Yield of rice and fish
The farmers in the two districts shared many basic characteristics (Table 3). They used almost the same amount of rice seeds, and the rice yields did not differ between the groups of farmers (P > 0.05, Table 4). The slightly lower yields among the rice–fish farmers could be explained by the fact that part of the field was used for the fish canal.
The two most common fish species grown among the rice–fish farmers were Snakeskin gourami (Trichopodus pectoralis) and Climbing perch (Anabas testudineus), with an average yield of 586 and 142 kg per hectare, respectively. Only three of the rice–fish farmers grew other fish species, such as grass carp (Ctenopharyngodon idella) and common carp (Cyprinus carpio).
The majority (80%) of the rice–fish farmers had changed from only rice farming to rice–fish farming. The main reason was that they had learned that rice–fish farming could increase their income. The fish yield had declined over the last 3 years for all rice–fish farmers, and most farmers felt that this was due to an overuse of pesticides. Farmers also perceived that the catch of wild fish had declined because of pesticides, the use of illegal fishing gear and loss of breeding habitat for aquatic animals, due to intensification of rice faming and the use of three crops per year.
Agrochemicals and pest management strategies
The rice–fish farmers used less amounts of fertiliser than the rice farmers in both Cai Be and LSWR (Table 5). The farmers in LSWR used higher amount of fertilisers than the farmers in Cai Be (Table 5, P < 0.05).
All farmers used pesticides as the main method to control pests. A total of 38 different pesticides and 35 different active ingredients (a.i.) were identified among the rice farmers in Cai Be. The rice–fish farmers in Cai be, used 36 different pesticides with 32 different active ingredients, which was slightly lower than the rice farmers. The highest number of pesticides was found in LSWR, with 40 different pesticides and 37 different active ingredients.
Fungicides and insecticides were the group of pesticides with the highest diversity. This could be due to problems with pesticide resistance in insects and fungal populations. The most problematic pest, mentioned by the farmers in Cai Be and LSWR, was the Brown planthopper (Nilaparvata lugens), which transmits a pathogenic virus and can cause significant crop losses. Brown planthopper was also a problem for the farmers in LSWR. The most commonly used insecticide, among all farmers was Chess 50 with the active ingredient pymetrozine.
Fungicides were commonly used by all farmers to control the rice blast disease caused by Pyricularia oryzae. The most commonly used fungicide was Anvil (a.i hexaconazole) in Cai Be and Amistar (a.i azoxystrobin and difenoconazole) in LSWR.
Herbicides and molluscicides were the group of pesticides with the lowest diversity. The most commonly used herbicide and molluscicide in Cai Be and LSWR were Sofit (a.i pretilachlor) and Toxbait (a.i metaldehyd), respectively.
All farmers said that they used pesticides that only killed target species. Rice–fish farmers were more cautious to use pesticides than the other farmers, because they had seen negative effects from pesticides on the fish. All farmers (except for two non-IPM farmers in Cai Be) knew about natural enemies to pests in their fields. The natural enemies that were mentioned were spiders, ants, bees, beetles, dragon flies, ladybugs and fish. All farmers knew that pesticides could kill these natural enemies, which in turn could lead to more problems with pests.
Most of the farmers in Cai Be, had learned how to use pesticides from governmental staff working at plant protection offices, which the rice farmers and rice–fish farmers on an average met 5 and 9.5 times per year, respectively. Most of the farmers in LSWR had learned how to use pesticides through personal experience and resellers. Five rice farmers met staff from the plant protection offices one to three times per year, while the other 15 rice farmers did not meet plant protection staff at all.
Many of the different pesticides were only applied by a small number of farmers. Rice–fish farmers used significantly lower number of different pesticides as compared to rice farmers, in LSWR (Table 6).
