Efficient nutrient use in rice production in Vietnam achieved using inoculant biofertilisers

This new ACIAR project has now been in progress for one year. Based on the positive results obtained in two shorter projects funded by ACIAR and AusAID in the period 1999-2002, the project has recently come through its first set of experimental field trials run from July-October 2004 with flying colours.

Earlier research findings that statistically significant improvements in the yield of rice could be obtained by inoculation with selected strains of biofertiliser microbes have now been confirmed. In a trial set up at Dai Mo near Hanoi by Professor Nguyen Thanh Hien of Hanoi University of Science (HUS), treatments with certain combinations of inoculated strains of bacteria and a soil yeast have yielded significantly greater dry rice (dry weight) than other combinations, or compared to no treatment with microbes at all. The variation observed in rice yield of about 1 tonne per hectare, depending on the strain combinations used, has confirmed the important role that many microbes in the rice plant's rhizosphere can have in crop production.

Other trials supervised by Dr Pham Van Toan based at the Vietnam Agricultural Science Institute (VASI) and in Nam Dinh province in the Gaio Hai district have confirmed the biofertiliser response. , giving yields either the same or with some improvement Aat the reduced 50% rate of fertiliser inputs, the same or improved yields were generally obtained. Dr Bo of MARD, Dr Hoang Minh Tam, VASI's director, Dr Toan of VASI, Professor Hien, and Misha Coleman, ACIAR's manager, visited the Nam Dinh experimental site last October just before harvest.

Dr Phan Thi Cong of the Institute of Agricultural Sciences of Southern Vietnam (IAS) supervised another large field trial at Cu Chi near Ho Chi Minh City, designed to examine the interaction between N-levels and biofertiliser response. No statistically significant effect of inoculation with thea particular combination of biofertiliser strains used was obtained. However, although there was a consistent trend of increased yield with BioGro at all with nitrogen levels used, indicating beneficial effects of inoculation. However, the excellent data set obtained by Dr Cong and her team is expected to be a good basis for future work in the project to help understand why this low lack of response occurred. For example, Dr Toan's trial at VASI suggests there may be a significant interaction between rice cultivar and biofertiliser response, with some rice cultivars responding more than others. There are several other differences in methods of rice production between the north and the south of Vietnam that could also have affected in the result needing investigation.

A rice trial with BioGro was also successfully conducted in collaboration with by Dr Laurie Lewin at the Yanco Rice Research Institute. Some interesting trends were observed, but no statistically significant (P<0.05) yield increase of grain was found. At Cowra in collaboration with Mr Ashley Mead of NSW Department of Primary Industries, a second Australian trial was conducted with wheat, incorporating the Citrobacter freundii (C3) strain as one treatment to be harvested in December 2005. This trial was AQIS-approved, conducted under a set of conditions for the application of imported bacterial strains. In earlier greenhouse research, C3 had significantly increased the grain yield of wheat. The project work at Cowra involves a complementary ARC Linkage project funded by the Australian Research Council and Bio-Care/Becker Underwood, the commercial inoculant manufacturers.

In March 2005 a project review workshop was held at the University of Sydney with visits to the Yanco Rice Research Institute and ACIAR in Canberra. The workshop was hampered by the need to postpone a visit by Vietnamese partners for 12 months but a productive exercise of review of the first year's results with recommendations as well as interaction with other relevant research at ACIAR was completed. In June 2005, a BioGro industry workshop was held at the Hanoi University of Science, to study economic and extension aspects of biofertiliser production and use (see attached reports). The workshop included travel by project team members (from all Vietnamese sites including Cantho University) to Phu Ninh in Phu To Province to inspect the Bai Bang Paper Company BioGro production system. The visit was hosted by Dai Van Hoi (Chairman) and Nguyen Van Khoi (Director Bai Bang Trade Union Joint Stock Company), involving inspection of field sites where maize and rice were grown with BioGro, and a hilly site where eucalypt seedlings were being raised using BioGro at rate of 400 kg per ha.

The Bai Bang Stock Company demonstrated anAn efficient production plant for BioGro. This useding waste tree bark from paper manufacture composted with Hien's specific compost inoculant strains to form the compost. The compost was then sieved and and then inoculatedion with BioGro starter strains for BioGro productionwas demonstrated. The Company applied 153 tonnes of BioGro to 437 ha (16 farms) on rice, peanut, soybean and maize, with 23 ha of farmer trials (see attachments). This was an impressive demonstration of vertical integration and a multi-use application of the BioGro technology. Currently, 15 tonnes of bark was being composted using Professor Hien's inoculants yielding about 12 tonnes per day of compost as carrier for BioGro (1N+HY+TB23) produced on 26 working days each month.

