SYNTHESIS REPORT 2009/10-2012/13 Wet Seasons Runoff and Water Quality from Best Management Practices in Sugarcane Farming Reef Water Quality Science Program in the Mackay Whitsunday Region K. Rohde, B. Billing, K. McDuffie and J. Agnew
Project Overview This synthesis report brings together four years of water quality and agronomic monitoring at the Victoria Plains sugarcane trial site located west of Mackay. The monitoring program was funded through the Paddock to Reef Integrated Monitoring, Modelling and Reporting Program in years 2009/10, 2010/11 and 2011/12 and by the Queensland Government s Reef Water Quality Science Program (RWQSP) for 2012/13. Under the Paddock to Reef program, paddock scale monitoring of water quality from various levels of management practices were implemented in selected GBR catchments and agricultural industries (Carroll et al. 2012). As part of this program and in conjunction with Project Catalyst, two sugarcane blocks (Victoria Plains and Marian sites) in the Mackay Whitsunday region were used to measure levels of herbicides, nutrients and sediments in runoff. Different sugarcane management strategies were investigated, with the emphasis on improving water quality with improved management practices. Each treatment and site was instrumented to measure runoff and collect samples for water quality analyses (total suspended solids, total/filtered nutrients and herbicides). report). Under the simulation experiment was used to improve understanding of nitrogen and sediment losses at the Marian site. Two additional sites, Multi-block and Multi-farm, were used to measure the effects of changes in management strategies The Rainfall at larger Simulation scales (results data not is included compiled in this in a synthesis separate report). report. Under the Reef Water Quality Science Program, a rainfall simulation experiment was used to improve the understanding of nitrogen and sediment losses at the Marian site. The rainfall simulation data is compiled in a separate report. This synthesis report focuses on the Victoria Plains site (uniform cracking clay) which was initially divided into two treatments of soil, nutrient and herbicide management This synthesis report focuses on the Victoria Plains site (uniform cracking clay) which was initially divided into two practices, treatments with of soil, an nutrient additional and herbicide two treatments management added practices, in 2012/13 with an additional (Table 1). two The treatments second added site, in the 2012/13 Marian (Table site 1). (duplex The Marian soil) site was (duplex divided soil) was into divided five treatments into five treatments of soil, of nutrient soil, nutrient and and herbicide management practices practices but is not but included is not included this synthesis in this due synthesis to inconsistent due quality to inconsistent of data due to site flooding. quality of data due to site flooding. Table 1: Description of the Victoria Plains sugarcane trial treatments ABCD Classification 1 Soil Management Nutrient Management Herbicide Management No. of years active 4 Treatment 1 CCC 1.5 m current practice Generalised recommendation Regulated broadcast 3 Treatment 2 BBB 1.8 m controlled Six Easy Steps 2 Non- regulated 4 traffic broadcast 4 Treatment 3 BCC 1.8 m controlled Generalised Regulated 1 traffic recommendation broadcast Treatment 4 BBB 1.8 m controlled Six Easy Steps Regulated 1 traffic banded 1 ABCD classifications for soil/sediment, nutrients and herbicides, respectively 2 Farm- specific nutrient management plan designed by BSES 3 Herbicides identified in the Chemical Usage (Agricultural and Veterinary) Control Regulation 1999 4 Herbicides not identified in the Chemical Usage (Agricultural and Veterinary) Control Regulation 1999 P2
Key Findings Annual runoff was reduced by 16% with controlled traffic (1.8 m row spacing), despite the above average rainfall over the four year monitoring period t the Victoria Plains site, we found that there was on average 15.6% less runoff from he 1.8 m row spacing (Treatment 2), despite receiving above average annual rainfall or the three year monitoring period (Figure 1). Furthermore, Treatment 2 also had a elayed onset of runoff (average 17 minutes) and a lower peak runoff rate (average 8%). These results suggest that by matching row spacing to machinery wheel spacing, here will be reduced compaction, improved infiltration and consequently reduced will be reduced compaction, improved infiltration and consequently reduced runoff. unoff. At the Victoria Plains site, we found that there was on average 16% less runoff from the 1.8 m row spacing (Treatment 2), despite receiving above average annual rainfall for the three year monitoring period (Figure 1). Furthermore, Treatment 2 also had a delayed onset of runoff (average 17 minutes) and a lower peak runoff rate (average 18%). These results suggest that by matching row spacing to machinery wheel spacing, there Figure 1: Runoff from the 1.8 m row spacing (controlled traffic) consistently had less overall runoff than the 1.5 m row spacing. igure 1: Runoff from the 1.8 m row spacing (controlled traffic) consistently had Sediment losses were reduced by maintaining a green cane trash blanket and reducing cultivation At the Victoria Plains site, sediment concentration in runoff revealed that by maintaining ground cover (green cane trash blanket GCTB) and reducing