Introduction
Zero or minimum tillage potato production through rice straw mulching is receiving increasing interest in Asia as a climate adaptation strategy. In this method, potato tubers are grown in the rice straw, instead of the soil. It has great advantages in improving soil health and saving labor, while reducing irrigation water, synthetic fertilizers, and greenhouse emissions compared to conventional manual tillage (Ramírez et al., Reference Ramírez, Silva-Díaz, Ninanya, Carbajal, Rinza and Kakraliya2022; Dey et al., Reference Dey, Sarkar, Dhar, Brahmachari, Ghosh, Goswami and Mainuddin2025). It also fosters natural enemies to mitigate pest and disease incidences (Ketelaar and Kumar, Reference Ketelaar and Kumar2011) and helps control weeds in the subsequent rice crop (Hoang, Ha and Dang, Reference Hoang, Ha and Dang2021). Recent studies have shown that this technology is particularly beneficial in the salt-affected coastal regions of the Ganges Delta, where, in the dry season, soil and water salinity limit crop production after rice cultivation (Sarangi et al., Reference Sarangi, Maji, Sharma, Digar, Mahanta and Burman2021, Reference Sarangi, Mainuddin, Raut, Mandal and Mahanta2024; Goswami et al., Reference Goswami, Roy, Gangopadhyay, Sen, Roy and Sarkar2024; Saimon et al., Reference Saimon, Mannan, Sultana and Mondal2024; Ramírez et al., Reference Ramírez, Hossain, Rahaman, Mestanza, Rinza and Ninanya2025). It has also been tested in the Indian states of Punjab (Brar et al., Reference Brar, Buttar, Thind and Singh2019), Assam (Ojah and Bhattacharjee, Reference Ojah and Bhattacharjee2021) and Madhya Pradesh (Parihar et al., Reference Parihar, Singh, Sharma, Chauhan, Gupta and Kumar2024); the Dhaka division of Bangladesh (Saha et al., Reference Saha, Hye, Haider and Saha1997; Ahmed et al., Reference Ahmed, Mahmud, Hossain, Zaman and Halder2017; Nowroz et al., Reference Nowroz, Roy, Haque, Ferdous, Noor and Mondal2021); northwest China by using maize residue (Li et al., Reference Li, Liu, Sun, Zhang, Liu, Li and Zhang2024; Ma et al., Reference Ma, Ma, Chai, Song, Han, Huang, Cheng and Chang2024); as well as in other regions such as Egypt (Farrag, Abdrabbo and Hegab, Reference Farrag, Abdrabbo and Hegab2016) and Hungary (Fehér et al., Reference Fehér, Zalai, Turóczi and Tóth2024).
Vietnam was ahead of other countries in widely disseminating this technology to farmers in the fallow winter season after double rice cropping. It was first introduced in 2008–2009 potato cropping period in the Red River Delta region as a form of minimum tillage instead of zero tillage (FAO, n.d.).
The pilot trials were completed with positive results, and in the early 2010s, it was eventually disseminated in 22 potato growing provinces (e.g., FAO, n.d.; Nguyen Hinh, 2012; Kim Uyen, 2013; Huu Duc, 2015). Scaling of this innovation was mainly led by the Departments of Plant Protection and of Agricultural Extension, and in some cases, with support from the FAO and Oxfam, or fertilizer companies. In some provinces, initial subsidies were given to farmers for purchasing seed potato as they were resource limited and could not risk investing in new practices (Minh Lieu, 2014; An Thuy, 2016).
This innovation was a timely initiative for the government to address environmental problems such as burning rice straw (Bac and Hien, Reference Bac and Hien2009; Duong and Higano, Reference Duong and Higano2015) and the overuse of pesticides (Pham et al., Reference Pham, Van Geluwe, Nguyen and Van der Bruggen2012). Furthermore, at that time, growing rice twice a year generated little profit to smallholder farmers (Fox et al., Reference Fox, Nghiem, Kimkong, Hurni and Baird2018), and therefore cash income from potato production in the winter fallow season was attractive to them.
