Extension > Agriculture > Nutrient Management > Nutrient/Lime Guidelines > Fertilizer Recommendations for Agronomic Crops in Minnesota > Grasses for Hay and Pasture
Grasses for Hay and Pasture
Several forage grasses and grass mixtures are adapted to Minnesota. As with other crops, adequate fertilizer programs are needed for optimum economic production. This is true for grasses grown for either hay or pasture.
The grasses and grass mixtures, whether grown for hay or pasture, are perennial crops. Therefore, previous crop is not a consideration when making fertilizer guidelines. Nitrogen fertilizer guidelines are based on expected yield. The expected yield will vary with such factors as intended use, management intensity, and soil texture. The suggestions for each expected yield are listed in Table 1.
Table 1. Nitrogen guidelines for grasses and grass mixtures in Minnesota.
|Expected Yield||N to apply|
|ton dry matter/acre||lb./acre|
Expected yields of 4 or more tons of dry matter per acre are reasonable for situations where soils have a good water holding capacity and intensive management practices such as the use of rotational grazing are used. Without irrigation, expected yields of 2 ton per acre are more reasonable when grasses are grown on sandy soils where moisture is usually limited. It's not possible to assign a yield expectation for every situation in Minnesota where forage crops are grown. This is a decision for the individual managing the production of forage grasses.
The time of nitrogen fertilizer application should match the growth pattern of the forage grasses. With cool season grasses, the majority of the growth takes place in late spring and early summer. Therefore, early spring application of nitrogen is suggested for these grasses. Brome-grass, orchardgrass, and reed canarygrass are three major cool season grasses grown in Minnesota.
Timing for warm season grasses should be different. These grasses thrive when temperatures are warm in mid-summer. Therefore, a late spring application of nitrogen is suggested. Switchgrass is an example of a warm season grass.
Split application of nitrogen fertilizer is an option for intensive management situations when expected yields are greater than 4 ton per acre. If the split application is an option, ¾ of the nitrogen should be applied in early spring and ¼ in late August.
Phosphate and Potash
The phosphate fertilizer guidelines are listed in Table 2 while the potash fertilizer guidelines are listed in Table 3. The listed rates are for all forage grasses and grass mixtures. The needed fertilizer should be broadcast to established stands in early spring for cool season grasses, and late spring for the warm season grasses.
Table 2. Phosphate fertilizer guidelines for grasses and grass mixtures.
|Phosphorus (P) Soil Test, ppm *|
|ton/acre||— P2O5 to apply (lb./acre) —|
* Use one of the following equations if a phosphate guideline for a specific soil test and a specific expected yield is desired.
P2O5 rec = [19.12 — 0.723) (Bray P, ppm)] (Expected Yield)
P2O5 rec rec = [19.12 — (1.012) (Olsen P, ppm)] (Expected Yield)
Table 3. Potash fertilizer guidelines for grasses and grass mixtures.
|Potassium (K) Soil Test, ppm *|
|ton/acre||— K2O to apply (lb.acre) —|
* Use the following equation if a potash guideline for a specific soil test and a specific expected yield is desired.
K2O rec = [40.43 — (0.286) (Soil Test K, ppm)] (Expected Yield)
Research trials in Minnesota have shown that forage grasses and grass mixtures have not responded to the application to other nutrients in a fertilizer program. Therefore, none are suggested.