List of Mini-projects

 

Contents

Effect of nitrate salts on methane production in an in vitro system using molasses and cassava leaf meal as substrate; Hoang Dinh Hieu.

Low cost diets for Muscovy ducks based on Taro silage or high-starch duckweed; Dang Thi My Tu.

Taro (Colocacia esculenta) silage and rice bran as the basal diet for growing pigs; effects on intake, digestibility and N retention; Nouphone MANIVANH..

Mitigation of methane production in ruminants; effects of Coriander seed (Coriandrum sativum) combined with nitrate on in vitro methane production using a substrate of sugar cane stalk and leaves of cassava; Outhen Phommasack.

Effect of supplementary sulphur and nitrate on methane production in an in vitro incubation using sugar cane stalk and cassava leaf  meal as substrate; Nguyen Thuy Binh Phuong.

Effect of sulphur and calcium nitrate on methane production by goats fed a basal diet of molasses supplemented with mimosa foliage. Phonevilay SILIVONG..

Mitigating methane production from ruminants; effect of calcium nitrate as modifier of the fermentation in an in vitro incubation using sugar cane as the energy source and cassava leaves as source of bypass protein; Sangkhom INTHAPANYA..

Growth of maize in acid (pH<4.5) soils amended with biochar or ash, derived from rice husks, with or without organic fertilizer (biodigester effluent); Sisomphone Southavong

Effect of a tannin-rich foliage (Mimosa pigra) on feed intake, digestibility and N retention in goats fed a basal diet of Muntingia calabura. : Sitone KONGVONGXAY..

Effect of mangosteen peel and nitrate salts on methane production in an in vitro system using molasses and cassava leaf meal as substrate. Vo Duy Thanh.

Effect of Taro leaves as supplement to rice bran for Cachama (Colossoma macropomum) in tanks fertilized with biodigester effluent Tick NOUANTHAVONG..

Growth of maize in acid (pH<4.5) soils amended with biochar or ash, derived from rice husks, with or without organic fertilizer (biodigester effluent); Huy Sokchea.

Effect of nitrate salts on methane production in an in vitro system using molasses and cassava leaf meal as substrate

Hoang Dinh Hieu

 

National Institute of Animal Science
Hanoi, Vietnam
: hieuthang@gmail.com

Background

 

The conditions that favour capture From a survey of the relevant literature, Leng (2008) concluded that the presence of nitrate salts in the rumen will act as a competitive sink for the hydrogen produced by fermentation of carbohydrate, such that it is converted to ammonia rather than methane.  Other favourable factors are a basal diet rich in fermentable carbohydrate, low in fermentable protein and with a supplementary protein source that mainly bypasses the rumen (Leng 2008; Leng R A, personal communication). A diet of molasses containing 3% urea and fresh cassava foliage has been shown to support growth rates of 800 g/day in fattening cattle (Ffoulkes and Preston 1978).

Hypothesis

Supplementing molasses with calcium nitrate rather than urea, with a supplement of cassava foliage,  will result in the same growth rate but reduced methane production in growing-fattening cattle.

Experimental procedure

A study will be made in an in vitro system to compare urea versus calcium nitrate as sources of fermentable N in diets based on molasses and cassava foliage.

The forage component of the diet (cassava leaves) is dried and milled through a 1 mm screen and mixed with molasses and the sources of N (urea of calcium nitrate) (Table 1). . Representative samples of the mixtures (20 g DM) are put in an incubation flask (2500ml) to which is added 1.6 liters of buffer solution and 400ml of rumen fluid (obtained from slaughter house), prior to filling each flask with carbon dioxide. The flasks are then incubated at 38 ⁰ C in a water bath for 72h. During the incubation, each flask is connected to an aluminium bag for total collection of gas over the 72h incubation.

At the end of the incubation the total gas volume is recorded and samples analyzed for the proportions of methane and carbon dioxide. Residual DM in the incubation flask is measured to estimate DM loss during incubation.

