Studies on the Effects of Liming Acidic Soils on Improving Soil Chemical Properties and Yield of Crops: A Review

Soil acidity is a major constraint to cropping globally, especially in temperate and tropical regions of the world where high precipitation has been a dominant influence on the pedogenic development of the soil. In agriculture, the limes play a great importance in improving soil acidity and hence favor plant nutrition. The review articles are support the idea that liming ameliorates soil acidity and improve soil chemical properties making it favorable for the crop growth. In an attempt to address soil acidity problems, the application of lime has remarkably improved soil pH to be optimum desired for crops, increased availability of nutrients and ultimately increased crop yield. Further research would have been required on the same farmer field lime was applied in the next cropping season to observe a significant increase in grain yield. Lime recommendations have to be as specific as possible, taking soils, crops, and climate as well as the financial position of farmers into account. Lime is a recent agriculture input, in Ethiopian context, which worsen the livelihood of smallholder farmers unless credit service or subsidy is facilitated; which also requires an in-depth research. the top (0-10cm) soil layer compared with sub-soil layer (10-20 cm). The acidity saturation and H + Al values were signiﬁcantly decreased with increasing application lime rate and values of these two soil chemicals properties were higher in the sub-soil (10-20 cm) layer compared with top soil layer (0-10 cm). The CEC signiﬁcantly decreased at 12 and 24 Mg lime ha -1 rates compared with control (no lime) treatment.

Values are averages of three bean crops at harvest. * * , NS Significant at the 1% probability level and no significant, respectively. Means followed by the same letter in the same line for the same parameter under different lime treatments are statistically not significant at the 5% probability level by Tukeys test. Source: (Fageria et al., 2008) Kebede and Dereje (2017) showed that application of lime results in reduction of exchangeable acidity 3.55±0.07 to 0.93 cmol Kg -1 , Al saturation 2.86±0.01 to 0.027cmol/kg and thereby increasing soil pH (H2O) 5.3 to 6.9. Asmare et al. (2015) revealed that the highest lime rate (11.2 ton ha -1 ) significantly increased the pH from 4.89 to 6.03 and reduced the exchangeable acidity from 2.22 to 0.14 cmolc kg -1 and exchangeable Al from 1.28 to 0.07 cmolc kg -1 . The highest lime rates (11.2 t ha -1 ) also significantly increased Bray I extractable P by 96% and the Olsen P by 1 24%, over the control.

