Đề tài Replacing fertiliser n with rhizobial inoculants for legumes in Vietnam

Collaboration for Agriculture and Rural Development (CARD) Program 218 REPLACING FERTILISER N WITH RHIZOBIAL INOCULANTS FOR LEGUMES IN VIETNAM Project title: Replacing fertiliser N with rhizobial inoculants for legumes in Vietnam for greater farm profitability and environmental benefits Project code: CARD 013/06VIE Authors: Tran Yen Thao1, Prof. Dr. Pham Van Toan2, Prof.Dr. Pham Van Bien3, Dr. David Herridge4, Rosalind Deaker5 Project implementing organizations: 1 Research Institute for Oil and Oil Plants (IOOP) 2 Institute of Soils and Fertilizers (ISF) 3 Institute of Agricultural Science of South Vietnam (IAS) 4 NSW Department of Primary Industries 5 University of Sydney SUMMARY The overall objective of the project was to decrease the use of N fertiliser used on legume crops soybean and groundnut in Vietnam by increasing adoption of legume inoculants. Replacing N fertiliser with legume inoculants will provide both economic and environmental benefits to farmers and alleviate financial stress for poorer farmers by reducing input costs. The approach was to increase awareness and demand for inoculants through an extension program including direct demonstration of the benefits of inoculants and training in their function and use. Simultaneously, a technical program targeted at increasing the production capacity of high quality inoculants in Vietnam was initiated. This included development of inoculant formulation suited to Vietnamese conditions, a system for quality control to ensure farmers would have access to high quality products and technology transfer to the commercial sector to scale up production to meet demand. The project has been successful in achieving its goals. A survey of farmers and extension officers at the beginning and end of the project indicated a clear increase in the awareness of the benefits of inoculation and demand for their availability in the market. Over the two years of the project, inoculant product formulation development reached a point where peat-based inoculants could be produced with consistently high quality by the research institutes. On-going research and development will continue to improve formulation technology to meet requirements of large scale production. Following a series of training workshops and capital investment a quality control laboratory was established at IOOP and national standards were modified to more specifically address issues relating to legume inoculant quality. The proposed standards define quality standards as well as quality control protocols. The private sector was engaged in inoculant production, distribution and extension during the project and foundations prepared for increasing involvement. Institutes have forged strong linkages with private sector companies and it is anticipated that effective relationships will continue to develop. A CARD 013/06 – Replacing fertiliser N with rhizobial inoculants 219 number of strategies have been proposed to allow future growth of the inoculant industry in Vietnam including increasing profitability to the private sector by expanding the market either by expanding the area for application or extending to the export market. 1. Introduction The Vietnamese government (MOIT, MARD) is committed to increase the area sown to legumes from the current 780,000 ha to >1,000,000 ha by 2010, with particular focus on soybean and groundnut in the Mekong Delta, the Central Coastal region and upland (highland) areas of the North, Central and North. The legumes are used for production of food, oil and protein meal, and are grown as rotation crops with rice (Mekong Delta), as intercrops in the upland areas with cassava, sugar cane, rubber, fruit and maize and as cover crops in the sandy coastal soils. ACIAR Small Project LWR2/98/27 (Increasing yield and nitrogen fixation of soybeans, groundnuts and mungbean in Vietnam through Rhizobium inoculation) identified that legume production in Vietnam currently relies on expensive imported fertiliser N, rather than cost-effective inoculants containing rhizobia. Replacing fertiliser N with rhizobial inoculants would save Vietnamese farmers A$50–60 million annually in input costs and, at the same time, help facilitate the desired expansion in legume production. There would also be positive environmental outcomes. Details of the economic benefits of replacing fertiliser N with rhizobial inoculation were outlined in the proceedings of the technical workshop to terminate LWR2/98/27. However, for this to happen, high-quality inoculants need to be readily available in the market. The current capacity of inoculant production in Vietnam is about 40,000 packets annually, and would need to be increased to about 500,000 packets annually to meet potential demand. Inoculant quality is also poor (LWR2/98/27 project) and would