Project Progress Report:" Investigation of rice kernel cracking and its control in the field and during post-harvest processes in the Mekong Delta of Vietnam - MS12 " pot

During the last three years, this CARD project has carried out abundant activities to enhance harvesting, drying and milling methods by both strengthening the knowledge of smallholder fa

Ministry of Agriculture & Rural Development

Project Progress Report

Cooperative demonstrations detailing the physical and financial benefits of implementation

of optimal harvest methods, optimal drying conditions and improved performance of milling plants

(Output 31 and 3.2)

July 2009

NONG LAM UNIVERSITY

Table of Contents

1 Institute Information 1 

2 Project abstract 2 

3 Executive summary _ 2 

4 Demonstration of benefit of harvesting practices _ 3 

5 Demonstration of benefits of flat bed and fluidised bed drying: _ 4 

6 Milling experiments to demonstrate the benefit of roller milling as against stone

8.4 Mill installation and training of mill owners/operators 17 

9 Physical and Financial Benefits 20 

9.1 Integrated data on harvest and post-harvest losses of rice and information on the use

of harvesters and dryers 21 

9.2 Assessment of benefits gained by Tan Phat A cooperative region _ 24 

9.3 Benefits from improvement of harvesting methods: _ 24 

9.4 Benefits from improvement of drying methods: 26 

9.5 Summary on the benefits gained by Tan Phat A cooperative from the project _ 28 

9.6 Assessment of overall benefits to a province or MRD _ 31 

1 Institute Information

Project Name Investigation of rice kernel cracking and its control

in the field and during post-harvest processes in the Mekong Delta of Vietnam

Vietnamese Institution Nong Lam University HCMC

Vietnamese Project Team Leader Assoc Prof Dr Vinh Truong

Australian Organisation The University of Queensland

Australian Personnel Professor Bhesh Bhandari

Professor Shu Fukai

Completion date (original) March 2009

Completion date (revised) April 2009

Contact Officer(s)

In Australia: Team Leader

Organisation: The University of Queensland Email:b.bhandari@uq.edu.au

In Australia: Administrative contact

Name: Mr Kerry Johnston Telephone: +61 7 3365 7493

Position: Research support officer Fax: +61 7 33658383

Organisation: The University of Queensland Email: k.johnston@research.uq.edu.au

In Vietnam

Position: Head, Department of Chemical Engineering Fax: 84-8-37245030

Organisation: Nong Lam University Email: tv@hcmuaf.edu.vn

During the last three years, this CARD project has carried out abundant activities to enhance harvesting, drying and milling methods by both strengthening the knowledge of smallholder farmers and demonstrating the methods of implementation of optimal harvesting, drying and milling practices At first, the data collection was carried out in terms of milling losses in various milling plants Experimental works were then undertaken to test the hypothesis of rice cracking during harvest and post-harvest periods and to find out the optimal harvesting time, harvesting methods, drying conditions and milling performance The systematically data collection and experimental results were prepared in the forms of training manuals and leaflets and distributed to stakeholders, particularly smallholder farmers via training workshops and study tours To date (since the project commencement) 2312 farmers and 300

Reduced whole rice grain yield due to cracking is one of the major issues that directly reduce income and availability of staple food to the farmers in the Mekong River Delta The cracking or partial fissuring of rice kernels may occur right in the paddy field due to incorrect harvesting time/practice, improper post-harvest drying conditions and inappropriate milling operations This project aims to improve the quality and value of the rice, through an integrated approach which encompasses farmers, millers, service providers and extension workers and education institution A key objective of this project

is to improve the knowledge of smallholder farmers by organizing workshops and demonstration for farmer cooperatives in the region so that appropriate harvesting and subsequent grain handling techniques are observed to improve rice grain quality Similarly there will be demonstration and workshops for small millers to encourage them

to install driers and/or provide them technical knowledge to practice optimum drying conditions Improvement of the capacity of the extension workers by providing updated knowledge is another objective The theory of grain drying will be advanced that would improve designs of future dryers The education institutions involved in the project will work together for capacity building of their staff members in the Nong Lam University

The data of milling losses in two provinces Tien Giang and Kien Giang were collected in

2007 To evaluate the current milling performance and investigate a new approach for better milling performance, two milling experiments were undertaken in Can Tho University (Aug 2008) and Kien Giang province (March 2009) A rice milling workshop was also successfully organised in Tan Hiep district, Kien Giang province to make local authorities, service providers, millers, extension workers and farmers’ representatives aware of using appropriate milling technology

