Introduction
Water availability is a critical factor in crop selection for agricultural production. This report compares the water needs of barley, alfalfa, and feed corn, highlighting their differences in water consumption, growing season, irrigation requirements, and overall efficiency.
1. Water Requirements
| Crop | Water Needed (inches per season) | Relative Water Demand |
|---|---|---|
| Barley | 12–18 inches (300–450 mm) | Low |
| Feed Corn | 20–30 inches (500–760 mm) | Moderate |
| Alfalfa | 30–60 inches (760–1520 mm) | High |
2. Growing Season & Water Consumption
| Crop | Growing Season Length | Key Water Demand Periods |
|---|---|---|
| Barley | 90–120 days (short) | Early vegetative and grain-filling stages |
| Feed Corn | 120–150 days (medium) | Tasseling and grain-filling stages |
| Alfalfa | Perennial (multiple years) | Constant throughout growing season |
3. Root System & Water Access
| Crop | Root Depth | Water Access Efficiency |
|---|---|---|
| Barley | Up to 3 feet | Shallow-rooted, less efficient in accessing deep moisture |
| Feed Corn | Up to 5 feet | Moderate root depth, better at accessing stored soil moisture |
| Alfalfa | Up to 10–15 feet | Deep-rooted, can access groundwater but requires consistent moisture |
4. Irrigation Needs
| Crop | Irrigation Dependence | Rain-fed Suitability |
|---|---|---|
| Barley | Low to moderate | Well-suited for rain-fed systems |
| Feed Corn | Moderate to high | Can grow with rainfall but benefits from irrigation |
| Alfalfa | High | Requires irrigation in most climates |
5. Water Use Efficiency & Yield Considerations
| Crop | Water Use Efficiency | Yield Consideration |
|---|---|---|
| Barley | High (low water use, moderate yield) | Lower total biomass but efficient in dry regions |
| Feed Corn | Moderate (higher yield, higher water use) | High grain and biomass yield for feed |
| Alfalfa | Low (high water use, high yield) | Very high biomass yield but water-intensive |
Conclusion & Recommendations
If water conservation is a priority, barley is the best option due to its low water needs and ability to grow in rain-fed conditions.
If maximizing feed yield is the goal and water is available, feed corn offers higher energy content per acre.
If high forage production is needed and ample irrigation is available, alfalfa provides the highest biomass output but at a significant water cost.
Final Considerations
- Dry regions should prioritize barley due to its drought tolerance.
- Moderate rainfall or irrigated areas can support feed corn for high-energy livestock feed.
- Alfalfa should only be grown where water is abundant or where deep-rooted crops can thrive with groundwater access.
References
For a comparison of different evapotranspiration (ET) methods, a study conducted in North Dakota examined various reference ET equations, including the Jensen-Haise (JH) method, the ASCE-EWRI grass and alfalfa equations, and the North Dakota Agricultural Weather Network (NDAWN) Penman-Monteith method. The study found that alfalfa-based reference ET (ETr-alfalfa) values were about 30% higher than grass-based values (ETr-grass). The JH method, developed using data from multiple crops, produced results close to the ASCE-EWRI grass-based ETr method.
The research also highlighted regional differences in ET values. For instance, in Oakes (southeastern North Dakota), the seasonal ETr was lower than in western locations like Dickinson. Differences in precipitation also impacted ET, with Oakes receiving more rainfall but lower ETr values compared to Dickinson.
For crop-specific ET data, the study reviewed evapotranspiration rates for major irrigated crops such as corn, sugar beet, potatoes, and alfalfa. The irrigation method and local climatic conditions significantly influenced the ETc (crop evapotranspiration), highlighting the importance of accurate crop coefficient (Kc) estimations.
If you need further details or the full study, you can refer to the original research conducted at North Dakota State University.
