When it comes to soil management, ask yourself three questions:
- What do I have?
- What does my crop need?
- What changes can I make to increase profitability?
In answering these questions, think about both soil conditions and soil nutrients. For example, grasses are more tolerant of saline soil condition than alfalfa, but does not have the deep taproots to access nutrients and water in the subsoil like alfalfa.
What do I have?
A soil test can tell you several important things about your soil, including nutrient and organic matter status, pH, and salt content. Most labs will provide fertilizer recommendations based on crops, yield goals, irrigation, and previous manure applications. A few things to keep in mind:
- Alfalfa produces it's own nitrogen (N) through a symbiotic relationship with Rhizobium bacteria. It is rarely, if ever, economical to apply N fertilizer to alfalfa.
- Test soils for nitrate annually in the spring every year before applying N fertilizer. N is very mobile in the soil and quickly lost by leaching due to irrigation or precipitation.
- Test soils every 2-3 years for phosphorus (P), potassium (K), micronutrients, organic matter, pH, and soluble salts. If you are making significant management changes, or monitoring a field for high salts or pH, consider testing more frequently.
Additional blog post on Soil Testing.
The Idaho Soil Health Card is a useful matrix for evaluating changes in your soil over time.
There are many good nutrient management resources available for forages. Here are a few to get you started:
- Fertilizer Management for Alfalfa - Utah State University
- Fertilizer Management for Grass and Grass-Legume Mixtures - Utah State University
- Phosphorus Fertilization of Garrison Creeping Foxtail - University of Wyoming
- Forage and Pasture Fertility Guide - Oklahoma State University
- Soil Nutrient Management for Forages - Montana State University
And some good resources on forage management from University of Wyoming Extension:
When making changes to your production system, be it tillage, fertilizer, or cropping systems,
keep good records. Remember, if you don't measure it you can't manage it! Depending on your soils and what your crop needs, here are some changes to consider:
- Decease fertilizer applications to reduce costs or wasted nutrients.
- Increase fertilizer use to reach optimum yields.
- Change the timing of fertilizer or manure applications to more closely match plant needs.
- Reduce soil compaction to increase rooting depth, and plant access to water and nutrients.
- Reduce tillage to increase soil organic matter, reduce erosion, and improve overall soil health.
- Use manure to build soil organic matter while providing all essential plant nutrients.
The Wyoming Ranch Tools website has some useful tools that can help you determine if the benefits of adding fertilizer are worth the additional costs, based on hay prices, input costs, and labor. Considering hiring a custom operator to do some of the work for you, or putting your tractor to work for someone else? Read my blog post on custom rates.