Applying Lime in the Winter

Liming fields to bring soil pH into the generally recommend range of 6.0 to 7.0 should be a high priority on every farm. Even though it’s well past time for fall lime applications, soil scientists and agronomists say applying needed lime in the winter can still be a good management decision.

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Figure 1

Figure 1. The best time to apply lime is anytime soil conditions will allow spreader traffic without causing rutting or compaction.

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The best time to apply lime is anytime soil conditions will allow spreader traffic without causing rutting or compaction.1 For typical lime applications, farmers should wait until soils are dry. An alternative is to apply lime on a frozen soil to minimize compaction. Farmers should consider field slope and ground cover when applying lime on frozen soil. Winter rains or snow melt can wash lime off a field with significant slope or lack of ground cover.

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One benefit of applying lime on a frozen soil, or on a dry soil in the fall, is there may be some shallow incorporation due to freezing and thawing action throughout the winter. This can be particularly beneficial in no-till or perennial crops where no tillage is expected.1

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Properly applied lime can correct problems that might otherwise occur under conditions of excess soil acidity. Proper soil pH increases the availability of essential nutrients, improves the activity of soil microorganisms, reduces the solubility (toxicity) of non-essential elements, and affects the performance and/or carryover of some herbicides.1 Some additional problems that may be prevented with proper liming include:

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  • Reduces aluminum and other metal toxicities
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  • Improves soil physical condition
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  • Stimulates microbial activity, including symbiotic bacteria that fix N
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  • Improves availability of essential nutrients
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  • Supplies calcium and magnesium for plants
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Soils become acidic over time and may be caused by:

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  • Nitrification of ammonia
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  • Bases removed by crops
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  • Bases removed by leaching
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  • Carbonic acid from microbial and plant respiration
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  • Organic acids secreted by plant roots
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  • Precipitation
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  • Oxidation of sulfide
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Figure 1
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Application of N fertilizer materials may also lead to increased soil acidity. Table 1 shows the pounds of lime required to offset the application of one pound N.

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How frequently lime is applied should be guided by regular soil tests that monitor soil pH over time. Lime should be applied on a regular basis and often enough that the soil pH never gets so low that the timing of maintenance liming is critical. Many soils will require liming every 3 to 4 years. However, farmers should consult with local agronomists for recommendations on ideal liming intervals in your area.

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Farmers should also keep in mind that even high quality lime takes some time to react and correct soil acidity. Lime should be applied 3 to 6 months before crops are planted. This may be especially important if the soil pH is very low. For example, if a new alfalfa seeding is planned, liming should be considered the year before seeding or at least the fall before seeding.2

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Finally, to be most effective, lime must be spread evenly over the field. Leaving a lime pile in a field for an extended period may lead to lumps that may make the lime difficult to uniformly spread.