Water, land, and why growing methods matter
Which way of farming is best?
It depends on what you want to save. Every farm uses something up.
A field or a water system? Each one costs something different.
Picture three jars: water, land, and energy. Every farm spends from all three.
Different farms empty different jars.
Farms use more fresh water than homes and factories put together.
On a field, some water sinks down past the roots. Some dries up into the air.
- A · water soaks down past the roots
- B · water dries up into the air
- C · water runs off into a stream
Many hydroponic and aquaponic systems keep their water in a loop. A pump sends it round and round.
So they often use much less water than a field.
- D · pump lifts the water
- E · water flows back to the tank
A field spreads its crop out across the ground.
A system can pack plants close, or stack them on shelves. So the same food fits on less land.
But pumps, lights, and heaters run on electricity.
So a system uses less water and land, but more electricity. It empties a different jar.
Heavy rain can wash plant food off a field and into a stream.
Water that runs across the ground like this is called runoffRain or extra water that runs across the ground instead of soaking in. It can carry plant food into rivers.
See it in the glossary. In a river, too much plant food can harm fish and plants.
- A · water soaks down past the roots
- B · water dries up into the air
- C · water runs off into a stream
Your turn. Less or more?
Think about a system that reuses its water, and sort each card.
Compared with a field, a water system usually uses...
Tap a card, then a bin. Or press 1 or 2 on a card.
- Nothing here yet
- Nothing here yet
Compared with a field, a water system usually uses...
The answer:
Less
- Water The water goes round in a loop, so little is lost.
- Land Plants grow close together, or stacked on shelves.
- Time spent weeding With no soil, weeds have almost nowhere to grow.
- Plant food washing into rivers The plant food stays in the loop instead of washing away.
More
- Electricity Pumps, lights, and heaters all need power.
- Money to build it Tanks, pumps, and lights cost money to buy.
No way of farming wins everywhere. In a dry place, saving water may matter most.
Where rain and land are plenty, a field uses far less electricity.
Which jar would your town want to save?
Check 1 of 3
A system keeps its water in a loop. What does it save the most?
Show the answer
Water. Right. The water goes round and round, so little is lost.
Check 2 of 3
What does a water system usually use more of than a field?
Show the answer
Electricity. Right. Pumps, lights, and heaters all need power.
Check 3 of 3
Is one way of farming always the best?
Show the answer
No. It depends on the place.. Right. Each farm empties a different jar.
You just learned how farms spend water, land, and energy.
Next up: Farms in cities, deserts, and space.
Go deeper: the numbers, and where the power comes fromOpenClose
Farming takes most of the fresh water people pull from rivers, lakes, and wells. Worldwide, reports put it at about 69 to 72 percent.
Averaged country by country instead, the share is closer to 60 percent. A few countries that use huge amounts of water pull the world total up.
Two studies of lettuce found that systems reusing their water used roughly 89 to 94 percent less water than fields. Real farms vary a lot.
A one-layer greenhouse system grew about 11 times more lettuce per square meter than a field. Indoor farms with stacked shelves reach roughly 50 to 100 times more.
The cost is energy. Per kilogram of lettuce, studies found these farms used from about 7 times to more than 80 times as much energy as a field. The studies disagree on how much.
In indoor farms with stacked shelves, lights use the biggest share of that energy. Cooling and drying the air come next.
Field farms use energy too: fuel and electricity on the farm, and natural gas to make fertilizer.
Where the electricity comes from changes the picture. Power from sun or wind adds less pollution than power from burning coal or gas.
Some systems use their nutrient water only once and then drain it. That waste water can pollute streams and groundwater if it is not handled with care.
Sources
- FAO. AQUASTAT - FAO's Global Information System on Water and Agriculture: Water use. Food and Agriculture Organization of the United Nations. Link
- UN News. UN sounds alarm over rising demands on water resources as scarcity increases. United Nations, 12 December 2025. Reports FAO's 2025 AQUASTAT Water Data Snapshot. Link
- Kranz, B. Irrigation Chapter 8: Irrigation Efficiencies. Irrigation Home Study Course, Plant and Soil Sciences eLibrary, University of Nebraska-Lincoln Extension. Link
- Rogers, D., Lamm, F., Alam, M., Trooien, T., Clark, G., Barnes, P., and Mankin, K. Efficiencies and Water Losses of Irrigation Systems. MF2243. Kansas State University Research and Extension. Link
- Barbosa, G. L., Gadelha, F. D. A., Kublik, N., Proctor, A., Reichelm, L., Weissinger, E., Wohlleb, G. M., and Halden, R. U. Comparison of Land, Water, and Energy Requirements of Lettuce Grown Using Hydroponic vs. Conventional Agricultural Methods. International Journal of Environmental Research and Public Health 12(6): 6879-6891, 2015. Link
- Pennisi, G., Gianquinto, G., Marcelis, L. F. M., Martin, M., and Orsini, F. Vertical farming: productivity, environmental impact, and resource use. A review. Agronomy for Sustainable Development 45: 57, 2025. doi:10.1007/s13593-025-01055-w. Link
- Sallenave, R., and Shultz, R. C. Hydroponics: Water-saving Farming for New Mexico's Arid Environment. Guide H-180. New Mexico State University, College of Agricultural, Consumer and Environmental Sciences, 2022. Link
- Treftz, C., Kratsch, H., and Omaye, S. Hydroponics: A Brief Guide to Growing Food Without Soil. FS-15-08. Extension, University of Nevada, Reno, 2015. Link
- Canelon, D. An introduction to hydroponics. University of Alaska Fairbanks Cooperative Extension Service, 13 December 2022. Link
- Cabrera-Garcia, J., Milhollin, R., and Ernst, M. Controlled Environment Agriculture: Hydroponic Farming. G6986. University of Missouri Extension, 2024. Link
- Li, H., Parcell, J., Roach, A., Solomon, A., Cabrera-Garcia, J., Dietterle, L., and Spell, A. The Economics and Optimal Design of Missouri Indoor Farming Supply Chains. University of Missouri Extension. Link
- Rakocy, J. E., Masser, M. P., and Losordo, T. M. Recirculating Aquaculture Tank Production Systems: Aquaponics, Integrating Fish and Plant Culture. SRAC Publication No. 454. Southern Regional Aquaculture Center; Oklahoma Cooperative Extension Service. Link
- U.S. Geological Survey. Runoff: Surface and Overland Water Runoff. USGS Water Science School. Link
- U.S. Environmental Protection Agency. Sources and Solutions: Agriculture. Nutrient Pollution. Link
- NOAA National Ocean Service. What causes nutrient pollution? Coastal Pollution Tutorial. Link
- NOAA National Ocean Service. What is eutrophication? Link
- Suttles, S. Farms spend more on indirect energy inputs like fertilizer than direct energy inputs like fuel. Charts of Note. USDA Economic Research Service, 12 February 2015. Link
- Hitaj, C. Energy consumption in agriculture increased in 2016, driven mainly by diesel and fertilizer use. Charts of Note. USDA Economic Research Service, 13 March 2018. Link