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Clover provides nitrogen for soil, forage for cattle
By Laura Whelan
MISSISSIPPI STATE -- Cattle producers looking to reduce rising fertilizer costs can enrich soil and feed livestock by seeding clover in grazing pastures.
Gregg Ibendahl, agricultural economist with Mississippi State University's Extension Service, said in the last two years natural gas wellhead prices have risen from $2 per British thermal unit to $5 per unit.
"Since natural gas is used in the manufacture of nitrogen-based fertilizers and accounts for about 75 percent of its production costs, the price of nitrogen-based fertilizers has also increased," Ibendahl said.
Richard Watson, Extension forage specialist, said clover is an economical alternative to manufactured nitrogen-based fertilizers and provides plenty of the essential nitrogen needed for plant growth.
"As a legume, clover obtains nitrogen from the atmosphere and fixes it into the soil in organic forms for its own use as well as for the grass growing around it," he said.
This translates into economic savings for farmers who plant clover to provide the nitrogen their pastures need rather than purchasing and applying nitrogen-based fertilizers.
"If 20 to 30 percent of the pasture is planted in clover, we can assume that amount of clover could fix 80 to 200 pounds of nitrogen per acre, depending on growth conditions and the clover species. This is often enough nitrogen for the whole pasture. Based on current gas prices, a farmer could achieve a savings of $40 to $50 per acre by reducing or eliminating the need for nitrogen-based fertilizer," Watson said.
In addition to nitrogen fixation, clover has other benefits.
"Clover often has a higher digestibility and contains more protein than grasses, so it can improve animal performance when incorporated into pastures. Animals enjoy eating clover, and it doesn't have some of the risks to the environment that nitrogen-based fertilizers can have," Watson said.
Clovers and other legumes fix nitrogen into a stable form -- in the decaying plant tissue -- that will not pollute surrounding areas. Manufactured nitrogen-based fertilizers often contain nitrogen in a very mobile form, potentially leading to significant losses if rainfall leaches soluble nitrogen into the groundwater. Some forms of nitrogen fertilizer, such as urea, will evaporate in hot weather, causing a loss of applied nitrogen.
But Watson said it is important to note that nitrogen fixation in clover is not a rapid process.
"For short-term treatment where a need for nitrogen might be limiting plant growth, a manufactured form of nitrogen would be better because the nitrogen is more readily available for use by the plant," he said.
Even though most farmers in Mississippi are aware of clover's benefits, Watson said there are three factors that hinder use of clover as forage in the state: the hot summer climate, adaptation to the state's acidic soils and overgrazing of pasture.
"These issues can be addressed by first performing a soil test and applying recommended lime levels to ensure the soil pH is above 6, which is ideal for clover growth. Then farmers can prevent overgrazing by rotating animals on pastures to limit grazing time in each area," Watson said.
Clover can be seeded in spring or fall. After a soil test and once the proper pH is established, clover can be broadcast into existing grass stands very easily.
"Clover will rapidly germinate and establish; the key is keeping the clover in the pasture by limiting overgrazing," Watson said.
Watson recommended maintaining a mixture of grass and clover in the pasture, with a combination of 20 percent to 30 percent clover and 70 percent to 80 percent grass. This amount of clover provides optimal animal performance and can generally fix enough nitrogen to meet the needs of clover and grass. Closely graze or clip pastures to reduce competition in an existing grass pasture and allow clover to establish.
Mississippi farmers can choose from a variety of annual and perennial clover species. Watson suggested using red and white perennial clovers because they will not have to be seeded as often.
Farmers should also ensure that animals grazing on clover are eating enough fiber.
"Clover has a high soluble protein level and breaks down quickly in the rumen, and this can form an emulsion that prevents belching to relieve gas pressure. If gas is not released, the resultant bloating can be serious, even proving fatal," Watson said. "But with adequate fiber in the diet, this bloating is not as likely to occur."