Abstract: A pot experiment was conducted in a greenhouse to determine the effects of Bio-charcoal and Organic Fertilizer on the Growth of Mini Chinese Kale The experimental design was a randomized complete block with a 4x3 factorial arrangement.
Factor A was growing medium: soil, 10:2 soil:rambutan charcoal (v/v)10:1 soil:Eucalyptus charcoal (v/v), and 10:2 soil:rice-husk charcoal (v/v). Factor B was fertilizer:46:0:0, vermicast, and commercial bio-extract. Fertilizer applications began one week after
transplanting (WAT). Plants were harvested at three WAT. Physical and chemical properties of the growing media were measured before transplanting and after harvesting. Leaf number, stem diameter, and plant height were measured weekly. Fresh and dry weights were also determined.
Results showed that, 10:2 soil:rambutan charcoal and 10:2 soil:rice-husk charcoal increased plant growth (20.43 and 19.73 cm in height, 6.17 and 5.85 leaves, 3.69 and 3.87 mm in stem diameter, respectively). Moreover, Chinese kale grown in 10:2 soil:rambutan charcoal and applied with chemical fertilizer had the tallest plants (24.29 cm). Vermicast (18.04 cm) resulted in taller plants
compared to commercial bio-extract (17.34 cm).
Keywords:vermicast, rambutan charcoal rice-husk charcoal, Eucalyptus charcoal Bio-charcoal
INTRODUCTION
In the agriculture sector, heavy application of fertilizers has polluted surface and
groundwater resources. There is an urgent need to find means to reduce pollution. Presently, organic-based agricultural production is a rapidly emerging technology, which partly reduces waste disposal problems through conversion of biodegradable wastes into organic compost. This ensures the availability of organic fertilizer for crop production. In addition, organic – based vegetable production provides unique opportunities for producing high quality vegetables because of reduced chemical application at any given time of the year. It also contributes to rehabilitating and sustaining the fertility of our croplands that have been degraded or are in
danger of degradation due to intensive crop production and improper soil management practices (dela Cruz et al., 2008 [11])
Organic fertilizers, produced by the activity of earthworms from a wide range of organic
residues, are commonly named vermicompost and are increasingly used in agricultural practices. Different forms of vermicompost are reported to have a beneficial effect on a number of crops both in greenhouse and field studies on seed germination, activation of growth, protection against pathogens, nematodes and herbivores, and increasing overall crop productivity (Ievinsh, 2011[5]). According to Sinha et al. (2010) [13], use of vermicompost over the years builds up the
soil’s physical, chemical and biological properties restoring its natural fertility. Subsequently, reduced amounts of vermicompost are required to maintain productivity. Earthworms and their vermicompost can work as the main ―driving force‖ in sustainable food production for food security while maintaining soil health and fertility. They may eliminate the use of chemical fertilizers and significantly reduce the use of chemical pesticides in crop production as well as the huge water requirement for crop irrigation.
Another emerging area of research revolves around bio-extracts, which are produced by
mixing plant and animal residues with sugar. After mixing these ingredients together,
fermentation and decomposition processes occur. The new mixture contains organic compounds, vitamins, minerals, hormones, and enzymes. Bio-extracts are type of natural fertilizers that help to develop soil fertility and plant nutrition (Noisopa et al. 2010) [3]. According to the Sustainable
Agriculture Forum (SAF) [17], bio-extracts can help to lessen the impact of disease, viruses and water pollution affecting fisheries. Bio-extracts also can enhance soil substance and fertility, reduce insects, viruses and other infestation.
One final area of interest is the addition of bio-char (charcoal) to the soil, which can
improve soil properties and have other environmental benefits. Glaser et al. (2002) [1] reported that charcoal could improve nutrient-retention capacity and increase soil fertility. The improved nutrient retention may also lead to less nutrient leaching. Applying charcoal to soil can improve water holding capacity (Chan et al., 2007) [9]. Charcoal usually increases soil pH because it contains some ash, which can act as a liming agent as well as phosphorus (P) and potassium (K) fertilizer. In addition, Smernik (2009) [12] reported that black C materials have a highly porous
structure and can absorb organic contaminants.
Beside these advantages, there are scientific researches indicating negative effects of Bio-charcoal on plant growth. According to McClellan et al. (2007) [18], most cases of decreased plant
growth due to bio-char application can be attributed to temporary levels of pH, volatile or mobile matter, and/or nutrient imbalances associated with fresh bio-char. In many instances, bio-char has been shown to have an initially high pH (alkaline), which is desirable when used with acidic, degraded soils; however, if soil pH becomes too alkaline, plants may suffer nutrient deficiencies.
―Mobile matter‖ refers to tars, resins, and other short-lived substances that remain on the bio-char
surface immediately after production and can inhibit plant growth (McClellan et al., 2007 [18];McLaughlin et al., 2009 [6]).
Informal observations of crop growth after bio-char applications of between 5 and 20
percent by volume of soil have consistently yielded positive and noticeable results. Some research indicates that much lower application rates yielded positive results (Glaser et al., 2002)
[1]. Bio-char can also be applied incrementally and incorporated with fertilizer regimens or
compost applications. Bio-char as a component of compost can have synergistic benefits. Bio-charcoal can increase microbial activity and reduce nutrient losses during composting (Dias et al.,
2010 [2]). In the process, the bio-char becomes ―charged‖ with nutrients, covered with microbes, and pH-balanced, and its mobile matter content is decomposed into plant nutrients.
Recently, insufficient field data is available to make general recommendations on Bio-charcoal application rates according to soil types and crops. Also, bio-char materials can differ
widely in their characteristics. Thus, the nature of a specific bio-char material (e.g. pH, ash
content) also influences application rate. Several studies have reported positive effects of bio-char application on crop yields with rates of 5-50 tones of bio-char per hectare, with appropriate
nutrient management. This is a large range, but often when several rates are used, the plots with the higher bio-char application rate show better results (Chan et al., 2008) [8]. Most bio-char materials are not substitutes for fertilizer, so adding bio-char without necessary amounts of
nitrogen (N) and other nutrients cannot be expected to provide improvements to crop yield.
Ogawa (2011) [10] also reported that the application of wood charcoal with chemical fertilizers,
wood vinegar and organic fertilizer gave better results than charcoal itself on tea plants, citrus
trees, vegetables, rice plants, apple trees, some leguminous plants and grasses.
The objective of this study was to investigate the effect of soil amendmened charcoal,
vermicast, and bio-extract on growth enhancement of Chinese kale. Chinese kale was chosen as the representative vegetable for growth enhancement because of its high value and consumption.
Results are expected to support self-sufficiency agricultural strategies and provide suitable soil amendments to solve pollution and environment problems.