Báo cáo khoa học nông nghiệp " Cuu Long Rice Research Institute " pdf

Ministry of Agriculture & Rural Development Project Progress Report SECOND SIX-MONTHLY REPORT 4th July, 2008 Table of Contents Institute Information _ Project Abstract _ Executive Summary 4 Introduction & Background _ Progress to Date _ 5.1 Implementation Highlights 5.2 Smallholder Benefits _ 19 5.3 Capacity Building _ 20 5.4 Publicity _ 20 5.5 Project Management 20 Report on Cross-Cutting Issues 20 6.1 Environment _ 20 6.2 Gender and Social Issues _ 21 Implementation & Sustainability Issues _ 21 7.1 Issues and Constraints _ 21 7.2 Options 21 7.3 Sustainability _ 21 Next Critical Steps 22 Conclusion 22 10 Statuatory Declaration Error! Bookmark not defined Institute Information Project Name 023/06VIE Vietnamese Institution Cuu Long Rice Research Institute Vietnamese Project Team Leader Dr Cao van Phung Australian Organisation Murdoch University Australian Personnel Dr Richard Bell Date commenced April 2007 Completion date (original) February 2010 Completion date (revised) March 2010 Reporting period October 2007 – March 2008 Contact Officer(s) In Australia: Team Leader Richard Bell Name: Professor Position: Organisation Murdoch University Telephone: Fax: Email: +61 93602370 +61 93104997 R.Bell@murdoch.edu.au In Australia: Administrative contact Richard McCulloch Name: General Manager Position: Organisation Murdoch Link Telephone: Fax: Email: +61 93607566 R.Mcculloch@murdoch.edu.au In Vietnam Name: Cao Van Phung Head, Soil Science Dept Position: Organisation Cuu Long Rice Research Institute Telephone: Fax: Email: +84 71 861452 +84 71 861457 phungcv@yahoo.com.vn caovanphung@hcm.vnn.vn Project Abstract In total, 240 questionnaires of rice and fish farmers were collected (2 districts) Stakeholders were concerned about surface water pollution because of its effects on their business sustainability and livelihood There were about 15-24 % of the farmers (including both fish and rice farmers) stating that water quality is bad There are only 3-8 % of fishpond holders having settling ponds, 15-24 % of them practice waste recycling on paddies and the rest discharge fishpond waste directly to the waterways A field study on the use of solid fishpond waste for rice cultivation was established during the wet season 2007 at Cuu Long Rice Research Institute There were no significant differences in rice yields over all treatments The experiment was repeated in the dry season 2008, and produced similar results That is, 1/3rd to 2/3rd of the inorganic fertiliser recommended for rice can be omitted when applying solid waste at 1-3 t/ha Results from trials indicated that that irrigation of rice by wastewater from fishponds can save 33 % of recommended N, and 50 % of the recommended P and K rice yields Further decrease in N and P fertiliser resulted in reduced yield Executive Summary Questionnaires for the baseline study were formulated in consultation with researchers of Can Tho University, and with extension officers in Can Tho city and An Giang provinces In total 240 questionnaires of stakeholders (rice farmers and fish farmers) were collected (2 districts/site) The results showed that all stakeholders were concerned about surface water pollution because of its effects on their business sustainability and livelihood There were about 15-24 % of the farmers (including both fish and rice farmers) stating that water quality is bad There are only 3-8 % of fishpond holders having settling ponds, 15-24 % of them practice waste recycling on paddies and the rest discharge directly to the waterway In Cantho, farmers practicing fish culture are richer, have more formal education and are younger than those carrying out rice cultivation However, about 15 % of fishpond holders are recent migrants who have bought or rented lands from local farmers In An Giang, fish farmers had similar age and education profiles to rice farmers suggesting that here fish farming was carried out as a diversification of farm activities Impacts reported on water quality include greenish-black colour, bad smell, high turbidity, causing itching on contact Moreover, farmers raising fish recognised that percentages of disease-infected fish were much higher (about 15%) than before (< %) The demand for effective and economical solutions for control of water pollution is the first priority of stakeholders Only 10 % of fish farmers surveyed in An Giang and 25 % of those in Cantho expressed the intention to increase production in the future Notwithstanding their concern about water quality, few expressed an intention to construct settling ponds (3-7%) in the future The survey of farmers’ practices on fishpond waste treatment was completed during the dry season 2007 at sites (An Giang province and Can Tho city) Most (68-80 %) of the wastes (liquid and solid) are pumped directly into waterways (rivers or canals) In the case of fishponds located nearby big rivers (Tien and Hau), waste is apparently diluted by the large volume of water flow and it is not reported to cause much problem in comparison with discharge situated at the far end of small rivers or canals A concern requiring management of waste