Rice–fish farmers also applied a significantly lower dose of insecticides compared to the farmers in LSWR. Their total use of pesticides also seemed to be lower compared to the other farmers, although this difference was not statistically significant (Table 7). The rice–fish farmers said that they had reduced their use of pesticides by around 40–50% during the last 3 years because of less pests and diseases. The non-IPM rice farmers in Cai Be had not changed their use of pesticides during the last 3 years. The farmers in LSWR had increased their use of pesticides by around 25%, because these farmers saw that pests had become more resistant to pesticides and their only solution to this was to increase the use of pesticides.
The farmers in Cai Be had learned about IPM from training courses. All rice–fish farmers had applied IPM for 3–12 years. The main reason for applying IPM was because it reduced the production costs (Fig. 2), and all of the farmers who applied IPM said that it had helped to increase their income. In LSWR, no farmer applied IPM because they thought it was difficult to combine with their rice farming practices.
All farmers in Cai Be said that the pesticides had been a problem for their health. Insecticides were seen as the most harmful pesticide (Fig. 3). Almost all of the farmers used a mask as the only protection when spraying.
In LSWR, 10 rice farmers had experienced health problems related to pesticide use. Their symptoms were similar to the farmers in Cai Be such as dizziness and headache (Fig. 3). All the farmers in LSWR used mask and protective clothes.
All the rice–fish farmers said that rice–fish farming had increased their gross income by 10–30%. This was confirmed by the finding that the additional fish yield gave a 20 percent higher gross income for the rice–fish farmers as compared to farmers who cultivated only rice (P < 0.05, Table 8). Overall, the increased income from fish and decreased costs for fertilisers and pesticides resulted in a higher net income for the rice–fish farmers as compared to the other farmers, although this difference was not statistically significant. The selling price for rice varied to some extent between different rice varieties, which explains why the farmers in LSWR had a slightly higher income for rice despite their slightly lower rice yield compared to the rice farmers in Cai Be (Table 8).
Overall, the financial analysis shows that integrated rice–fish farming is a financially competitive alternative to rice monoculture, and that it uses less pesticides and fertilisers, which is likely to have positive effects on the environment and the farmers’ health, with additional positive long-term economic effects.
Farmers’ perception of ecosystem services status and trends
As shown in the previous financial analysis, rice has a large and direct impact on the farmers’ income and all farmers said that the rice yield was the most important service gained from the rice field ecosystem (Table 9). Still, the farmers also identified a number of other ecosystem services of importance to their livelihoods and wellbeing (Fig. 4).
Provisioning services included, in addition to rice, clean water, aquatic animals, wild vegetables and fuels. Among supporting services, habitats for wildlife and soil structure, were most commonly mentioned. Regulating services such as pollinators and natural enemies to control pests and diseases, were identified as important. Cultural services such as aesthetic values and festivals, were not so commonly mentioned by the farmers, but still seen as important (Fig. 4; Table 9). Overall, provisioning services seemed to be easiest for the farmers to understand and directly relate to.
Trends in the abundance of key ecosystem services
The farmers felt that during the last 15 years, there had been an increased production of rice but a decrease in many of the other ecosystem services (Fig. 4; Table 10). Contrary to the farmers in Cai Be, 35% of the farmers in LSWR had experienced an improved water quality during the last 15 years.
The future trend, for the coming 15 years, was perceived mostly as a continued increased production of rice and a continued decrease of the other key ecosystem services (Table 11). However, 19 farmers from the three different groups thought that natural enemies would increase.
All farmers said that their rice yields had increased during the last 15 years (Table 10). The majority of farmers felt that the rice yields would continue to increase. However, some farmers, especially intensive rice farmers in Cai Be, thought that the rice yield had peaked and would not be possible to increase in the coming 15 years (Table 11). The most common reasons for the increased rice production were the introduction of high-yielding rice varieties and new farming techniques, including IPM (Fig. 5).
