Tough celery: is climate change the scapegoat?

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Foodthink’s Take

How exactly is agriculture being affected by climate change? Foodthink has published a series of articles on this topic. Today, we share the insights of a grower on the front line. Zhao Fei graduated from the College of Agriculture at China Agricultural University, after which he joined Pingren Farm, an organic farming operation, where he oversees vegetable production in Changping, Beijing, and Lingqiu, Shanxi. On 8 January, he and two fellow organic farmers attended a climate change sharing session at Beijing’s Fengnianqing. Using common vegetables as examples, Zhao Fei explained how extreme weather impacts agriculture and the unique countermeasures the farm has implemented.

This article has been edited from his presentation. We hope these vivid examples provide a deeper understanding of the complex interplay between farmers, crops, and the weather.

You are welcome to click the link below to watch the full replay of the Fengnianqing session.

At the farm, consumers often ask us: “Why does the produce look like this?”, “Why are the vegetables so tough?”, “Why are they so sweet?”, “Why are there insect holes?”

More often than not, the answer is related to the weather. As climate change intensifies, ordinary consumers can now sense its effects directly through their food.

● Autumn 2022: Thriving strawberry fields. Xingshou Town in Changping, where Pingren Farm is located, is one of Beijing’s primary strawberry-growing regions.

Let’s start with the strawberries currently in season. Temperatures were higher than usual in October 2022, leading to vigorous growth. However, this wasn’t necessarily a good thing, as the strawberries focused on foliage growth rather than flowering. This pushed back the overall time they hit the market, moving from December last year to January this year.

In the spring of 2022, the broccoli we grew in Changping became weathered and yellowed under the sun; neighbouring farmers fared no better than in previous years. In the past, we always worried about temperatures being too low, but last year they were actually too high. A few abnormal, brief heatwaves were enough to change the colour of the broccoli heads.

Customers taking such produce home would notice that the layer of “waxy powder” on the leaves is thicker than usual. This is the plant’s way of protecting itself from solar radiation to prevent water loss caused by high temperatures.

● Open-field celery affected by leaf spot disease in Lingqiu, Shanxi.
Customers who bought celery from our farm last year will know exactly what I mean. This variety is called “French Queen” and is typically very succulent. However, last year’s high temperature and humidity caused it to develop excessive fibre, making it tough and woody to eat. Such weather also makes cool-weather celery prone to disease; an outbreak of leaf spot meant several harvests were lost entirely. Even when we could harvest, the leaves were so affected by the disease that they had to be stripped off before sale, meaning customers were left with nothing but the celery stalks.

I. “The whims of nature”: No longer possible to simply rely on the heavens for a harvest

We often hear the saying that “agriculture depends on the weather”. Many assume this simply means that natural disasters are common and that farming is a gamble, with harvests vulnerable to drought or flooding. But “depending on the weather” first and foremost refers to the predictable order of nature—the belief that the heavens follow a constant pattern and that the seasons are reliable. It is only by recognising these stable local climatic patterns that farmers can effectively plan their production. When I first started working at the farm in Lingqiu, Shanxi, the first thing I did was visit the local agricultural supply stores. Through these conversations, I began to understand the local weather patterns. By combining this with data on average and extreme temperatures, as well as rainfall and other meteorological records from recent years, I was able to draw up a general production plan. This allowed me to determine when to plant which crops, what potential disasters to anticipate, and how to prepare for them. Spending time learning from the experienced local farmers also revealed the traditional planting habits of the area. Much of this wisdom has been distilled into local agricultural proverbs. For instance, at our farm in Xingshou, Changping (Beijing), peas are typically planted around the time of *Jingzhe* (the ‘Awakening of Insects’ solar term). In the old Beijing dialect, they say, “peas must be in by the ninth nine,” meaning they should be sown before the ninth nine-day period after the winter solstice. This is the farmers’ way of identifying the ideal temperature and season for peas; if the temperature is too high or too low, their growth will be affected.

●Local farmers typically plant Chinese cabbage around the autumn equinox and cultivate onions around the ‘End of Heat’ (Chushu). The planting windows for these vegetables have traditionally been quite fixed.

