Increasing Productivity and Water Use Efficiency in Australia's Rice Industry through Nitrogen Management

Increasing Productivity and Water Use Efficiency in Australia’s Rice Industry through Nitrogen Management RIRDC Publication No. 09/173

RIRDC

Innovation for rural Australia

Increasing Productivity and Water Use Efficiency in Australia's Rice Industry through Nitrogen Management

by Ranjith Subasinghe and John Angus

November 2009 RIRDC Publication No 09/173 RIRDC Project N. DAN 207A

© 2009 Rural Industries Research and Development Corporation. All rights reserved. ISBN 1 74151 970 5 ISSN 1440-6845 Increasing Productivity and Water Use Efficiency in Australia's Rice Industry through Nitrogen Management Publication No. 09/173 Project No. DAN 207A The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable regions. You must not rely on any information contained in this publication without taking specialist advice relevant to your particular circumstances. While reasonable care has been taken in preparing this publication to ensure that information is true and correct, the Commonwealth of Australia gives no assurance as to the accuracy of any information in this publication. The Commonwealth of Australia, the Rural Industries Research and Development Corporation (RIRDC), the authors or contributors expressly disclaim, to the maximum extent permitted by law, all responsibility and liability to any person, arising directly or indirectly from any act or omission, or for any consequences of any such act or omission, made in reliance on the contents of this publication, whether or not caused by any negligence on the part of the Commonwealth of Australia, RIRDC, the authors or contributors. The Commonwealth of Australia does not necessarily endorse the views in this publication. This publication is copyright. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. However, wide dissemination is encouraged. Requests and inquiries concerning reproduction and rights should be addressed to the RIRDC Publications Manager on phone 02 6271 4165. Researchers Contact Details Ranjith Subasinghe Yanco Agricultural Institute, Department of Primary Industries, Yanco, NSW 2703 Phone: 02 69512679 Fax: 02 69557580 Email: [email protected] In submitting this report, the researchers have agreed to RIRDC publishing this material in its edited form. RIRDC Contact Details Rural Industries Research and Development Corporation Level 2, 15 National Circuit BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: Fax: Email: Web:

02 6271 4100 02 6271 4199 [email protected]. http://www.rirdc.gov.au

Electronically published by RIRDC in November 2009 Print-on-demand by Union Offset Printing, Canberra at www.rirdc.gov.au or phone 1300 634 313

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Foreword Nitrogen management is one of the critical issues for sustainable and profitable rice production in NSW. This is not just because nitrogen status of the crop is a key determinant of yield potential, but also because high nitrogen status is associated with extreme cold sensitivity. Rice farmers pay a large yield and profit penalty for under fertilising their crops, but also can increase their risk of cold damage by over fertilising. As new varieties are developed and released, the nitrogen and low temperature response of these varieties need to be understood and described. Furthermore, nitrogen requirement of a crop is site specific and time dependent. Constant upgrading of fertiliser recommendations is therefore necessary, especially for a crop like rice because the properties of rice growing soils change enormously with time due to the intensity of cultivation. To enable rice growers to manage the nitrogen fertiliser application and risk involved in it, a range of technologies are available. These include the nitrogen tissue test at panicle initiation (PI), soil testing and the computer based decision support system “maNage rice”. maNage rice, a user friendly computer based decision support system allows growers to experiment with a range of options for their crop and determine the best management regime for their particular crop. The primary aim of this project was to provide information to the NSW rice industry on how to manage nitrogen fertilisation based on field and glasshouse experiment results, so that the maximum benefit of new varieties can be quickly obtained on farm. This project has successfully improved the maNage rice and released several enhanced versions to rice growers. Findings of this project are the key to make new recommendations for nitrogen management under different water management systems. The recommended nitrogen management options published in the NSW DPI Ricecheck was considerably altered in the light of findings of this project. Many rice growers successfully adopted these recommendations during 2005-06 and 2006-07 rice seasons. This report provides the detail information of the findings of the project and will benefit the rice industry to further improve the productivity and water use efficiency through proper nitrogen management. This report was funded from RIRDC Core Funds provided by the Australian Government. This report, an addition to RIRDC’s diverse range of over 1900 research publications, forms part of our Rice Research and Development Program, which aims to improve the profitability and sustainability of the Australian rice industry through the organisation, funding and management of a research, development and extension program that is both market and stakeholder driven.

Most of RIRDC’s publications are available for viewing, downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313.