None of the rice farmers in LSWR, but 13 rice–fish farmers and 9 rice farmers in Cai Be, thought that pesticides could have a negative effect on the rice yield. These farmers had experienced that the use of pesticides could result in resistant pests, increased disease problems and decreased populations of natural enemies to the rice pests.
In LSWR, the farmers said that they would like to have three crops per year because that would increase their income, but it was difficult for a single farmer to switch to three crops if not all neighbouring farmers did the same.
All farmers said that the number of aquatic animals found in the rice fields and related wetlands had decreased during the last 15 years, and the majority said that this trend would continue (Table 10, 11). All farmers felt that the high use of pesticides was the biggest problem (Fig. 6).
The rice–fish farmers also mentioned that intensive farming, with three crops per year, was a reason for the increased loss of aquatic animals (Fig. 6). Having one or two crops per year was seen as beneficial for aquatic animals, since it gave them more time and space to breed and feed. One farmer in Cai Be said that he used to harvest around 100 kg of wild fish per year, but today, he only caught around 40 kg due to more intensive rice farming. Some older villagers in LSWR said that fish were not as plentiful as they used to be, and that the size of the fish was much smaller than before.
All farmers felt that a decreased use of agrochemicals would help to halt the loss of aquatic animals. Rice–fish farmers said that integrated rice–fish system could contribute to an increased abundance of aquatic animals. Seven of the farmers in LSWR emphasised the need for more education to improve the situation.
The majority of farmers thought that the abundance of wild vegetables had decreased (Table 10), mainly because of an overuse of agrochemicals (Fig. 7).
The most common solution proposed to stop the decrease in wild vegetables was to minimise the use of agrochemicals, and especially herbicides. The rice farmers in Cai Be also saw IPM as a way to improve the conditions for wild vegetables and plants. Rice–fish farmers said that intensive farming and the lost connectivity between rice fields and surrounding areas had contributed to the loss. To improve the situation, they proposed to integrate wild vegetables with rice, both in the canals and on the dikes. Wild vegetables could provide food for fish and also be used for their own consumption and for sale. The idea of having a rotation between rice and vegetables was also mentioned by several of the rice farmers in Cai Be, which could be a sustainable alternative of having three crops of rice per year.
The majority of farmers in Cai Be felt that the water quality had decreased and was going to get worse in the future (Tables 10, 11). None of the farmers used the water for household consumption anymore. They stopped using it 10 years ago, since the quality had decreased a lot, and people experienced negative health aspects like rashes from exposure to the water. None of the farmers in Cai Be believed that the water quality could get good enough to use it for household consumption again. They believed that the change had gone too far to reverse. The farmers were concerned about how upstream activities impacted on the water quality. The rice–fish farmers said that they closed their water intake when neighbouring rice famers released water from their rice fields, to stop the polluted water from entering into the fields, since they had experienced negative effect on their fish. Some of the farmers also had rice fields without fish as a buffer zone between their rice–fish fields and the surrounding rice fields, to avoid getting pesticides into their rice–fish fields.
All farmers felt that the use of agrochemicals and the environmental pollution from farms, households and industries, were the main reasons for the decreased water quality (Fig. 8). Seven of the farmers in LSWR, however, said that the quality of the water had improved due to measures taken against acid sulphate soils (flushing out iron sulphide). Many farmers in LSWR also said that they still used the water for household consumption and drinking. However, many of them said that the water quality had decreased, due to chemicals from rice fields and they were concerned that an overuse of pesticides and wastewater would reduce the water quality in the future.
A reduced use of chemicals and better wastewater treatment systems were seen as possible solutions to improve the water quality by all farmers. Some farmer said that these measures needed to be supported by improved education.
Most farmers felt that the use of rice straw for fuel was increasingly being replaced by gas or electricity (Fig. 9). Many farmers mentioned that rice straws could be beneficial in other ways, such as substrate for mushrooms or as food for animals.