The estimation of physical and financial benefits of this project showed that Tan Phat A cooperative will gain USD 50,326 every year from the improvement of harvesting and drying practices without further installation of the equipments If the benefits from service of harvesting and drying are included, the cooperative will gain USD 125,826 every year Under the circumstances if the advanced system is applied to MRD in rice production, i.e correct harvesting, combined-harvesting cutting, mechanical drying, milling using modified dehusker, MRD may reduce 13% total losses which are equivalent to USD 190 million per annum

4 Demonstration of benefit of harvesting practices

Timely harvesting plays an important role in controlling rice cracking Reduced whole rice grain yield due to cracking causes the value loss and reduces the farmers’ income Field experiments were carried out to study the effect of harvesting time around crop maturity on rice cracking and head rice yield for seven common rice varieties (OM1490, OM2718, OM2517, OM4498, AG24, IR50404 and Jasmine) in three different locations, namely Seed Centre (An Giang Province), Tan Phat A Cooperative (Kien Giang Province) and Tan Thoi 1 Cooperative (Can Tho City) in four consecutive harvesting seasons during two years (2006-2008) The results showed that the rice cracking was strongly influenced by both the variety and time of harvesting around maturity There was a general trend of increase in percentage

of cracked rice with late harvesting in relation to estimated grain maturity date The head rice yield also followed the same trend in response to delayed harvesting A delay of 4-6 days reduced the head rice yield by 11.3 % an average and up to 50 % Similar trends were observed in both wet and dry seasons The large varietal difference in percentage of cracked grain (0.9 to 60.5%) on 6 days after maturity date indicated that the level of rice cracking caused by late harvesting time can be minimized by the selection of suitable varieties The detailed report about effects of harvesting time around grain maturity on rice cracking and head rice yield in MRD is presented in Appendix 1

Consecutive field experiments showed that a few days early harvesting (before maturity) is better than late harvesting by 4 to 6 days because late harvesting will make the grain more sensitive to cracking The unavailability of harvesting machines or the shortage of harvesting labours will make the situation more severe because any delay or longer harvesting time can cause more losses, as is often the case of harvesting by hand Therefore, using appropriate

harvesting methods such as combine-harvesters to prevent late harvesting is necessary In addition to prevent grain losses caused by late harvesting, mechanization of harvesting methods using combine-harvesters can reduce 1.5% grain losses owing to threshing is not applicable after mechanical harvesting

5 Demonstration of benefits of flat bed and fluidised bed drying:

Rice drying became an issue in Mekong Delta in early 1980’s when a second crop was promoted, of which the harvest fell into the rainy season Mechanical drying not only reduces grain losses caused by germination and spoilage but also be an utmost intervention opportunity to minimize rice grain cracking after drying or during milling stage The project activities carried out rice drying experiments in both actual and laboratory conditions in order

to improve drying efficiency and promote the mechanical drying, i.e flat-bed and fluidised bed rice drying

The study, including experiments and survey on the flat-bed dryer, focused on the cracking

of paddy grains, and on comparing the air reversal mode Results showed that, in both the ton production-scale dryer and the 20-kg laboratory dryer, the effect of air reversal was very apparent in reducing the final moisture differential; however, its effect on the drying time or the drying rate was not statistically significant Mechanical drying, whether with or without air reversal, was superior to sun drying in terms of reducing rice crack However, compared

8-to shade control drying, drying (with or without air reversal) did decrease the head rice recovery and increase the crack The decrease in head rice recovery was inconsistent, slightly lower or higher in each specific pair of experiments with and without air reversal; this was not expected in line with data on the final moisture differential Testing of a 4-ton dryer at Long-An equipped with the solar collector as supplementary heat source resulted with good grain quality and confirmed the good economic potential

The actual drying time involved with the use of flat bed driers ranges from 8-10 h for wet

paddy, if farmers want to reduce the grain moisture content to a safe level (14% wet basis) If

the paddy needs to be dried to 15-16% moisture, the fluidized bed drying system can be used

as a compact drier In this project, Response Surface Method (RSM) experiment for optimum drying condition was determined in terms of HRY using a high temperature fluidised bed dryer The drying air temperature and time in the first pass of RSM experiments (75-87oC and 2.5 mins) were used effectively to determine the drying rate and HRY At optimum condition, the head rice yield (HRY) was found almost similar to the controlled sample However, sensory experiment showed that the whiteness of optimum sample was lower than

