Effects of Biochar and Compost on Cocoa (Theobroma Cacao) Seedlings Growth
Abstract
The research was carried out at the experimental field of the Kumasi Institute of Tropical Agriculture (KITA) to evaluate the effect of biochar and compost on the growth of cocoa seedlings. There were four (4) treatments including biochar, compost, a combination of biochar + compost, and a control. Treatments were applied at a rate of 0 g (control), 60 gcompost, 60 gbiochar, and 30 geach of biochar and compost combination into 60 kg soil in polybags. The treatments were laid out in a randomized complete block design (RCBD) with three replications. Data were collected on the number of leaves, plant height, stem girth, and leaf area, all analyzed using analysis of variance. Significant treatment means were separated LSD at P≤0.05. The analysis of variance indicated significant differences among treatment types in plant height (P<0.00001), the number of leaves (P<0.034), stem girth (P<0.044) and leaf area (P<0.012). The highest seedlings height was recorded in soil amended with biochar (55.3 cm) and the least in the control (28.1 cm). Soils amended with compost (15.3) recorded the highest numbers of leaves while a relatively low number was recorded by control (9.0). Stem girth was very high in soils amended with compost+biochar (0.76 mm) and the least in the control (0.62 mm). The highest leaf area was recorded in soils amended with biochar (84.6 cm2) while the control recorded 57.0 cm2. It can be recommended that the application of 60g biochar influences significantly growth parameters of cocoa seedlings at nursery.
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Introduction
Soil amendments are materials, which are worked into the soil to improve the soil'sproperties. The use of fertilizers (organic and inorganic) over the years on Ghanaian soil has been found to aid crop growth and yield tremendously. Synthetic fertilizers according to Chen (2006) have high nutrient contents, are relatively cheap, and also quickly taken by plants when applied. However, the increasingly continuous use of inorganic fertilizers in the soil results in soil acidity, decrease microorganisms, pollution of underground water, and nutrient loss (Aciego Pietri & Brookes, 2008). The use of biochar and compost as organic products has become an important technique for enhancing soil structure and also for improving soil water availability and holding capacity for plant growth. Biochar is an organic product partially burnt (carbonated with little or no oxygen) through a process called pyrolysis (Duku et.al.,2011, Zheng et.al.,2010). According to Braida et.al., 2003, the large pore spaces and high specific capacity possessed by make it a highly strong absorption material. Additionally, biochar is made up of major soil nutrient constituents such as Ca2+, K+, Mg2+ which help to improve soil base saturation and also increase the soil pH values (Chen et.al., 2013). The use of biochar has been confirmed to increase activities of beneficial microorganisms in the soil (Zheng et.al.2010), reduce greenhouse emissions through carbon sequestration (Crombie et.al., 2015), improve moisture or water holding capacity (Duku et.al., 2011) and also provide nutrients (Paz-Ferreiro et.al., 2014). To produce quality cocoa seedlings, there is a need to use an amendment that improves the quality of soil media. Amending soils with organic materials have been proven to improve soil quality and structure over the years. However, fewer studies have been done on the use of biochar made from cocoa pruned branches and compost in raising seedlings. The research work is carried out to evaluate the effect of biochar and compost (ACARP) on the growth of cocoa seedlings. 1.1 Statement of Problem The use of infertile soil as a medium for the raising cocoa seedlings is major factor affecting large production of seedlings. Application of soil amendments is one major solution to improving the quality of growing medium and hence improving significant production of cocoa seedlings. Organic amendments improve soil fertility, increases aeration and water holding capacity of soil, improves effective nutrient use and plant growth. The study sought to investigate the impact of organic amendments such as compost and biochar on growth of cocoa seedlings. 1.2 Purpose of the Study The purpose of the study was to evaluate the effect of biochar and compost(ACARP) on cocoa seedlings growth parameters such as height, number of leaves, stem girth and leaf area. 1.3 Research Questions In order to achieve the purpose of the study, the following research questions were formulated to guide the study: 1) What impact do compost, biochar, biochar+compost and control have on cocoa seedlings height? 2) What are the differences in the number of leaves when growth of cocoa seedlings is amended with compost, biochar and biochar +compost? 3) What are the differences in stem girth of cocoa seedlings through the application of compost, biochar and biochar+compost? 4) What impact do compost, biochar, biochar+compost and control have on cocoa seedlings leaf area?
Conclusion
The additions of biochar and compost either alone or in combination were found to increase significantly growth response parameters (plant height, number of leaves, stem girth, and leaf area) of cocoa seedlings. Application of 60g ACARP compost was found to increase significantly the number of leaves of cocoa seedlings, 60g of biochar increased significantly plant height and leaf area whiles 30g compostb+30g biochar increased significantly stem girth of cocoa seedlings. We recommend a study on the effects of the treatments on the yield response parameters of cocoa.
CONFLICTS OF INTERESTS The authors declare that there are no conflicts of interest regarding the publication of this paper. AUTHORS’ CONTRIBUTION We wish to state that all the authors have been personally and actively involved in substantive work leading to the research report. All the authors actively took part in the research design and data analysis of the manuscript preparation. We are therefore responsible for the content of this manuscript.