Most farmers felt that there had been a decline in natural enemies during the last 15 years (Table 10), mainly because of a high use of agrochemicals and habitat destruction (Fig. 10). Proposed solutions to the decline in natural enemies included the use of less toxic and lower amounts of pesticides. Many of the farmers in Cai Be also mentioned that IPM builds on protecting natural enemies to control rice pest, and, therefore, could help to both reduce the use of pesticides and increase the number of natural enemies. Some farmers felt that the number of natural enemies had increased and would continue to do so in the future, because people increasingly knew about the benefits from natural enemies and, therefore, were willing to protect them.
Habitat for wildlife
The majority of farmers said that habitats for wildlife had decreased compared to 15 years ago (Table 10). Environmental pollution, intensive farming, high use of agrochemicals and illegal fishing gears were mentioned as the most common reasons for the decline (Fig. 11). Farmers in Cai Be said that the low water levels kept for the rice created problems for aquatic organisms and that the use of machines, instead of harvest by hand, had limited the breeding time for many animals.
Some farmers in Cai Be expected that the habitat situation would improve in the future (Table 11) because of the use of IPM and because people had started to recognise the importance of ecosystem services for a sustained production of rice. In LSWR, three famers said that the habitat status was good and would continue to be so, because they only had two crops of rice per year, as the fields were flooded during the time for the third crop. They felt that this and the closeness to the reserve area safeguarded a good habitat for wildlife.
All farmers felt that a decreased use of agrochemicals and increased protection of habitats would improve the status of habits for wildlife. Farmers from Cai Be also mentioned that stronger laws against illegal fishing, having two crops instead of three crops, treating wastewater, integrating rice with other crops and education, would help to improve the situation.
Aesthetic values and festivals
Cultural services were the most difficult services for the farmers to understand, although most farmers could relate to aesthetic values and festivals after some discussions and explanations. Some farmers also talked about the importance of rice fields for generating employment. The majority of farmers experienced a decline in cultural services due to intensive farming systems, use of machines and urbanization (Table 10; Fig. 12). All farmers felt that younger people did not see the countryside in the same way as older people. They did not appreciate the aesthetic value and the life of being a rice farmer, but preferred to move to the cities to work (Fig. 12). This was believed to be the future trend (Table 11). However, some farmers believed that cultural ecosystem services would increase in the future, because of better income and more festivals.
Several of the farmers did not know how to enhance the status of cultural services, but a few mentioned that education could help to increase the awareness of cultural services. Some of the rice–fish farmers and farmers in LSWR mentioned ecotourism as a way to enhance cultural services, and the need to preserve old farming methods.
Preferences to future farming systems
In Cai Be and Lang Sen, 20 and 15% of the rice farmers, respectively, preferred intensive rice farming with the main aim to produce high yields of rice, whereas 80 and 85% of the farmers, respectively, preferred rice farming systems that would enhance or preserve multiple ecosystem services at the expense of somewhat decreased rice yields (Fig. 13).
However, if the rice yield would become less than 6 tons per crop, they might re-consider their choice. In Cai Be, the farmers felt that three crops of rice per year was necessary to get enough income, even though they were aware that this could have a negative effect on the yield, since the rice field did not have time to recover between the crops. They also knew that these intensive farming strategies could cause increased problems with diseases and other pests. However, they could not see any option due to the high competition and the low market price for rice.
Only 10% of the rice–fish farmers in Cai Be preferred a system with a high yield of rice, and 90% preferred rice farming systems with lower rice yield, but that would help to keep all ecosystem services in a good quality (Fig. 13).
The rice–fish farmers said that an integrated system could provide both many ecosystem services and an acceptable rice yield, but that this was hard to establish since neighbouring farmers used a lot of pesticides that influenced negatively on their rice–fish fields. They also said that they could not accept their rice yield to decrease too much since it was their main income. They were positive about the income from fish, and wanted to continue with integrated rice–fish farming, because it diversified their income opportunities and provided benefits to the environment.