Ngoc Huyen L T, Do H Q, Preston T R and Leng R A 2010: Nitrate as fermentable nitrogen supplement to reduce rumen methane production. Livestock Research for Rural Development. Volume 22, Article #146. Retrieved August 25, 2010, from http://www.lrrd.org/lrrd22/8/huye22146.htm
 

Low cost diets for Muscovy ducks based on Taro silage

Dang Thi My Tu 

Cantho University, Vietnam
tudangmk@yahoo.com

Background

Silage made from Taro leaves and stems has proved to have higher nutritive value than other foliages (eg: mulberry, sweet potato vines, cassava leaves) when used as a protein-energy supplement in basal diets of rice bran fed to pigs and (Chhay Ty et 2010) and ducks (Nguyen Thji ?Giang et al 2010).

Hypothesis

Silage made from Taro (Colocacia esculenta) leaves and stems will improve the digestibility and N retention by ducks  when fed as a supplement to rice bran.

Experimental procedure

The design will be a 4*4 Latin square arrangement of 4 treatments:

TS100: Taro silage ad libitum

TS75:   Mixture of 75% TS and 25% rice bran

TS50: Mixture of 50% TS and 50% rice bran

TS25: Mixture of 25% TS and 75% rice bran

Periods will be of 12 days; 7 for adaptation and five days for collection of excreta and reed refusals.

Leaves and stems (petioles) of Taro are collected locally, chopped into small pieces 2-3 cm, wilted for 4 hours in the sun and then stored anaerobically in ploastic PVC sealed containers

Measurements are made of feed intake, apparent digestibility of DM, N balance, and changes in Live weight.

Requirements:

Taro silage: 30 kg

Rice bran 10 kg

4 Muscovy ducks (about 1 kg LW)

4 metabolism cages

Chhay Ty, Khieu Borin and Preston  T R 2010 Effect of Taro (Colocasia esculenta) leaf + stem silage and mulberry leaf silage on digestibility and N retention of growing pigs fed a basal diet of rice bran. MEKARN Conference 2010  Live stock production, climate change and resource depletion, Pakse, Lao PDR. http://www.mekarn.org/workshops/pakse/abstracts/chhay.htm

Nguyen Tuyet Giang, Preston T R and Ogle B 2010 Effect on the performance of common ducks of supplementing rice polishings with taro (Colocacia esculenta) foliage.  MSc Thesis, MEKARN-SLU http://www.mekarn.org/MSC2008-10/theses/giang.htm

Managing duckweed culture to increase the concentration of starch

Dang Thi My Tu 

Cantho University, Vietnam
tudangmk@yahoo.com

When duckweed grown in water with high nutrient density substrate (eg: fertilized with biodigester effluent) is suddenly transferred to zero-nutrient water, the metabolism changes to convert the protein and other nutrients into starch.  potential for starch production. When duckweed was transferred from a nutrient-rich solution to tap water for 5 days, the starch content in the duckweed was found to be 45.8% (DM basis) (Cheng et al 2009).

Hypothesis

·         Duckweed exposed to environmental “shock” (by transfer from nutrient-rich pond to plain water pond) will have a higher content of starch and thus an increased nutritive value (higher digestible energy) than duckweed grown on high nutrient density pond (by fertilization with biodigeste effluent).

Experimental

Duckweed is grown in shallow ponds lined with plastic and fertilized with biodigester effluent. When the duckweed reached a CP content of 35% it will be transferred to a pond with clean water for 5 days. At this time samples are taken to determine concentration od DM,  starch and CP.

Requirements:

Duckweed ponds

Duckweed seed

Biodigester effluent

References

Cheng J J and Stomp A M 2009  Review: Growing Duckweed to Recover Nutrients from Wastewaters and for Production of Fuel Ethanol and Animal Feed. Clean; Soil, Air, Water  37 (1), 17 – 26 

Taro (Colocacia esculenta) silage and rice bran as the basal diet for growing pigs; effects on intake, digestibility and N retention

Nouphone MANIVANH

Souphanouvong University (SU)
Laungprabang, Lao PDR
nouphone2007@yahoo.com

Hypothesis

 The optimum ratio of rice bran and taro silage will be about 50: 50 DM basis.

Objectives

Mixtures of rice bran and taro silage will be: 0, 25, 50, 75% rice bran; and 100, 75, 50 and 25% Taro silage (DM basis). Measurements will be of intake, apparent digestibility of dry matter and nitrogen retention growing crossbred pigs.

