Posts in Irrigation
Permanent beds in bays for sustainable cropping (2007)

This IREC Farmers Newsletter reports on the continuation of the permanent beds for sustainable cropping which has been running since 2000. The reports for 2005, 2006, and 2007 are included in this library.  The report covers 05/06 results, weed control, rice growth and yields, irrigation and fertilisers. This report concluded that high yields of wheat were achieved in 2005. This was seen on both raised beds and flat layouts – in a year without rainfall- induced water logging in winter or spring. It was also seen that the rice yields on both raised beds and flat treatments were excellent during an exceptional rice growing season. It was acknowledged that the rice yield from the bed systems is as high as that from conventional flat systems where rice is grown using permanent flooded conditions and deep water is applied during the early microspore stage.

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Using Raised Beds on Rice Farms - sustainable cropping systems on rice farms- Link (2006)

This RIRD report presents the results of the project using raised beds on rice farms - sustainable cropping systems on rice farms. The project was an experiment evaluating a new irrigation layout for rice and other crops. The targeted audience included rice and grain growers within rice based farming systems, advisory and commercial agronomists, irrigation surveyors and designers, irrigation distribution companies and, land and water management plan implementers operating in these areas. The project aim was to increase the sustainability, resource use efficiency, yield and profitability of rice-based cropping systems through improved soil, water and nutrient management using permanent raised bed systems. The method undertaken was a large replicated field experiment conducted at Coleambally Demonstration Farm, NSW. Double cropping with side-by-side demonstration of permanent raised beds (including sub surface drip irrigation) and traditional ‘flat’ layouts were investigated. Three broad types of crop sequence were selected to include both traditional and novel crop sequences (double cropping with both winter and summer crops each year). Different crop options were included within each broad sequence. In addition to this experiment the project estimated the potential benefits and costs involved in switching over to permanent raised beds over common irrigation layouts of rice based farming systems within a benefit cost framework. The key findings demonstrated that where irrigation supplies are sufficient rice can be grown in close rotation with winter cereals and other summer crops on raised beds. This demonstrated that the adoption of raised beds in terraced, bankless channel layouts provides an opportunity for this to occur. Barley/soybean double cropping was successful on raised beds in rotation with rice.  With the technology available it is viable from a financial perspective and as seen in the benefit cost analysis revealed that there are significant benefits in switching to permanent raised beds in terraced, bankless channel layouts.

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Effect of Rice Stubble Burning on Soil Health - Link (February 2006)

This RIRDC report present the findings of the investigation comparing the effects of stubble burning and stubble retention on a range of soil chemical and biological properties. The method  included comparing paired sites on eight properties, four pairs, with different histories and soil types in the Murrumbidgee Irrigation Area. The chemical properties included total soil carbon, nitrogen, phosphorus and sulphur (C, N, P and S). Soil biological properties included the size and activity of the microbial biomass, the microbial and metabolic quotients, the rate of cellulose decomposition and a range of information concerning the composition of the microbial population derived from fatty acid methyl ester (FAME) analysis. The findings included sites retaining stubble had significantly more C, N, P and S than the corresponding property that burnt stubble despite differences in other management strategies. It is considered that the biological properties of the stubble retained soils healthier than the corresponding stubble burnt soils. Whilst  two measurements used to indicate soil stress, the microbial quotient and a stress indicator derived from FAME analysis, indicate that the stubble retained soils were less stressed than the stubble burnt soils. The findings supported the view that for rice, or other summer crop stubble, to decompose at the fastest rate in the field it should be incorporated as soon as possible after harvest, before winter, and not during the sowing of the following summer crop, before summer. It is suggested that there needs to be a balance of available nutrients to optimise nutrient availability and potential carbon sequestration in stubble retained systems, especially in the early years after switching from a stubble burning regime. 

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Effects of raised beds, irrigation, and nitrogen management on growth, yield and water use of rice in south eastern Australia - Link (January 2006)

To remain economically and environmentally sustainable, Australian rice growers need to be able to readily respond to market opportunities and increase cropping system productivity and water productivity. Water availability is decreasing whereas its price is increasing. Alternative irrigation layouts and water management approaches could contribute to reduced water use and increased irrigation efficiency. This paper reports results for the first crop (rice) in a cropping system experiment to compare permanent raised bed and conventional layouts on a transitional red-brown earth at Coleambally, New South Wales. The performance of conventional ponded rice grown on a flat layout was compared with rice grown on 1.84-m wide, raised beds with furrow and subsurface drip irrigation. In addition, deep and shallow ponded water depth treatments (15 and 5 cm water depth over the beds) were imposed on the rice on beds during the reproductive period. A range of nitrogen (N) fertiliser rates (0-180 kg N/ha) was applied to all treatments. The traditional flat flooded treatment (Flat) achieved the highest grain yield of 12.7 t/ha, followed by the deep (Bed 15) and shallow (Bed 5) ponded beds (10.2 and 10.1 t/ha, respectively). The furrow (Furrow) irrigated bed treatment yielded 9.4 t/ha and the furrow/drip (Furr/Drip) treatment yielded the lowest grain yield (8.3 t/ha). Grain yield from all bed treatments was reduced owing to the wide furrows (0.8 m between edge rows on adjacent beds), which were not planted to rice. Rice crop water use was significantly different between the layout-irrigation treatments. The Flat, Bed 5 and Bed 15 treatments had similar input (irrigation + rainfall - surface drainage) water use (mean of 18.3 ML/ha). The water use for the Furrow treatment was 17.2 ML/ha and for the Furr/Drip treatment, 15.1 ML/ha. Input WP of the Flat treatment (0.68 t/ML) was higher than the raised bed treatments, which were all similar (mean 0.55 t/ML). This single season experiment shows that high yielding rice crops can be successfully grown on raised beds, but when beds are ponded after panicle initiation, there is no water saving compared with rice grown on a conventional flat layout. Preliminary recommendations for the growing of rice on raised beds are that the crop be grown as a flooded crop in a bankless channel layout. This assists with weed control and allows flooding for cold temperature protection, which is necessary with current varieties. Until we find effective herbicides and other methods of weed control and N application that do not require ponding, there is little scope for saving water while maintaining yield on suitable rice soil through the use of beds.