Peter O’Brien Managing Director Rural Industries Research and Development Corporation iii

Acknowledgments Authors thank the Rural Industries Research and Development Corporation, NSW Department of Primary Industries and CSIRO, Australia for financial and in-kind support. Authors also wish to express gratitude to Messrs Alexander Suladze, Dionne Wornes, Tina Dunn, Kathryn Bechaz and John Smith for their valuable contributions and support. Authors are grateful to rice growers and Rice Research Australia who provided their valuable resources to conduct the trials in their farms. Authors also wish to extend their gratitude to Dr. Laurie Lewin for his invaluable suggestions throughout this study.

Abbreviations N:

nitrogen

PI:

panicle initiation

Pre-flood:

before permanent water and sowing

PFN:

pre-flood nitrogen application

PIN:

nitrogen application at panicle initiation

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Contents Foreword ............................................................................................................................................... iii Acknowledgments................................................................................................................................. iv Abbreviations........................................................................................................................................ iv Executive Summary ............................................................................................................................ vii Introduction ........................................................................................................................................... 1 Objectives ............................................................................................................................................... 3 Methodology .......................................................................................................................................... 4 Environmental conditions at experimental locations .........................................................................4 Common cultural practices adopted...................................................................................................4 Trials 2002-03....................................................................................................................................4 Trials 2003-04....................................................................................................................................5 Trials 2004-05....................................................................................................................................5 Trials 2005-06....................................................................................................................................6 Trials 2006-07....................................................................................................................................7 Sample collection and analysis ..........................................................................................................7 Statistical analysis..............................................................................................................................8 Results and Discussions......................................................................................................................... 9 Continued development of maNage rice............................................................................................9 Trials 2002-03..................................................................................................................................11 Trials 2003-04..................................................................................................................................17 Trials 2004-05..................................................................................................................................25 Trials 2005-06..................................................................................................................................29 Trials 2006-07..................................................................................................................................34 Discussions ........................................................................................................................................... 36 Implications.......................................................................................................................................... 38 Recommendations ............................................................................................................................... 39 References ............................................................................................................................................ 40

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Tables Table 1. Treatment structure of the field experiment at Wakool in 2004-05. ...................................................... 6 Table 2. Version of maNage rice, number of copies distributed and new features of each version .................. 10 Table 3. Average N uptake at PI (kg ha-1) of four varieties at different nitrogen treatments in Jerilderie, Leeton and Hay in 2002-03.................................................................................................................. 12 Table 4. Average grain yield (t ha-1) of four varieties at different nitrogen treatments in Jerilderie, Leeton and Hay in 2002-03.............................................................................................................................. 13 Table 5. Average N uptake at PI (kg ha-1) of four varieties at different nitrogen treatments with different sowing time in Bay 1 and 3 at Yanco in 2002-03. ............................................................................... 15 Table 6. Average grain yield (t ha-1) of four varieties at different nitrogen treatments with different sowing time in Bay 1 and 3 at Yanco in 2002-03. ............................................................................... 16 Table 7. Soil Chemical properties of 3 experimental sites in 2003-04. ............................................................. 19 Table 8. Average grain yield (t ha-1) of four varieties at different N treatments in Jerilderie, Leeton and Coleambally in 2003-04. ............................................................................................................... 21 Table 9

Incremental F-statistics for fitted fixed effects..................................................................................... 22

Table 10. Effect of midseason dry down on nutrient content of the flag leaf. ..................................................... 28 Table 11. Average grain yield at 180 N kg ha-1 with two N fertilisers at Griffith in 2005-06............................. 33

Figures Figure 1.

Air and water temperatures during January and February 2004 at 3 experiment sites...................... 18

Figure 2.

The relationships between N uptake at panicle initiation and grain yield of 3 cultivars at the 3 experimental sites in 2003-04 (Δ Leeton, □ Coleambally, ○ Jerilderie)......................................... 20

Figure 3.

Yield response of each variety to applied N at each 3 experimental sites in 2003-04 ...................... 23

Figure 4.

Relationship between sterility and applied N in Jerilderie in 2003-04.............................................. 24

Figure 5.

Yield responses to different timing of N application at Yanco in 2003/04 season ........................... 25

Figure 6.

Yield response to rate and timing of N application at Jerilderie in 2004-05..................................... 26

Figure 7.

Yield response to rate and timing of N application at Wakool in 2004-05. ...................................... 27

Figure 8.

Yield response to different nutrients treatments under two water regimes at Wakool in 2004-/05 .. 28

Figure 9.

