Lime is used to raise soil pH levels when soil tests reveal levels below the optimal range. Defined, pH is the negative log of the hydrogen ion concentration. More simply stated, we use lime (calcium hydroxide) to knock hydrogen off of the soil nutrient exchange sites. The optimal pH range varies for plants. Many vegetable and field crops do best when soil pH levels are between 6.0 and 6.5 on the scale of 0 to 14. However alfalfa grows best at slightly higher levels like 6.8 while blue berries, azalea and rhododendron bushes perform best at lower levels like 5.0 to 5.5. Typically yard and garden enthusiasts end up with pH levels too high due to adding lime or other materials and agricultural fields are too low due to the cost of liming large acreages. Lime is more difficult to understand than other soil nutrients so let's take a look at lime from both the garden and the farm perspective.
Interestingly, soil pH affects the availability of other nutrients. For example, high soil pH levels will result in one being more likely to find manganese, iron, boron, magnesium, and zinc deficiencies. Low soil pH values will result in one being more likely to find aluminum toxicity or phosphorous, calcium, and magnesium deficiencies. Soil testing every few years is critical to know what is going on with soil fertility.
Meters for pH are more accurate than other indicator kits are for other nutrients. However, it is economical and typically best to submit a sample for a basic soil test with a certified lab that typically costs anywhere from $10-$15 per sample. Contact the office for a list of certified labs, sampling instructions and to borrow a probe to collect samples.
Another difficult concept to understand about lime is the fact that different amounts of lime are needed to change the soil pH from 6.0 to 6.5 due to differences in soil types. Clay and organic matter function as nutrient exchange sites in soil allowing soil its ability to hold nutrients and soils with higher levels of these two materials are more buffered. The more clay and organic matter a soil has characteristically, the greater the amount of lime that is needed to change the soil pH, relative to soils with lesser clay and organic matter. For this reason on a soil test report, one will see the column titled buffer pH in addition to soil pH. Use the recommendations with the soil test report or contact the office if you need help in calculating the amount of lime needed based on the buffer index.
Further complicating matters, not all lime is created equal. Lime varies in quality in terms of its neutralizing value and the lime also functions more quickly and efficiently according to how finely it is ground. Visit http://www.aglime.org/qualrept.htm to see the Indiana Lime Council report for quarries listed by county in Indiana. One should price lime and determine vendors according to its relative neutralizing value which factors in both the quality and the fineness of the lime.
Calcitic lime is typically the type of lime found in southern Indiana whereas dolomitic lime is typically found in northern Indiana. Dolomitic lime is also a source of magnesium. Locally, it is typically not necessary to have the expense of transporting northern Indiana lime as we have enough magnesium naturally available in our soils.
In the agricultural arena, the producer must consider lime when needed as worth the expense in this time of very high fertilizer prices to most optimize the efficiency of both applied and inherent soil fertility.
Historically landlords have typically paid lime costs as lime is a long term investment. Recent trends though have shown that lime costs are being shifted towards the tenant more than in the past or at least are part of the cash rent equation.
By nature, most folks feel the need to do something with soil when garden centers and hardware stores push out the materials every year after Christmas to get us started thinking spring. Consequently, blindly adding lime or other materials without a soil test, results in gardens with too high of pH other fertility levels. Soil testing is important to know what to do so that one avoids problems and also does not waste dollars when materials are not needed. Spreading ashes from fire places or wood burners results in raising soil pH levels and potassium values.
This is commonly done during this time of year resulting in problems during the next growing season. I personally have a red maple that shows manganese deficiency on half the tree, due to ashes that were spread in an area on one side of the tree's root system which elevated the pH too high and immobilizing the manganese in the soil. Areas adjacent to current or past gravel roads typically have too high of pH levels as a result of dust from the road which can continue to have problems when yard trees and gardens are established.
You can contact the local Purdue Extension Office by calling 829-5020 x14 in Owen County or 448-9041 in Clay County for more information or publication copies regarding this week's column topic or to RSVP for upcoming events. Please call first to assure items are ready when you arrive and to RSVP for programs. While most publications are free, some do have a fee. All times listed are Eastern Time.
Jan. 8 Region 5 Indiana Beef Cattle Assoc. Program, Greencastle, 6:30 p.m.
Jan.9-12 National No-till Conference, Cincinnati, Ohio
Jan. 15 Starting Bee Keeping, Session 1 of 4, Spencer, 6:30 p.m.
Jan. 17 First of six weekly Marketing Commodities for Farm Women, Brazil, 7 p.m.
Jan. 22 Central Indiana Pork Conference, Frankfort, 9 a.m.
Jan. 25-26 Farming Together Workshop, Purdue
Jan. 28 Clay County Extension Advisory Council Annual Meeting, 6:30 p.m.
Jan. 29 Crop Management Workshop, Purdue, 8:30 a.m.
Jan. 28-30 Indiana Hort Congress, Indianapolis
January 30 Crop Management Workshop, Danville, 8:30 a.m.
Feb. 2 Purdue Ag Alumni Fish Fry, Indianapolis
Feb. 9 Bi-state Livestock Conference, North Vermillion High School
Feb. 13-16 National Farm Machinery Show, Louisville, Ky.
Feb. 20-21 Women in Ag Conference, Columbus, Ind.
Feb. 26 Starting Bee Keeping, Session 2 of 4, Spencer, 6:30 p.m.