People frequently ask the queries like “How much fertilizer per acre of pasture?” in the comment section as they are seeking a better fertilizing solution that really improves the dry matter production in pastures.
I have seen many farmers who were blindly spreading the fertilizers in their pasture fields but it results in the form high cost per unit of dry matter with low production of grass and forages in the fields.
So, I decided to write a guide on pasture fertilization that could put them on the right path and answer their question i.e. what is the cheapest way to fertilize pasture? How much fertilizer per acre for hay?.
But before fertilizing a pasture field for horses or cattle or any lawn or garden, with chemical or organic fertilizer, soil testing is done to know the current status of any fertilizing the fields accordingly.
Let’s get started from the primary step of fertilization i.e. soil testing and then pasture fertilizer recommendations.
Soil testing is the primary step in managing the fertility status of pastures and hayfields. Testing of soil with proper kits clarifies the current status of phosphorus, potassium, nitrogen, and other nutrients in the soil.
The person growing pastures neglects the soil testing as they think it is a low-value crop, grown for grazing, so they don’t adopt the regular nutrient management program for pasture fields.
Soil testing helps you recognize the areas with low or high fertility in pasture fields and protects the excessive levels of nutrients level and money loss. These high levels of phosphorus and potassium cause major problems like fueling algae blooms and milk fever in grazing cattle respectively.
Fields grown with specialty crops and more susceptible to nutrient changing levels soil like sandy soils are frequently tested before any new planting.
Samples of soil are collected from various points in the field and a soil test is run, giving N,P, K and pH values. High values of phosphorus and potassium are found in the soil in early spring samples.
After soil testing, the amount of fertilizer to be added in the pasture may alter accordingly.
How much fertilizer per acre of pasture?
The amount of fertilizer per acre of pasture primarily depends on the type of grass and soil fertility conditions. All of the macronutrients i.e. nitrogen, phosphorus, and potassium, and some micronutrients like boron and sulfur have prime roles in dry matter production of pasture fields.
By providing the ideal amount of these nutrients to the pasture fields, you can get the maximum output in the form of maximum yield as well as better utilization of nutrients.
These are some pasture fertilizer recommendations:
Nitrogen and moisture are the two main components that limit the growth in pasture fields. Sometimes, the low productive fields increase yields impressive folds by applying the nitrogen fertilizer.
The light green shades seen in the pasture fields are the main indication of nitrogen deficiency and it can only be cured by nitrogen application.
According to a research conducted at the University of Wisconsin estimated the 100 pounds of nitrogen fertilizer per acre of pasture.
But most of this amount is covered by recycling of nitrogen from the organic sources like manure, urine, and dead plants that add up to 15 to 30 pounds of nitrogen per year, to field on decomposition.
If mixed pasture fields are grown, adding the 30% of standing legume at the planting will add up the 30 to 50 pounds of nitrogen per year to the grasses in the pasture.
If you adopt the above two techniques of adding 30% legumes in pasture fields and grazing animals’ urine and manures in fields, it will allow you to add the remaining pounds of nitrogen fertilizer to get the potential yield from the pasture fields.
2. Phosphorus and Potassium
Phosphorus and potassium have the same vital role in pasture production as nitrogen but it works differently on the grasses. By cutting or grazing each ton of dry matter from the pasture field does remove the 12 to 15 pounds of phosphorus and 55 to 60 pounds of potassium.
To maintain these nutrients in the optimal level for optimal and maximum production of dry matter, it is dire need to add these nutrients in the soil profile in the form of fertilizers.
The recommended amount of P and K fertilizer per acre of pasture field producing 4.1 to 5 tons of dry matter is as:
- 60 pounds of P
- 240 pounds of K
Any potassium or phosphatic fertilizer can be added along with nitrogen fertilizer to maintain optimum levels.
Each ton of dry matter removed from legume-grass pasture removes 12 pounds of P and 48 pounds of K but the nutrient recycling by urine and manures from grazing animals favors the pasture fields.
Due to nutrient cycling, the actual amount of P and K per acre of legume-grass pasture is 2 pounds and 10 pounds respectively.
Maintaining the optimal levels of P and K in the pasture field becomes unavoidable especially if you have legumes along with grass in pastures. Grasses being more competitive for P and K than legumes, it suppresses the growth of the legumes in case of deficiency of P and K. So, the addition of P and K fertilizers is also the primary need of pastures.
3. Sulfur and Boron
Sulfur and Boron are micronutrients and it seems like they can be avoided as other crops, but in the case of pastures, their application has become essential for intensively grazed pastures.
From the results of soil testing, if the sulfur and boron appear then make sure to add both of these micros for better production in the future.
In a grazing pasture field, each ton of forage removes the 5 lbs of sulfur per year. To maintain the regular intensive production of grasses, you will do the application of sulfur accordingly.
If the boron deficiency appears in the soil test, then topdress the 2 pounds of boron fertilizer per acre every three years. But in the case of pasture fields in sandy soils, topdressing of boron at 0.5 to 1 pounds will be enough.
When to apply pasture fertilizer?
The better utilization of nutrients and fewer losses in form of leaching and volatilization for maximum output is completely dependent on the time of fertilizer application.
For pasture fields having cool-season grasses, the split application of fertilizers in late and early spring is a premium option to maximize the yields.
Make sure to never add N fertilizer during the mid-summer for cool-season grasses as it will be mostly consumed by weeds and grasses.
It does not mean from the above sentence that the summer application of N is never good for pastures. However, the N application is done for many grass pastures during the late summer for more growth.
Tips for better utilization of pasture fertilizers
These are some tips for better utilization of pasture fertilizers, and both of these tips would only be beneficial for you if you do soil testing.
1. Soil pH
Soil pH has a premium role in the availability of nutrients at the root zone of plants. Soil testing clarifies the current pH status of soil and allows you to do the pre-planting techniques to make it optimal for pasture growth.
The optimal level of pH for pastures is 5.8 to 6.0 and any level beyond or below this will adversely affect the pasture growth. High pH supports legume growth.
Mostly, the farmers faced the low pH levels in their fields and it can be optimized for pastures by lime application.
Lower pH is cured by lime application and the application of lime at the recommended rate and incorporation in plow layers should be done 6 months to 1 year before the pasture seeding.
Topdressing of lime is another option of applying lime in pastures but it will work slowly as the lime will grow more ¼ to ½ inches per year according to soil structure and lime fineness.
Always choose the finely graded lime for top dressing and continue the top dressing for a few years unless you achieve the desired pH level.
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Management practice to improve nitrogen level in pasture
To improve the nitrogen levels in pastures, there are many techniques to improve nitrogen by organic sources like manure, urine, and dead plants. But there is another improved technique to adopt that works both for grazing and improving the soil nitrogen.
That technique is to add the legumes with a ratio of 30% in the pasture fields. Legumes are white and red clovers, having the ability to fix nitrogen from the atmosphere and convert it into usable plants.
It is an economical approach to increase the production of grass pastures.
The best practice is broadcasting the seeds between mid of February and the end of March when the soil surface is going through the periodic freeze/thaw cycles. It does help to cover the bare patches in pastures as well as improve the yield by adding tons of nitrogen.