When I was a child, my grandfather often told me: “Rain on the twenty-fifth of last month, and no dry soil next month.” This is a farming proverb from my home province of Anhui; it means that if it rained on the twenty-fifth day of the previous lunar month, the following month would bring persistent rain. Another says, “Gloomy during Grain Rain, drizzling during the Start of Summer”—overcast weather during the Grain Rain period signals that the next forty-five days will be wet. These are all pieces of wisdom distilled from generations of observing the seasonal shifts in weather.

Nowadays, there is much debate over whether climate change is ultimately beneficial or detrimental to agriculture in different regions. Regardless, whenever the climate becomes disrupted and unpredictable, the traditional knowledge of farmers is put to a severe test. We are left to discover new patterns through trial and error in the field.

●This carrot has turned out rather mediocre because local temperatures were too high; the above-ground foliage withered prematurely, meaning the root failed to form properly.
●These early spring open-field baby oilseed rape plants are riddled with holes, eaten by striped flea beetles. The intention behind planting early was to harvest before the pests became active, but last winter’s unusually high temperatures caused them to emerge ahead of schedule.
●Climate change can also bring surprises. This year in Lingqiu, Shanxi, higher temperatures resulted in fewer cases of late blight in tomatoes, leading to a bumper crop for local farmers. However, reports indicate that a nationwide surplus has driven farm-gate prices down; in some areas, they have dropped as low as 0.3 yuan per half-kilogram, once again creating a situation where “a cheap harvest hurts the farmer”.

II. Extreme Weather Events

Climate change also brings more severe weather disasters. The traditional array of hazards—wind, frost, snow, rain and hail, as well as droughts, floods, pests and disease—has become more unpredictable and frequent. On 4 May 2021, Changping in Beijing experienced an exceptionally rare frost. At the same time, heavy snow fell in Lingqiu, Shanxi, during May. Uncle Song, a local man in his sixties who works on the farm, recalls: “Goodness, heavy snow in May is truly rare.” Soil temperatures were lower that spring, meaning all planting had to be delayed. It leaves one wondering: is the climate actually warming or cooling? In truth, it is simply that the climate has become unstable, and extreme weather is now more common.

●A scene of the greenhouses being flooded in 2018.

Before I joined Pingren Farm, it hadn’t been flooded for seven years. But since I arrived, the farm has already been inundated three or four times; at the worst of it, almost the entire farm was submerged in water.

●Winter 2021: an overnight blizzard collapsed several greenhouses. The aunties on the farm remarked that it had been a long time since they had seen snow this heavy.
●In 2021, we also suffered from windstorms, with winds that were stronger and lasted longer than in previous years. Almost every greenhouse film was ripped away by the gales.

When faced with minor mishaps, such as frost, we can manage using our facilities or simple methods like lighting heating blocks. However, a single major disaster can mean that a year’s—or even several years’—work has been for nothing.

We have considered agricultural insurance, but in reality, it only covers certain types of damage. For example, ‘rain damage’ as defined by the insurance refers specifically to short-term torrential rain. The continuous rainfall of 2021 saturated the soil, and because our land is low-lying, saline groundwater rose to the surface, leading to soil salinisation. Prolonged rain also caused water to seep into the greenhouses, leaving the soil too damp for vegetables to be sown—yet none of this falls under the insurance coverage.

Because rainfall has increased, the farm has to dig drainage ditches every year, and they have grown deeper over the last few years. However, the terrain of our farm is higher at the edges and lower in the centre. Although there are drainage ditches nearby, they have been largely abandoned due to a lack of maintenance and no longer connect to the nearby river channels. No matter how deep we dig our own ditches, it is pointless; in fact, it may even cause rainwater to flow back into the fields.

Consequently, these broader environmental issues cannot be resolved in isolation, and it is difficult for a single farm or farmer to fight this battle alone. This year, we paid to help clear the public drainage ditches, and we are looking for ways to work together with several neighbouring farms to solve the problem.

●We have also dug drainage ditches inside the greenhouses to prevent flooding.

III. How Farms are Adapting

Having discussed the challenges facing the farm, I would now like to share some of the unique strategies we have developed over the last few years.In 2021, persistent rainfall caused some of the earthen bunkers to suffer minor landslides and collapses. This was only manageable thanks to the abundance of weeds behind the slopes; their roots anchored the soil. Without them, the collapse could have been far worse, potentially rendering the entire year’s work pointless.

