Dry Farming
Farming without irrigation using precipitation and soil moisture storage
Overview
Dry farming is farming without irrigation or with irrigation only for crop establishment, where water supplied through precipitation is below the potential water demands of the crop.
Water Savings
No irrigation used.
Other Benefits
No cost and labor associated with irrigation systems and groundwater use. Dry farming systems are often compatible with other alternative management systems such as regenerative, biodynamic, etc. in areas with sufficient rainfall. Potential for differentiation in the marketplace for both fruit and wine.
Factors to Consider
Annual precipitation, soil type and depth, topography, water accessibility; proximity to depleted groundwater, market, economic feasibility.
Dry Farming Quick Facts
- Dry farming differs from "rainfed" agriculture, where managing excess water during the growing season may be a challenge.
- Typical dry farming crops include winter forages, grain, and pasture, though other crops are dry farmed as well in some parts of California. Dry farmed crops are also sometimes used in rotation to break disease cycles.
- In California, dry farming is practiced in coastal and Foothill regions with mild summers and at least 20 inches of precipitation per year. Crops typically dry-farmed include tomatoes, olives and wine grapes.
- Dry farming in these areas is accomplished with increased plant spacing and site selection for deep soils that enable deep rooting.
- Lower revenue commodity crops such as feeds, forages and winter grains are grown with specific practices for timing of planting and harvest using specific cultivars and seasonal fallow.
- Outside of the growing season, seasonal fallow is used to conserve soil moisture until the next cropping cycle and shallow tillage or other weed control practice is important to reduce water loss.
- The key consideration for dry farming include having adequate precipitation to supply the crop requirements, and having a soil with sufficient available water holding capacity to store this precipitation. Available water holding capacity is a function of soil texture and depth. Fine-textured soils such as clays hold more water than coarse textured soils such as sandy soils. The depth of soil along with the soil texture determines the volume of water that can be stored for plant use. Soils with good infiltration characteristics which can store moisture relatively deeply will be optimum to support deeply rooted perennial crops; for shallower rooted crops such as grains a shallower soil may suffice.
Dry Farming Winegrapes
The development of pressure-compensating drip irrigation technology in the 1970s and 1980s enabled irrigated vineyards to be grown in areas that would not have been farmable with other irrigation systems. Irrigation has the advantages of both increasing yields and maintaining them by compensating for varying levels of stored soil moisture, mitigating the effect of the variation in annual rainfall. Vineyards that are not irrigated develop deep roots that can access soil moisture built up through winter rainfall but are still subject to yield reductions during dry years, and during extended drought periods.
In dry areas like the Basin, dry farmed winegrapes will yield less fruit than irrigated vineyards but may benefit from differentiation in the marketplace, assuming that only limited acres in the region are dry farmed.
The key factors that are used to site dry farmed vineyards are average annual precipitation and soil characteristics relating to rainfall capture and soil moisture storage. Potential fruit yield is directly proportional to the amount of precipitation received; annual precipitation of 20 inches per year has often been considered the threshold to produce economically viable levels of dry farmed wine grape production; however, winegrapes are dry farmed with as little as half that amount. Smaller crops can be produced under drier conditions but the economic viability is reduced. A soil suitable for dry farming needs to be able to infiltrate and store adequate moisture at a depth where it will not be lost to evaporation.
If cover crops are grown in a dry farmed vineyard in a region where precipitation is a limiting factor, the cover crop will need to be managed to not create additional competition for soil moisture with the vines. This includes limiting the width of the cover crop strip, using very shallow-rooted species, and terminating its growth at the end of winter.
The California Sustainable Winegrowing Alliance interactive web tool that provides information on growing conditions, including climate and soil, by field for the grape footprint in California also includes information on existing dry farms, their conditions, practices, and rootstock and variety choices. (URL to be published.)
Resources
Dry Farming and Water-Limited Cropping Systems — Summary
| Measure | Description | Water Savings Benefits | Other Benefits | Factors to Consider |
|---|---|---|---|---|
| Dry Farming | Farming without irrigation in semi-arid conditions. | No irrigation used. | No cost and labor associated with irrigation systems and groundwater use. Dry farming systems are often compatible with other alternative management systems such as regenerative, biodynamic, etc. in areas with sufficient rainfall. Potential for differentiation in the marketplace for both fruit and wine. | Annual precipitation, soil type and depth, topography, water accessibility; proximity to depleted groundwater, market, economic feasibility. |
| Extended Fallow | Lengthening the fallow period between removal and replant of a perennial crop. | No irrigation (winegrapes) or reduced irrigation of low water use interim crops. | Soil rest and/or opportunities to improve soil quality through amendments, treatments, cover crops, pest and disease control, time to plan and design new crop installation. | Crop type, severity of issues that the fallow can help correct, cost (changes in market prices that might influence length of fallow). |