6 Milling experiments to demonstrate the benefit of roller milling as against stone milling

Due to the current post-harvest system in the Mekong River Delta the mechanical drying can cover only 30% of the total wet paddy Most of the rice is processed by sun drying In addition, the price of paddy between 14% and 17-18% moisture is not differentiated clearly

by the traders Thus, the farmers prefer to sun-dry the paddy to final moisture content of 18% A large amount of high moisture paddy (17-18%) is demanded for milling Thus, the milling operators have used the stone-dehusker for husking of paddy to suit this high moisture content paddy This system has reduced HRY and needed to be investigated

17-Two milling experiments were undertaken using medium and large capacities of milling plants (1-ton/hour and 7-ton/hour, respectively) The main purposes of milling experiment were (i) to evaluate the current milling performance and find out a new approach for better milling performance; (ii) to propose a strategy how to upgrade from current milling system to

a better performance system with less investment; (iii) to propose an integrated rice management model from harvesting to milling for a better rice quality and higher farmers’ income

The first milling experiment was carried out with 1-ton milling system (RS10P – SINCO) at Can Tho province The purpose of this experiment was to determine the effect of paddy moisture content on the HRY while using rubber-roll dehusker The paddy variety was OM1490 and paddy samples with three moisture levels (14, 15 and 16%) were compared It was found that HRY was not significantly different between 14% and 15% paddy moisture contents However, when the moisture content of paddy increased to 16%, the HRY reduced significantly from 46.7% to 37% This reduction is quite high and implies the importance of moisture content level regarding milling performance The complete result is submitted in MS11 report

The second experiment was carried out with 7-ton milling system for two varieties (OM6561 and IR50404) at two moisture levels (14% and 17-18%) using two milling techniques, i.e., stone and rubber roll dehusking Currently, in MRD, in a milling system, 70% and 30% of paddy are processed by stone and rubber roll dehusking, respectively The modified milling technique processes 0-30% and 70-100% of paddy by stone and rubber roll dehusking, respectively In this experiment, the modified milling system with 30% husking by stone dehusker and 70% husking by rubber-roll dehusker is called modified 70% rubber-roll dehusker and denoted by M70RD Similarly, the modified system with 100% rubber-roll husking is denoted by M100RD The traditional system is therefore denoted by M30RD (only 30% of paddy processed by rubber-roll dehusker) The Hung Loi milling plant at Tan Hiep district, Kien Giang province was used for this experiment

In this experiment, the following results were obtained:

A First experiment (March 2009):

1) For moisture content of paddy of 17-18%, the recovery of rice containing 15%

broken rice (it is called “rice grade 15”) for M70RD system was 2.44% higher than

that from M30RD system

2) For the same M70RD system, the recovery of (rice grade 15) was 3.25% higher at

14.5% moisture than at 17-18% moisture

The above results indicated that M70RD system for rice moisture of 14% improved the HRY

of the rice

B Second experiment (August 2009):

The results of this experiment are shown in following Table 1

Table 1 Total recovery and head rice yield (HRY)

CD: stone dehusker; CS: rubber-roll dehusker

Results showed that:

+ For sun drying rice (moisture = 17%): HRY of 70% stone dehusker (M30RD) was

higher than that of 30% stone dehusker (40,71% - 35,89%)

+ For mechanical drying rice (moisture = 14-15%): HRY of 70% stone dehusker

(M30RD) was lower than that of 30% stone dehusker ( 49,28% - 53,36%)

+ HRY of mechanical drying rice was higher than that of sun drying rice about 13-14%

Therefore, dehusking using rubber roll will improve HRY only when the paddy is dried

correctly up to moisture content of 14-15%

The Appendix 3 presents the technical report of these milling experiments

7 Survey results

Farmer survey was carried out in Tan Phat A cooperative, Tan Hiep district, Kien Giang

System

Product

smallholder farmers A total number of respondents for the survey in dry season 2009 were

162 included CARD-trainees (41%, 66 out of total 162 respondents) The survey approach was one-to-one interview Survey results are listed as followings:

7.1 Harvesting time

Correct harvesting time is the first intervention opportunity in the field to reduce grain loss after harvesting Field experiments undertaken during CARD project implementation period from 2006 to 2008 showed that late harvesting for 4-6 days after grain maturity (varied for each rice variety) caused the reduction of head rice by 9-50% Among 162 respondents, 95.1% were aware of the negative impact of delayed harvesting compared to the awareness of recommended harvesting time for each rice variety Training activities jointly organised by CARD project and extension centre provided this knowledge for 49.35% respondents in addition to the initiation of smallholder farmers through their self-learning (Figure 1) Despite the awareness of almost all respondents on the consequences

of late harvesting, 45.34% smallholder farmers still delayed their paddy harvesting The major problems identified were the shortages of harvesting labours (65.82%) and harvesters (25.32%) This implies that not only the extension propaganda of correct harvesting time is important but also the facilitation of harvesting equipment availability for harvesting mechanisation