The labor-saving aspect of minimum tillage was also appealing to farming communities in the Red River Delta as they were facing a shortage of labor due to the new industrial estates absorbing a large workforce from the region, leaving mainly women and the elderly to do the manual labor on family farms (Nguyen et al., Reference Nguyen, Nguyen, Le, Burny and Lebailly2018). According to the FAO, 70% of the beneficiaries of this initiative were women. The income from this intervention enabled the women, for example, to purchase television sets and even pay university fees for their grandchildren (FAO, n.d.). The women also learned new concepts of conservation agriculture, climate adaptation, and greenhouse emissions (Hoang, Nguyen and Le, Reference Hoang, Nguyen and Le2018).
There was some discussion on potential challenges in expanding this technology in large areas of winter fallow land in Northern Vietnam such as establishing an infrastructure of cold storages and seed systems (Tat Thac, 2013a); water control in the cases of flooding and drought at the beginning and end of the crop season, respectively (Tat Thac, 2013b); farmers’ capacity to invest in quality seed without subsidies; and trade-offs with space and feed for livestock (Theo, Reference Theo2013).
The literature on conservation agriculture in the global South suggests that despite the advantages of the approach, its applicability in wider contexts for smallholder farmers is questionable. This is because the application of conservation agriculture is context specific depending on the particular farming systems that determine the availability of crop residue; trade-offs with livestock; rotation of crops and its rotation timing; and the demand and supply of male and female labor, among others (Giller et al., Reference Giller, Witter, Corbeels and Tittonell2009; Stevenson, Serraj and Cassman, Reference Stevenson, Serraj and Cassman2014; Somasundaram et al., Reference Somasundaram, Sinha, Dalal, Lal, Mohanty and Naorem2020). Hence, an innovation package developed based on data from few experimental fields does not fit all. Instead, the technology needs to be flexible, tailored to specific farming contexts (Tittonell et al., Reference Tittonell, Scopel, Andrieu, Posthumus, Mapfumo and Corbeels2012; Thierfelder et al., Reference Thierfelder, Rusinamhodzi, Ngwira, Mupangwa, Nyagumbo, Kassie and Cairns2014; Giller et al., Reference Giller, Hijbeek, Andersson and Sumberg2021).
In this case of minimum tillage potato cultivation in Vietnam, it is not clear if farmers continue this method or have reverted to the conventional tillage method. To explore it, a follow-up study was planned with two objectives: (1) to understand the current status of farmers’ implementation of potato minimum tillage rice straw mulching, especially any reasons for discontinuation; and (2) to develop a long-term strategy for scaling it in South Asia by applying lessons learned from Vietnam’s experience.
The evaluation of technology adoption in conservation agriculture is also complex. There are many cases of partial adoption and continuous adaptation (Rodenburg, Büchi and Haggar, Reference Rodenburg, Büchi and Haggar2021; Han and Niles, Reference Han and Niles2023).
The focus of this study is therefore not about looking at the rates of adoption or nonadoption, but to understand how socioeconomic and agroecological variability and change influenced the process of nonadoption, partial adoption, adaptation, and/or discontinuation after initial adoption. By so doing, our study seeks to contribute to the scholarship of conservation agriculture under the rapidly changing farming systems and socioeconomic contexts in Asia.
Research methods
This study consisted of four methods/activities: (1) a literature review to collect evidence of past interventions implemented by extension centers in Vietnam; (2) phone interviews with extension centers in areas where past interventions had been confirmed through the literature review; (3) the development of site selection criteria for a case study based on information from the phone interviews; and (4) a case study in three selected communities to understand the details of current situations (Table 1).
Table 1. The methods used in this study
A literature review
Potato minimum tillage interventions were implemented under different schemes, and we could not find a consolidated document with the list and scale of the interventions at a national level.
Some documents mention that 22 provinces implemented interventions/trials (Huu Duc, 2015; Ngo and Hoang, Reference Ngo and Hoang2016; FAO, n.d.). To confirm it, we conducted a literature review to identify the name of provinces, districts, and/or communes where the interventions took place. Information was mainly collected through the government websites and online newspaper articles. We identified the name of 17, of 22, provinces (Table 2).