Materials and methods

The Taro leaves+stems will be collect from around Angang University (AGU). The experiment will be conducted in the laboratory of Angang University (AGU), Vietnam, from 24th August to 16th October, 2010.

Experiment design

The experiment will be carried out according to an arrangement of 4 x 4 Latin Square with 4 pigs and 4 periods (Table 1). The treatments are:

TS100: Only silage of leaf and stem of taro (TS)

TS75: 75% TS and 25% rice bran (RB)

TS50: 50% TS and 50%  (RB)

TS25: 25% TS and 75% (RB)

Table 1. Layout of experimental design

Duration of the experiment will be 4 periods with overall 40 days. The first 5 days for adaptation then 5 days for data collection (feed residues, faces and urine). 

Animals and housing

Four male castrated crossbred pigs with average live weight of 10 kg will be used. The cages to separate faces and urine for the pigs will be made by wood with the each size of cage 60*60 cm.

Mitigation of methane production in ruminants; effects of Coriander seed (Coriandrum sativum) combined with nitrate on in vitro methane production using a substrate of sugar cane stalk and leaves of cassava 

Outhen Phommasack 

Savannakhet University of Laos

Hypothesis

There will be positive symbiotic effects in reduction of methane production by combining a spice (Coriander seed; Coriandrum sativum).) with a source of nitrate (from Calcium nitrate) in a basal diet of sugar cane stalk.

Procedure

An in vitro incubation system will be used to test the following treatments:

• Calcium nitrate (CN)

• Urea

• CN  + Coriander seed (Coriandrum sativum) extract

• Urea plus Coriander seed (Coriandrum sativum) extract

Arranged as a 4*4 Latin square

Substrate will be ground  sugar cane stalk and sun-dried cassava leaves.

The forage components of the diet (sugar cane stalk, cassava leaves) are dried and milled through a 1 mm screen and mixed with the sources of N (urea of calcium nitrate) and the coriander extract. Representative samples of the mixtures (20 g DM) are put in an incubation flask (2500ml) to which is added 1.6 liters of buffer solution and 400ml of rumen fluid (obtained from slaughter house), prior to filling each flask with carbon dioxide. The flasks are then incubated at 38 ⁰ C in a water bath for 72h. During the incubation, each flask is connected to an aluminium bag for total collection of gas over the 72h incubation.

At the end of the incubation the total gas volume is recorded and samples analyzed for the proportions of methane and carbon dioxide. Residual DM in the incubation flask is measured to estimate DM loss during incubation.

Ngoc Huyen L T, Do H Q, Preston T R and Leng R A 2010: Nitrate as fermentable nitrogen supplement to reduce rumen methane production. Livestock Research for Rural Development. Volume 22, Article #146. Retrieved August 25, 2010, from http://www.lrrd.org/lrrd22/8/huye22146.htm

Effect of supplementary sulphur and nitrate on methane production in an in vitro incubation using sugar cane stalk and cassava leaf  meal as substrate 

Nguyen Thuy Binh Phuong 

Nong Lam University, Thu Duc, Vietnam
Binhphuongty27@yahoo.com

Background

 From a survey of the relevant literature, Leng (2008) concluded that the presence of nitrate salts in the rumen will act as a competitive sink for the hydrogen produced by fermentation of carbohydrate, such that it is converted to ammonia rather than methane.  Other favourable factors are a higher level of sulphur in the diet rich in fermentable carbohydrate, that is also low in fermentable protein and with a supplementary protein source that mainly bypasses the rumen (Leng 2008; Leng R A, personal communication). A diet of sugar cane with 3% urea (in DM) and with rice polishings as a bypass protein sources has been shown to support growth rates of 800 g/day in fattening cattle (Preston et al 1976).

Hypothesis

Supplementary levels of sulphur will reduce methane production in sugar cane diets when the diets also contain calcium nitrate

Experimental plan

A study will be made in an in vitro system to compare urea versus calcium nitrate, as sources of fermentable N,  without or with two levels sulphur  (0.4 and 0.8% in DM) in diets based on sugar cane and cassava leaf meal.

