The Economic Benefits of Lime
Author: Michael Quin 12/8/2015
The benefits of lime prove to be not only economically significant but the consequence of improved soil quality and increased nutrient uptake makes cropping more sustainable. However, a liming scheme does not result in overnight success. The amelioration of acidified soils is a lengthy process but it is worthwhile in the retention of a healthy, vibrant and sustainable soil. The longer the beneficial effects of lime persist, the more the investment in liming becomes economically favorable (1). Soil quality, nutrient availability and long term sustainability are three critical concepts to consider when dealing with soil acidity.
Reduced soil quality is of detriment to the growth of plants and must be ameliorated in order to achieve successful yields. As soil quality decreases, major components of soils that support the growth of plants degrade and cease to be of any benefit to the plant. A consequence that may come of this is the decreased rate of root elongation. Subsoil constraints such as acidity result in decreased rates of root elongation and limit the plant’s ability to access water and nutrients (2). Subsoil acidity is caused by the excess application of acidic substances such as ammonium fertilisers. Surface liming is a common practice for ameliorating topsoil acidity in the relatively short-term, but is generally slow in ameliorating subsoil acidity (4). It is often too late to rectify the effect of acidity on the sub soil due to the ineffectiveness of lime reaching the subsoil and being able to reverse the effect of acidity. This further extends the need for the introduction of liming schemes to prevent the discontinuation of farming practices due to unmanageable acidic soils.
Nutrient availability in soils varies with the level of the pH. When acidity is increased, important nutrients such as nitrogen and phosphorus are less available to plants whilst nutrients only needed in trace amounts such as aluminum and manganese are increased. This can lead to Aluminum and Manganese toxicity resulting in a dramatic decline of plant growth. Lime substantially reduces the level of exchangeable Al and exchangeable Mn whilst raising soil pH by about 1.0 unit. Liming soils can remove the toxicities of aluminum and manganese and dependent on the extent of acidity and species (i.e. wheat, canola, etc), plants may differ in their response to soil amelioration with lime (3). A pH level of 5.5 is often seen as the optimum value for the growth of the plants. The nutrients available to a plant are largely dictated by the pH levels and therefore must be administered with lime in order to ensure growth and development within an acidic soil.
Long term sustainability
Due to the common constraints of partaking in a soil acidity amelioration scheme, the investment in liming has been a questionable proposition for many farmers (1). However, farmers must implement long term sustainable practices, such as liming, in order to maintain soil quality for the continual process of product removal. In order to continue a cropping enterprise, certain precautions must be carried out to ensure that soils do not degrade to a point where they do not provide an ability to uphold plant growth. Nor should soils be at state where their effect on the growth of plants has a negative impact rather than a positive one. Therefore liming schemes are an appropriate solution to this problem and ensures the longevity of soils that may be succumbing to acidity. The long-term residual benefits of limestone have been shown to extend for beyond 8-12 years and indicate that liming should be profitable in the long term (1). This reiterates the common notion of liming every 10 years in order to maintain the optimum pH levels for the production of crops. By implementing these procedures, long term productivity is assured and therefore upholds the consistent productivity of high quality yields for years on end.
Due to continual farming practices, soil acidity will forever exist to be of detriment to yields and hence economically unfavorable. Therefore, it is crucial to ensure that liming schemes are undertaken because their long term effect is vital for the continuation of cropping and also profitability.