need to be improved. Shelf life and distribution and marketing are issues that would also need to be addressed. Moreover, there is limited awareness of the benefits of inoculants and methods of application among Vietnamese farmers and extension workers. Capacity gaps are evident at the national and institutional level. The major gap at the national level is the lack of a coordinated, focussed national legume inoculant program. At the institutional level, the gaps are capacity for medium-scale inoculant production and associated quality assurance (QA) as well as R&D and training capacity. The proposed project would address these issues of production, quality, distribution and marketing and farmer education. Involvement of the private sector in both production and marketing will ensure the long-term viability of the concept. The project objectives are to: i. Increase production of high-quality inoculants for soybean, groundnut and other legumes in Vietnam through enhancement of production capacity (personnel and equipment) at participating institutions, implementation of QA, and increased inoculant R&D; ii. Increase farmer interest and use of inoculants in Vietnam through development and implementation of an effective extension and training program on inoculants and legume nitrogen fixation for researchers, MARD extension officers and farmers through demonstration trials, workshops and meetings, and publications; iii. Ensure the long-term viability of the project through involvement of the private sector in this ‘pilot production’ of legume inoculants, with the aim that the private sector would progressively take over production as the technology and markets are developed. Tran Yen Thao, Pham Van Toan, Pham Van Bien, David Herridge & Rosalind Deaker 220 2. Project approach and methodology The project strategy is to enhance inoculant production, quality, distribution and marketing and farmer education through the collaborating institutions. It will involve both Government institutions – Research Institute for Oil and Oil Plants (IOOP), the Institute of Agricultural Science (IAS) and the Institute for Soils and Fertilisers (ISF) – as well as private sector companies (Fitohoocmon Fertiliser JSC, Cu Chi Bio-Chemical Fertiliser JSC and Humix). The latter would be involved initially in marketing and distribution of inoculants and would be provided with advice and technical expertise to improve and expand their inoculant production capabilities. In time, it is envisaged that the private sector would take over inoculant production, leaving QA to the public institutions. Involvement of the private sector in both production and marketing will ensure the long-term viability of the concept. Increased production of high-quality inoculants and QA Rhizobial strains for inoculant production – selection of strains from the collections in Vietnam and/or other institutions, eg. ALIRU (Australia), NifTAL (University of Hawaii), Suranaree University (Thailand). Strain maintenance - Protocols and operation manuals for maintaining strain effectiveness and recognition to ensure stability of inoculant quality during long-term storage were developed and implemented. Production technology – Draw on experiences from Thailand and Australia to develop production technology of inoculants at medium-scale in Vietnamese institutes through:  Modifications to broth formulations and experiments in procedures for maintaining sterility and dispensing broths into the inoculant carrier.  Testing appropriate forms of inoculant (peat, granular, liquid) that allow compliance with quality control standards and are easy to use, supply and transport. Economic benefits will be determined by assessing their effectiveness in laboratory and field trials.  Strain selection: Different strains will be tested for survival in inoculant products and during delivery of products to the field. Quality assurance (QA) - Australian QA protocols was used initially as a model. From that, QA protocols, training and working manuals specific to inoculant production in Vietnam was developed jointly between Australian and Vietnamese project scientists. Training on inoculant production and QA - Vietnamese researchers from institutes were trained in Vietnam by Australian collaborators and at Suranaree University of Technology (Thailand) in inoculant production, QA and laboratory management, as well as R&D in rhizobiology. Training on inoculant production and QA - Vietnamese researchers from institutes were trained in Vietnam by Australian collaborators and at Suranaree University of Technology (Thailand) in inoculant production, QA and laboratory management, as well as R&D in rhizobiology. Extension and training of farmers and advisers The extension-training program for farmers and extension officers was built around simple, multi-location inoculation experiments in the legume production