Table 2. The list of provinces where minimum tillage potato cultivation was introduced by the government extension center
Phone interviews
We then contacted the provincial agricultural extension centers of the 17 provinces to identify contact persons who were involved in or knew about the projects implemented in their respective provinces. Of 17 provinces, 8 provided contacts at provincial, district, or commune levels, while the remaining provinces informed us that the people who had been in charge of the pilot intervention were unidentified or retired, or had been transferred elsewhere.
We conducted semistructured phone interviews with the identified representatives from 8 provinces, who comprised 17 government officers and 2 farmers (see details in Table 2).
We asked five questions: (1) the year of intervention in their respective commune, district, or province, if available; (2) current adoption status to their knowledge; (3) the reasons for nonadoption or discontinuation after initial adoption; (4) current potato production status; and (5) their willingness to host us for a field visit and farmer interviews. In many cases, detailed information, such as the list of participants and areas of interventions, were not available (see details in Table 2).
Site selection criteria for conducting a case study
Based on aforementioned information obtained through a literature review and phone interviews, we developed site selection criteria for conducting a case study as follows:
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1. The community where farmers still grow potatoes so that we can see how they adapted the technology to fit in their contexts.
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2. The community where the government officers can identify at least four farmers who participated in the trial and the farmers are available to share their experiences with us during our visit.
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3. The communities less affected by the super typhoon Yagi that hit the Red River Delta in early September 2024, and whose government officers are not very busy with postdisaster recovery.
Criterion 2 was a challenge in many sites as farmers who had participated in the intervention were already in their 50s and 60s at that time, and the government officers have not all preserved the list of participants and their contacts.
Based on the criteria before, three provinces were selected for a case study: (1) Ha Noi Province, (2) Phu Tho Province, and (3) Thai Binh Province. The identification of districts and communes within the province was guided by the government officers whom we interacted with phone interviews.
Results
The minimum tillage potato cultivation methods and benefits
The initiative ‘Growing potatoes using the minimum tillage method with straw mulching’ was first undertaken in the winter cropping season in Hanoi, Hai Phong, and Thai Binh provinces in 2008 and 2009.
The method introduced by the Ministry of Science and Technology (2013) was as follows: after harvesting rice, the field is drained, making furrows with 25- to 30-cm wide and 20- to 25-cm deep at 1.0–1.2 m spacing. Seed potatoes are planted in two rows per bed, each 30–35 cm from the bed edge; row spacing is 35–40 cm and within-row spacing is 30 cm (50000–60000 seed tubers per hectare). Immediately after planting, rice straw is applied to cover the bed surface with 7–10 cm thickness; after 15–20 days, mulch is topped up to 10–12 cm. The recommended quantity of rice straw required to cover one unit of potato plot was equivalent to the straw yield from three units of rice plots. Irrigation water is applied in furrows 2–3 times per crop season, with water raised to one to two third of bed height and then should promptly be drained (Ministry of Science and Technology, 2013).
Nutrient management follows standard recommendations for potato cultivation: 15–20 metric ton per hectare well-decomposed manure and 120–150 kg N, 80–120 kg P₂O₅, 120–150 kg K₂O per hectare, adjusted for soil fertility, with basal fertilizers placed away from seed and topdressings applied beneath mulch at 15–20 and 35–40 days after planting. A plant health strategy includes virus-free seed and timely late blight management (Ministry of Science and Technology, 2013).
The trial results from Hanoi, Thai Binh, and Hai Phong in 2008 and 2009 show that this method reduces 25–67% of irrigation water, 75% of pesticides, and 28–47% of labor (mainly in tillage), increasing productivity from 8% to 25% and profitability 19% to 31% (Ngo and Hoang, Reference Ngo and Hoang2016). It also suppresses weeds, improves soil moisture conservation, and reduces soil disturbance (Ministry of Science and Technology, 2013).
In 2012, the method was disseminated to 20 provinces with the total area applying this method reached nearly 430 hectares, of which Hanoi has 170 hectares and Thai Binh has 130 hectares (Nguyen Tat Do, 2012; Kim Uyen, 2013). By 2014, 22 provinces with 4500 households had applied this solution (Ngo and Hoang, Reference Ngo and Hoang2016).
