Evaluate effect of concentrate of bio-char and soil base on the growth of maize (Zea mays)

Nguyen Huu Yen Nhi and T R Preston*

Angiang University (AGU)

Angiang province, Vietnam

nhynhi@agu.edu.vn

* University of Tropical Agriculture, TOSOLY, AA #48 Socorro, Colombia
regpreston@utafoundation.org

Abstract

The experiment was conducted at Kampong Cham National school of Agriculture, Cambodia from 04 August to 15 September, 2008. Bio-char was produced in Colombia, from a gasifier using sugar cane bagasse as the fuel. Soil and sand collected in the farm of Kampong Cham National School of Agriculture to measure effect of  bio-char added into soil with difference levels by using the bio-test with maize (Zea mays) as indicators, according to a  5*2 factorial arrangement  with two replications. Concentrate bio-char added into soils was 0%, 2%, 4%, 6%, 8% which were put into 2 liters capacity plastic bags and 3 seeds of  maize was planted in each bag (2 bags per level of bio-char per soil or sand soil). Date to germinate, plant height at every 5 days intervals and final weight of biomass after 30 days were measured.

There were non significant differences between levels of bio-char added in the growth in height and the amount of biomass of the maize after 30 days measurements. There was a positive curvilinear response of biomass weight to height of maize (R²= 0.86), but negative response between biomass and levels of bio-char added.

It is suggested that bio-char added in soils have low pH and concentration of  carbon in soil is also low.  However, this possibility needs further research about the limit of pH when supplying bio-char by the bio-test method is a simple or what kind of soil pH can supply to reduce cost procedure in integrated farming systems.      

Key words: Bio-test method, pH, carbon, soil fertility

Introduction

Nowadays, fertilizer is very important in agriculture, especially with poor soil. Moreover, the price of the fertilizer is more and more expensive so, using another resource to replace fertilizer is very important for poor rural farmers. Bio-char is the product of biomass pyrolysis that not only sequesters carbon when applied to soil, but also improves soil quality dramatically.

Biochar is a high-carbon, fine-grained residue which can be produced either by smoldering biomass utilizing centuries-old techniques (i.e., covering burning biomass with soil and letting it smolder) or through modern pyrolysis processes. Pyrolysis is the direct thermal decomposition of biomass in the absence of oxygen to obtain an array of solid (biochar), liquid (bio-oil) and gas (syngas) products. The specific yield from the pyrolysis is dependent on process conditions, and can be optimized to produce either energy or biochar (Gaunt et al 2008).

Soil organic matter consists of a variety of components. These include, in varying proportions and many intermediate stages: raw plant residues and microorganisms (1 to 10 percent), "active" organic traction (10 to 40 percent) resistant or stable organic matter (40 to 60 percent) also referred to as humus. Organic matter in soil serves several functions. From a practical agricultural standpoint, it is important for two main reasons: First as a "revolving nutrient bank account"; and second, as an agent to improve soil structure, maintain tilth, and minimize erosion (J. Lickacz et al 2001).

The measurement of the  fertility of soils is usually done by chemical analysis for plant nutrients such as nitrogen (N), potassium (K), phosphorus (P) and trace elements, as well as physical measurements of soil structure. Such analyses require access to a laboratory and this is not feasible  for most farmers, especially those with limited  resources.  Planting some indicator plants in the soil and measuring their growth and production is one way to measure fertility of soils in an indirect way (Nguyen Phuc Tien et al 2003).

Maize (Zea mays) is widely cultivated in the tropics and sub-tropics for both human and animal feed. It requires a long, warm period to ripen the grain and cannot withstand frost. There are many types of maize and the grain may be yellow, white or red. The maize bio-test is suitable for evaluation of soil fertility (Promkot 2001).

Besides, bio-char also has positive effects in both reducing emissions and increasing the sequestration of greenhouse gases. The production of bio-char and its application to soil will deliver immediate benefits through improved soil fertility and increased crop production (Lehmann et al 2006).

Higher nutrient availability for plants is the result of  both the direct nutrient addition by the bio-char and greater nutrient retention (Lehmann et al 2003).

