ACP Project 2.2 Regulating phosphorus in sugarcane to decrease production costs and to protect fresh water resources in ACP states Collaborative project: Sugar Industry Research Institute of Jamaica Sugar Research Institute of Fiji Mauritius Sugarcane Industry Research Institute Mid-term review October 2012

Importance of P to sugarcane kg N/ha kg K 2 O /ha kg P 2 O 5 /ha P a major nutrient

Importance of P to sugarcane kg N/ha kg K 2 O /ha kg P 2 O 5 /ha P a major nutrient Total P 2 O 5 (kg/ha) Cane yield (T/ha) Increase due to P (T/ha) Benefit of P fertilisation in sugarcane (Mauritius) Cavalot et al. (1986)

Reduit Pamplemousses Belle Rive Union Park SUBHUMID SUPERHUMID HUMID 2500mm 1500mm Sugar cane areas (green) and three climatic zones Sugar factory MSIRI experiment station N 64,000 ha sugarcane land 4,400,000 T cane 450,000 T sugar Sugarcane in Mauritius Sugarcane in Mauritius 3,000 T P 2 O 5 applied annually

Environmental concern with phosphorus  Major cause of non-point source pollution of water resources  P (and not N) is the limiting nutrient influencing eutrophication  Conc > 30 µg P L -1 sufficient to trigger eutrophication  For optimum plant growth P conc > 200 µg L -1 required

P (µg L -1 ) Jan May Aug Dec Apr Aug Dec Apr Aug Dec Runoff P concentration in runoffs in Mauritius (ACIAR project) Values >> 30 µg P L -1 have been recorded in runoffs 30 µg P L -1

ACP Project 2.2 Regulating phosphorus in sugarcane to decrease production costs and to protect fresh water resources in ACP states Collaborative project: Mauritius Sugarcane Industry Research Institute Sugar Industry Research Institute of Jamaica Sugar Research Institute of Fiji Mid-term review October 2012

 Better match P inputs to optimise sugarcane production  Control P already present in soil to prevent movement to surface waters PROJECT PURPOSE ACP Project 2.2

9 Regulating phosphorus in sugarcane to reduce cost of production and protect fresh water resources in ACP states Specific Objectives: I.Develop a soil P test to indicate environmental status of sugarcane soils II.Determine the field site’s vulnerability to erosion and runoff III.Develop a P index to identify critical source areas in a watershed

10 Regulating phosphorus in sugarcane to reduce cost of production and protect fresh water resources in ACP states Eutrophication High conc of P in runoff High soil P Specific Objectives: I.Develop a soil P test to indicate environmental status of sugarcane soils II.Determine the field site’s vulnerability to erosion and runoff III.Develop a P index to identify critical source areas in a watershed

11 Regulating phosphorus in sugarcane to reduce cost of production and protect fresh water resources in ACP states Specific Objectives: I.Develop a soil P test to indicate environmental status of sugarcane soils II.Determine the field site’s vulnerability to erosion and runoff III.Develop a P index to identify critical source areas in a watershed Sloping topography Flat topography High soil P status Potential for P movement not the same Soil P test provides an incomplete assessment of the risk of P loss

12 Regulating phosphorus in sugarcane to reduce cost of production and protect fresh water resources in ACP states Specific Objectives: I.Develop a soil P test to indicate environmental status of sugarcane soils II.Determine the field site’s vulnerability to erosion and runoff III.Develop a P index to identify critical source areas in a watershed Source Factors -Soil P status -Fertiliser application rates Transport factors - Surface runoff - Soil erosion Delivery point Streams, rivers, lakes Critical source P areas

Interpretation of P index P index Site P loss vulnerability < ? Low ? – ? Medium ?- ? High > ? Very high Low P index Low risk of P loss High P index High risk of P loss Note: Interpretation is qualitative

Research approach Rainfall simulation Vary rainfall intensities Study movement of P on different slopes

Capacity building  Procurement and shipping of rainfall simulators to Jamaica and Fiji  Visits of scientists from MSIRI to: SIRI (Jamaica) in December 2010 SIRI (Jamaica) in December 2010 SRIF (Fiji) in April and October 2011 SRIF (Fiji) in April and October 2011 Jamaica

Capacity building a.Commissioning, testing and calibration of rainfall simulator b.Training in use of rainfall simulator c.Audit infrastructure and level of expertise d.Staff training for analytical methods

Upgrade of infrastructure Chemicals, glassware and consumables Equipment Spectrophotometer (UV/VIS) Atomic absorption spectrophotometer Chillers for storage of runoff samples Water bath, heated concentric ring steaming bath Hot plate

18 SIMULATEDRAINFALL Rainfall simulation tests Site selection 20 sites selected in each country Main soils Main soils Three slope ranges Three slope rangesIntensity: 50, 100, 150mm/hr Duration: 30 minutes each rainfall event Field experimentation