discharge into paddy fields arises from the content of nitrogen in waste causing yield loss by lodging However, judicious use of waste in balance with inorganic fertiliser application may increase rice yield in some cases as reported below During the dry season 2007, we conducted a study on 32 paddies comprising 16 fields that received waste through discharge from fishponds while the others did not Results showed that rice yields in fields receiving waste were 0.8-1.0 tonnes/ha higher than those that did not receive waste This is attributed to higher available nitrogen, phosphorus, potassium as well as secondary and micronutrients A field study on the beneficial use of solid fishpond waste for rice cultivation was established during the wet season 2007 at the experimental farm of Cuu Long Rice Research Institute Three dosages of waste at the rate of 1, and tonnes/ha were applied in combination with 1/3 and 2/3 dosages of inorganic fertilisers The 100 % rate of inorganic fertilisers (60N40P2O5-30K2O) served as the control There were no significant differences in rice yields over all treatments This indicated that uses of solid waste from fishpond can save money for farmers by reducing fertiliser inputs The experiment was repeated in the dry season 2008, and produced similar results That is, 1/3rd to 2/3rd of the inorganic fertiliser recommended for rice can be omitted when applying fishpond solid waste at 1-3 t/ha Fifteen isolates of Pseudomonas stutzeri were selected from liquid and solid waste of catfish ponds located along the Tien river, in the Mekong Delta, Vietnam using SW-LB medium (artificial seawater Luria-Britani medium) supplemented with 10 mM NH4 and NO3 Eleven isolates were identified as Pseudomonas stutzeri based on similarity of PCR-16S rRNA using universal primers and specific primers Four isolates were effective in lowering soluble N (NH4, NO2 and NO3) levels in fishpond water from 10 mg/L to negligible amounts after four days Further experiments are underway to determine the fate of N lost from solution and the relative activity of ammonia oxidation, and nitrite and nitrate reduction by Pseudomonas stutzeri isolates Ozone treatment was evaluated for treatment of wastewater The levels of ozone produced in waste water were < 40 % of those produced in shrimp pond water, and effects on water quality were mixed No mortality to fish of varying sizes was caused by ozone treatment of the water Future laboratory experiments are planned to determine whether ozone can improve water quality either on its own or in combination with aquatic plants Aquatic plants are being evaluated for use in combination with settling ponds to improve water quality Results are still being analysed but preliminary examination of them suggests that N and P levels and total suspended solids are decreased when aquatic plants are grown in waste water AYAD Stephanie Birch will undertake research on vermicomposting in 2008 Experiments will examine the optimal ratio of rice straw or water hyacinth relative to fishpond sediment Two local worms have been recovered in soils at O Mon In addition the introduced Tiger worm which is commonly used elsewhere for vermicomposting will be used in experiments The relative effectiveness of the three worm species and mixtures of species will be evaluated The training workshop on Land application of Waste was held at CLRRI on 26-29 December 2007 with 17 participants from the provinces of Cantho, Vinh Long, An Giang and Dong Thap Participants were from fisheries, agriculture extension and natural resources management positions Introduction & Background Fishpond aquaculture is as a major industry in the Mekong Delta However, wastewater and solid waste discharge from fish ponds is causing pollution of canals and rivers harming the quality of water used for household purposes and threatening the future of the aquaculture industry itself There is a clear and urgent need to develop strategies for reducing waste discharge from fish ponds so that the fishpond aquaculture industry can continue to support income diversification in the Mekong Delta, while complying with the water quality discharge standards outlined in Vietnamese law and regulations (Ministry of Fisheries 2006)1 Water in fish ponds is replaced frequently generating large quantities for disposal or re-use Currently wastewater is mostly discharged into communal rivers and canals, but this has caused significant downstream water pollution, such that most of the aquaculture is now located in the headwaters of catchments In order to reduce pollution, National Environmental Law introduced in 2005 prohibits direct wastewater discharge into rivers and canals Offenders may either be fined or their operation closed until compliance is achieved In addition annual emptying and cleaning of solid waste from the base of fish ponds is essential to control the spread of diseases among fish This produces an organic-rich slurry comprising about 35 % solids Discharging this slurry into communal waterways is also prohibited under the law However, there appears to be poor compliance with the law by operators of fish ponds Strict compliance with the law