s

The fertility of soils is important in agriculture particularly in making decisions on planting of crops. 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 (Chamnanwit Promkot 2001 and Nguyen Phuc Tien 2003). . According to Boonchan Chantaprasarn (2003), maize is a better indicator plant than rice.

Soil organic matter is partially decayed plant and animal matter. It helps the soil hold water and supplies nutrients, which are crucial for crop production; it also protects against erosion and helps support a healthy and diverse set of microscopic plants and animals. Organic matter content, erosion, soil salinity, and soil biological condition are key indicators of soil quality, reflecting the effect of agriculture on soils and the influence of changing crop and soil management practices.

pH is a measurement of how acidic or basic is the soil and is measured using a pH scale between 0 to 14, with acidic media having a pH between 0-7 and basic media having a pH from 7 to 14. For instance, lemon juice and battery acid are acidic and fall in the 0-7 range, whereas seawater and bleach are basic (also called "alkaline") and fall in the 7-14 pH range. Pure water is neutral, or 7 on the pH scale. The pH of soil or more precisely the pH of the soil solution is very important because soil solution carries in it nutrients such as nitrogen (N), potassium (K), and phosphorus (P) that plants need in specific amounts to grow, thrive, and fight off diseases.

Biochar is biomass (wood plants, plant waste) that has been converted to charcoal and it produced by pyrolysis: heating in the absence of oxygen, which prevent burning of the biomass (which happen in open fires).In addition, Biochar and its byproduct has multiple uses, when added to the soil it can significantly improve soil fertility (especially if some volatile are left or recycle back in), The volatile fluids and gasses produce usable bio-fuels, that can be produce on the sustainable basic and then the carbon, when recycle into the soil, provides a stable long term removal of carbon (dioxide) from the atmosphere. Removing carbon from the atmosphere is called sequestration (Lukas Van Zwieten 2006 and Rick Davies 2007).

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).

In this experiment, maize was chosen as bio-test indicator plant for measuring fertility of soils.

Hypothesis

Mixing of biochar with 5 types of soil sample will increase the growth of maize but the increase will depend on the basic fertility of the soils that are chosen.

Objectives

Materials and methods

Location

The soil will be collected from 5 different origins. Located around Kampong Cham district. The experiment will be conducted in the experimental area of Kampong Cham National School of Agriculture, Cambodia from 7 August to 7 December, 2008.

Experimental design

The treatments are source of soils and levels of biochar arranged as a 5*2 factorial in a Completely Randomized Design (CRD) (see table 1) with 10 treatments and 4 replications. The factors are:


Photo1: Peaty soil	Photo2: Chalky soil	Photo3: Clay soil

Photo4: Silty soil	Photo5: Loam with compost	Photo6: Biochar

Table 1: Experimental layout
Block	Treatments
Block1	CK4	PSB3	CSB4	LCB2	PS2	CS1	SSB1	CKB3	LC2	SS4
Block2	SSB3	PSB4	CSB1	CS4	CK3	PS3	CKB2	LC1	LCB3	SS2
Block3	CSB2	SSB4	PSB1	CKB4	SS1	LC4	CK2	PS1	LCB1	CS2
Block4	LC3	PSB2	CKB1	SS3	SSB2	CS1	PS4	LCB4	CSB3	CK1

Table 2 : 5 types of soil
Types of soil	Detail
Peaty soil	Take from it’s far from Kompong Cham National school of Agriculture Livestock around 30 Km, 0-20 cm. depths.
Chalky soil	Take from rice field it’s far from Kompong Cham National school of Agriculture Livestock around 25 Km.0-20 cm. depths.
Clay soil	Take from rice field it’s far from Kompong Cham National school of Agriculture Livestock around 20 Km.0-20 cm. depths.
Silty soil	Take from rice field it’s far from Kompong Cham National school of Agriculture Livestock around 15 Km.0-20 cm. depths., more than 20 cm. depth
Loam with compost	Loam with compost Take from Kompong Cham National school of Agriculture Livestock, 0-20 cm. depth.

Procedure

Five types of soil (see table 2) will be taken from different places around Kampong Cham province and put into plastic bags (2 litters). Three seeds of maize will be planted in each bag according to the experimental layout in Table 1. A hole was put in the bottom of each bag so the excess water could drain away. Water will be applied uniformly to all bags every morning and evening and observations made of germination and growth of the plants. When the seeds will germinate 1 or 2 plants will be removed to leave only one seedling in each bag. In addition the Color of plant, germination and growth of plants will be observed every day. After germination the height of the plants will be measured every 3 days over a total period of 30 days.After 30 days, the plants and roots will be removed from the bags, will be washed free of soil, and weighed 30 minutes later, the green parts (leaves and stems) and the roots separately.

Chemical analysis

Soil samples will be analyzed for dry matter (DM), nitrogen (N), Ash, organic matter (OM), and pH in the laboratory of Kampong Cham National school of Agriculture laboratory. The DM content will be determined using the micro-wave relation method of understander et al (1993). N, OM and Ash will be determined following by AOAC (1990) procedures. pH of soil samples will be determined by using Soil pH Test Kit (compare with examine colour in natural light not fluorescent).

Statistical analysis

The linear regression of height on days will be calculated to determine growth rate in height. The ANOVA GLM option of the Minitab software (version 13.1) will be used to analyze the data. The sources of variation in the model will be: soils, biochar, interaction soil*biochar, blocks and error. The Tukey test in the Minitab software will be used to separate mean values that differed when the F-test was significant at P<0.05.

References

AOAC 1990 Official methods of analysis. Association of Official Analytical Chemists, Arlington, Virginia, 15^th edition, 1298 pp.

Chamnanwit Promkot 2001 Study of the use of maize and water spinach in a biotest for evaluation of soil fertility. MSc. Course 2001-2003, Sida-SAREC http://www.mekarn.org/MSc 2001-03/minipro/cham.htm

Nguyen Phuc Tien, Ngo Tien Dung Nguyen, Thi Mui Dinh Van Binh and Preston T R 2003: Mulberry (Morus alba) and cassava (Manihot esculenta) on sloping land in Bavi area. In: Proceedings of Final Improving biomass yield and soil fertility by associations of Flemingia (Flemingia macrophylla) with National Seminar-Workshop on http://www.mekarn.org/sarec03/tienbavi.htm

Davies R 2007 Biochar/Agri-char /Terra Preta: Its potential use for carbon sequestration, improve soil fertility and sustainable (carbon-negative) energy production

and poverty reduction. (www.\biochar 2\Magic biochar recycles, fertilizes and sequesters NSW Department of Primary Industries.htm)

Van Zwietenoe Lukas 2006 Magic biochar: Recycle, fertilizes, and sequesters (www.\biochar 2\Going Carbon Negative.htm)

Determining the relative fertility of soil using the biotest method with maize as indicator plant

Lotchana Tayxayngavong

Champasack University

Champasack province, Lao PDR

Introduction