Effect of lime treatment on crops yield
Application of lime improves the yield of crops if an acidic soil has essential nutrients reduced unavailable to crops due to low pH. However, if the soils are already depleted of nutrients, limited response is expected to application lime only (Marschner, 2011). According to Osundwa et al. (2013), soil acidity problems can be corrected by the use of lime. Applications of lime improved soil conditions resulting in increase in, available P, yield and nutrient uptake (N and P). A combination of lime and phosphorus fertilizer resulted in higher grain production than that with lime or P used independently (Kisinyo, 2016). Sultana et al. (2009) observed that the grain yields of wheat were positively correlated with soil pH, available P, Ca and Mg contents of postharvest soils. Tiller number per plant, grains per spike, grain and straw yields were significantly affected by liming. The application rate of 2.0 ton lime ha -1 produced grain yield of 4659 kg ha -1 which was statistically similar to those treatments in 2.5, 3 and 3.5 t ha -1 lime rates but higher to those in applications of 0, 05, 1 and 1.5 t ha -1 lime rates. Application of lime was increased total uptake of P, S, Ca and Mg which was mainly associated with increased wheat yields.
Liming is an important practice to achieve optimum yields of all crops grown on acid soils. Shiferaw and Anteneh (2014) have reported increase in barley yield as a result of increased pH and reduced exchangeable aluminum and in part due to improved nutrients recovery as a result of lime application. Sole application of 3.7 ton lime ha -1 has also been reported to have increased wheat grain yield by twice of the control treatment (no limed) (Guangdi et al., 2009).
The application of lime showed to increase the overall production of various crops. The previous studies done on different crops demonstrated that when 2, 1.5 and 2.2 t ha -1 of lime applied in wheat; there were yield increases of 1767, 2020 and 1090 kg ha -1 , respectively. The lime rate of 10, 6 and 1.65 t ha -1 applied in the fields of barley; there were yield increases of 361, 670 and 2057 kg ha -1 , respectively. The lime rate of 10 and 6 t ha -1 applied in the fields of maize; there were yield increases of 2640, 1400 and 6100 kg ha -1 , respectively. The lime rate of 5.6 and 1t ha -1 applied in the fields of soybean; there were yield increases of 148 and 481 kg ha -1 , respectively. The lime rate of 4.2 t ha -1 applied in the field of potato the yield increase was 10,000 kg ha -1 . The lime rate of 2 t ha -1 applied in the field of cabbage and cauliflower the yield increases were 10,000 kg ha -1 and 5,000 kg ha -1 , respectively ( Table 2). Journal of Biology, Agriculture and Healthcare www.iiste.org ISSN 2224-3208 (Paper) ISSN 2225-093X (Online) Vol.10, No.15, 2020 (2013) reported that the applications of combined NP fertilizers along with Wukro and Sheba limes (NP + Wukro lime and NP + Sheba lime) revealed significant increase over control by about 239 and 233% in grain yield and by 174 and 172% in biomass yield, respectively. As a result of the application of NP + Wukro lime and NP + Sheba lime, the grain yield obtained by application of only NP rise by about 86 and 90%, respectively. Mekonnen et al. (2014) revealed the combined application of 5 t manure and 2.2 t ha -1 lime increased grain yield and straw yield by 279% and 187%, respectively over the control treatment. As Fageria et al. (2008) study indicated that liming is an effective method of increasing common bean yield in Brazilian Oxisols. Application of 12 Mg lime ha −1 increased mean bean yield about 40% compared with control treatment (no limed). Increases in shoot dry weight and pod number were mainly responsible for yield increase with liming treatments.
According to Temesgen et al. (2014), that studies on the effects of lime on grain yield and yield components of barley combined over two years is presented in Table 2. The highest mean grain yield, biomass yield, plant height and number of tillers were recorded in the lime amended plots. The results showed that the highest significant grain yield and biomass yield were recorded by application of 1.65 and 2.2 t ha -1 lime. Analysis of variance showed that all limed treatments had higher mean values of thousand seed weight, number of seeds per spike and hectoliter weight relative to control (no lime and P) both in 2010 and 2011 cropping seasons. Applications of 1.65 Mg ha -1 of lime gave the maximum grain yield of barley, which was five times the yield obtained by conventional way of barley production (Table 3).  Temesgen et al. (2014). Getachew et al. (2017) reported that the application of lime and P fertilizer had significantly improved grain yield of barley and soil chemical properties. Barley grain yield increased progressively with higher application of lime and P rates. The highest yield was 2.2 lime t ha -1 and 30 P kg ha -1 fertilizer applications. Mean barley grain yield increment in the combined analysis at 1.65 t ha -1 lime combined with 20 kg ha -1 P application was 183.5% control.

SUMMARY AND CONCLUSION
Soil acidity associated to Al toxicities, soil erosion and soil nutrient depletion are the main soil related constraints to agricultural development in parts of developing countries relying on agricultural to feed their growing Journal of Biology, Agriculture and Healthcare www.iiste.org ISSN 2224-3208 (Paper) ISSN 2225-093X (Online) Vol.10, No.15, 2020 population. The smallholder farmers possess small sizes of land and are resource poor and have difficulties in managing acidic soils. The potentials of using lime for soils sustainable management are among the other options to explore in restoring soil health and fertility. In agriculture, the limes play a great importance in improving soil acidity and hence favor plant nutrition. In addition, lime requirement calculation is of help tool in avoiding under or over liming acidity soils which are detrimental and compromising soil health and plant growth in general. Therefore, there is a need of advocating the use of lime in proper manner and take precaution before liming any acidic soils.
The review articles are support the idea that liming ameliorates soil acidity and improve soil chemical properties making it favorable for the crop growth. Further research would have been required on the same farmer field lime was applied in the next cropping season to observe a significant increase in grain yield. Lime recommendations have to be as specific as possible, taking soils, crops, and climate as well as the financial position of farmers into account. Other alternatives should also be tried. Choice of acid-tolerant crop varieties and use of compost and farm manure may further reduce the amounts of lime required and make farming more attractive. Lime recommendation should be developed for major crop types produced in the area and would be respondent to the change in soil pH, as lime recommendation is crop specific. Socioeconomic (e.g. cost-benefit) analysis would be vital as farmers adoption for lime application to their acidic soils is another challenge and they need to be convinced it will be worth investing in. Lime is a recent agriculture input, in Ethiopian context, which worsen the livelihood of smallholder farmers unless credit service or subsidy is facilitated; which also requires an in-depth research.