MARD recognized this initiative as a technical advance according to Decision No. 204/QD-TT-CLT dated May 28, 2013. In 2014, the initiative was awarded the ‘Vietnam Environment Award 2014’ by the Ministry of Natural Resources and Environment; in 2015, the Ministry of Agriculture and Rural Development awarded the Second Vietnam Golden Rice Award (Ngo and Hoang, Reference Ngo and Hoang2016).
The current status of minimum tillage potato cultivation in eight provinces
Phone interviews with 19 respondents across eight provinces highlighted that the technology offered some benefits compared to conventional tillage practices such as cleaner tubers with longer shelf life, reduced pest and disease pressure, and less labor in harvesting, while yields remained unchanged. Despite these advantages, all respondents reported that, to their knowledge, minimum tillage potato cultivation had not been adopted after the pilot or had been discontinued after initial adoption, though there might be a few farmers who still practice this method in small plots (Table 3).
Table 3. The outline of the reasons for discontinuation of minimum tillage during phone interviews in nine provinces
The discontinuation was linked to a chain of interrelated factors: the introduction of combine harvesters which reduced the availability of rice straw, creating a shortage that in turn required more labor for straw collection; this coincided with rising labor costs due to increased off-farm employment opportunities. Meanwhile power tiller became increasingly available, reducing the labor and cost for conventional tillage potato cultivation.
Furthermore, in all eight provinces, respondents noted that industrialization and the rise of off-farm employment opportunities eventually reduced both rice cultivation areas and the number of farmers. Consequently, the remaining farmers had to spend more time to collect rice straw from scattered locations. In Ninh Binh province, potato production was shifted to mechanized large-scale production in consolidated areas, in which the advantages of minimum tillage became less relevant. In Phu Tho, Ninh Binh, and Yen Bai, respondents mentioned that farmers shifted to other winter crops such as high-value vegetables, maize, and sweet potatoes.
The issue of disease transmission from rice straw to potato plants was mentioned in two specific sites in Thai Binh and Phu Tho. Rhizoctonia solani, causing rice sheath blight, also infects potatoes through contaminated rice straw, causing potato black scurf. The solution was to apply fungicide to the rice straw, which was not realistic for smallholder famers for both economic and food safety reasons.
Poor drainage was mentioned by respondents in four provinces: Hanoi, Phu Tho, Thai Binh, and Yen Bai. During unexpected rain, additional labor was required for digging trenches, otherwise potatoes can be rotten in straw.
There are other minor disadvantages which may have contributed to nonadoption such as higher rodent infestation in potatoes grown in rice straw mulch than those in conventional tillage and labor/time for foliar fertilizer application. In Hai Phong province, the sandy soil area is reserved for potato production, and since it is easy to till, farmers had less incentive to use rice straw.
These dynamics outweighed the perceived benefits of the technology, and farmers eventually reverted to adopting conventional tillage practices.
The Adaptation of minimum tillage potato cultivation
Study sites
Building on the results from the literature review (see ‘The minimum tillage potato cultivation methods and benefits’ section) and phone interviews (see ‘The current status of minimum tillage potato cultivation in eight provinces’ section), we conducted a case study to understand current situations. Three communities are located in Thai Binh, Hanoi, and Phu Tho provinces (Fig. 1).
Figure 1. The locations where a case study was conducted.
At each study site, we conducted in-depth interviews with six people that consists of four farmers who have experience of minimum tillage potato cultivation and two key informants: one district government officer who has knowledge on past interventions and one agricultural cooperative director who have knowledge on current potato production in the study site. The majority of respondents were women (Table 4).
Table 4. The number of respondents per case study community
In Ha Noi province, the technology was introduced in 11 districts over 170 hectares between 2011 and 2016. Huong Ngai Commune in Thach That district implemented farmer field trials from 2011 to 2013 for three crop seasons over 8 hectares. This commune has also had a cold store since 2008 and imports seed tubers from Europe.
In Thai Binh province, the potato minimum tillage technology was implemented in eight districts in 2012 and 2013 on a total of 130 hectares. An Khe Commune joined the pilot study in 2012 and 2013, but few households participated, with an area of about 3600 m2 only. Potato has long been grown as a cash crop, and the current potato growing area in this commune is 20 ha. The commune’s farmers corporative owns a cold storage unit. They import seed tubers from Europe and implement seed production from December to March in addition to the main potato production from October to January.