Previously, we viewed excessive weed growth as a risk; the dryness of winter made them a fire hazard, so we covered the areas with plastic sheeting to prevent growth. However, with the increase in rainfall over recent years, the benefit of using vegetation to stabilise the slopes has become clear. As our earth walls are quite thick, the roots have not yet penetrated fully; I hope to encourage them to grow deeper over time.

Similarly, we are “planting grass” on bare land where no crops are grown. Following the mentions of ryegrass in Foodthink’s Regenerative Agriculture lecture, we have been experimenting with open-field planting this winter—not for the harvest, but to protect the soil with the root systems. Since intensive tillage causes significant soil degradation, we are also trialling no-till cultivation methods this year.

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These are our greenhouses in Lingqiu, Shanxi, where we have experimented with planting species such as *Cyperus rotundus*. Insects are highly sensitive to temperature, and climate change can easily trigger unexpected pest outbreaks. By encouraging these “weeds”, we hope to provide a suitable habitat for natural predators, thereby keeping pests under control.

We also plant aubergines in the greenhouses. They provide a dense, sheltered cover where sensitive insects can dwell, creating an ideal environment for natural predators. The aubergines shown here grew from December 2021 to December 2022; during that year, we noticed an abundance of aphid parasitoid wasps, aphid flies, and lacewings. Since introducing the aubergines, I have stopped worrying about pests such as aphids.

In the past, growing cucumbers in the greenhouses every year was a constant struggle against aphids. To cope, we relied on a cycle of rapid planting and harvesting, always keeping a stock of seedlings on hand to quickly replace any that had been decimated by the aphids.

Last year, however, we tried a new approach: we first planted a section of chillies and aubergines to act as a lure for the aphids. Both aubergines and chillies have a strong ability to branch and regenerate quickly. Soon, the natural predators of aphids appeared on their own, without the need for artificial introduction. It was only then that I planted the cucumbers alongside them.

While these predators do not entirely eradicate the aphids, they keep them in check. Because the aphid population remains controllable, they no longer cause significant damage. Free from the interference of aphids, the cucumbers were able to produce fruit from December right through to July.

Moving forward, we intend to experiment with intercropping aubergines with “weeds” that attract natural predators, such as *Cyperus rotundus* and pyrethrum.

● Homemade tomato enzymes produced on the farm.
The farm also produces various homemade microbial fertilisers, including enzyme-based solutions, *Bacillus subtilis* created through fermentation, and fermented compost. These prove incredibly useful following a flood. Soil naturally contains a vast array of microbial communities; on organic farms like ours, the high organic matter content makes these microorganisms even more abundant. They are the key to maintaining soil health. However, flooding disrupts the existing balance of the soil ecosystem; beneficial bacteria die off, and harmful anaerobic bacteria become dominant. Consequently, if seedlings are planted immediately after the water recedes, they struggle to survive. Much like the need to spray disinfectants in a disaster zone, the soil also requires a form of ‘disinfection’. Typically, once the water has receded, the land is ploughed and left to be exposed to the sun for a period. Introducing large quantities of microbial fertilisers at this stage helps beneficial bacteria multiply quickly, restoring the microbial community to its normal state.

IV. Flexibility and Diversity

Our farm employs many other coping strategies. As an organic operation, our primary focus is on striving to increase species diversity to build a more stable ecosystem. For a simple example, we grow over 100 types of vegetables throughout the year, with dozens planted simultaneously. Because they react differently to the climate, we avoid total losses even when conditions shift. When climatic characteristics change, we have the flexibility to experiment with new varieties and cultivation methods. This echoes the sentiment in *The Earth Doesn’t Care*: When facing climate change, increasing the richness of the agro-ecosystem within each region enhances its stability. Only by combining these small ecosystems can the capacity of the larger system to withstand climate risks be improved.

Flexible and diversified agriculture will undoubtedly prove its value in the face of climate change.

Unless otherwise noted, images are provided by the author

Compiled by: Wan Lin

Edited by: Wang Hao

Published by Foodthink