Pasture Improvement: Soil Tests

Table of Contents

1. Soil Tests
2. Fertility Program
3. pH
4. Other Pasture Improvement Recommendations
   • Choosing the Improvement Technique
   • Rejuvenation
   • Renovation
   • Seeding into the Sod
   • Broadcast Seeding
   • Limited Tillage
   • Frost Seeding
   • Using Livestock to Renovate Pastures
   • Fertilizing Pastures
   • Nutrient Cycling
   • Impact of Grazing Animals on Pasture Fertility
   • Weed Control
   • Trampling Effects
5. Related Links

Soil Tests

A basic soil test measuring pH, phosphorus and potassium levels is sufficient for most pasture management. Soil tests for northwestern Ontario should include sulphur testing. Further tests may be beneficial if a specific deficiency is suspected, but are not required on a regular basis. See Appendix A, Accredited Laboratories in Ontario.

Fertility Program

Apply phosphorus and potash according to soil test recommendations. Apply nitrogen according to yield goals, the cost of nitrogen and the value of the animal product being produced on the pasture. The economics of using nitrogen on pastures depends on the utilization of the additional production. This normally requires high stocking rates. For full-season production, apply nitrogen in the spring, the end of June and the middle of August. A light application in early September can build root reserves to help grass pastures overwinter and get off to a faster start the following spring.

pH

The pH is a measurement of the acidity or alkalinity of the soil. Most pasture species are most productive at pHs in the range of 6.0 to 7.5. A pH below 6.0 is low or acid, while a pH above 7.5 is high or alkaline.

If the pH is too low to successfully grow a desired species, it can be raised by adding lime. Calcitic lime raises the pH and adds calcium to the soil, while dolomitic lime raises the pH and adds both calcium and magnesium to the soil. Liming the soil to raise the pH of acid soils may cause an increase in soil fertility, as phosphorus becomes more available at near neutral pH and soil micro-organisms are more active.

Lime is slow acting in soil. It is best incorporated throughout the root zone; it has limited value when applied to the surface without incorporation. Once applied, lime raises the pH for several years, but with time the pH gradually falls to the original value.

Alkaline soils with a high pH can limit plant growth, although this is rarely a problem for pasture production. High pH soils may be deficient in micronutrients. In this case, it is more economical to add the micronutrient than to adjust the pH.

Related Links

... on forages and pastures, visit Forages and Pastures (OMAFRA)
... on weed control, order Publication 75 Guide to Weed Control: Forage Crops
... on agronomy for field crops, order Pub. 811 Agronomy Guide for Field Crops: Chapter 3 Forages
... on field crop protection, order Publication 812, Field Crop Protection Guide
... on livestock, visit Livestock (OMAFRA)