Water and air temperatures during 2005-06 rice season at Griffith and Wakool.............................. 30

Figure 10. Yield response of Langi and YRL 125 to N treatments in 2005-06.................................................. 31 Figure 11. Yield responses of Amaroo in 2005-06 season to different N treatments at Griffith and Wakool (combined data for 2 sites), where midseason dry down was practiced............................................ 32 Figure 12. The relationship between N uptake at PI and grain yield in two systems of water management...... 33 Figure 13. Yield responses to different N treatment under two water management systems at Jerilderie in 2006-07. ............................................................................................................................................ 35 Figure 14. Relationship between grain yield and biomass accumulation at PI for Amaroo under continuous flooding (combined data for 2002- 2005). ........................................................................................ 36

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Executive Summary What the report is about? Research into nitrogen management in rice cultivation has been ongoing for many years. Constant upgrading of fertiliser recommendations is necessary because the properties of soils change enormously with time, release of new varieties and use of new management practices. Therefore, it is imperative to upgrade nitrogen management options to suit these changes. In addition, it is required to upgrade the maNage rice software, a user friendly computer based decision support system used by rice growers, to include new information. This project provided facilities to carry out investigations to further enhance the knowledge of nitrogen management in Australian rice paddocks. Since 2002, this project has investigated issues related to nitrogen management under different scenarios and developed nitrogen management options for newly released varieties and for different water management systems. The project has also gathered information on effects of other nutrients on rice productivity under different water management systems, and the influence of sowing date on nitrogen responses. 2006-07 rice season was the final year of the project. The key findings of each season’s work and the conclusions of the five seasons’ worth of work are presented in this report. Who is the report targeted at? This report is intended for Australian rice industry particularly growers, agronomists and consultants and also rice breeders, related scientific experts and range of government agencies responsible for land and water resource development. Background Nitrogen management is one of the critical issues for sustainable and profitable rice production in NSW. This is not just because N status of the crop is a key determinant of yield potential, but also because high N status is associated with extreme cold sensitivity. Nitrogen is the primary fertilizer used for the production of rice in Australia and N uptake by the plant is considered a key determinant for achieving high yields. The response of current commercial rice varieties to N has been shown to alter from year to year and site to site hence making accurate N recommendations for rice crops is a challenging task for researchers. Constant upgrading of fertiliser recommendations is therefore, necessary, especially for a crop like rice because the properties of rice growing soils change enormously with time due to the intensity of cultivation. As new varieties are developed and released the nitrogen and low temperature response of these varieties also need to be understood and described. Rice farmers pay a large yield and profit penalty for under fertilising their crops, but also can increase their risk of cold damage by over fertilising. To enable rice growers to manage the nitrogen fertiliser application and risk involved in it, they use a computer based decision support system “maNage rice”. maNage rice, a user friendly computer based decision support system allows growers to experiment with a range of options for their crop and determine the best management regime for their particular crop. Many rice growers use the tool for day to day management of their rice paddocks. This important software need to be upgraded to include information on new varieties and other practices.

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Aims/Objectives This project was implemented to enhance the rice yields by improving the nitrogen management practices in rice paddocks and to upgrade/update the maNage rice software based on findings of the project. This project also aimed to provide information on nitrogen management option for new varieties to the NSW rice industry, so that the maximum benefit of new varieties can be quickly obtained on farm. Methods used During 2002-07, several investigations were carried out in Riverina region of New South Wales, Australia, centred at 35oS and 146oE.to evaluate different nitrogen management strategies in rice growing paddocks. Most of the investigations were carried out in farmers’ paddocks representing major rice growing soils and climatic zones for the area. Responses of key commercial rice varieties to rate and timing of nitrogen fertiliser application were evaluated in the investigations. Performances of new varieties released by rice breeders were also compared with their older counterparts. Investigations were carried out using local production standards under two water management systems currently practiced by farmers in the area. Many farmers keep the bays under continuous flooding whereas some practiced a midseason dry down where paddocks are kept without surface water for 12 – 14 days prior to panicle initiation. Results/Key findings •

Results indicated that there are no significant differences in nitrogen responses among Australian rice varieties and optimum nitrogen requirement lies around 170–180 kg N ha-1 depending on the inherent soil nitrogen supply

•

Five years worth of results show that the best yields are obtained when nitrogen application is split between pre-flood and panicle initiation applications in continuously flooded bays.