Treatments in a 6*6 Latin square arrangement are:

CaN: Calcium nitrate

U: Urea

CaN-4S: Calcium nitrate plus 0.4% S as sodium sulphate

U-4S: Urea plus 0.4% S as sodium sulphate

CaN-8S: Calcium nitrate plus 0.8% S as sodium sulphate

U-8S: Urea plus 0.8% S as sodium sulphate

The forage component of the diet (cassava leaves and sugar cane stalk) is dried and milled through a 1 mm screen and mixed with the sources of N (urea of calcium nitrate) and sulphur (Table 1). . Representative samples of the mixtures (20 g DM) are put in an incubation flask (2500ml) to which is added 1.6 liters of buffer solution and 400ml of rumen fluid (obtained from slaughter house), prior to filling each flask with carbon dioxide. The flasks are then incubated at 38 ⁰ C in a water bath for 72h. During the incubation, each flask is connected to an aluminium bag for total collection of gas over the 72h incubation.

At the end of the incubation the total gas volume is recorded and samples analyzed for the proportions of methane and carbon dioxide. Residual DM in the incubation flask is measured to estimate DM loss during incubation.

Leng R A 2008  The potential of feeding nitrate to reduce enteric methane production in ruminants. A Report to The Departmernt of Climate Change

Commonwealth Government of Australia. ACT Canberra Australia For paper and PPT presentation see http://www.penambulbooks.com

Preston T R,, Carcaño C, Alvarez F J and Gutierrez D G 1976 Rice polishings as a supplement in a sugar cane diet effect of level of rice polishings and of processing the sugar cane by derinding or chopping. Tropical Animal Production Volume 1, (3). http://www.utafoundation.org/TAP/TAP13/1_3_1.pdf

Ngoc Huyen L T, Do H Q, Preston T R and Leng R A 2010: Nitrate as fermentable nitrogen supplement to reduce rumen methane production. Livestock Research for Rural Development. Volume 22, Article #146. Retrieved August 25, 2010, from http://www.lrrd.org/lrrd22/8/huye22146.htm

Effect of sulphur and calcium nitrate on methane production by goats fed a basal diet of molasses supplemented with mimosa foliage 

Phonevilay SILIVONG

Animal science Department, Facultu of agriculture and forest resource
Souphanouvong University, Luangprabang province,Lao PDR
Silipvl@yahoo.co.th

Hypothesis

 

A basal diet of molasses and Mimosa foliage, with NPN from Calcium nitrate, satisfies the basic requirements to facilitate capture of hydrogen from rumen fermentation as ammonia instead of methane. Additional sulphur will increase the rate of capture of hydrogen as ammonia.

Experimental procedure

Treatments in a basal diet of molasses (ad lib) and mimosa foliage (1% of LW, DM basis):

U: Urea as source of NPN (2% of diet DM)

US: same as U but with 0.8% added sulphur as sodium sulphate

CN:  N from Calcium nitrate (3.8% of diet DM)

CNS: Same as CN but with 0.8% added sulphur as sodium sulphate

Design is a 4*4 Latin square to measure:

Intakes, digestibility and N retention

Rumen ammonia

Methane in expired gas

4 goats of about 10 kg LW; with periods of 12 days = 48 days.

Feed needs are

Molasses 0.3*4*48 = 60 kg

Mimosa; 140 kg

Calcium nitrate (20*2*48 = 2kg)

Urea 1 kg

Sodium sulphate (4% of diet DM) 2 kg (4% of diet DM) 2 kg

The molasses will be diluted to 30 Brix (% DM) and the urea / nitrate ‘sulphate dissolved in the molasses. Feeding of the diluted molasses will be 4 times daily (7.00am, 11.00am, 3pm, 7pm) in quantities consumed completely.

The mimosa foliages is suspended above the feed trough.

Mitigating methane production from ruminants; effect of calcium nitrate as modifier of the fermentation in an in vitro incubation using sugar cane as the energy source and cassava leaves as source of bypass protein

Sangkhom INTHAPANYA 

Souphanouvong University
inthapanyasangkhom@yahoo.com

Hypothesis

There will be a reduction of methane production by using calcium nitrate rather than urea as NPN source in an in vitro system using cassava root meal as basal diet and mimosa leaf meal or cassava leaf meal as the source of bypass protein. alk.