The scientific principle being tested in this project is that biochemical interactions between plants and microbes can result in more efficient use of soil nutrients, such as nitrogen and phosphorus. We consider tThe improved efficiency in the use of plant nutrients by rice observed is considered to be a result of bearliertter root growth and improved mobility of key nutrients caused by the microbes. The effect is symbiotic in that the microbes depend on carbon compounds excreted by the plant roots for their growth while the plant benefits from the improved nutrient supply provided in return by the microbes. In the second year of the project, farmer trials are planned foralso expected to be conducted in the Mekong Delta (Dr Be, Cantho University) as well as the experimental trials at the other three sites (HUS, VASI, IAS).

This project aims to establish inoculant biofertilisers for rice as a reliable technology and to foster extension of its application by studying its economic, social, and environmental benefits.

Objective 1: Conduct field trials in Vietnam and Australia designed to optimise, extend and promote biofertiliser technology on rice farms for profit increase, extending this technology to the south of Vietnam,

Objective 2: Design and evaluate a set of simple field tests for quality control of biofertiliser products aimed at ensuring their effectiveness under typical paddy rice field conditions,

Objective 3: Investigate the economic and commercial feasibility of inoculant biofertiliser production in Vietnam,

Objective 4: Conduct laboratory and field research to reveal the mechanisms of the PGPR biofertiliser effect.

This project has now been in progress for two years. After one year, positive results with the biofertiliser product known as BioGro obtained in two shorter projects funded by ACIAR and AusAID in the period 1999-2002 had been confirmed, although positive responses ranging from commercially important at Dai Mo village near Hanoi to relatively insignificant in a trial at Cu Chi near Ho Chi Minh City were obtained. Variations in rice yield up to about 1 tonne per hectare are obtained, depending on the microbial strain combinations used. In the second year of the project, a clearer understanding of the field conditions producing positive responses is being obtained. A new field trial to test whether there is a need for repeated inoculation set up at Dai Mo near Hanoi by Professor Hien of Hanoi University of Science (HUS) has confirmed the biofertiliser effect (P<0.05). However, a repeat trial on the same plot sites showed considerable inconsistency between rice yield and strain combinations when comparing the year 1 results with those in the second year, and no significant yield response was obtained although the fact that the yield of the uninoculated control had increased suggested possible cross-inoculation of bacterial strains between plots. Another trial with high quality rice supervised by Dr Pham Van Toan in Nam Dinh province confirmed the biofertiliser response as significant, but only at limiting levels of urea application similar to those employed at Dai Mo.

Rice trials with BioGro have now been conducted in collaboration with Dr Laurie Lewin at the Yanco Rice Research Institute in year 1 and at the Australian Rice Institute at Jerilderie in the 2005-6 season. No statistically significant (P<0.05) yield increase of rice grain was found with BioGro strains in the Yanco trial but a trend towards a positive effect from inoculation with Rhizobium trifolii from Egyptian clover known to be an endophyte of rice was confirmed in the Jerilderie trial. At panicle initiation, statistically significant gains in vegetative dry yield from inoculation with Rhizobium strain R4, responsive to the level of inoculant were obtained, although this effect diminished by grain harvest and non-significant. We consider that the much longer growth period for Australian rice allows it to compensate for biofertiliser effects often apparent as yield increase with relatively short-season rice in Vietnam.

In September 2005, a Microbiology Workshop was held at Hanoi University of Science attended by 20 project participants from HUS, VASI and IAS, including two PhD students from the University of Sydney. The workshop considered microbial factors important in biofertiliser action, including classical and modern molecular quantitative methods of microbial isolation, counting and identification from inoculants such as peat. The concept of the yield polygon was introduced as a means of clarifying and possibly quantifying the actual potential for yield increase as a result of biofertiliser inoculation. This concept can accommodate the likelihood that variable responses to inoculation may indicate that the potential for yield increase is not indefinite and that in some cases, plant crop needs for nutrients may already be close to optimal preventing a response. As a result, a program of research was proposed in the ACIAR project to obtain quantitative methods indicating yield potential for inoculation with, for example, phosphorus or nitrogen mobilisers, related to objective 4 in the project.

In March 2006 a project review workshop was held at the University of Sydney attended by Vietnamese colleagues, Professor Hien, Dr Cong and Dr Toan. The results of about 10 field trials conducted in the project were reviewed and important issues regarding application of biofertilisers that had been identified during the term of the ACIAR project were discussed. Included in resultant recommendations regarding the conduct of field trials and quality control of inoculants were (i) the preparation of a common template for recording the experimental inputs of field trials (ii) correct identification of biofertiliser strains to ensure human and environmental safety; on this basis and their variable response two bacterial strains formerly included in BioGro (C3, 4P) were now rejected (iii) the use of the current commercial version of BioGro for all farmer field trials. Professor Hien reported that strong demand pressure for biofertiliser or probiotic products had resulted in her activities being diverted away from BioGro for application to rice towards products for aquaculture and other horticultural crops, neither area being a focus of the current project. Professor Hien also visited the Jerilderie field site, subsequent discussion resulting in suggestions for improved experimental trials. Objective 3 regarding economics and extension was examined from the point of view of input costs and yield increases, considering marginal factors and maximising cash returns to farmers. The considerable increase in the cost of urea as a result of high oil prices would have the effect of increasing the benefits of biofertiliser substituting for urea.