•

A minimum pre-flood application of 90 kg N ha-1 is necessary to ensure adequate nitrogen supply during the vegetative growth stage of the crop to produce sufficient biomass to sustain a good yield

•

A maintenance requirement of nitrogen at panicle initiation is necessary to ensure adequate nitrogen supply to the plant during the reproductive stages

•

The results suggest that N uptake at PI beyond 150 kg N ha-1 is detrimental when plants are exposed to low temperature spell during young microspore stage

•

Mid-tillering nitrogen applications are warranted if an inadequate amount of pre-flood nitrogen was applied, early nitrogen application was not managed correctly, or the soil is inherently low in fertility

•

Results indicated that it is better to carry out nitrogen topdressing just prior to re-irrigation in bay with midseason dry down.

Implications for relevant stakeholders Project contributed to develop, improve and distribute “maNage rice” model which contains up to date tools to best manage their rice crop. More than 750 “maNage rice” CDs were distributed annually among growers and advisors during last 4 years. Since January 2007, version 6.3 has been available for download on a grower-only part of the Sunrice website. viii

In addition, findings of investigations will enhance the farmers’ knowledge on nitrogen management of their rice paddocks resulting in increased yields. Recommendations The following recommendations could be made from the findings of this work. •

Split nitrogen application of 2/3 pre-flood and 1/3 panicle initiation could be recommended in continuously flooded bays to improve the grain yields and reduce the risk of cold damage and lodging.

•

Minimum application of 90 kg N ha-1 at pre-flood is required in fields with low nitrogen status, to sustain a good grain yield.

•

A maintenance requirement of nitrogen at panicle initiation is recommended to ensure adequate nitrogen supply to the plant during the reproductive stages.

•

It is important to target N uptake at panicle initiation below 150 kg N ha-1 to avoid a possible yield loss due low temperature spell during young microspore stage.

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Mid-tillering nitrogen applications are warranted if an inadequate amount of pre-flood nitrogen was applied, early nitrogen application was not managed correctly, or the soil is inherently low in fertility

•

Mid-tillering nitrogen applications should be based on tissue tests that quantify the nitrogen requirement of the crop at that stage based on plant biomass and nitrogen uptake, rather than visual observations

•

It could be recommended to carry out nitrogen topdressing just prior to re-irrigation in bays with midseason dry down.

•

It would be wise to practice midseason dry down during the first half of December to avoid hot weather during the later half.

•

Nitrogen uptake at panicle initiation in mid-season dry down bays is different to that in conventionally managed bays therefore, new calibrations are necessary to assess the nitrogen status at panicle initiation in drained bays.

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Introduction Nitrogen (N) is the primary fertilizer used for the production of rice in Australia and nitrogen uptake by the plant is considered a key determinant for achieving high yields (Williams and Angus 1994). The response of current commercial rice varieties to nitrogen has been shown to alter from year to year and site to site hence making accurate nitrogen recommendations for rice crops is a challenging task for researchers. Constant upgrading of fertiliser recommendations is therefore, necessary, especially for a crop like rice because the properties of rice growing soils change enormously with time due to the intensity of cultivation. New rice varieties also need to be assessed for their response to nitrogen. Nitrogen is usually applied as a heavy single dose before seeding (pre-flood) and placed at 5 - 10 cm below the soil surface. However, depending on the N uptake at panicle initiation (PI) stage, a second dose of nitrogen may be applied as a top dress at PI. It is estimated that a 12 t ha-1 crop of rice would remove about 208 kg of N per hectare (NSW DPI, 2004). It is recommended to apply 120 – 180 kg of N per hectare at pre-flood to achieve a target nitrogen uptake of 130-150 kg N ha-1 at panicle initiation to obtain 12 t ha-1 rice yield (NSW DPI, 2004) depending on the history of the paddock. A rice crop after a 2 to 3 year pasture phase usually does not require any nitrogen fertiliser as pasture sufficiently builds up the soil nitrogen reserves. However, high nitrogen fertiliser rates at pre-flood can increase the risk of cold damage during reproductive stages due to low night temperatures during late January and early February (Farrell et al. 2001). Historical weather data illustrates that the average minimum temperature during this period is 17°C (Heenan 1984; Lewin and Heenan 1987). However, temperature variability, which can include extreme periods of low temperature, is a major problem that is shared by Australia and other temperate rice producing countries. High nitrogen content in the rice plant increases the risk of yield reductions due to low temperatures during reproductive development (Sasaki and Wada 1975; Yoshida 1981; Haque 1988) by reducing the number of engorged pollen grains per anther resulting increased spikelet sterility (Gunawardena et al. 2003). High nitrogen conditions can also delay panicle development (Gunawardena 2002), thereby increasing the risk of encountering low temperatures during the young microspore and flowering stages. The extra biomass produced due to heavy doses of nitrogen fertiliser applications at pre-flood could also increase the risk of exposing the rice plant to extreme temperatures during reproductive development. As such, timing and rate of nitrogen application is very critical in avoiding low temperature damage in Australian rice production. Research into the effect of the timing of nitrogen fertiliser application on yield has been ongoing for many years. Some findings have shown that total application of nitrogen fertiliser before flooding improves yield (Fageria and Baligar, 1999) as well as the nitrogen fertiliser efficiency (Patrick and Reddy, 1976; Humphreys et al., 1987; Russel et al., 2006). However, some findings revealed that midseason nitrogen top dressing is as efficient as pre-flood application (De Datta, 1987; Cassman et al., 1998). Other findings have demonstrated that heavy total nitrogen applications before flooding can increase the risk of damage to the crop in cold seasons, and induce lodging at harvest (Bacon and Heenan, 1984; Barmes, 1985; Fujisaka, 1993; Heenan and Lewin, 1982). Therefore, it is an imperative task for growers to manage the nitrogen requirement of their crop to achieve high yields and at the same time to avoid risk involved in it. A range of technologies are available to manage nitrogen in rice paddocks. These include the soil testing, tissue testing at various stages and use of computer based decision support systems. Currently, rice growers use a computer-based decision support system, “maNage rice”, developed jointly by CSIRO and NSW Department of Primary Industries, to evaluate the risk and rewards of 1

