges, and the pre-planting inputs are still holding up. It's important that the vines have enough nutrients, but not too much. The best way to get premium fruit is to monitor your vine nutrition and keep it spot on". 

Segment 7- No tests

The few growers we interviewed that had not used soil or petiole testing had either inherited established vineyards or had extensive experience in growing vines in their vineyard.  These growers said that they use the same nutrition program each year, and, if any problems had occurred, they had been able to identify the cause of the problem and solve it. The growers in this segment were satisfied with the performance of their vineyards and said they did not require the information soil and petiole testing would provide.

Angello is a Sunraysia grower of both wine and dried fruit grapes. Angello said

"I don't soil or petiole test, I just look at the vines. If the vines start to look poor I fertilise with nitrogen. I don't seem to have any soil or nutrition problems, the vines usually look fine".

Another example of a grower in this segment was Bill who has been growing wine grapes in the Barossa valley for 25 years. Bill said

"My grandfather started this vineyard in the 1920s, then my father ran it and I've run it for the last 25 years, I grew up working it so I've got a lot of experience and know this vineyard. We put in a cover crop and the rest takes care of itself, if the cover crop looks healthy then I assume the nutrients are all right. I don't see any nutrient deficiencies, so I don't do any tests. Our Shiraz is close to top of the range so there is no reason to mess with that".

Problems associated with soil tests

A number of the growers we interviewed stated that they were not entirely satisfied with some aspect of their soil or petiole tests. In a few cases these concerns resulted in the growers either changing the type of test they used, changing their service provider, or ceasing use of the tests. The problems growers described with soil tests were as follows.

Analysis of the samples

A few growers said that they were confused by the results of their soil tests because different service providers use different methods of analysis. Different methods produce different results which can be confusing or even misleading. These growers sought to manage this problem by using the same service provider each year where possible.

What the test measures

A small number of growers were concerned that the standard soil tests did not reveal anything about important aspects of soil health, such as organic matter, microbial activity, acidity, salinity and soil structure.

Presentation and interpretation of the test results

Some of the growers interviewed said that they found the presentation of test results extremely difficult to understand or confusing. They stated that the results were often only presented as numbers without supporting information to enable the grower to determine the implications of these numbers. These growers then had to have the test results interpreted by another service provider such as an agronomist or fertiliser reseller. This added further expense to the testing procedure, and the grower had to trust that the service provider was correct in their interpretation.

Recommendations arising from test results

Growers indicated that they had experienced problems in regard to the recommendations arising from test results. Some of the growers interviewed said that the fertiliser recommendations written by some of the service providers, especially those linked with fertiliser companies, suggested applications of fertiliser were required that they, the grower, believed were excessive, were not appropriate to their vineyard, or did not include the product or brand best suited for their vineyard or their preferred methods of application. Rather the growers suggested that the recommendations favoured the resellers own products and brands. A small proportion of the growers we interviewed found that the nutrition needs of their vines had not been met by following the fertiliser recommendations.

Some growers dealt with these problems through gaining experience with fertiliser products on their vineyard and talking to other growers or experts who understood the specific characteristics of their location. Some growers used a consultant to design their nutrition program, while others used independent soil test service providers. Growers also spent time learning about tests results, vine nutrition and fertilisers.

Opportunities to improve soil tests

On the basis of the interviews with growers we concluded that soil tests would be more useful to grape growers if:

• common methods and units of analysis were used to test soils,
• tests and services were offered to evaluate aspects of soil health,
• guidelines were developed on interpreting soil tests results and the implications of these results in regard to product choices and product application rates.

Problems associated with petiole tests

Petioles are sampled for tests when the vines are flowering. Growers stated that this provided them with a narrow window of opportunity to conduct petiole tests and, if they missed this opportunity, they must wait a year before flowering occurs in the following season and there is another opportunity to petiole test.

Many growers said they felt the standards used to define deficient, optimum and toxic nutrient ranges in petiole tests were not always consistent, nor relevant to the grape varieties, and growing conditions found in Australia. Many of the growers believed that the current standards could only be used as a rough guide and therefore did not have complete confidence in the interpretation of petiole test results. Hence, recommendations based on the tests should be treated with caution.

Some growers dealt with this problem by collecting data from the tests over a number of years to identify trends in nutrient levels, rather than relying on the results of a single test. Growers also said that when they use petiole testing the results and recommendations were not always returned to them in time for any nutrition management to be implemented that same season.

Other growers suggested that petiole tests only provide a snapshot of what is in the vine at that specific time, and that they had found that the results varied season to season, without any obvious explanation.

Growers said that these constraints limited the usefulness of petiole tests as a management tool, making it necessary to collect the petiole results over a number of years to build up sufficient data to identify trends in nutrition levels. Some growers had begun using sap or leaf blade tests to gather information on plant tissue nutrition levels at different times of the year. However industry standards have not yet been developed for these tests (Dimos pers.comm).

Opportunities to improve petiole tests

On the basis of the interviews with growers we concluded that there is a need for a plant tissue test that could be conducted any time during the growing season and that uses standards developed for Australian conditions. The usefulness of petiole tests could be improved if test results could be returned more promptly to growers and if the results were presented in a format that is easier to interpret.