cultivation, sediment losses to runoff could be reduced (Figure 2 and t the Figure Victoria 3). In the Plains initial site, trial sediment year, the ground concentration was bare following in runoff a fallow revealed with that a legume by crop ploughed into aintaining the soil. ground With no cover ground (green cover, cane sediment trash losses blanket were GCTB) significantly and reducing higher than cultivation, the subsequent years where the ediment GCTB losses was retained to runoff after could harvest be reduced and the soil (Figure was undisturbed 2 and Figure by 3). cultivation. In the initial The difference trial shown in 2009/10 ear, is the thought ground to was be due bare to following sampling a differences fallow with rather a legume than treatment crop ploughed differences, into the with soil. Treatment 2 being low ith rather no ground than Treatment cover, sediment 1 being losses high. This were is significantly despite higher higher than average than the rainfall subsequent in each of the four years. ears where the GCTB was retained after harvest and the soil was undisturbed by ultivation. The difference shown in 2009/10 is thought to be due to sampling ifferences rather than treatment differences, with Treatment 2 being low rather than P3
treatment 1 being high. This is despite higher than average rainfall in each of the four years. Figure 2: Sediment concentrations decreased over the four year monitoring period due to the retention of a GCTB and no cultivation being undertaken in the 2010/11, 2011/12 and 2012/13 seasons. Figure 2: Sediment concentrations decreased over the four year monitoring Figure 3: Sediment loads decreased over the four year monitoring period due to the retention of a GCTB and no cultivation being undertaken in the 2010/11, 2011/12 and 2012/13 seasons. P4
The amount of nutrients applied and timing of application were critical in reducing runoff losses t was found that the greater the time between application and the first runoff event, nd the amount of infiltrating rainfall during this period, between application and the irst runoff event, reduced the amount of nitrogen lost in runoff (Figure 4). The urea- N o NOx- N ratio also appeared to decrease with the increase of time between application nd the first runoff event, and the amount of infiltrating rainfall during this period Figure 4). Furthermore, it was evident that the lower the application rate of nitrogen, he lower the amount of nitrogen was lost via runoff (Figure 4). Moreover, background itrogen levels in the soil also had an effect on the amount of nitrogen lost via runoff ith other 2009/10 seasons due season to a having legume higher fallow prior levels to of the soil planting nitrogen of the than cane the for other this seasons field trial. ue to a legume fallow prior to the planting of the cane for this field trial. It was found that the greater the time between application and the first runoff event, and the amount of infiltrating rainfall during this period, between application and the first runoff event, reduced the amount of nitrogen lost in runoff (Figure 4). The urea-n to NO x -N ratio also appeared to decrease with the increase of time between application and the first runoff event, and the amount of infiltrating rainfall during this period (Figure 4). Furthermore, it was evident that the lower the application rate of nitrogen, the lower the amount of nitrogen lost via runoff (Figure 4). Moreover, background nitrogen levels in the soil also had an effect on the amount of nitrogen lost via runoff with the 2009/10 season having higher levels of soil nitrogen than the Figure 4: Nitrogen loads and the urea-n to NO x -N ratio in runoff decreased with increasing time between application and the first runoff event, as well as with the amount of infiltrating rainfall during this period. Nitrogen loads in runoff also decreased with lower application rates of nitrogen. igure 4: Nitrogen loads and the urea- N to NO - N ratio in runoff decreased with Timing and amount of herbicide application were critical in reducing runoff losses The greater the time between application and the first runoff event, the less herbicide was lost in runoff (Figure 5) every additional 25 days halved runoff losses. Also, the amount of infiltrating rainfall during this period, between the application and the first runoff event, reduced the amount of herbicide lost (Figure 6) every additional 50 mm halved runoff losses. The critical period for reducing herbicides losses to runoff he greater is therefore within time between ~25 days application of herbicide and application. the first Prior runoff to event, the 2012/13 the less season, herbicide an additional treatment as lost of banding runoff regulated (Figure residual 5) every herbicides additional was added 25 days to halved the trial runoff site. Results losses. showed Also, the that a 33% band (over mount the of cane infiltrating stool area) rainfall vs broadcasting during this herbicides period, (100% between blanket) the application resulted in and a reduction the first of runoff losses of unoff approximately event, reduced 50% the (Figure amount 7). of Row herbicide spacing lost had (Figure little effect 6) on every herbicide additional runoff 50 losses. mm alved runoff losses. The critical period for reducing herbicides losses to runoff is herefore within ~25 days of herbicide application. Prior to the 2012/13 season, an dditional treatment of banding regulated residual herbicides was added to the trial P5