Bio-char additions not only affect microbial populations and activity in soil, but also plant–microbe interactions through their effects on nutrient availability and modification of habitat. Rhizobia spp. living in symbiosis with many legume species are able to reduce atmospheric N₂ to organic nitrogen through a series of enzymatic reactions (Giller 2001).

However, there is little information on the most appropriate level of bio-char to add to the soil. This will be studied in the following experiment.

Hypothesis

Different concentrations of bio-char in the soil will have different effects on the growth of plant.

Objectives

To measure fertilizer value of bio-char which came from Colombia by using maize as indicator plant.

Materials and methods

Location and duration

The experiment will be conducted in the farm of Kampong Cham National School of Agriculture, Kampong Cham province, Cambodia about 129 km from Phnom Penh capital from 04 August to 15 September, 2008.

Experiment design

The experiment will be designed as randomized complete block (RCB) 2*5 factorial design with ten treatments and two replications of each. The factors are:

• Level of soil (50% and 100%)
• Level of biochar (0%, 2%, 4%, 6%, 8%)

Five treatments are five levels of biochar (0%, 2%, 4%, 6% and 8%) mixed with soil only. Other five treatments are mixtures of  50% soil:50% sand mixed with five levels of bio-char (0%, 2%, 4%, 6% and 8%)

S: Soil

SS: Mixture (50% sand with 50% soil)

The soil where earthworms live is collected in the farm of Kampong Cham National School of Agriculture (Photo 1). The sand is also collected from the farm of Kampong Cham National School of Agriculture (Photo 2). The biochar was produced in Colombia, from a gasifier using sugar cane bagasse as the fuel (Photo 3).

Ten treatments will be designed with 5 levels bio-char which will be mixed with soil or mixture (50% soil and 50% sand). They will be put into plastic bags (two liters capacity) which have many holes around so the excess water can go out. Then, 3 seeds of maize will be planted in each bag according to the experimental layout in Table 2. Water will be applied uniformly to all bags every morning and evening except case of raining, observations made of germination and growth of the plants. When the seeds germinate one or two plants will be removed to leave only one seedling in each bag.

Measurements

The soil and sand will be analyzed for the dry matter (DM), organic matter (OM), N and pH; the bio-char will be measured only for DM and organic matter (OM) at the beginning. The height of the plants will be measured every 5 days over a total period of 30 days. After 30 days, the plants and roots will be removed from the bags, washed free of soil, and weighed 30 minutes later, the green parts (leaves and stems) and the roots separately. 

Laboratory analyses

The chemical analyses will be done following standard procedures according to the Association of Official Analytical Chemists procedures (AOAC 1990), except for DM which will be determined by micro-wave radiation (Undersander et al 1993).

Statistical analysis

The data will be analyze by Analysis of variance (ANOVA) using the General Linear Model (GLM) procedure of the Minitab software (version 13.3) to determine growth rate in height of maize. The sources of variables in the model are: Soil type, Levels of bio-char, interaction Soil type*bio-char level and error. The Tukey test in the Minitab software will be used to separate mean values that differ when the F-test is significant at P<0.05.

Results and discussion

Chemical composition of soil, sand and bio-char

The soil had percentage of dry matter (DM) is 78.43% lower than sand (97.37%) and bio-char (98%). However, proportion of organic matter (OM) in bio-char was highest (33.44%) and lowest in sand (5.36%). There was 0.28% nitrogen (N) in soil (table 3).

The bio-char had pH high 9.5 (table 3) leads to pH of soil more and more higher than previous added more and more bio-char into the soil. pH of soil with different levels of bio-char were form 6.5 to 9. This result is equivalent to the result of Rodriguez Lylian (2008) in which biochar was supplied (5 % of soil) as shown in following figure 1.

In addition, bio-char contented more than 30% carbon inside so concentrate of carbon in soils form 0 tone per hectare to 32.5 tone per hectare after supplying levels of bio-char form 0 percent to 8 percent into soil (table 4).

Germination

The germination of maize average from 3.5 to 4 days which were no significant differences (p>0.05) between treatments with  different levels of bio-char and different kind of soils.

Biomass production

In figure 2, the amount of biomass yield (g DM) of maize decreased from low level to high level of bio-char added to two kind of soils, similar to result in study of Rodriguez Lylian (2008) in Colombia which presented in figure 3.