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Better predictions of groundwater recharge from rice growing. (2005)

 This CRC project investigated better prediction of ground water recharge form rice growing. The objective of the project were to improve rice land soil suitability identification and assessment approaches. The key focus was investigating ways of refining the electromagnetic (EM) technology approach to include soil chemical characteristics specifically soil sodicity or exchangeable sodium percentage, in the rice land assessment process. Further objectives were to identify the horizontals modes of EM31 and EM38 could provide better definitions of suitable rice land by using the vertical version. The project also aimed to promote adoption of the finding to date amongst the irrigation staff, DLWC regulatory staff and EM service providers to industry. There were six key results presented from the project were consistent with the projects objectives. One key results was irrigation companies showed a high level of interest in the project s project and adoption of the project findings. 

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Quantifying climate and management impacts on watertables and soil salinity (2005)

This CRC report describes the development of a surface-groundwater interaction model for the Murrumbidgee Irrigation Area (MIA) in Southern NSW. Rising  watertable and salinisation have threatened the viability of the MIA and this work is part of management strategies to ensure the sustainability of the area. The project presents the Hydrogeology and Soils of the MIA, conceptual model, model calibration, model results, prediction of groundwater levels, spatial distribution of groundwater levels, model performance, water balance of the Murrumbidgee Irrigation Area. Six scenarios are also presented including the analysis of dry conditions continued for next 25 years, relatively wet conditions continued for the next 25 Years, 50% and 75% reduction in rice area, partial and full reduction in seepage from channels, regional groundwater trends. The result of the investigation include the model being calibrated and used to simulate possible management scenarios. The authors states that as with any model there is a need to keep the model updated. It is also advisable to use it with other tools such as SWAGMAN Farm to convey modelling results and help determine sustainable irrigation levels on a year to year basis. The model is ready to formulate different land and water management options and to help determine on farm actions required to meet regional targets. 

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Quantifying and maximising the benefits of crops after rice (2005)

This CRC project had 5 key objectives these included determining the knowledge of farmers perception of three key factors; constraints to growing crops/pastures following rice, factors leading to successful production of crop after rice and impacts of sustainability. Objective two  was to determine and undertake demonstrations of  the impact of growing wheat after rice and the water use efficiency of this system and net recharge.  Objective three was to compile existing data from rice-wheat cropping in southern Australia, and use these data to do. Objective 4 was to calibrate and validate the CERES wheat and Swagman destiny models in southern NSW wheat growing areas. Objective five aimed use the calibrated models to predict impacts of wheat after rice on watertables and rootzone salinity for a range of seasonal conditions, watertable depths, soil types, sowing dates and irrigation management, and tradeoffs between yield and net recharge management. The methodology used for the project were the use of mail survey, field experiments and demonstrations, review and compilation of water and soil  data and the use of data to validate and calibrate CERES and SWAGMAN. The results of the project suggest that establishment of wheat shortly after rice harvest is beneficial in terms of net recharge management, capture and use of winter rainfall and financially. 

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Study of water use and environmental aspects of rice growing (2005)

This CRC report presents the results of the project undertaken to examine the rice growing industry in Southern NSW. The investigation focuses on reviewing the past and current policies of the government in relation to water access for rice growing and irrigation. The second part of the project was that water use, water availability, ground water and salinity data was compiled for rice production.  

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The Efficacy of Rice as a Leaching Crop - Project No. 2105 (2005)

The concluding phase(s) of a rice rotation experiment presented the opportunity to assess the effect of consecutive crops of rice on the chemistry of the soil profile.  An experiment which aimed to determine the potential to use high salinity groundwater for the irrigation of the non-rice phases of a wheat - sub.clover - rice rotation, and then use rice, irrigated with low salinity channel water (<0.1 dS/m), as a leaching crop was undertaken.  The rotation included a single rice crop between each cycle of the application of saline groundwater.  Although soil salinity of most horizons under saline treatments could be reduced by leaching in the rice phase (single crop), this was not true for sodicity. Average rootzone sodicity remained elevated above control values at the end of each cycle and increased following successive cycles.

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A GIS Approach to Quantify Impact of Flooding on Shallow Groundwater Levels in the Wakool Irrigation District (October 2005)

Environmental degradation associated with shallow saline watertables is a major threat to the sustainability of agricultural industry throughout the Murray-Darling Basin. Located in the
western part of the Murray Valley of NSW, the Wakool Irrigation District has experienced a history of water table rise, including likely contribut ions from widespread flooding. The
community is interested in scientific evidence quantifying the impact of flooding on the shallow groundwater, in order to target management actions to control water table rise and salinity in this area.
This study estimates the spatial and temporal impact of flooding on shallow groundwater for the Wakool Irrigation District through an extensive GIS analysis based on a large amount of piezometric data monitored over many years.

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