without cost-effective treatment and recycling strategies would have a crippling effect on the fishpond aquaculture industry It is critically important to develop effective strategies for fishpond operators so that they can treat wastewater and solid wastes to meet discharge standards without large costs While there is widespread acceptance that water pollution from fishpond discharge is prevalent, there appears to be little evidence gathered and published on the problem In particular there appears to be a lack of baseline water quality data from which to demonstrate a decline in water quality Moreover, there is little current monitoring of water quality in the medium to small sized canals in which the water pollution problem is most obvious Hence it remains unclear what water parameters fail to meet the Vietnamese water quality standards, how frequently breaches occur, where they occur and the key risk factors From first principles, it is likely that the water pollution problems are most severe during the dry season when flushing and mixing of discharge water is least, and in the smaller canals especially where their flow is blocked by aquatic plants and by barriers The Mekong Delta produces 400,000 t of catfish per annum mostly in freshwater ponds Most of the fish are exported to the USA, and increasingly to European countries and Japan The exported fish must meet sanitary requirements in these markets A major variable in producers’ capacity to control the inputs to fish ponds is the water used to fill ponds, which is drawn from rivers and canals However, under the cumulative influence of intensive fishpond aquaculture, a decline in quality of river and canal water from the discharges is limiting productivity and expansion of fishpond aquaculture by causing the downstream spread of Ministry of Fisheries (2006) Maximum concentration limits allowable for pollutants discharged to waterways Regulation No 02/2006 Issued March 2006 bacterial disease and parasites in the water It may also be impacting adversely on the health of families that draw significant amounts of their domestic water from these polluted sources The challenge of this project is to protect the fishpond aquaculture industry which is a source of diversified income for farmers in the Mekong delta by treating the waste water and solids from fish ponds, whilst at the same time protecting the environment and householder users from water pollution The expected outputs are directed to improving competitiveness of fishpond aquaculture producers in the Mekong Delta In addition, technologies to be developed will improve natural resources management by decreasing water pollution from uncontrolled discharge of fishpond waste water and solids into rivers and canals The overall Project objective is to improve the sustainability of fishpond aquaculture production and water quality in the Mekong Delta Specific Project objectives are: • Develop effective treatment strategies for wastewater and solids from fishponds before discharge to reduce water pollution; • Develop resource recovery and re-use strategies for waste water and solids from fish ponds including land application and novel end uses; • Increase stability of household income from fishpond aquaculture through encouraging diversification of production and markets in the Mekong Delta This project targets fishpond aquaculture, not other types of aquaculture such as cage aquaculture and shrimp aquaculture Cage aquaculture is declining in importance due to rising costs and riskiness of the production system compared to pond culture Other studies have examined shrimp aquaculture in brackish water environments (Be, 1997) Shrimp aquaculture is also under threat due to environmental impacts Hence, there are lessons to be learnt from other forms of aquaculture, in particular the need to address environmental issues that can impact on the sustainability of the industry even when economics for it are favourable Fishpond aquaculture is practiced by three main groups in the Mekong Delta: farmers using the VAC system to recycle waste water and solid wastes from fish ponds; small farmers who have both fish ponds and crop land but without integration of these components of the farm; specialist producers who essentially use all of their land for fish ponds The VAC system already practices re-cycling of wastewater and solid waste to recover nutrient resources In so doing the level of pollution caused by water discharge is probably decreased However, there appears to be little evidence to demonstrate the benefits of the VAC system for downstream water quality The present project will assess the impact of the VAC system on water quality in downstream canals, and as necessary examine modifications to the recycling of wastewater and solid waste in order to meet water quality standards for discharge The second group of producers comprises small farmers who have a few fish ponds within a farm carrying out crop production for padi and/or fruit trees and vegetables The present Project is particularly relevant to these two groups of producers who have sufficient land for wastewater and solid waste treatment by re-cycling, but