In Phu Tho province, Phu Tho Plant Protection Department introduced this technology in six districts, over a total area of 27 hectares, from 2010 to 2012. Dao Xa Commune hosted the farmer field trials on 2.5 hectares. Training was organized 8 times for 400 farmers and government extension workers, and the commune hosted study tours from other districts. Currently, fewer farmers grow potatoes, with potato growing areas of only 1.2 ha and 40 ha in the commune and the district, respectively.
The initial forms of this method have been adapted by farmers, especially women, to fit into their contexts, in which the principal of conservation agriculture partially remains.
Power tillage with rice straw mulching
In An Khe commune in Thai Binh, Nguyen Huong (pseudonym) learned the protocol 15 years ago and has modified it to grow potatoes on her rice field (1080 m2). After applying fertilizer onto her rice plot, she uses a power tiller to make beds (1.3 m width, 15 cm depth, and a 30-cm-wide trench between beds). Then she continues with the protocol. The rice straw is of her sticky rice variety (nếp cái hoa vàng), as it is less likely to be affected by rice sheath blight (R. solani). Also, it is harvested manually, hence it is convenient for mulching. She irrigates the furrows rather than the mounds to reduce the risk of potato diseases. Although she spends additional labor and time carrying and spreading the rice straw, she found this method easier than that of the conventional tillage. This is the third year she has implemented this method; her grandchildren are school age now and she has more time for farming (Fig. 2).
Figure 2. Power tillage rice straw mulching with furrow irrigation.
There are some challenges, however. Her potato field is located in the middle of other farmers rice plots, and as they do not grow winter crops in their rice plots, hers is surrounded by fallow paddy fields. This creates some problems for her. Her potatoes must be grown in her plot near a water source as the irrigation system in the paddy field is stopped as nobody uses it. She has also needed to fence the potato plot with nets to keep rodents out as her crop is only the food available for them.
Although a power tiller disturbs the soil significantly more than does manual minimum tillage, the principals of conservation agriculture, including reduced irrigation, fostering natural enemies, and recycling of rice straw remains in her adapted method.
Conventional tillage with partial rice straw mulching
The other farmers in An Khe Commune transferred potato production into a newly consolidated farming area made by bringing sandy soil from the riverbanks. This new farming area had been established to enable farmers to grow cash crops such as vegetables to earn income in all seasons. This was led by the government to respond to the demand for cash crops as well as crop diversification beyond rice production.
On those plots, potatoes are grown by conventional tillage with thin coverings of rice straw of a sticky variety to avoid the transmission of R. solani. The purpose of rice straw mulches is to keep soil moisture and prevent weeds at the sprouting stage. When earthing up the potatoes, the straw is pushed into the soil (Fig. 3).
Figure 3. Conventional tillage with rice straws at sowing and sprouting stages: sowing (left), sprouting (center), and earthing (right).
Similarly, in Dao Xa Commune in Phu Tho, farmers reverted to the conventional tillage method but still use short rice straw cut by combine harvesters as a mulch. After earthing up, some farmers add a further layer. There is no rice sheath blight observed in this commune (Fig. 4).
Figure 4. Conventional tillage with lightly covered rice straws until the earthing up stage.
Intercropping with leafy vegetables on furrows
On the areas where farmers grow potato in smaller home-garden style plots, they intercrop potato with leafy vegetables on the side of potato ridges. There are several other crops grown in the same plot such as sweet potato, maize, and beans (Fig. 5).
Figure 5. Potato production intercropping with leafy vegetables on the side of potato ridge.
Discussion
The findings of this study extend the current understanding of conservation agriculture in the global South, especially the site- and crop-specific reasons for nonadoption and discontinuation.