Discussion

The findings of this study were that most of the growers we interviewed considered soil and petiole tests to be valuable management tools that assisted them to reach decisions in relation to determining nutrition requirements prior to planting vines, identifying the reasons for unhealthy vines, understanding conditions in vineyards, evaluating changes in management practices, and monitoring soil problems or monitoring for early detection of problems relating to soil and vine nutrition.

However, some of these growers also reported there were some major weaknesses associated with these tests. This suggests that, while growers do obtain useful information from soil and petiole testing, they would find tests that overcame these weaknesses attractive. In this regard it would be interesting to investigate the use of the other agronomic tests available, such as sap testing or leaf blade analysis, to determine why these tests are not as widely used as soil and petiole tests.

Our findings also suggest that there may be common patterns in the reasons for using tools such as soil and petiole tests across horticultural industries. Studies have shown that wine grape, fruit and vegetable growers all used soil moisture monitoring technology to identify problems, to detect the emergence of problems, to monitor problems, and to manage product quality (Kaine and Bewsell 2001a, 2001b, 2002, Bewsell and Kaine 2003, Kaine et al. 2005). These findings correspond closely to our findings in regard to the market segments for soil and petiole testing.

Interestingly, Bewsell and Kaine (2001) found that, similar to the wine grape growers in segment 1 in this study, vegetable growers usually conducted soil tests when they moved to a new lease. Bewsell and Kaine (2003) found that some grape growers in New Zealand reported they no longer used soil moisture monitoring after a few years as they had become familiar enough with conditions in their vineyards to confidently anticipate the results of monitoring. This is similar to the wine grape growers in segments 2 and 3 in the present study, which stopped using soil and petiole testing once they were sufficiently familiar with conditions in their vineyards.

Further, Kremer et al. (2003) found similar themes regarding the low adoption of the N-track self-administer soil nitrogen test amongst Iowa, farmers. Kremer et al. (2003) found that farmers who rejected, or initially adopted then discontinued use of the N-track test found it incompatible with their needs. Some of these farmers behaved very similar to segments 2 and 3, in that they stopped testing after a few years because they had developed a good understanding of their crop nitrogen requirements.

This suggests that experience in developing and promoting diagnostic and monitoring tests in one horticultural industry could be useful when planning research and extension programs for similar types of tests in other industries.

Conclusion and Future Work

Soil and petiole tests were widely used by wine grape growers to assist them in vine nutrition and soil management. However we found growers had experienced some problems with these tests. These could provide opportunities for research and extension to improve the relevance and value to growers of soil and petiole tests in particular, and plant tissue tests generally. Specifically, there are opportunities for research and extension to improve:

• the relevance of petiole test standards to Australian conditions
• the presentation and interpretation of the results of soil and petiole tests,
• the reliability of recommendations arising from soil and petiole tests,
• identify tissue tests that overcome the limited opportunities for conducting petiole tests

Further research should be conducted to estimate the size of the market segments we identified for soil and petiole tests and to determine why the use of tissue tests, such as sap tests and leaf analysis, is not more widespread.

References

Bewsell, D. and Kaine, G. (2001). Soil Monitoring, Irrigation Scheduling and Vegetable Production. Client Report, Prepared for New Zealand Winegrowers. AgResearch Ltd, NZ.

Bewsell, D. and Kaine, G. (2003). Adoption of Sustainable Practices in the Wine Grape Industry. Client Report, Prepared for New Zealand Winegrowers. AgResearch Ltd, NZ.

Dimos, Nicole Soil Scientist, Department of Primary Industries, Irymple.

Hill, M., Rowbottom, B., Kaine, G., and Dimos, N. (2007) The Management of Nutrition in Wine Grapes. Milestone Report, Prepared for Grape and Wine Research Corporation. Department of Primary Industries, Victoria.

Kaine, G. (2004). Consumer Behaviour as a Theory of Innovation Adoption in Agriculture. Social Research Working Paper, 01/04. AgResearch, NZ.

Kaine, G. and Bewsell, D. (2001a). Managing Irrigation for Grape Production, Interim Report to the Victorian Department of Natural Resources and Environment, School of Marketing and Management, University  of New England, Armidale.

Kaine, G. and Bewsell, D. (2001b). Managing Irrigation for Grape Production, Second Report to the Victorian Department of Natural Resources and Environment, School of Marketing and Management, University  of New England, Armidale.

Kaine, G. and Bewsell, D. (2002). Managing Irrigation for Grape Production, Third Report to the Victorian Department of Natural Resources and Environment, School of Marketing and Management, University of New England, Armidale.

Kaine, G., Bewsell, D., Boland, A. and Linehan, C. (2005). Using Market Research to Understand the Adoption of Irrigation Management Strategies in the Stone and Pome Fruit Industry. Australian Journal of Experimental Agriculture. 45 (9):1181-1187.

Kremer, K.S., Carolan, M., Gasteyer, S., Tirmizi S.N., Korsching, P.F., Peter, G. and Tong, P. (2001) Evolution of an agricultural innovation: the N-Trak soil nitrogen test – adopt and discontinue, or reject? Technology in Society. 23 (1):98-108.

Footnote

¹ The study by Kremer et al. (2001) into the adoption of the N-track self-administered soil nitrogen testing by farmers in Iowa is one of these.