site. Results SYNTHESIS showed REPORT that 2009/10 a 33% - 2012/13 band WET (over SEASONS the cane stool area) vs broadcasting herbicides (100% blanket) resulted in a reduction of runoff losses of approximately 50 percent (Figure 7). Row spacing had little effect on herbicide runoff losses. Figure 5: The amount of herbicides lost to runoff halved with every additional 25 days between application and the first runoff event. Figure 5: The amount of herbicides lost to runoff halved with every additional 25 Figure 6: The amount of herbicides lost to runoff halved with every additional 50 mm of rainfall/ irrigation before runoff. P6
Figure 7: Banding herbicides (33% band) halved runoff losses. Row spacing had little effect on herbicide losses. Implementing best management practices did not significantly affect productivity The The data data suggests suggests that by that implementing by implementing best management best management practices (BMP s), practices there (BMP s), will not be there a significant will effect not on be productivity a significant with effect BMP s on (B-class productivity practices) performing with BMP s as (B- class well current practices) management performing practices as (C-class well practices) as current even management in a monitoring practices period that (C- class exhibited practices) extreme weather even in events a monitoring (Table 2). period The data that suggests exhibited that extreme by implementing weather best events management (Table 2). practices (BMP s), there will not be a significant effect on productivity with BMP s (B- class practices) performing as Table 2: Productivity was not significantly affected by implementing best management practices (BMP), with well as current management practices (C- class practices) even in a monitoring period the BMP (BBB) performing as well as current management practice (CCC). that exhibited extreme weather events (Table 2). management practice (CCC). a) Average of 2009/10, 2010/11 and 2011/12 seasons ABCD Nitrogen Cane yield Sugar Sugar Net return Classification 1 applied (t/ha) yield content ($/ha)* (kg/ha) (t/ha) (%) Treatment 1 CCC 183 79 13 17 2365 Treatment 2 BBB 112 75 12 16 2395 b) 2012/13 season ABCD Classification 1 Nitrogen applied (kg/ha) Cane yield (t/ha) Sugar yield (t/ha) Sugar content (%) Net return ($/ha)* Treatment 1 CCC 197 69 13 18 2500 Treatment 2 BBB 135 71 13 18 2680 Treatment 3 BCC 197 77 14 18 2815 Treatment 4 BBA 135 72 13 17 2660 1 ABCD classifications for soil/sediment, nutrients and herbicides, respectively * Excluding irrigation, other fertiliser (nutrients) and fixed costs other than harvesting Overall, these results are not surprising and are all supported by other studies. For further details, please refer to the Mackay Whitsunday Paddock to Sub- catchment Scale P7 Water Quality Monitoring of Sugarcane Management Practices Final Report for the 2009/10 to 2011/12 Wet Seasons (Rohde. 2013a) and 2012/13 Wet Season
SYNTHESIS REPORT 2009/10-2012/13 WET SEASONS Overall, these results are not surprising and are all supported by other studies. For further details, please refer to the Mackay Whitsunday Paddock to Sub-catchment Scale Water Quality Monitoring of Sugarcane Management Practices Final Report for the 2009/10 to 2011/12 Wet Seasons (Rohde et al. 2013a) and 2012/13 Wet Season (Rohde et al. 2013b). Caption: Extension activities undertaken on site with a wide range of field day participants, delegates and stakeholders during the course of the project. P8
References Carroll C., Waters D., Vardy S., Silburn D.M., Attard S., Thorburn P.J., Davis A.M., Halpin N., Schmidt M., Wilson B., and Clark, A. (2012). A Paddock to reef monitoring and modelling framework for the Great Barrier Reef: Paddock and catchment component. Marine Pollution Bulletin 65, 136-149. Rohde, K., McDuffie, K., and Agnew, J. (2013a). Paddock to Sub-catchment Scale Water Quality Monitoring of Sugarcane Management Practices. Final Report 2009/10 to 2011/12 Wet Seasons, Mackay Whitsunday Region. Department of Natural Resources and Mines, Queensland Government for Reef Catchments (Mackay Whitsunday Isaac) Limited, Australia. Rohde, K., McDuffie, K., and Agnew, J. (2013b). Paddock to Sub-catchment Scale Water Quality Monitoring of Sugarcane Management Practices. Interim Report 2012/13 Wet Season, Mackay Whitsunday Region. Department of Natural Resources and Mines, Queensland Government for Reef Catchments (Mackay Whitsunday Isaac) Limited, Australia. Authorship K. Rohde, B. Billing, K. McDuffie and J. Agnew Acknowledgements We would like to give a special thanks to the cooperating landholders for allowing us to conduct the research trials on their properties. We would also like to thank the landholders, their families and staff for applying the nutrient and herbicide treatments, harvesting the individual treatments, and general site maintenance. We also greatly appreciate the many individuals for their assistance in the collection of soil, water and trash samples throughout the project. This project was supported by the Department of Natural Resources and Mines, and was funded by the Australian and Queensland Government s Paddock to Reef and Reef Water Quality Science Programs and Project Catalyst. P9
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