In the literature, securing sufficient crop residue for mulching has been a major challenge in expanding conservation agriculture due to trade-offs with livestock in both Africa and South Asia (Wall, Reference Wall2007; Valbuena et al., Reference Valbuena, Erenstein, Homann-Kee Tui, Abdoulaye, Claessens, Duncan, Gérard, Ru no, Teufel, van Rooyen and van Wijk2012; Thierfelder et al., Reference Thierfelder, Rusinamhodzi, Ngwira, Mupangwa, Nyagumbo, Kassie and Cairns2014). Our study sites in Vietnam also observe lack of crop residue as a major issue. However, the reason was not trade-off with livestock but mechanization.
The rapid diffusion of combine harvesters and power tillers in the 2010s played a critical role in a reduced number of farmers who implement potato minimum tillage. Four-wheel combine harvesters caused three problems.
First, their weight on their tires creates ruts. The field becomes uneven with many grooves, making it harder for farmers to perform minimum tillage. Second, when the machinery turns on the corner in the field, extra pressure is applied on the soil, leading to soil compaction and drainage issues as rain or irrigation water stagnates on those corners. Third, the quality and quantity of rice straw cut by combine harvesters are different from those cut manually. The main combine harvester used in the region is a half-feed harvester. This means that the machine cuts only the top half of rice plants while the bottom half remains in the field uncut. The top of the straw is short and very soft, and much of it is crushed into the tires. According to farmers we interviewed, it resulted in more than 50% reduction in rice straw for mulching compared to that harvested manually. This short soft straw can also cause green tubers unless the covering is thick enough. As a result, farmers needed to collect rice straw from five plots (1800 m2) to prepare one plot (360 m2) for potatoes. By contrast, rice straw cut manually is longer, easy to carry, and effectively covers the soil. The straw from two to three paddy fields is enough to make one plot for potatoes. Furthermore, combine harvesters cannot thresh 100% of the grain, and some grains remaining in the rice straw in the potato field start sprouting, requiring additional labor for weeding. Finally, power tillers for potato crops were also widely spread at that time. The conventional potato tillage by power tillers requires 30–40% less labor and time than manually performing minimum tillage rice straw mulching, according to farmers’ calculation. As a result, many communities reverted to the conventional tillage method after the introduction of the machinery in the mid- to late 2010s.
Those findings suggest that full-feed mini- or microcombine harvesters may have less problems of grooves and soil compaction, and allow farmers immediately use rice straws for mulching on the same field. The development of an add-on sowing attachment in combine harvesters (Singh et al., Reference Singh, Singh, Kushwaha, Singh and Ekka2020) specifically designed for potato seed is also required. It may not be a realistic for a community to have two types of rice harvesters, one for animal feeding and another one for potato zero tillage, and there might be trade-off with livestock in some specific contexts. However, providing an optional machinery for potato zero tillage is the first step.
In the cases of grain crops, there is a significant progress in developing machinery for conservation agriculture (Ma et al., Reference Ma, Li, Xu, Li, Ding, Li, Trang, Li and Hou2025). For example, no tillage seedling machines have been developed for soybean with wheat straw mulching (Hou et al., Reference Hou, Zhu, Zhu, Wang, Ji and Chen2022), groundnut (Gu et al., Reference Gu, Hu, Chen and Wu2016), and wheat with rice straw mulching (Gu et al., Reference Gu, Gao, Wu, Hu, Chen and Zhang2018; Kaur et al., Reference Kaur, Malik, Malhi, Sardana, Bolan, Lal and Siddique2022; Chaleka et al., Reference Chaleka, Goyal, Gupta, Singh, Singh and Sharma2024). This progress resonates with the global movement toward environmentally responsive mechanization for smallholder farmers (Sims and Kienzle, Reference Sims and Kienzle2017). However, the topic of mechanization for conservation agriculture has been absent in the case of potato, though potato is an important rotation crop with wheat, maize, and rice. Moreover, existing potato mechanization has been designed for a single purpose and in the context of conventional tillage (Mehta et al., Reference Mehta, Singh, Gholap and Patle2018; Nare and Singh, Reference Nare and Singh2019). This knowledge gap needs to a priority research agenda for potato zero/minimum tillage and associated residue crops for mulching.