Runoff and bedload collected 19

20 Laboratory analysis Runoff Total Filtered –P Total Filtered –P Total Unfiltered –P Total Unfiltered –P Orthophosphate-P Orthophosphate-P Bedload Soil erosion Soil erosion Total P Total P Soil Agronomic soil P level Agronomic soil P level 0.01M CaCl 2 -P 0.01M CaCl 2 -P Soil characterisation Soil characterisation Rainfall simulation tests Sample collection

Work status Jamaica 8 sites completed (350 runoffs, 70 bedload, 68 soil samples collected) Fiji 13 sites completed (727 runoffs, 136 bedload, 39 soil samples collected) Analysis of samples in progress

Problems encountered Jamaica Long travelling and working hours Accommodation of workers out of base provided Delay due to heavy rainfalls Fiji Delay due to heavy rainfalls High turn-over rate of trained staff Fiji Fiji

Work status in MauritiusCompleted: Field measurements at 20 sites In progress: Analysis of soil samples Data processing and interpretation

P extractable by 0.01M CaCl 2 is a good predictor of runoff-P for sugarcane soils of Mauritius y = x r² = 0.92 RUNOFF P Orthophosphate-P (mg L - 1 ) SOIL P 0.01M CaCl 2 -P (mg kg -1 )  Elaborate labour intensive field experimentation with costly equipment such as rainfall simulator not needed  Laborious and lengthy laboratory analyses are unnecessary to determine runoff P  Determination of environmental P status can possibly be extended to other ACP sugarcane producing countries

0.01M CaCl 2 -P (mg kg -1 ) Enlarging scope of current agronomic soil P test in Mauritius  Critical limit of runoff P is 30 µg P L -1  Environmental threshold of 160 mg kg -1  Environmental threshold of 160 mg kg M H 2 SO 4 -P 0.1M H 2 SO 4 -P (mg kg -1 ) (Agronomic soil P test in Mauritius)

OPTIMUM UNSOUND ACCEPTABLE 160 UNACCEPTABLE OPTIMUM 145 SOUND Soil P level (mg kg -1 ) Agronomic perspective Environment viewpoint Outcome in Mauritius Agronomic soil P test also suitable as an environmental test

Future work Completion of 20 sites in Fiji and Jamaica by March 2013 Completion of 20 sites in Fiji and Jamaica by March 2013 Develop/enlarge scope of the existing soil P test Develop/enlarge scope of the existing soil P test Training in the development of the P index – hiring of expert needed Training in the development of the P index – hiring of expert needed P index available for use by stake holders P index available for use by stake holders Submission of final report Submission of final report Dissemination of the findings of the project to ACP states Dissemination of the findings of the project to ACP states

Visibility and dissemination of results Presentation at conference - IAPSIT MARDAMOOTOO, T, NG KEE KWONG, K F, Du Preez, C C (2011). Evolution of the agronomic and environmental phosphorus status of soils in Mauritius after a seven year sugarcane crop cycle. Proceedings of the International Sugar Conference IS2011. New Delhi, India, November 21-25, (Also published in Sugar Tech Journal) Publication Agricultural Water Management MARDAMOOTOO, T, NG KEE KWONG, K F, Du Preez, C C (2012). Assessing environmental phosphorus status of soils in Mauritius following long-term phosphorus fertilisation of sugarcane. Agricultural Water Management (Accepted for publication). (Accepted for publication). ISSCT congress MARDAMOOTOO, T, NG KEE KWONG, K F, Du Preez, C C. Managing soil phosphorus movement on the sloping lands of Mauritius cropped with sugarcane. XXVIII ISSCT Congress 2013.

Expected Outcome 29  A reliable decision support tool for predicting P movement in a watershed, i.e. the P index  Critical source areas representing a threat to fresh water sources identified in the ACP states  Improved P management practices in critical source areas  Foster an improved collaboration between research institutions of the ACP states

Team work Mauritius Dr René Ng Kee Kwong Dr Ronald Ng Cheong Mr Kumar Muthy Mr Bruce Bonarien Ms T Mardamootoo Mr Jai Gawander & team in Fiji Mr Clarence Fearon & team in Jamaica

Thank you

32 Lemunyon and Gilbert (1993) P loss rating value Site characteristic WeightNone(0)Low(1) Medium (2) High(4) Very high (8) (8) Soil erosion 1.5 Not applicable < 5 tons/acre tons/acre tons/acre > 15 tons/acre Irrigation erosion 1.5 xxxxx Runoff class 0.5 xxxxx Soil P test 1.0 xxxxx P fertiliser application rate 0.75 xxxxx P fertiliser application method 0.5 xxxxx Organic P source application rate 1.0 xxxxx Organic P source application method 1.0 xxxxx Calculation: P index = ∑ (Site characteristic P loss rating value x weight) P index = ∑ (Site characteristic P loss rating value x weight)