1. Why Farmers Change the Water Depth in a Rice Paddy
In a rice paddy just after planting, farmers keep shallow water at a depth of 2–4 cm (about 1–1.5 inches). It is said that shallow water helps rice plants increase the number of stems, which leads to more ears of rice [1]. Materials from Kyoto Prefecture show photos of how three seedlings grew to about 21 stems approximately 50 days after planting [5]. This increase is in the number of stems, not the number of rice grains.
Later, when ears appear and flowers bloom, the rice needs the most water. During this time, the water is kept much deeper, at 6–10 cm (about 2.5–4 inches) [1]. While farmers decide the water depth, the clue for that decision is the growth condition of the rice plants. It looks like they are watching the water, but farmers are actually watching the rice.
However, water is not just increased continuously. About one month after planting, farmers deliberately drain the water.
2. Why Farmers Drain the Paddy One Month After Planting
About one month after planting, farmers drain the water and let the paddy dry for a while. The purpose is to make the roots of the rice plants strong [1]. This work is generally called "nakaboshi" (mid-season drying).
It may seem surprising to drain water that was added to help the plants grow. However, changing the amount of water is itself part of the method for growing rice. Before the harvest, the water is drained completely. This makes it easier for machines and people to work inside the paddy [1].
So far, we see that the water depth in a paddy moves in a pattern: "shallow water → dry → deep water → drain completely." However, the details of when to add and drain water vary by region and variety, and the source does not describe those adjustments in detail. Is this work of watching and adjusting water only about rice paddies? Next, we look at a cow barn, where living things are cared for.
3. How Dairy Farmers Care for Their Cows Every Day
Cows that produce milk are called dairy cows, and dairy farmers make caring for them their job. A dairy cow drinks 60–80 L (about 16–21 gallons) of water a day [2]. That is equivalent to 30–40 bottles of 2 L (about 0.5 gallon) water.
They also eat a large amount. If eating freshly cut pasture grass, they consume about 50–60 kg (about 110–130 lbs) per day [2]. This equals 5–6 bags of 10 kg (about 22 lbs) of grass. The amount changes depending on the type of grass.
Milking is done twice a day, in the morning and evening, and continues every day [2]. Rice plants progress through stages by season, but cows need water and grass every day. This helps explain why dairy work is said to be hard to take days off from.
So, what order does this daily routine follow?
4. What a Dairy Farmer's Day Looks Like, Starting with Barn Cleaning
A page on food education by Meiji lists an example of a dairy farmer’s day. At 5:00 AM, they clean the barn and change bedding. At 6:00 AM, they feed the cows. At 8:00 AM, they milk the cows. At 10:00 AM, they care for calves. At 12:00 PM, they check the health of each cow one by one. In the afternoon, they repeat the morning tasks [2].
This is just one example listed on a corporate website and is not the standard schedule for all dairy farmers in Japan. What stands out in this example is how much of the day is spent watching: cleaning is a chance to check the barn, feeding to see how the cows eat, and the health check to look at each cow. The health check of "each cow" at 12:00 PM is very similar to the work of changing water based on the condition of rice plants.
Thus, the center of a farmer’s work is not just the water in the paddy or the feed for cows. It is watching the thing being raised every day and continuing to adjust water, feed, and timing.
How many people are currently doing this important work in Japan?
5. How Many People Have Agriculture as Their Main Job
The Ministry of Agriculture, Forestry and Fisheries counts people who make agriculture their main job as "core agricultural workers." These are household members whose main occupation is self-employed agriculture [3].
This number decreased from 1.363 million in 2020 (Reiwa 2) to 1.036 million in 2025 (Reiwa 7). The average age in 2025 is 67.7 years, and 721,000 people are 65 or older [3]. Calculating 72.1 divided by 103.6 gives about 69.6%, meaning about 69.6% are 65 or older.
Compared to about 2.4 million people in 2000 (Heisei 12), the current number of 1.036 million is less than half [4].
On the other hand, the value of agricultural output is not small. The total agricultural output in 2024 (Reiwa 6) was 10.7801 trillion yen, with livestock being the largest at 3.6654 trillion yen [4]. The ratio is about 34.0% (3.6654 divided by 10.7801). This ratio is a calculated value and is not a number written in the white paper.
The number of people whose main job is agriculture has fallen. What machines help with agricultural work?
6. How Drones and Auto-Tractors Help Farmers
According to a machine introduction by Mynavi Agriculture, some agricultural drones fly automatically 30–50 m (about 100–165 feet) above fields. They simultaneously spray chemicals and diagnose growth [6]. It is introduced that they can spray stably without being heavily influenced by the skill of the operator.
Autonomous tractors can automatically change the depth of plowing depending on the location and crop. It is introduced that operating 3–5 machines unmanned by one person is "theoretically possible" [6]. However, this is an introduction of specific models and is not the standard for all sites.
The farmer’s work we have seen so far was "watching and adjusting." Drones help the eyes that watch growth, and tractors help the hands that adjust plowing depth. Even as machines increase, deciding what to watch and how to decide remains human work.
7. Try It at Home: Compare 2 cm and 8 cm of Water
Try putting water in shallow containers at home and measuring the depth with a ruler. First make 2–4 cm (about 1–1.5 inches) of water, then make 6–10 cm (about 2.5–4 inches) and line them up. Do this in a place where spills are okay, using cold water.
Comparing shallow and deep water helps you slightly realize that both are used in the same rice paddy. When deciding water depth, farmers are watching the rice plants. How those rice plants grow is explained on the Ministry of Agriculture, Forestry and Fisheries children’s page "About Rice Paddy Water Management" [1].
There should be another way to look at the work of farmers raising cows or vegetables. If you could ask people who make familiar foods what they watch and how they decide, new questions might arise from there.