Procedure

An in vitro incubation system will be used to test the following treatments:

• Calcium nitrate with mimosa leaf meal (CN-M)

• Urea (U-M) with mimosa leaf meal (U-M)

• Calcium nitrate with cassava leaf meal (CN-CL)

• Urea (U-CL) with cassava leaf meal (U-CL)

Arranged as a random block with 4 repetitions

 Substrate will be cassava root meal.

The forage components of the diet (cassava root meal and mimosa or cassava leaves) are dried and milled through a 1 mm screen and mixed with the sources of N (urea of calcium nitrate).  Representative samples of the mixtures (12 g DM) are put in an incubation flask (1500ml) to which is added 1.2 liters of buffer solution and 300ml of rumen fluid (obtained from slaughter house), prior to filling each flask with carbon dioxide. The flasks are then incubated at 38 ⁰ C in a water bath for 72h. During the incubation, each flask is connected to a bottle suspended in water to collect the gas by displacement.  At the end of the incubation the total gas volume is recorded and samples analyzed for the proportion of methane . Residual DM in the incubation flask is measured to estimate DM loss during incubation.

Ngoc Huyen L T, Do H Q, Preston T R and Leng R A 2010: Nitrate as fermentable nitrogen supplement to reduce rumen methane production. Livestock Research for Rural Development. Volume 22, Article #146. Retrieved August 25, 2010, from http://www.lrrd.org/lrrd22/8/huye22146.htm

Growth of maize in acid (pH<4.5) soils amended with biochar or ash, derived from rice husks, with or without organic fertilizer (biodigester effluent) 

Sisomphone Southavong

Champasack University (ChU)
Champasack province, Lao PDR
spdeuk@yahoo.com

Experimental design

The experiment will be arranged in a completely randomised design (CRD) as a 3*2 factorial with 4 replications (Table 1).

The factors will be:

·         Soil amender: Biochar from rice husks, ash from rice husks, no additive

·         Fertilizer: Biodigester effluent (10 g N/m²) or none

The individual treatments will be:

·        BE:            Soil with biochar at 5% + Effluent from biodigester at 100 kg N/ha

·        BWE:        Soil with biochar at 5%, Without Effluent

·        AE:            Soil with Ash + Effluent from biodigester at 100 kg N/ha

·        AWE:        Soil with Ash, Without Effluent

·        SE:            Soil (no additive) + Effluent from biodigester at 100 kg N/ha

·        SWE:         Soil (no additive), Without Effluent

Acid soil with or without soil amender will be put in plastic bags of 1-2 litre capacity. Three seeds of maize will be planted in each bag according to the experimental layout in Table 1. Water will be applied uniformly to all bags every morning and evening and observations will be made of germination and growth of the plants.

Biochar and biodigester effluent will be collected from An Giang university. Ash produced locally by burning maize husks. Growth of maize studied will covered 40 day period. Maize seed will be the local varieties purchasing at the local market.

Effect of a tannin-rich foliage (Mimosa pigra) on feed intake, digestibility and N retention in goats fed a basal diet of Muntingia calabura

Sitone KONGVONGXAY

Livestock Research Centre,
 NAFRI,
 Laos
 sitonek@yahoo.com

 

Background

Muntingia calabura is commonly used as a shade tree in SE Asia countries. However, when fed as the sole diet to goats, growth rates and N retention are low.

Hypothesis

The protein in Muntingia is very soluble and easily fermented in the rumen of goats, leading to losses of N in the urine. Combining Muntingia foliage with a tannin-rich plant such as Mimosa pigra will facilitate the reaction of the Muntingia protein with tannins to form complexes less available to rumen microbes, thus enhancing the “bypass” properties of the Muntingia protein.

Experimental  design:

There will be 4 treatments arranged in a 4*4 Latin square with 4 periods each of 12 days. The four experimental diets have 4 levels of Muntingia (100; 75; 50 and 25%) combined with  Mimosa foliage at levels of 0, 25,  50 and 75%) with 48 days trial.

The goats are housed in cages that permit collection of freed residues, feces and urine.

Supposing DM of tithonia and mimosa are 20% and 30% respectively, and average body weight of of goats is 12 kg, then the needs are approximately:

- Muntingia leaf : 300 kg

- Mimosa leaf : 200kg

Measurements:

Feed  intake, digestibility, N balance, rumen ammonia and methane in expired air.


