Lesson guide · Lesson 24 · Grades 4–8 · 6 min

Water, land, and why growing methods matter

Every farm spends water, land, and energy. Different ways of growing spend different amounts.

Open the lessonPrintable worksheet

Students will

  • Explain that every way of farming spends water, land, and energy in different amounts.
  • Describe why a system that reuses its water often uses less water and land, but more electricity.
  • Explain what runoff is and why it matters for rivers.

New words

runoff
Rain or extra water that runs across the ground instead of soaking in. It can carry plant food into rivers.

Talk about it

What does your town have plenty of? What does it need to save?

Check questions and answers

  1. A system keeps its water in a loop. What does it save the most?

    • Water (answer) Right. The water goes round and round, so little is lost.
    • Electricity Not quite. Pumps and lights use more electricity, not less.
    • Sunlight Not quite. Think about what goes round and round in the loop.

  2. What does a water system usually use more of than a field?

    • Electricity (answer) Right. Pumps, lights, and heaters all need power.
    • Water Not quite. Its water goes round in a loop, so it uses less.
    • Land Not quite. Plants can grow close or stacked, so it needs less land.

  3. Is one way of farming always the best?

    • No. It depends on the place. (answer) Right. Each farm empties a different jar.
    • Yes. A water system always wins. Not quite. It saves water, but it uses more electricity.
    • Yes. A field always wins. Not quite. A field spends lots of water and land.

Sources

  • FAO. AQUASTAT - FAO's Global Information System on Water and Agriculture: Water use. Food and Agriculture Organization of the United Nations.
  • 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.
  • Kranz, B. Irrigation Chapter 8: Irrigation Efficiencies. Irrigation Home Study Course, Plant and Soil Sciences eLibrary, University of Nebraska-Lincoln Extension.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • Canelon, D. An introduction to hydroponics. University of Alaska Fairbanks Cooperative Extension Service, 13 December 2022.
  • Cabrera-Garcia, J., Milhollin, R., and Ernst, M. Controlled Environment Agriculture: Hydroponic Farming. G6986. University of Missouri Extension, 2024.
  • 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.
  • 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.
  • U.S. Geological Survey. Runoff: Surface and Overland Water Runoff. USGS Water Science School.
  • U.S. Environmental Protection Agency. Sources and Solutions: Agriculture. Nutrient Pollution.
  • NOAA National Ocean Service. What causes nutrient pollution? Coastal Pollution Tutorial.
  • NOAA National Ocean Service. What is eutrophication?
  • 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.
  • 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.