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The tea industry currently uses fertiliser recommendations developed over 25 years ago and these are being reviewed in this project. Over the last several years increased demand for Australian tea and increasing cost pressures have prompted growers to seek out better production techniques including fertiliser practices to increase yields and reduce their costs of production. The research findings are important because they will help growers to better understand the nutritional requirements of tea and improve their yields. This will reduce their costs of production and increase the economic viability of the tea industry.

Who is the report targeted at?
The research project was developed in conjunction with a group of Australian tea growers’ who harvest greater than 90% of Australia’s total production. They identified nutrition management as a high priority for the industry. The report and findings are targeted primarily at the Australian tea producers to help improve their production through better nutritional management of their crops. The report is also useful for tea researchers, extension officers and potential new and existing tea growers.

Background
The Australian Tea Industry has been able to compete with low cost overseas producers because of the use of mechanical harvesters, low costs of production and the high quality produced. To remain internationally competitive, producers must optimise their production systems including fertiliser practices. With the area of land planted to tea unlikely to increase greatly, growers are keen to increase their production by increasing their yields/ha to meet increasing demands. Besides climate (temperature and rainfall), the fertilizer inputs are the next most likely major factor determining yields of tea. While some work has been done on the fertiliser requirements for tea in North Queensland, this was done 25 years ago and little work has been done since. In North Queensland yields have varied from 1.5 t/ha to 4.7 t/ha and the highest yields have usually been associated with higher nutritional inputs, suggesting that nutritional research work could significantly improve production.

Aims/Objectives
The aims of the project were to monitor changes in leaf and soil nutrient status over three years in blocks of tea receiving different fertiliser inputs and to assess the effect of nutrient status and fertiliser inputs on crop productivity. The information from this work was used to develop a fertiliser program based on a nutrient budget and the yearly growth cycle.

Through this project, tea researchers, extension officers and growers have an increased knowledge of the nutritional requirements of tea.

This research will directly benefit the Australian Tea Growers. Their success will in turn benefit the rural communities in which they are located with employment opportunities and financial contributions.

Methods Used
Information on fertilising practices including rates, timing and frequency; leaf and soil nutrient levels and yields were collected from different paddocks over several years from three farms across the Australian production area. Climatic information (including rainfall, evaporation, temperature and humidity) was also collected. The relationships between fertilising practices, climatic data and yield were studied.

Results and Key Findings
The current nutritional status (leaf and soil) and fertiliser inputs of the tea growing in North Queensland has been documented. Results indicate that the climate (rainfall, temperature), pruning cycle and fertiliser inputs all interact to determine the yield of tea. The overall pattern of growth was generally influenced by the climate while the amount of growth and the length of the growing season were determined by the fertiliser inputs. Only in years where annual rainfall was less than 1500mm was yield reduced. The pruning cycle as expected reduced yields during that year and the recovery in yield was delayed by poor fertilising practices.

The fertiliser records, leaf and soil nutrient levels and yield data suggest that higher levels of a broader mix of nutrients and smaller more frequent applications than currently being used by the industry could improve the nutrient availability and yields. Smaller more frequent fertiliser applications are also likely to reduce losses and wastage of nutrients through leaching and runoff, reducing costs and reduce environmental impacts. A suggested fertiliser program has been developed, based on the results of the project, the literature, a nutrient budget and the growth cycle. It is recommended this be used as a guide within a grogram that includes soil and sap/leaf testing.

A fertiliser with a mix of nutrients in the following ratios - 10 N: 1 P: 4 K: 0.5 S: 0.5 Ca: 0.5 Mg plus small amounts of Zn, Cu, Fe and B is recommended.

Depending on the expected yield the following table gives the recommended fertiliser application rates for the major nutrients.

The poor soil availability of Zn and Cu suggest these nutrients should be added via foliar applications (1% Cu and Zn sulphate plus 1% Urea). Fe and B could be added to the soil in the overall fertiliser mix or individually using 10 kg/ha Solubor and 10 kg/ha Fe SO4.

Fertilisers should be applied in six even applications at 6-10 week intervals during the growing season and 10-16 week intervals during winter.

Implications for Relevant Stakeholders
Industry. With the information developed in this project, growers will have a greater understanding of the nutritional requirements of tea and are likely to modify their fertilising practices to incorporate some of the findings. This is expected to lead to an overall improvement in the yields of Australian tea plantations leading to industry expansion

Communities. Industry expansion in turn will help support rural communities in which tea is grown by providing financial input and employment opportunities.

 Policy Makers. Industry expansion will also contribute to the Australian economy with valuable export income and import substitution. Although this industry is small, it does contribute to the economic diversity of the horticulture industry and regional employment opportunities.

Recommendations
The recommendations from this research are targeted at the Australian Tea Growers` who can use the findings to help them improve their production.

Growers should trial the higher rates, broader mix of nutrients and smaller more frequent applications recommended in the fertiliser program developed in this project. The fertiliser program should ensure all nutrients are adequately supplied which will help to increase yields, reducing the costs of production and improve the economic viability of the industry.

Tea growers are encouraged to keep records of fertiliser inputs and yields and to conduct one leaf and soil sample each year so that the yield responses to fertiliser practices can be monitored and adjusted as necessary over time.

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