Dryland farming is the practice of growing crops without irrigation in regions that receive limited rainfall, typically less than 500 to 750 millimeters (about 20 to 30 inches) per year. Instead of relying on wells, rivers, or sprinkler systems, dryland farmers use specific soil and water conservation techniques to capture every drop of rain and make it last through the growing season. Nearly half of the world’s agricultural land (44%) sits in drylands, mainly across Africa and Asia, and these areas supply roughly 60% of the global food supply.
How Dryland Farming Differs From Other Rainfed Agriculture
All dryland farming is rainfed, but not all rainfed farming qualifies as dryland. The distinction comes down to how much rain falls and how carefully water must be managed. In areas receiving more than about 1,150 mm of rain per year, crops can grow with relatively little water management. Between roughly 750 and 1,150 mm, farmers still depend on rain but face fewer constraints. Below 750 mm, and especially below 500 mm, every management decision revolves around conserving moisture. That lowest tier is where dryland farming operates.
What makes dryland regions particularly challenging isn’t just low rainfall. It’s the unpredictability. In a typical dryland farming zone averaging 400 to 600 mm of annual rain, any given year might deliver as little as half that average or as much as double. A farmer might plan for 500 mm and receive 250. The entire system has to be built around that uncertainty, which is why dryland farming developed its own distinct set of techniques rather than simply borrowing from wetter agricultural traditions.
Climate scientists classify these zones using the ratio of annual precipitation to potential evapotranspiration, essentially measuring how much water falls versus how much the atmosphere could pull back out. Arid zones lose far more to evaporation than they gain from rain. Semi-arid and dry subhumid zones are slightly better off but still face growing seasons as short as 60 to 179 days, compared to year-round growing potential in humid climates.
The Core Principle: Capturing and Keeping Moisture
The central challenge in dryland farming is that rain arrives in brief, sometimes intense bursts, then nothing falls for weeks or months. When rain does hit the soil, some runs off the surface, some soaks in and percolates past the root zone, and the rest evaporates back into the air. Dryland farming techniques aim to tip those proportions: minimize runoff, reduce evaporation, and hold as much water as possible in the top few feet of soil where roots can reach it.
Mulching is one of the most effective tools. A layer of organic material (straw, crop residue, compost) or plastic film on the soil surface acts as a barrier between wet soil and dry air. It slows evaporation, moderates soil temperature so roots aren’t stressed by extreme heat, suppresses weeds that would compete for moisture, and reduces erosion from wind and rain. Organic mulch has additional benefits: it slows water flow across the surface, giving rain more time to soak in rather than run off, and it reduces nutrient leaching by keeping water and dissolved minerals in the root zone.
Plastic film mulching takes this further. Moisture that evaporates from the soil surface condenses on the underside of the film and drips back down, creating a small recycling loop that keeps the topsoil moist for days longer than it would otherwise stay. Research on dryland maize found that plastic film mulching could increase both total plant growth and seed yields by over 20% compared to unmulched fields, even under warming climate conditions projected over the next 50 years.
Building Soil That Holds More Water
Soil composition matters enormously in dryland systems. Sandy soils drain fast and hold little moisture. Clay soils hold water tightly but can become waterlogged or form crusts that repel rain. The sweet spot is soil rich in organic matter, the decomposed remains of plants and microorganisms that act like a sponge within the soil structure.
For each 1% increase in soil organic matter, soil can store an additional 16,000 gallons of water per acre-foot. That’s a substantial buffer in a system where every gallon counts. Dryland farmers build organic matter over time by returning crop residues to the field, planting cover crops, composting, and minimizing practices that accelerate decomposition (like excessive tilling, which exposes organic material to air and breaks it down faster).
No-till farming, where seeds are planted directly into undisturbed soil rather than plowed fields, has measurable benefits for moisture retention. Compared to conventional tillage, no-till systems increase the water content in the upper soil layers by around 8.5% and in deeper layers by about 6.8%. That difference can determine whether a crop survives a dry spell. No-till also reduces surface runoff, meaning more of each rainfall event actually enters the soil rather than flowing away.
Fallowing: Resting the Land to Store Water
One of the oldest dryland strategies is summer fallow, where a field is left unplanted for an entire growing season. The idea is straightforward: skip a crop, let that season’s rainfall accumulate in the soil, then plant the following year with a deeper moisture reserve. In the American Great Plains, wheat-fallow rotations (one crop every two years) were standard practice for much of the 20th century.
The approach works in principle, but decades of research have revealed serious downsides. Fallow turns out to be surprisingly inefficient at storing water. Much of the rain that falls on bare ground still evaporates. Meanwhile, the exposed soil loses organic matter over time, and in some regions, fallow has contributed to saline seeps, where dissolved salts accumulate near the surface and poison the soil.
More intensive crop rotations, where different crops are planted every year instead of alternating with fallow, have proven more water-efficient overall. Growing a diverse sequence of crops with different root depths, water needs, and growing seasons captures more total water and produces higher yields per unit of rain received. The tradeoff is that any individual grain crop may yield slightly less than it would following a fallow year, but total productivity across the rotation goes up.
Where Dryland Farming Happens
Dryland farming spans every continent except Antarctica. The largest concentrations are in sub-Saharan Africa, the Middle East, Central and South Asia, and Australia. In the United States, it dominates the western Great Plains from Montana through Texas, as well as parts of the Pacific Northwest east of the Cascades. Mediterranean climates like those in southern Spain, North Africa, and parts of California also rely heavily on dryland techniques, where wet winters and bone-dry summers create a compressed window for soil moisture storage.
The crops grown vary by region but share common traits: drought tolerance, relatively short growing seasons, and efficient water use. Wheat, sorghum, millet, chickpeas, lentils, and certain varieties of corn are staples of dryland systems worldwide. In the Pacific Northwest, farmers have successfully dry-farmed vegetables like tomatoes, potatoes, and squash by selecting varieties bred for low water conditions and spacing plants far enough apart that each one commands a larger share of soil moisture.
Adapting to a Warming Climate
Dryland regions are disproportionately affected by rising temperatures. Higher heat increases evapotranspiration, meaning the atmosphere pulls more water from the soil and from plants, effectively making an already dry system drier. Precipitation patterns are also shifting, with some dryland areas receiving the same total rainfall but in fewer, more intense storms that cause more runoff and less infiltration.
Current adaptation strategies focus on several fronts. Adjusting planting dates to align with shifting rainfall patterns is one of the simplest interventions. Under moderate warming scenarios, the optimal planting window for dryland crops is projected to extend by a few days, giving farmers slightly more flexibility. Plastic film mulching shows particular promise: modeling suggests it allows crops to better handle severe swings in precipitation, temperature, and solar radiation compared to unmulched systems.
Breeding programs are developing crop varieties that mature faster, tolerate higher temperatures, and extract water more efficiently from dry soil. Combined with improved weather forecasting and soil moisture monitoring, these tools give dryland farmers more information to work with than any previous generation had. The fundamental principle, though, remains unchanged: waste nothing, store everything, and plan for the year the rain doesn’t come.