are currently discharging wastewater and solid wastes directly into canals Both liquid and solid waste from aquaculture contain carbon and nutrients which can be recycled on farms to boost production of rice, vegetables and fruit trees, as well as novel products for small scale agro-industry Solid wastes can be treated in a number of ways, including land application, vermi-composting, microbially-activated decomposition and ozone treatment However, research is needed to ascertain the potential of each method for treating wastes and improving water quality, and to gather evidence of their effectiveness in meeting water quality outcomes The specialist fishpond producers generally have inadequate land remaining for recycling wastewater and solid waste Currently wastes are discharged directly into canals and rivers, sometimes after treatment with biocides Further investigation is needed to determine the impacts of biocides on the downstream environment In addition, opportunities need to be explored for cooperative arrangements that allow the disposal of wastewater and solid wastes from the specialist producers onto neighbouring farmers’ land However, the best practices for carrying this out still need to be developed, and once established can be extended to this group of producers Progress to Date Implementation Highlights Baseline study: Questionnaires for the baseline study were formulated in consultation with researchers of Can Tho University, and with extension officers in Can Tho city and An Giang provinces The survey was conducted in October-November 2007 at Cantho city and January-February, 2008 at An Giang province In total 240 questionnaires of stakeholders (rice and fish farmers were sampled in equal numbers) were collected (2 districts/province) (Table 1, 2) Results showed that all stakeholders were concerned about surface water pollution because of its impacts on sustainability of production and livelihoods There were about 15-24 % of the farmers (including both fish and rice farmers) stating that water quality is bad Only 30-55 % of farmers were fully satisfied with the quality of water available for fish farming In Cantho, 80 % of farmers accessed household water from public water supplies and groundwater and in this province 83 % of farmers were satisfied with water quality for household use However, in An Giang, where 57 % of farmers used river water for household purposes, the level of satisfaction with water quality was only 36 % Most farmers (91 %) attributed poor water quality for household use to fishpond farming in An Giang, but to fishponds (37 %), pesticide use in rice fields (15 %) and other causes (48 %) in Cantho Most farmers anticipated that water quality improved during the period of flooding (September- November) Farmers practicing fish culture are richer, had more formal education and were younger than those carrying out rice cultivation, based on numbers of concrete houses, living commodities, pumping machines and incomes However, about 15 % of fishpond holders are recent migrants who have bought or rented land from local farmers Impacts reported on water quality include greenish-black colour, bad smell, high turbidity, and skin itching on contact Moreover, farmers raising fish recognised that percentages of disease-infected fish is much higher now (about 15%) than before (< %) The demand for effective and economical solutions for control of water pollution is the first priority of stakeholders The investment cost for raising fish is large and most of farmers lend money from either banks or their neighbours hence they are concerned about threats to the viability of the operation Survey of farmers’ practices on fishpond waste treatment: The survey of farmers’ practices on fishpond waste treatment was completed during October-November 2007 at Cantho and January-February, 2008 at An Giang province Most (68-80 %) of the wastes (liquid and solid) are pumped directly into waterways (rivers or canals) In the case of fishponds located nearby large rivers (Tien and Hau), waste is apparently diluted by the large volume of water flow and it is not reported to cause much problem in comparison with discharge situated at the far end of small rivers or canals There are only 5-8 % of fishpond holders with settling ponds, 14-25 % of fishpond farmers who practice waste recycling on paddies and the rest discharge directly to the waterway The higher adoption of wastewater recycling was reported in An Giang (25 %) A concern requiring management when using wastewater arises from the high content of nitrogen in waste water causing rice yield loss by lodging However, as our results below show, judicious use of waste in combination with reduced inorganic fertiliser application may maintain rice yield and increase it in some cases Table General socio-economics aspects of rice and fish farming households from a survey of 240 farmers practicing rice or fish farming in Can Tho and An Giang provinces Can Tho An Giang Items Fish culture Rice culture Fish culture Rice culture Age of household head 43 49 47 47 (years) Level of education 7/12 5.5/12 5.7/12 5.8/12 Years of experience 3.6 20 9.4 20 No