The problem of disease transmission from rice straw to potato sprouts underscores the complexity and dynamics of pests and diseases in crop rotation and crop residue mulching (Thierfelder et al., Reference Thierfelder, Rusinamhodzi, Ngwira, Mupangwa, Nyagumbo, Kassie and Cairns2014). Currently, rice sheath blight disease and potato black scurf have been widely observed in South Asia (Singh et al., Reference Singh, Mazumdar, Harikrishna and Babu2019; Senapati et al., Reference Senapati, Tiwari, Sharma, Chandra, Bashyal and Ellur2022; Ahamad and Khan, Reference Ahamad and Khan2023; Chaudhary et al., Reference Chaudhary, Lal, Sagar, Sharma and Kumar2024). Crop rotation with another host plant increases disease incidences in the next rice production (Rodrigues et al., Reference Rodrigues, Vale, Datnoff, Prabhu and Korndörfer2003; Groth and Bond, Reference Groth and Bond2007). The site-specific risk assessment and monitoring of R. solani are required before and during the introduction of the technology.
Poor drainage and wet rice straws were another issue that increased risks of potato diseases according to farmer observation. The main potato growing season in the Red River Delta is from October to January, which is the dry season. However, during unusual heavy rain or persistent rain, the field can be flooded as rice fields are located in lower land with limited drainage systems. Farmers believe that straw mulching is useful in a dry condition for maintaining moisture in the soil, but in a wet condition, this advantage becomes a risk of potato diseases. To avoid such a risk, farmers needed to dig deeper drainage trenches, creating extra labor. Furthermore, frequent monitoring and adjustment were required before/after raining. Farmers therefore decided that conventional tillage is easier and has less risk of crop loss from diseases and damage. We suggest projects starting from codesigning with farmers to develop adapted versions suitable in the wet condition. Also, designing mechanized drainage systems with minimum soil disturbance is a priority agenda for research in potato zero/minimum tillage as extreme weather is increasing in elsewhere.
The requirement of gender-specific additional labor, especially of women’s increased labor burden, is frequently mentioned as a factor for low adoption among smallholder farmers, for example, in the case of maize zero/minimum tillage (Halbrendt et al., Reference Halbrendt, Kimura, Gray, Radovich, Reed and Tamang2014; Farnworth et al., Reference Farnworth, Baudron, Andersson, Misiko, Badstue and Stirling2016; Wekesah, Mutua and Izugbara, Reference Wekesah, Mutua and Izugbara2019; Somasundaram et al., Reference Somasundaram, Sinha, Dalal, Lal, Mohanty and Naorem2020). In contrast, the potato minimum tillage introduced in Vietnam does not have such constraints as the technology was initially designed for smallholder farmers and overall input costs are less than that of conventional tillage, favoring resource-limited households. However, this advantage eventually mismatched in a changing context in which an increasing number of women as well as men were shifted for off-farm employment. In the 2010s, several industrial estates were established in the Red River Delta region, and farmers and the government officers mentioned that a large number of both male and female farmers of working age changed to off-farm employment near their communities. The following four strategies were undertaken by farming households to maintain agriculture in the study sites: (1) minimizing agriculture, only growing vegetables, including potatoes, in home gardens or upper land usually sandy soil; (2) continuing rice production for two crop seasons, but discontinuing the winter crop, including potato; (3) hiring labor for potato production; (4) renting out the plots to other farmers, or the private sector, who consolidate land for mechanized farming including potato production. In consequence, the shortage of labor in farming, increased on-farm labor costs, accelerated mechanization, and land consolidation took place concurrently, as a result of which the initial advantages of potato minimum tillage designed for smallholder farmers using family labor became less relevant.
The agricultural transition of Vietnam observed in the 2010s is similar to current trends in many parts of South Asia where small-scale agriculture is increasingly managed by women in the context of male labor migration (Pattnaik et al., Reference Pattnaik, Lahiri-Dutt, Lockie and Pritchard2018; Southard and Randell, Reference Southard and Randell2022). Subsequently, ongoing male labor shortage and increased wage rates are boosting the demand for combine harvesters for major grain crops, especially for implementing timely crop rotation (Aryal, Thapa and Simtowe, Reference Aryal, Thapa and Simtowe2021; Khandai et al., Reference Khandai, Vipin, Vivek, Goswami, Minhas and Singh2022). Therefore, lessons learned from the case of Vietnam are immediately applicable in ongoing interventions of potato zero and minimum tillage with rice straw mulching in South Asia.