Mr Michael Rose, a PhD candidate at the University of Sydney, was awarded an Australian Youth Ambassadorship from AusAID, to work in Vietnam associated with this ACIAR project. It is anticipated that his skills will add value to aspects of the project related to strain identification and quantification as well as the development of the concept of the yield polygon as a tool designed to predict conditions under which biofertiliser can be beneficial to farmers.

This project aims to establish inoculant biofertilisers for rice as a reliable technology and to foster extension of its application by studying its economic, social, and environmental benefits.

Objective 1: Conduct field trials in Vietnam and Australia designed to optimise, extend and promote biofertiliser technology on rice farms for profit increase, extending this technology to the south of Vietnam.

Objective 2: Design and evaluate a set of simple field tests for quality control of biofertiliser products aimed at ensuring their effectiveness under typical paddy rice field conditions.

Objective 3: Investigate the economic and commercial feasibility of inoculant biofertiliser production in Vietnam.

Objective 4: Conduct laboratory and field research to reveal the mechanisms of the PGPR biofertiliser effect.

In its third year, a major development in this project was the extension of this project to farmer trials of biofertiliser technology in the Mekong Delta region of Vietnam. Cantho University's Mekong Delta Development Research Institute (MDI CTU) held a project workshop in September 2006 focussing on this development. At the commencement of the ACIAR project, the MDI's Director, Dr Tran Thanh Be had discussed the following features of the Mekong Delta: (i) variation in soil types from acid sulphate soils (low pH, 4-6), alluvial soils and grey soils; (ii) the different style of rice farming in the south, with farm sizes on average about 2 ha, broadcast sowing of rice, and features such as the use of the leaf colour chart used to indicate N-status of rice crops; and (iii) work would be carried out developing a suitable production function to optimise economic production of rice with substitution of chemical fertilisers with BioGro. Since there was currently a strong government-sponsored extension program in the Mekong region promoting the concept of "less seed, pesticide and fertiliser for more yield, quality and income" (that is "3 giam, 3 tang" in Vietnamese, i.e. "3 reductions, 3 gains"), the use of BioGro for efficient nutrient utilisation at this stage was highly consistent with this goal. The highlight of the workshop was the presentation by Dr Be reporting the results of a set of BioGro farmer field trials in three regions, acidic saline (normally 2 crops per year, Long Phu, Soc Trang), alluvial (3 crops per year, Tra On, Vinh Long) and flood prone (2 crops per year, Cho Moi, An Giang). BioGro (300 kg/ha) provided by Professor Hien in Hanoi was applied by mixing with rice seed, which was broadcast into flooded paddies. Net costs, benefit-cost ratios and production costs were presented for all sites and cropping seasons. Advantages of BioGro were identified as decreased urea N-inputs, stronger stems and less lodging, less pests, cleaner grains and less environmental pollution. Disadvantages were noted as prevalence of golden snail in wetter conditions maintained (unnecessarily) with BioGro, inconvenient weight, inability to mix with pesticides or fertiliser, difficulty to apply by dry seeding and, most importantly, the unavailability of BioGro in the Mekong Delta because of the lack of local production. The field trials of BioGro conducted in both dry and wet seasons in the An Giang, Vinh Long and Soc Trang planned by Dr Tran Thanh Be's team at the MDI have shown clear economic benefits to farmers exceeding 1 million VND per hectare compared to normal farmer practice regarding chemical fertilizer use. This was the result of being able to lower their fertilizer inputs to half and yet still achieving the same or increased yields of rice. Farmers reported improved quality of rice with brighter grain, reduced lodging and less need for chemical pest control as well as more efficient use of the nutrient N, P and K. Mr Nguyen Thanh Tam, a junior member of the MDI team, reported these results to the Biennial Conference for Young Researchers in Science and Technology for Agriculture, Forestry and Aquaculture held in Hue on March 24-25.

The reasons for such success in applying BioGro can now be better understood as a result of field experiments conducted by Dr Phan Thi Cong's group at the IAS in Ho Chi Minh City. Carefully replicated experiments in both the dry and the rainy seasons at Tay Ninh east of Ho Chi Minh City showed that applying BioGro, prepared by Professor Hien in Hanoi, allowed the same or increased yields of rice with much lower inputs of urea-N or fused magnesium phosphate-P. Supplementary experiments including the use of nitrogen-15 conducted in the IAS laboratories by Dr Cong's youthful group assisted by AYAD scheme's Dr Michael Rose from the University of Sydney have verified the ability of the microbial strains in BioGro to improve transfer of N and P to rice plants. Antibodies prepared to biofertiliser strains to be employed in quality control tests for BioGro were also returned to the University of Sydney by Dr Rose for further use in the project's research.

Research was continued in Australia on the feasibility of applying immunoblotting as a rapid means of identifying and counting biofertiliser strains. Unfortunately, a new field trial to follow up previous results obtained at the Australian Rice Research Institute at Jerilderie could not be conducted because of the continuing drought.