various management options. The maNage rice has shown to be a dependable tool for rice growers and farm advisers as it allows growers to experiment with a range of options for their crop and to determine the best management regime for their particular crop. The core of maNage rice is an integrated system first designed to estimates the yield response of rice to top-dressed nitrogen fertiliser. This system consists of a simple simulation model that has been calibrated on field experiments and tested against other field experiments. The strong feature of manage rice is that it considers all the available information in estimating the response to nitrogen fertiliser. This information includes sowing date, plant-N status, variety and risk of cold damage. In addition, it considers the grain price and nitrogen fertiliser cost in calculating the economic optimum rate of nitrogen fertiliser. Furthermore, most of the previous work on nitrogen management in Australian rice systems has been focused on nitrogen requirements under continuously flooded conditions. However, many rice farmers in Australia are currently practising a mid-season dry down to mitigate the occurrence of straighthead, a physiological condition which reduces the yield significantly. Moreover, very little information on the requirement of nutrients and their interactions in rice except nitrogen is available apart from their uptake at different nitrogen levels. If high target yields continue to be achieved, nutrients other than nitrogen should also be given consideration as they will be rapidly become depleted. In addition, time of sowing can alter the responses of rice plant to nitrogen fertiliser applications. When sowing is delayed, there is a high risk of yield loss due to cold damage during young microspore stage as it occurs after early February especially with high nitrogen rates. However, about 10-15% of rice farmers in Australia do not adhere to the recommended sowing windows due to variety of reasons. Therefore, nitrogen management in paddocks with delayed sowing is a key to achieve good yields. Our knowledge on the effect of delayed sowing on nitrogen responses is fragmentary. Since 2002, this project has investigated issues related to nitrogen management under different scenarios and developed nitrogen management options for newly released varieties and for different water management systems. This project also gathered information on effect of other nutrients on rice productivity under different water management systems. The influence of sawing date on nitrogen responses was also investigated. The information gathered during these investigations was used to further upgrade maNage rice for new varieties and to add new functions with each annual update.The key findings of each season’s work and the conclusions are presented here.

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Objectives Improved farm yields through genetic and crop-management gains, based on knowledge of rice physiology by developing and improving maNage rice and other decision support systems for rice growers and advisers, with most emphasis on N nutrition and its interaction with low temperature.

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Methodology Environmental conditions at experimental locations The trials were located in Riverina region of NSW, centred at 35oS and 146oE. The altitude throughout the region is approximately 120m. The climate of the area is temperate and characterized by high temperatures and high total radiation during summers. The region has a large diurnal temperature variation of 12° to 15°C and low humidity. Due to the climate variability of the area, only one rice crop could be grown in a year. The rice growing season (October to March) is characterised by long days and high levels of solar radiation averaging 27MJ m-2 day-1 during December, with low temperatures at the beginning and end of the season. Although areas in the southern Riverina can be slightly cooler than in the northern Riverina, temperatures usually vary little within a given season across the whole rice-growing area. However, temperature variability, which can include extreme periods of low temperature, is a major problem of the area. Very low temperatures (