Insights before inform the potential and limitation of the current form of potato zero tillage rice straw mulch in South Asia (Ahmed et al., Reference Ahmed, Mahmud, Hossain, Zaman and Halder2017; Brar et al., Reference Brar, Buttar, Thind and Singh2019, Sarangi et al., Reference Sarangi, Maji, Sharma, Digar, Mahanta and Burman2021, Reference Sarangi, Mainuddin, Raut, Mandal and Mahanta2024; Nowroz et al., Reference Nowroz, Roy, Haque, Ferdous, Noor and Mondal2021; Ojah and Bhattacharjee, Reference Ojah and Bhattacharjee2021; Ramírez et al., Reference Ramírez, Silva-Díaz, Ninanya, Carbajal, Rinza and Kakraliya2022, Reference Ramírez, Hossain, Rahaman, Mestanza, Rinza and Ninanya2025; Goswami et al., Reference Goswami, Roy, Gangopadhyay, Sen, Roy and Sarkar2024; Parihar et al., Reference Parihar, Singh, Sharma, Chauhan, Gupta and Kumar2024; Saimon et al., Reference Saimon, Mannan, Sultana and Mondal2024; Dey et al., Reference Dey, Sarkar, Dhar, Brahmachari, Ghosh, Goswami and Mainuddin2025). Knowledge of this study can contribute to forming research agenda in South Asia as well as identifying suitable intervention sites.
Finally, our study concurs with the previous literature emphasizing the needs for developing site-specific adaptation strategies for conservation agriculture (Tittonell et al., Reference Tittonell, Scopel, Andrieu, Posthumus, Mapfumo and Corbeels2012; Thierfelder et al., Reference Thierfelder, Rusinamhodzi, Ngwira, Mupangwa, Nyagumbo, Kassie and Cairns2014; Giller et al., Reference Giller, Hijbeek, Andersson and Sumberg2021), but the unique insight of this follow-up study was that the site-specificity changes over time as socioeconomic conditions and farming systems are dynamic. Continuous revisions and adaptation are therefore required overtime even in the context where farmers initially adopted the technology. Also, our study demonstrates that socioeconomic and agroecological factors are interwoven with each other, highlighting the importance of forming interdisciplinary and multidisciplinary teams to critically evaluate the whole context (Hermans et al., Reference Hermans, Whitfield, Dougill and Thierfelder2020).
Conclusion
There has been a significant progress in generating evidence on the benefits of potato minimum or zero tillage rice straw mulching from agronomic, soil, and environmental perspectives, primarily based on findings from demonstration field trials in South Asia. However, literature on conservation agriculture across various crop systems emphasizes that such innovations are context specific, encountering challenges in application within diverse socioeconomic and agroecological contexts.
This study aimed to learn from farmer experience in Vietnam where this technology was widely disseminated 15 years ago. Initially, farmers adopted it, and great advantages were observed in saving labor and input, increasing profit, and generating positive environmental impacts. However, the introduction of mechanization reduced farmer incentives and created some technical problems in the field. Additionally, crop-specific issues such as the transmission of R. solani disease and poor drainage during unexpected dry-season rains highlight the need for site-specific solutions.
Based on lessons learned from the case of Vietnam, a new research agenda is proposed with a focus on adapting the technology to the mechanized rice farming context. This includes developing rice harvesters tailored for potato minimum and zero tillage with crop residue mulching, adapting mechanized tillage methods to incorporate rice straw mulching, and developing solutions for poor drainage.
Acknowledgements
We thank the farmers and government officers who participated in this study. We are grateful to Jan Kreuze (CIP) and Nguyen Van Hung (IRRI) for their valuable feedback on the manuscript, and to Javier Ochoa (CIP) and Nguyen Van Tuan (IRRI) for their assistance in designing the figures.
Funding statement
This work was supported by the CGIAR Science Program on Scaling for Impact. We thank all funders who supported this research through their contributions to the CGIAR Trust Fund. https://www.cgiar.org/funders/
Competing interests
The authors declare none.
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