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LIMING

By Hubert Earl

(Hubert Earl believes you'll see far more benefit applying lime, than you're likely to see applying nitrogen. Find out why he says this, and what liming has done for his crops.)

The soil is the farmer's most important resource. However, the continual use of fertilizer, pesticides, poor land management practices, plus acid rain, and poor initial soil structure have led either to soil compaction and/or soil acidity. Although much of our Ontario soil is derived from bedrock high in calcium, factors such as those above have caused an imbalance of calcium in the top 6 or 7" of soil. This often impedes the growth and quality of later crops.

Lime is considered an indirect fertilizer. It is not regarded as a plant food, and shouldn't be. However, it is just as essential to plant growth and life, as are the major nutrients (nitrogen, phosphorus and potash). Livestock producers recognize forage crops as their best source of calcium, yet too few realize that calcium-deficient soil will produce calcium-deficient crops. Even if the soil is rich in the essential elements, it is absolutely useless for growing crops without sufficient calcium or lime. Green or composted livestock manures are also of little value if there isn't enough calcium to activate decomposition, and unlock the major nutrients. Liming yields another benefit. Earthworms, essential for fast manure recycling, soil aeration and mixing, are said to double in population within 30 days of liming.

Garden crops such as the nightshade family (tomatoes, peppers, potatoes) and the brassicas (cabbage, broccoli, cauliflower) and celery are also heavily dependent upon calcium. Alfalfa, clover root crops, soybeans, grasses, small grains and even corn all require lime in substantial quantities.

We've observed that when lime was applied to pastures and older hay fields, there was a sudden resurgence of red and white clovers in astonishing masses. Vaughan Jones, a renowned authority on pasturing, reinforces with our observations and thinking: "You don't lime for pH. You lime to get calcium into your forage and to get clover. You can have a high pH/low calcium soil and you won't get clover. Clover is to the dairymen what oil is to the Arabs. You absolutely must have it for high milk production and low costs." So, while many farmers consider nitrogen most important, I believe that applying ground limestone is far more beneficial.

Initially, a soil test can help determine soil acidity or the absence of lime. However, on our farm we believe that the forage, and not the soil, should be tested for minerals - after all it's the forage that our livestock eat! (A pH test on the soil doesn't reveal what calcium levels are present in our hay, haylage, pasture and small grains.) Some farmers use the presence of dandelions in pastures and hay fields as an indicator of low levels of calcium. This is something we intend to monitor.

Much advice exists on the amount of lime to apply and at what times. Personally, we feel it is better to apply a small amount of lime every year, rather than a large dose at one time. For example, 1500 lb./acre each year for 3 years is better than 4500 lb./acre all at once. Lime can be applied in spring or fall on pastures and hay fields. Ours is spread in the spring. On cropland, it should be applied after ploughing and then immediately incorporated in by discing or cultivating. It can also be applied after a grain harvest and then incorporated in. It's critical to apply raw, green or composted manure at least several weeks in advance of liming. Applying them at the same time as the lime just seems to tie both of them up.

There is probably no other aspect of farm soils that can increase your productivity and profitability like the continual use of lime. Start with your garden or take a few fields, apply ground limestone and assess the results. Leave a check strip or area to compare performance. I suspect you will be pleasantly surprised. In most instances, calcitic limestone is preferable, being faster-acting than dolomitic limestone. However, in areas where magnesium levels are low, dolomitic limestone should be considered. To spent money wisely, look for a source which has: 40% total calcium, 100% neutralizing value, and an Agricultural Index of 75.

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