NC Cooperative Extension

Fertilizer Prices and Usage


As many of producers have already seen, Nitrogen and fertilizer costs have risen from 50% to as much as 100% over last year. This has prompted many producers to take a closer look at the need to lime and fertilize this spring. While cutting back on certain fertilizer and liming practices will help your immediate economic cash flow, it could reduce your overall profits for the year. Pastures require nutrients to be productive. These nutrients are derived from several sources including residual nutrients in the soil, nitrogen produced by nitrogen fixing organisms in legumes , nitrogen from rain and snow, nutrients derived from the breakdown of manures and organic matters in the soil and lastly nutrients applied from fertilizers and lime.

In some situations a fair percentage of nutrients can be derived form these residual fertilizer sources however seldom can all the nutrient needs be met without some commercial fertilizer application. The only way to know what residual nutrients are available is to soil test. Never has it made more sense to soil test than now!!! Another factor that needs consideration is the availability of these nutrients to the plant. While most soils have some level of nutrients present, if the soils are acidic low PH), the negatively charges particles bind some of these nutrients to the soil so that they are not available for the plant to utilize. In these soils, the most economic beneficial application would be that of lime rather than higher levels of fertilizer. Pastures that have significant percentages of broom sedge are often needing lime or Phosphorus. The only sure way to know is to soil test! Following are a few tips to help make the best economic use of your lime and fertilizer budget:

1. Soil test. Even though it will likely take about 2 months to get your results, you can use a standard recommendation of 300-350 lbs of 17-17-17 and make up any deficiencies later in summer or fall applications if needed. The only true way to know what you need is to know what is available in you soil and what nutrients are needed by the forage you are growing.

2. If you have not limed in the last 2-3 years, chances are you will need an application of lime (1-2 tons per acre). (Especially if you are noticing an increase in broomsedge). Pastures that receive higher levels of Nitrogen to increase yields will tend to become acidic more rapidly requiring more frequent applications of lime.

3. Utilize livestock and poultry manures whenever it is economically and environmentally feasible. These sources are often available at a lower cost than commercial fertilizers. There are also by-product and municipal waste sources available that make excellent liming and/or fertilizer sources. However, often there is paperwork required in the utilization of these low cost resources and there may also be a limitation as to how much can be used. There may also be restrictions as to how soon livestock can graze these fields after application.

4. Apply only the nutrients you need! Fertilizers are sold based on the percent Nitrogen(N),  Phosphorus(P) and Potash(K) in the blend. 100 lbs of 17-17-17 contains 17 percent Nitrogen, Phosphorus and Potash respectively. 100 lbs of 18-46-0 contains 18 % nitrogen, 46% phosphorus and 0% potash. Many of our soils have adequate levels of Potash. On these soils utilizing 17-17-17 to meet our fertility needs would give us unneeded levels of potash. Soil test and match the ratio of N-P-K in the fertilizer blend we use to the ratio of N-P-K recommended for our soil.

5. Split applied Nitrogen into 2 or more applications. Nitrogen is very volatile and can move or leach from the soil rapidly compared to P and K. Usually a majority of the Nitrogen applied in a commercial fertilizer is gone in 60 days. Applying all our N in one application would leave our pastures deficient towards the middle and end of the season giving us reduced yields.

6. Interseed clovers into our grass stand to help provide N for our grasses. Clovers are legumes and have the ability to fix Nitrogen in the soil making it available for grasses to utilize. This is an excellent way to economically increase production of our grass pastures. (Legumes do require a higher PH than grasses so be sure to lime) With cattle prices at a higher level it may not be economically feasible to cut back on pasture fertility to the point of realizing a reduction in pasture production, weaning weights and cow fertility. Don't be penny wise and pound foolish!!!


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