Liming (soil)
Liming is the agricultural practice of adding calcium and magnesium to soil to neutralize acidity and enhance the activity of soil bacteria. The effectiveness of liming depends on the soil's pH level and buffering capacity, which is its resistance to pH changes. By improving soil conditions, liming promotes nutrient uptake from fertilizers but must be applied judiciously, as excessive liming can harm plant life. The most commonly used liming material is ground limestone, which primarily consists of calcium carbonate and typically contains a minimum percentage of magnesium as mandated by state laws. Beyond enhancing soil health, liming plays a role in addressing freshwater acidification by neutralizing nearby water bodies. It also has implications for climate change; lime may act as a carbon sink, potentially sequestering up to half of its carbon content, although the overall impact on CO2 emissions remains complex and somewhat unclear. Liming can be particularly crucial in farming acidic peatlands, but it may inadvertently lead to increased greenhouse gas emissions when applied to carbon-rich soils. Understanding these dynamics is vital for sustainable land management.
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Liming (soil)
Definition
Liming is the addition of calcium and magnesium to soil to neutralize acidity and increase the activity of soil bacteria. The amount of lime needed to reach the desired acidity depends on the pH and the buffering capacity of the soil. The is a measurement of acidity or alkalinity. Buffering capacity refers to the soil’s ability to resist change to its pH. Additionally, liming improves nutrient efficiency by encouraging fertilizer uptake. However, there are important limits to liming, as oversupply may cause harm to plant life. The most common liming materials come from grinding natural limestone. Limestone is composed mostly of (CaCO3) and by most state laws must contain 6 percent magnesium for purposes of liming. In addition to buffering the soil, the main way to reverse acidification in freshwater is through liming the water body or its surrounding drainage basin.
Significance for Climate Change
Carbon dioxide (CO2) does not absorb the Sun’s energy, but it does absorb the heat energy released from the Earth. Some of the released heat energy returns to Earth and some goes out into space. This describes the of CO2; that is, CO2 lets light energy in, but not all the heat energy can get out. Soil liming can act as either a source or a sink for CO2. A heat sink absorbs and dissipates the heat energy.
Some studies indicate that rather than all the carbon in lime becoming CO2, the lime may sequester up to half of its carbon content, thus becoming an effective carbon sink. If this is so, liming might even be part of the strategy to moderate climate change. Streams draining agricultural watersheds generally show a net CO2 uptake. However, as nitrate (a common fertilizer ingredient) concentrations increase, lime may switch from a net CO2 sink to a CO2 source.
Peat soil contains large amounts of carbon and therefore is a significant emission source of greenhouse gases—especially of methane. When farming acidic peat lands, adjustment of the acidity through liming is essential. However, when adding lime to these soils often rich in carbon and methane, CO2 production increases. In addition, because of the enhanced decomposition of through liming, soluble organic carbon increases and may factor into climate change.
Finally, it is important to note that the amount of CO2 emissions from liming is not completely clear. This is because the amount of carbonate lime applied to soils is unclear, as is the net amount of carbon from liming that is released as CO2.
Bast, Laura. "Facts About Soil Acidity and Lime." Michigan State University, 9 Nov. 2015, www.canr.msu.edu/resources/facts‗about‗soil‗acidity‗and‗lime‗e1566. Accessed 17 Dec. 2024.
Mullen, Robert, et al. "Soil Acidity and Liming for Agronomic Production." Ohio State University, 2 Nov. 2016, ohioline.osu.edu/factsheet/AGF-505-07. Accessed 17 Dec. 2024.
"Nurturing Soil Health: The Importance of Liming for Optimal Yields." Washington State University, 7 May 2024, smallgrains.wsu.edu/liming-yields/. Accessed 17 Dec. 2024.