 

Effect of mangosteen peel and nitrate salts on methane production in an in vitro system using molasses and cassava leaf meal as substrate

Vo Duy Thanh

Cantho University
Vietnam
: vothanh69@gmail.com

Background

 

The conditions that favour capture From a survey of the relevant literature, Leng (2008) concluded that the presence of nitrate salts in the rumen will act as a competitive sink for the hydrogen produced by fermentation of carbohydrate, such that it is converted to ammonia rather than methane.  Other favourable factors are a basal diet rich in fermentable carbohydrate, low in fermentable protein and with a supplementary protein source that mainly bypasses the rumen (Leng 2008; Leng R A, personal communication). A diet of molasses containing 3% urea and fresh cassava foliage has been shown to support growth rates of 800 g/day in fattening cattle (Ffoulkes and Preston 1978).

Hypothesis

A combination of dried mangosteen peel (Suchitra and Wanapat 2008) and calcium nitrate will have a positive synergistic effect in reducing methane production in cattle fed a basal diet of molasses and cassava foliage.

Experimental procedure

A study will be made in an in vitro system to compare urea versus calcium nitrate, as sources of fermentable N,  in presence or absence of mangosteen peel,  in diets based on molasses and cassava foliage.

Treatments in a 4*4 Latin square arrangement are:

CaN: Calcium nitrate

CaN-MP: Calcium nitrate plus mangosteen peel

U: Urea

U-MP: Urea plus mangosteen peel

The forage component of the diet (cassava leaves and mangosteen peel) is dried and milled through a 1 mm screen and mixed with molasses and the sources of N (urea of calcium nitrate) (Table 1). . Representative samples of the mixtures (20 g DM) are put in an incubation flask (2500ml) to which is added 1.6 liters of buffer solution and 400ml of rumen fluid (obtained from slaughter house), prior to filling each flask with carbon dioxide. The flasks are then incubated at 38 ⁰ C in a water bath for 72h. During the incubation, each flask is connected to an aluminium bag for total collection of gas over the 72h incubation.

At the end of the incubation the total gas volume is recorded and samples analyzed for the proportions of methane and carbon dioxide. Residual DM in the incubation flask is measured to estimate DM loss during incubation.

Ffoulkes D and Preston T R 1978  Cassava or sweet potato forage as combined sources of protein and roughage in minerals based diets: effect of supplementation with soybean meal  Tropical Animal Production (3): 186-192  http://www.utafoundation.org/TAP/TAP33/3_3_1.pdf

Leng R A 2008  The potential of feeding nitrate to reduce enteric methane production in ruminants. A Report to The Departmernt of Climate Change

Commonwealth Government of Australia. ACT Canberra Australia For paper and PPT presentation see http://www.penambulbooks.com

Suchitra K and Wanapat M 2008: Effects of mangosteen (Garcinia mangostana) peel and sunflower and coconut oil supplementation on rumen fermentation, milk yield and milk composition in lactating dairy cows. Livestock Research for Rural Development. Volume 20, supplement. Retrieved , from http://www.cipav.org.co/lrrd/lrrd20/supplement/such2.htm

Ngoc Huyen L T, Do H Q, Preston T R and Leng R A 2010: Nitrate as fermentable nitrogen supplement to reduce rumen methane production. Livestock Research for Rural Development. Volume 22, Article #146. Retrieved August 25, 2010, from http://www.lrrd.org/lrrd22/8/huye22146.htm

Effect of Taro leaves as supplement to rice bran for Cachama (Colossoma macropomum) in tanks fertilized with biodigester effluent

Tick NOUANTHAVONG

LARReC, Laos
tick_a@hotmail.com

Background

There is a need to study alternatives systems of fish production that do not depend on purchased feeds and which make better use of available resources in farming systems that recycle organic wastes. The leaves of Taro (Colocacia esculenta) have been shown to hve high nutritive value for pigs and ducks. Recent observations indicate that the fresh whole leaves are readily consumed by Cachama (Colossoma macropomum) and Tilapia.

Hypothesis

Supplementing a basal diet of rice bran with fresh leaves of Taro will increase the growth rate of Cachama (Colossoma macropomum) in tanks fertilized with biodigester  effluent.