labor/family 3.4 3.6 3.7 3.0 Land tenure area (ha) 0.6 1.2 0.58 1.50 House types (%) 48 42 23 43 - Concrete 44 39 73 42 - Brick 19 15 - Thatch Water quality (%) 46 51 55 30 - Good 39 25 22 52 - Medium 15 24 23 18 - Bad Wastewater discharge method (%) 100 68 100 80 - River or canal 24 15 - Paddy - Settling pond However, there have been instances reported of farmers applying high levels of salt (NaCl) to fishponds to control disease The use of salt-affected wastewater in one case led to failure of the rice crop In the long term, the high P in sediment relative to N may cause a build up of soil P levels, although previous research suggests that the soils of the Mekong delta, especially the acid sulfate soils, have very high P sorption capacity We have heard reports that one farmer constructed a sand bed filter with activated charcoal for the treatment of waste water from fishponds by using a water recycling system However, we have not been able to inspect this system Concerning the use of bio-products for water treatment in catfish culture, nearly 50 % of farmers at both sites used Vikong, BKC, Bioca, Yulai, Aquapure, Prawbac and some others (Table 3) They also used antibiotics to control mainly bacterial diseases in the digestive tract of catfish Some common antibiotics like Amoxycilline, Cotrim, Penicilline, Kanamycine, Oxamet, and Tetracylline had been used mainly by mixing into feeds in An Giang (96%) or putting directly in water (40% of farmers in Cantho follow this method) According to farmers, these antibiotics were very effective to control catfish diseases Fortunately, almost all of farmer used antibotics at recommended dosage For sanitary purpose and control of algae in fishpond, 93% of farmers in Cantho and about 66% in An Giang province applied copper sulphate, BKC, Vikong, chlorine, Juka and even salt or lime (Table 3) Among these, BKC and chlorine were the most common chemicals which had been used both in An Giang and Cantho Table 2: Quality of water for irrigation and for household use as a % for 240 respondents Items An Giang (%) Can Tho (%) Water source for household use (cooking & drinking) River/ canal 57 17 Tube well 13 57 Public water supply 30 26 Water quality for household purposes Good 46 80 Medium 18 13 Bad 36 Reason for bad quality of water Waste from fishpond 91 37 Pesticides from paddy 15 Others 48 Time when good water quality is available for irrigation Flooding 62 58 Winter-Spring 13 All year round Rainy season 28 17 Table 3: Chemicals used for water treatment in catfish ponds % of respondents Items Cantho An Giang Bio-products (%) 48 43 Antibiotics (%) 72 54 Mixing antibiotics with feed 60 96 Mixing antibiotics with fishpond water 40 Water treatment methods BKC (benzalkonium chloride), 21 28 Vikong 43 Copper sulfate Chlorine (sodium hypochlorite) 21 10 Others 49 Efficacy (2+3) 100 100 Water management is very important in catfish culture All farmers normally spread lime or salt along the sides and at the bottom of ponds after constructing new ponds or after draining out all water during harvesting of fish (Table 4) Dosages of lime and salt varied from 300-400 kg/ ha/yr Ponds are kept dried for 3-5 days before refilling with water for the new crop of fish More than 95% of farmers changed and/or added water to fish ponds regularly (about 1/3 volume of pond) and there was about 50% farmers at both sites that practiced cleaning of the bottom of the fishpond by pumping out sludge during time of raising catfish However, most farmers had to pump sludge out of their pond after harvesting 10 fish (Table 11) The practice of discharge waste directly to water source caused water pollution Most of farmers had handheld pH meter to monitor water quality Other ways to detect water quality were by observation of water colour or smelling odour of water If oxygen is deficient, most fish will come to the surface of water in the early morning; farmers will then know oxygen in fishpond is sufficient or not Table 4: Water management in catfish culture Items Renewed fishpond (%) Lime (kg/ha) Salt (kg/ha) Dried bottom of pond (%) Days of drying Added and/or changed water periodically (%) Percentage of added or changed water Water quality monitoring pH Color or odour Ammonia and oxygen (from fish behaviour and odour) Sludge discharged During raising time (%) After harvesting Cantho 100 425 325 100 3.5 98 33 An Giang 100 350 300 100 100 33 95 62 90 12 65 50 60 50 75 Survey data on diseases of catfish are presented in Table The most severe and widespread disease to catfish is caused by bacteria (about 90%) besides the others disease causing death of catfish The most common symptoms of bacterial disease called haemorrhage are red colour appearing on the mouth, fins and tail Other diseases called swelling head and slimy loss occur but they are of minor importance Table 5: Catfish diseases and control measures Items Cantho Symptoms Haemorrhage 93 Slimy loss Swelling head Occurrence All year round 26 Rainy season 53 Dry season Flooding time Climate change Control efficacy High 92 Medium Low An Giang 74 24 17 61 6 10 82 10 Diseases on catfish occurred mainly in the rainy season when catfish are younger (