Understanding the ways that volcanic tephra can affect agriculture in the short and long terms is a question that affects millions of people around the world.
Indeed, while impact of tephra fall on agriculture has been the focus of some studies, the field is still quite in its infancy. Namely, agriculture is being studied as a simple collection of crops and livestock, completely neglecting the functioning of the farm itself and overlooking the fact that two farm who produce the same types of food in different ways might not be affected by tephra fall in the same manner. In the same vein, the farm’s environment such as neighbour solidarity as well as government, can shape the way a volcanic event will impact the farm’s production. Therefore, data is needed to investigate those avenues further and incorporate them into our comprehension of farm vulnerability to tephra fall.
To that end, two successive ten-days field missions, were conducted in the Philippines, around the Taal volcano. These were co-funded by a Synergy project grant from ARES, titled “Agricultural livelihoods in Taal eruption-affected provinces of Luzon: assessment of impact and recovery opportunities». The first was conducted in March 2022 and the second in February 2024.
The Taal volcano, located on the main island of the Philippines, Luzon, 60 km south of Manila, is situated on a 5-km-wide volcanic island in a large caldera which hosts the Taal lake. Its last violent eruption occurred in January 2020, taking the one million people living in a 17 kilometres area around the volcano completely by surprise, since the last violent eruption dated back to 1965. The lake around the volcano hosts many fisheries. The volcano is still in activity five years later, and it is forbidden to approach it by boat; only the fishermen are allowed to sail on the lake at this time.
Figure 1: Localisation of the Taal volcano (red) and the eight surveyed farms during the 2022 fieldwork (yellow) inf the Philippines (map made with AcrGIS Pro)
Figure 2: Taal volcano emitting volcanic ash and gas, February 8th, 2024 [picture: Sophie Malherbe]
Both missions were conducted with the help of local NGOs, namely Viva Salud, the Manila chapter of Solidagro, and Climate Change Network for Community-based Initiatives (CCNCI).
During our first stay, we conducted semi-structures interviews of seven farmers around the volcano, especially to the north- and south-west of the lake. Those farms had very contrasted agricultural productions, ranging from a pineapple monoculture to complex systems which integrated both livestock and several types of crops cultivated with a crop rotation system. The farms were all of very moderate sizes, from 0.7 ha to 2 ha. Most of the production from the farms was destined both to the household itself and to be sold at the market for revenue, which is a very common practice in the Philippines, were subsistence agriculture is essential to the population.
We learned that the tephra fallout from the 2020 eruption had had very different consequences for all the people we interviewed, prompting a variety of post-eruption responses. While some reported some crop loss and small inconveniences regarding their livestock, others had suffered quite severe losses. The farm that only cultivated pineapple lost all of its production and had to sell twelve out of the fourteen hectares of land it had, only to be able to replant the two remaining hectares. Since, as a precaution, the farmer had decided to purchase another land on the other side of the volcano, hypothesizing that the next tephra fallout, which depends on wind direction, would only affect one of his two lands and not the other. Another farmer, who among other things raised white hybrid pigs, had his piggery collapse on top of his animals. While some died of the accident, the others, being a quite fragile species, died of exposure to the ash. Two years later, the farmer raises pigs again but decided to go for the Philippines native species which takes longer to mature and feed but is more resistant to a less clement environment.
Figure 3: Pitaya (dragon fruit) field, from one of the studied farms, March 2022 [picture: Sophie Malherbe]
Figure 4: Corn field, from one of the studied farms, March 2022 [picture: Sophie Malherbe]
Figure 5: Philippines native cow and nursing calf, from one of the studied farms, March 2022 [picture: Sophie Malherbe]
Figure 6: Banana field, from one of the studied farms, March 2022 [picture: Noa Ligot]
Figure 7: Pineapple field, from one of the studied farms, March 2022 [picture: Sophie Malherbe]
During our second fieldwork, we wanted to visit the same farms as two years prior in order to see if the aftereffects of the eruption were still being felt and if the farmers had had to adapt their activities in other ways since the last time we visited.
Out of the seven farms we studied in 2022, we were only able to go back to five due to scheduling conflicts. We were able to interview a new farmer, however, whose farm itself had not been affected by the tephra fall in 2020, but who had many things to say about the solidarity efforts put into place after the eruption to help feed the people and replant the fields to “go back to normal” as soon as possible.
Most of the farmers we saw for the second time were operating in the same way as 2022, growing the same crops and raising the same livestock. Some still had not been able to resume activities they had had prior to the eruption, such as growing certain crops for which they now say the soil is too hot to grow, presumably because the ash that was incorporated in the ground made it darker and therefore warmer when the sun hits it.
One of the farmers who had been cultivating two plots of land when we visited in 2022, one with sugar cane and one, next to the Taal lake, with rice, had had to abandon his rice field. Indeed, while the tephra itself was not to blame, the succession of earthquakes from the volcanic activity had made the ground near the lake subside, and the field is now subjected to regular salt water incursions from the lake, rendering it unfit to grow anything.
Figure 8: Localisation of the Taal volcano (red) and the eight surveyed farms during the 2024 fieldwork (yellow) inf the Philippines (map made with AcrGIS Pro)
The fieldworks around the Taal showed that the repercussions of a volcanic eruption are many and can last for years after the fact, and do not only stem from the thepra fall itself but can also result of other volcanic activities. The data collected will help, with that of other field studies conducted elsewhere, in proposing a new way to evaluate the vulnerability of agriculture and farms in close proximity to a volcano. All this data is being used in a PhD thesis on the subject.
In time, we strongly believe that understanding how today’s farms are impacted by tephra fall will help us shed light on how past civilizations reacted to similar natural hazards. Much as studying pre-mechanization ways of farming allow us to recreate Antique techniques, delving into current crop and livestock production and associations, and how that production system might be affected by a volcanic eruption causing tephra fall, could help pinpoint patterns and fragilities that are as valid now as they were millenias ago.
Figure 9: Beans field, from one of the studied farms, February 2024 [picture: Sophie Malherbe]
Figure 10: White hybrid pigs in piggery, from one of the studied farms [picture: Juliette Glorieux]