National Pingtung University of Science and Technology Pingtung, Taiwan. Odette Varela Milla Wu-Jang Huang PhD.

National Pingtung University of Science and Technology Pingtung, Taiwan. Odette Varela Milla Wu-Jang Huang PhD.

Contents: Objectives Introduction Characteristics of carbonized rice residues Biochar preparation and characterization Scanning electron microscopy analysis Water spinach Worm avoidance test Soil Application of rice husk biochar and wood biochar to soil Results 2

Objectives: Realize an investigation of the short-term effects related to slow pyrolysis biochar effects in plant growth. Furthermore it is planned to determine biochar characteristics such as biodegradability, porosity and cation exchange capacity, produced from agricultural waste. 3

Organic waste as feedstock for biochar production Many different materials have been proposed as biomass feedstocks for biochar, including wood, grain husks, nut shells, manure and crop residues, (Lua et al., 2004, Martinez et al., 2006, Gonzaléz et al., 2009). 4

The use of rice straw and rice husk has been practiced for a long time (Ponamperuma, 1982; Eagle et al., 2000; Singh et al., 2008; Kaewpradit et al., 2009). Karmakar et al., (2009) studied the effect of application of fly ash and rice husk ash, the study showed that the application of these type of waste improved soil properties by decreasing soil bulk density and increasing soil ph, organic carbon, available nutrients, and crops yield. 5

The total amount of crop residues produced each year in rice-based systems of Asia can be roughly estimated at about 112 million tons of rice husks (based on 2005 production and a husk/paddy ratio of 0.2). (Pandey 1998) Asia and China Rice Production 2008 Source: http://www.fao.org/corp/statistics/en/ Residue burning is widely practiced and causes air pollution, human health problems, and considerable nutrient losses. 6

Taiwan s cultivated land area 250000 0.14% Hectares 200000 150000 100000 50000 0.64% 0.34% 99.36% 99.66% 99.86% 0.54% 99.46% 0 Rice Vegetable Fruits Tea Others s crops Organic (ha) 949.44 518.43 295.52 139.84 453.1 96.66% No organic (ha) 147081.56 151573.57 215067.48 25647.16 13107.9 3.34% Source: Organization of certification Agriculture and Food Agency,Council of Agriculture. 2009

Characteristics of Carbonized Rice Residues Carbonized rice husks are a very light material with a microporous structure and a bulk density of about 0.150 g cm 3 (Nakajima 1986). The structure of rice husks is preserved in the carbonization process but carbonized husks break easily, especially if carbonized at high temperatures. 8

Biochar preparation and characterization Biochar was found to be alkaline in nature (ph 8.2). Rice husk biochar produced under temperatures between 500 and 600, showed a noticeable increment in silicon, calcium, potassium and magnesium content. 9

Scanning electron microscope analysis The EDS point analysis of rice husk indicated that the biochar particles consisted of high silicon mineral agglomerates on lower carbon content fibers with structures typical of its biomass origin 10

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Wood biochar EDS point analysis, indicated that the biochar particles consisted of high potassium, chlorine, and calcium. Mineral agglomerates also showed high carbon content 12

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To investigate and quantify effects of rice husk-based biochar and wood-based biochar on the growth of water spinach, a field experiment was carried out under different treatments, consisting of: (1) control soil and fertilizer, (2) soil with rice husk biochar and fertilizer in five different quantities, (3) and soil with wood biochar and fertilizer in five different quantities. 14

From the literature, the recommends amount of rice husk biochar that should be applied is: 10 ton per hectare (Biochar and Carbon Sequestration, a regional perspective, 2009). 1.10 m 1.94 m

Water spinach Water convolvulus has been widely grown throughout the world. It is found in South and Southeast Asia, Tropical Africa, South America, and Oceania (Wenfang, 1997). However, it is only in south and Southeast Asia that it is an important leafy vegetable. http://waynesword.palomar.edu/ww0804.htm 16

Worm avoidance test A toxicity test was conducted before starting the biochar experiment. Following the guidelines from A guide to conducting biochar trials (Major. J., 2009) we realized a worm avoidance test 17

We made our trial with 50 worms that were purchased in a fish shop The container was prepared with rice husk biochar and soil from the experimental field. We had as a result that most of the worms shown an acceptance for rice husk biochar 18

Soil The experiment was conducted on an uncultivated clayey Ultisol soil, which are strongly leached, acid forest soils with relatively low native fertility. http://eusoils.jrc.ec.europa.eu/esdb_archive/eudasm/asia/maps/tw3000_1so.htm 19

Germination comparison between Soil field with Biochar and soil field without biochar Soil with biochar shows the best germination 20

Application of rice husk biochar and wood biochar to soil Soil preparation 21

Biochars were weighted and later added to each one of the plots 22

Top soil mixing technique (Major, 2009) Before transplanting was necessary to irrigate for 10 minutes Following the literature recommendations, plants were transplanted in a distance of 15cm between them. Each plot had 22 plants 23

Morphology Leaf number Leaf length and wide Stem size Stem number Root size Weight 24

Results: Water spinach plants for all of the considered treatments were harvested after 8 weeks. 25

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Effect of rice husk biochar and wood biochar on plant root growth All water spinach plants were measured before harvesting; carefully plants and roots were removed from soil. 27

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Statistical analysis Both biochar treatments where compared using least significant difference (LSD), for their main effects on plant growth properties (SAS 9.1, 2004). 29

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Leaf wide (mm) Leaf length (mm) Leaf length (mm) Leaf number Rice husk Wood 40 30 20 20 15 10 5 0 10 0 1 2 3 4 5 Treatments 0 0 1 2 160 3 4 5 Treatments 140 Rice husk Wood 120 100 80 60 40 20 0 160 140 120 100 Rice husk Wood 80 0 1 2 3 4 5 60 Treatments 40 20 0 0 1 2 3 4 5 Treatments Rice husk Wood 31

Stem size (mm) Stem number Rice husk Wood 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 1 2 3 4 5 Treatments 200 Rice husk Wood 150 100 50 0 0 1 2 3 4 5 Treatments 32

Randomly we choose water spinach plants from each treatment, T1, T2, T3, T4, T5, treated with each one of the biochars. 33

Root size (mm) Rice Husk Wood 150 100 50 0 0 1 2 3 4 5 Treatments 34

Effect of rice husk biochar and wood biochar on plant fresh weight From each treatment, plants were collected All plants were classified by treatment Plants were weighted 35

Weight (kg) 0.6 Rice Husk Wood 0.5 0.4 0.3 0.2 0.1 0.0 0 1 2 3 4 5 Treatments 36

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Conclusions Rice husk biochar showed better holding capacity than wood based biochar, due to the differences in their particle size, rice husk biochar was able to integrate better into soil making the distribution more uniform. Water spinach requires plenty of water because of its high succulence, regardless of this information, we irrigated the plants every 2 days for only 10 minutes. The plants were able to absorb the water that biochar was retaining, being not affected by the lack of water. 39