areas (Mekong Delta, the Central Coastal region and upland (highland) areas of the North and Central and the South East). They will involve participation of farmers and extension officers in all aspects, from the design of experiments to sowing, sampling, harvesting and interpretation of results. The MARD extension service played a large role in extension activities. Data from field demonstrations was used to produce an economic model for production and use of legume inoculants in Vietnam. In addition, training courses were organised for farmers, CARD 013/06 – Replacing fertiliser N with rhizobial inoculants 221 extension workers and researchers in methods of inoculant use, and economic as well as environmental benefits of inoculation. This extension-training program was conducted by Vietnamese researchers in collaboration with Australian counterparts. Involvement of the private sector in production, distribution and marketing Three Vietnamese companies who produce and distribute biofertilizers were involved in the project. Private sector was progressively become involved as the production technology was developed and the market for the inoculants expanded. The companies were initially involved in marketing and inoculant distribution. Training workshops were open to researchers from the collaborating private companies. 3. Research results and discussions 3.1 Increased production of high-quality inoculants and QA 3.1.1 Strain selection While there is specificity in the legume- Rhizobium symbiosis, there are a range of rhizobial strains capable of forming root- nodule symbioses within plant-host groups. Inherent in this diversity is a range of effectiveness in relation to plant-growth promotion through N2 fixation. In this regard, strains should be selected for commercial production according to a set of criteria including their effectiveness and manufacturability.  Tests for effectiveness In this project, elite international strains were evaluated for their effectiveness in both potted field soil and field trials across the country and compared with national strains. Strains were also compared in the laboratory for their growth characteristics including any inherent tolerance to temperature and pH. Included in the studies were local and imported strains from Vietnamese institutes, from NifTAL (USA), ALIRU (Australia), DOA (Thailand), Korea and Argentina. Several of these strains are currently used in commercial inoculants in Australia such as CB1809 (soybean) and NC92 (groundnut). In the potted field soil trials, 11 groundnut strains for groundnut and 17 soybean strains were tested against +N control without inoculation and –N uninoculated control. All strains increased groundnut and soybean nodulation and yield compared to the control treatments. As expected, there were close correlations between nodule number, nodule weight and plant biomass while correlations between nodulation and plant height were poor. Strains producing the highest plant biomass were NC92 (Australian commercial strain), GL1 and GL2 (local strains) for groundnut and CB1809 (Australian commercial strain), SL2, SL1, CJ2 and U110 (old US commercial strain) for soybean. The total number of field experiments during 2007–09 was 36 in the 10 provinces. The experiments were conducted in the main legume-growing areas in Vietnam, from the highlands in the North, to the Central Coast area to the highlands in the South and Mekong Delta. The provinces involved were Son La, Nghe An, Binh Dinh, Binh Thuan, Dak Lak, Dak Nong, Tay Ninh, Dong Thap, An Giang and Tra Vinh. There were at least 5 treatments in each experiment comparing CB1809, SL1, SL2 (soybean); NC92, GL1 and GL2 (groundnut). Control treatments were farmer’s practice without N fertilizer and farmer’s practice with N fertilizer. The Australian strains were the most effective in terms of nodulation, biomass yield and grain yield. Compared with the uninoculated control, CB1809 and NC92 increased nodulation of soybean and groundnut, respectively, by an average of 51%, biomass yield by 31% and grain yield by 28%. Compared to the local Vietnamese strains, CB1809 and NC92, increased soybean and groundnut nodulation by an overall average of 22%. Biomass yields Tran Yen Thao, Pham Van Toan, Pham Van Bien, David Herridge & Rosalind Deaker 222 were increased by an average of 12% and grains yields increased by an average of 11%.  