Experimental procedure

There are treatments arranged as 2*2 factorial.with 3 replicates

The factors are:

Fresh or ensiled Taro foliage

With or without earthworm supplement

FTL                 = Fresh Taro Leaves ad libitum

            ETLS               = Ensiled Taro Leaves + Stem ad libitum

            FTLEW           = FTL ad lib + earth worms

            ETLSEW        = ETLS ad lib + earth worms

 Biodigester effluent will be added to all tanks at equivalent of 240 mg N/m²/day (about 0.3 litres biodigester effluent/m²/day).

The fish are cultured in tanks of capacity 0.5m³. The stocking density will be 50 fish/m³  with  initial weight of  40-50 g, and  length about 10 cm. A total of 50*12 = 600.

Water in the tanks is exchanged every 3^rd

Feeding is two times a day at 7:00 am and 5:00 pm. The taro leaves and stems will be harvested from lakes and pond. To make the silage, the leaves + stems are chopped, wilted for 4 hours then packed in plastic PVC containers and ensiled for minimum of 7 days before feeding. For the fresh leaves, these are fed immediately after harvesting without chopping.  The earth worms are fed live.

Measurments

• Fish weight

-          Weight and length of fish before releasing them into the At the end of the trial all fish will be measured individually for weight and length.

-          A sample of 10 fish will be weighed every 14 days

§  Water quality

-          Ammonia-N and NO₂  once per week

pH two time a day (6:00 am &  5:00 pm) daily

-          Dissolved oxygen and temperature measure every day at 6.00 am and 5.00pm

Growth of maize in acid (pH<4.5) soils amended with biochar or ash, derived from rice husks, with or without organic fertilizer (biodigester effluent)

Huy Sokchea

CelAgrid, PhomPpenh, Cambodia
huysokchea@yahoo.com

Background

The biochar residue (65% carbon: 35% ash) after gasification of sugar cane bagasse has been shown to  support major improvements in growth of maize especially on acid soils with low organic matter, and with organic fertilization from biodigester effluent (Rodriguez et al 2009).

Hypotheses

On the acid soils in Vietnam it is expected there will be similar positive effects from application of biochar in combination with biodigester effluent. It is also hypothesized that the biochar from an updraft (TLUD) gasifier stove will have similar properties in stimulating plant growth as bioochar from a downdraft gasifier

Experimental design

The experiment will be arranged in a completely randomised design (CRD) as a 2*2*2  factorial with 4 replications.

The factors will be:

·         Biochar from rice husks used as fuel in a downdraft gasifier or in an updraft (TLUD) gasifier stove.

·         Biodigester effluent (10 g N/m²) or none

·         Acid soil or neutral soil

The individual treatments (n=16) will be:

·        ABGE:      Acid soil with biochar from gasifier + Effluent from biodigester

·        ABG:        Acid soil with biochar from gasifier, Without Effluent

·        ABSE:       Acid soil with biochar from stove  + Effluent from biodigester

·        ABS:         Acid soil with biochar from stove  without effluent

·        AE:            Acid soil (no biochar) + Effluent from biodigester

·        A:              Acid soil (no biochar, Without Effluent

·        NABGE:   Neutral soil with biochar from gasifier + Effluent from biodigester

·        NBG:        Neutral soil with biochar from gasifier, Without Effluent

·        NBSE:       Neutral soil with biochar from stove  + Effluent from biodigester

·        NBS:         Neutral soil with biochar from stove  without effluent

·        NE:            Neutral soil (no biochar) + Effluent from biodigester

·        N:              Neutral soil (no biochar, Without Effluent

The soils with or without biochar and effluent will be put in plastic bags of 1-2 litre capacity. Three seeds of maize will be planted in each bag according to the experimental design. Water will be applied uniformly to all bags every morning and evening and observations will be made of germination and growth of the plants.

Biochar from stoves fuelled with rice husk will be produced in An Giang University. Biochar from a commercial gasifier that uses rice husk as fuel will be brought from Cambodia. Growth of maize will be studied will over a 42 day period. Maize seed will be the local variety purchased at the local market.

Rodríguez L, Salazar P and Preston T R 2009:  Effect of biochar and biodigester effluent on growth of maize in acid soils.  Livestock Research for Rural Development. Volume 21, Article #110.  http://www.lrrd.org/lrrd21/7/rodr21110.htm

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