Regular liming is an essential part of agricultural practice. It supplies the soil with important nutrients (calcium, magnesium). Furthermore, lime neutralises harmful acids, the humus is regenerated, and soil fertility increases.
Soil acidity is one of the factors limiting the achievement of high yields in most crops and vegetables. Problems due to acidic soils are most often encountered in the production of barley, oil pumpkins, oilseed rape, alfalfa, wheat, and in vegetables, especially in fruiting vegetables and cabbages.
Acidic soils occur due to the formation of humus and due to fertilization with mineral fertilizers. In acidic soils, plants grow poorly and crops often fail. Most of the crops we grow today need neutral or slightly acidic soils with pH value between 6 and 7, as in such soils the plants make the best use of the nutrients given.
A pH value between 6.8 and 7.2 is considered as neutral soil. The optimal soil pH value varies according to different soil types. For lighter sandy soils, the optimal pH is 5.5 to 6. For sandy-loam soils, the optimal pH is 6.5. For heavier clay and loam soils, the optimal pH is 7.
Liming is carried out on the basis of the measured soil pH value which should be measured every 3 to 5 years.
Research shows that the availability of nutrients to plants is highly dependent on soil’s pH value. Thus at pH 4.5, plants use only 30% of nitrogen, 23% of phosphorus and only 33% of potassium available. At neutral pH the availability of nutrients from mineral and organic fertilizers is almost 100%.
After the application of lime fertilizers in acidic soils, the availability of microelements also increases, as does the release of nitrogen from organic matter.
Lime also plays a very important role in the formation of structural particles in the soil. If there is a sufficient amount of calcium in the soil the soil is lumpy, which affects better soil aeration. Such soils are able to retain moisture for a longer time. The maximum single doses depend on the fertilizer and the soil to be limed. Doses should be lower on light soils and much higher on heavier soils.
In Slovenia farmers mostly use ground limestone which is not so aggressive to soil organisms. Limestone can be applied at any time; before crops start to grow, on crops or after harvest when plants are not growing. With lime, however application is recommended only when the plants are dormant. The first results of liming with limestone can be seen about a year after the application of lime fertilizer, when it is mixed over the entire arable surface, while the results with lime with lime can be seen in a very short time.