Tests for manufacturability Strains were also compared for their growth characteristics including rate of growth, growth in different media and their ability to grow and survive at different temperature and pH. Apart from a small increased tolerance to low pH by local strains, growth of all strains was comparable in all conditions indicating that local strains were not any more tolerant to stressful conditions than Australian strains and no survival advantage may be conferred through their application. Media with more affordable ingredients for large scale production supported growth as much as the benchmark medium yeast mannitol broth (YMB) and may be adapted for large scale commercial production. It was concluded that Australian strains NC92 and CB1809 were best able to meet the selection criteria and that these should be adopted as the commercial inoculant strains, respectively for groundnut and soybean in Vietnam. In the future, more strain evaluation will be done to develop even more effective inoculant strains. It is also proposed that cultures of these strains will be maintained, authenticated and supplied annually from the independent QA laboratory to private and public sector laboratories producing inoculants together with protocols for strain maintenance and production of broth cultures. 3.1.2 Institute capacity to produce high quality of inoculants During the almost three years of the project, technology for inoculant production at the three institutes (SFI, OPI and IAS) was developed. The principal aim was production of high quality of inoculants containing ≥5 x 108 rhizobia/g and a maximum 1 x 108 contaminants/g. Different approaches were taken to inoculant formulation development at the collaborating institutes depending on facilities and expertise. To some extent, the inoculant technologies have been adapted from those used in countries with existing successful inoculant industries, e.g. Australia, US. All institutes investigated the use of peat as a carrier and a range of peat from different sources were tested for suitability. Comparison of sterilisation techniques to reduce contaminant load was done. Some research on liquid inoculants was also carried out.  Inoculant quality in Vietnam Quality control of inoculants produced throughout the project by the collaborating institutes was carried out by IOOP. During two years 2007-2008, a total of 261 samples were tested over two years, 2007-2008 (from a total of 465 samples received, 60 from IAS, 180 from SFI and 225 from IOOP). A total of 117 samples were tested in 2007 and 144 samples in 2008. The number of rhizobia ranged between 109 cfu/g inoculant and number of contaminants between <105 and >106 cfu/g However, the number of rhizobia was high, between 5 x 108 and 3 x 109 cfu/g, in the majority of packets (72%), and contaminant numbers were low (≤106 cfu/g). Plant-infection MPN counts indicated rhizobial numbers ranging from 108 rhizobia/g moist peat but as was the case with plate counting, most inoculants (75%) had ≥108 rhizobia/g. Current standards for peat inoculants in Australia and elsewhere are ≥ 1x109 rhizobial cfu/g moist peat at the point of manufacture and MPN plant-infection counts are ≥108. Therefore, in relative terms, a high percentage of legume inoculants produced in Vietnam already meet the high standards set in other countries. During 2009-2010, the QA program was continued doing by checking inoculants produced by participating institutes as well as private companies (two companies in Nghe An and Son La). The variation in rhizobial and contaminant counts for the different batches resulted from differences in procedures and expertise amongst the three institutes. The number of CARD 013/06 – Replacing fertiliser N with rhizobial inoculants 223 rhizobia/g inoculant was unstable between production batches in 2007 but improved during 2008 – 2010. This resulted from improvement of production technology  Inoculant technology development It is likely that peat will be the major inoculant carrier for Vietnam. Vietnam has many peat mines located throughout the country but quality ranges from poor (Can Gio), moderate (Binh Phu) to good peat (U Minh). Properties of peat that have been identified as being important for inoculant production include source of peat, moisture holding capacity and sterility prior to injection with inoculant cultures. Tests on effects of peat sources on inoculant quality revealed that several of the Vietnamese peats were suitable for inoculant production supporting good growth of rhizobia. The number of rhizobia in five Vietnamese peats reached ≥ 109 cfu/g moist peat, equal to numbers supported by high quality Australian peat. There was some variation in quality. Numbers in one peat provided by Komix was only 3.4 x 107 cfu/g moist peat at 6 months. While there is some information known about properties of peat required for high quality inoculant production, it is difficult to identify the specific physico-chemical properties and measuring quality in terms of growth and survival of rhizobia is essential. In Vietnam currently, sterilization by autoclaving is used. The moisture content of the peat before autoclaving should be adjusted to approximately 20%. Depending on contamination in terms of numbers and types of microorganisms in carriers, sterilization conditions are different. Peat is often ster