Another way, biomass production of maize declined when organic matter (OM) in soil go up. Difference relationships for maize were reported by Boonchan  Chantaprasarn et al (2004) and Chamnanwit Promkot (2001).

The biomass yield had tent to decrease while amount of carbon in soils increase (figure 4). Evidence suggests that significant productivity gains are possible at application rates as low as 0.4 to 8 tones of carbon per ha, but at extremely high applications crop productivity may actually drop due to nitrogen limitation. There is evidence that legumes will thrive under high bio-char applications, perhaps because their nitrogen-fixing ability enables them to compensate for limited nitrogen availability in the soil. This might suggest some potential for New Zealand’s clover-based pasture systems (Peter Winsley 2007). Biochar can reduce nitrogen fertilizer requirements and nitrous oxide emissions (Baum & Weitner, 2006).  Actually, Carbon is a cation (ion +)  which absorbs nitrogen and nutrient in soil and stores, after that steadily supply for plants in for a long time. However, the soil in this experiment was poor soil (0.28% N) so carbon absorbed nearly all nutrient in soil leaded to the maize did not enough nutrient to grow in the short time.

 Therefore, in this experiment amount of carbon in soil was higher than 8 tones per hectare so biomass production of maize low.

According to Nyle C. Brady et al 1996, soil pH affects phosphorus availability to plants. In alkaline soils, in arid climates, calcium phosphate (CaPO₄) is dominant. If soil pH gets too high a chemical reaction takes place that fixes the phosphorus and makes it insoluble and unusable by plants. In addition, Phosphorus (P) plays an important part in how plants and animals form and in how they function and grow. Phosphorus is known to help plants during photosynthesis, P helps plants respire (breathe), P provides energy transfer and storage, and P also helps plants efficiently use water. Seedlings and roots grow more quickly and vegetable and fruit production is increased when plants get enough phosphorus.

In this study, pH in soil increase from 6.5 to 9 leaded to phosphorus insoluble and unusable by maize, for that reason the result maize yield go down. It can be observed from figure 5.

The proportions of roots, stems and leaves in the fresh biomass of maize plants did not differ among the treatment (Figure 6).  The content of crude and organic matter also non-significant difference in difference levels of bio-char and difference kind of soils (figure 7).

The height and grow rate of plants

The height after 30 days and growth rate per day of maize was highest (3.67 cm/day) in soil did not add bio-char (0% bio-char) and lowest (1.64 cm/day) in soil added highest level of bio-char (8% bio-char). However, non significant different between the treatments with difference levels of bio-char in soils.

Figure 8 and 9 point-outs that  the height of maize had up down trend either levels of bio-char or pH in soils increase.

According to the research of Taysayavong Lotchana (2008), the response of bio-char with pH in soil is followed this formula y = -0.112x + 1.7278 (R² = 0.4773) for that reason pH  of soil at least 6.5 leads to nearly no effect with bio-char when adding into soils.

There is a linear increase (R²=0.86) between two factors: plant height and total biomass yield after 30 days growth, which plant high had more biomass. This information is shown in figure 10.

Similar relationships for maize were reported by Boonchan  Chantaprasarn et al (2004).

Conclusions

·         There are no difference between soil and sand soil as well as the levels of bio-char. Further more, the growth of maize had tent to decrease while concentrate of bio-char added in soil increase.

·         Maize growth was closely correlated with carbon and pH of the soils.

·         The yield of maize reduce when carbon and pH in soils raise.

·         However, this possibility needs further research about what kind of soil appropriate to add bio-char and how concentrate.

·         Need supply more nitrogen resource when adding biochar into the poor soil.

Acknowledgements

The mini-project was carried out at Kampong Cham National school of Agriculture, Cambodia. We wish to thank the SIDA- SAREC for funding this research - a part of the MSc course through the regional MEKARN project.  We also would like to express our gratitude to Dr. Do Van Xe, Mr. Chhay Ty of CelAgrid (Cambodia) and Mrs. Latsamy,  and Kampong Cham National school of Agriculture staff and students who provided and prepared the materials for conducting the project.

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