7.2 Harvesting methods

Figure 2 represents the percentage of respondents who used different harvesting methods

in 2006 (before this project started) and 2009 There were 83.65% respondents who pointed out that they harvested rice manually three years ago After three years, the number of respondents using manual harvesting practice decreased remarkably by approximately 70% Alternatively, the percentage of respondents employing harvesters went up significantly from 6.29% in 2006 to 63.35% three years later Almost all respondents in this survey obtained knowledge of appropriate rice harvesting method For instance, there were 80% of respondents who knew paddy threshing should be done immediately after harvesting

7.3 Rice drying

Drying is considered as an utmost intervention opportunity to minimize rice grain cracking after drying or during milling stage According to the field experiments carried out in this project, it is estimated that the average percentage of grain loss caused by sun drying and field drying was about 8.7% for Winter-Spring crop This number will be higher in wet season due to the fluctuation of weather and rains As shown in Figure 3, there was a decrease in the percentage of respondents who used sun drying (from 79.5%

in 2006 to 39.75% in 2009) and the number of respondents using dryers increased by 40% (8.70% to 47.83% during three years 2006-2009) The unavailability of dryers and the high cost of mechanical drying as compared to sun drying were two reasons that caused 12% respondents not being able to apply mechanical drying Though over 80% of respondents thought the mechanical drying is better than sun drying and reduces grain cracking during milling (92.5%), there were only 53% respondents who knew mechanical

drying improved rice quality The remaining respondents pointed out that mechanical drying is energy-consuming (21.12%) and they had no idea about mechanical drying (26.09%) About 63.3% respondents stated that CARD project and local extension centres were the providers of these drying knowledge and information (Figure 4)

Figure 1 Three information sources of

harvesting knowledge gained by

respondents

Figure 2 Comparisons of various harvesting methods used by respondents in 2006 and 2009

Figure 3 Trends of using sun drying and

mechanical drying among respondents in

2006 and 2009

Figure 4 Three information sources of rice drying knowledge obtained by respondents

7.4 Training program and extension activities

Among 162 respondents, the percentage of respondents who took part in the training program of CARD project was 41% (66 respondents) The effectiveness of these training

and non CARD trainee-based) who had correct answers in terms of harvesting time, harvesting method and rice drying It was obvious that the percentage of respondents giving correct answers in relation to harvesting time (95.1%), harvesting method (63%) and rice drying (80%) was higher than that of CARD trainee-based respondents (41%) (Figure 5) This implies that the non CARD trainee-based respondents gained farming knowledge from somewhere else This can be explained partly by a spreading effect within farmers’ community as 91.5% of CARD trainee-based respondent stated that they did talk about the interesting information received during the training to friends or neighbours who did not participate in the training In addition, farmers also play an active role in self-learning to build up their farming knowledge day by day To improve the effectiveness of training activities, respondents stated that it should have both presentations and study tours (54.5%) and invited experts to give a talk (31.8%)

7.5 Cooperatives

Within 162 respondents, (including cooperatives with or without the equipment provided

by CARD) 83.2% of the respondents were members of cooperatives Almost respondents regarded cooperatives are the valuable resources in terms of farming knowledge dissemination (86.3%) and production support (73.5%) However, there were only 41.9% respondents who pointed out that they will use the dryers and harvesters that are managed

by cooperatives to reduce the losses and increase the product value The particular reasons were not mentioned in this survey but it showed the necessity of improving cooperatives’ competency to win the farmers’ confidence

Figure 5 Comparison between the percentage of respondents attending CARD training

activities (41%, 66 out of total 162 respondents) and the number of respondents (out of 162 respondents including CARD-trainee-based and non CARD trainee-based) who had correct answers in terms of harvesting time, harvesting method and rice drying

7.6 The impact of this project to smallholder farmers

In general, all the information presented in above sections showed that CARD activities carried out during two years have a very satisfactory impact on the knowledge and farming practices of smallholder farmers belonging to the cooperatives involved in this project The results of this survey indicated that smallholder farmers have improved farming practices, i.e less sun drying, more mechanical harvesting, and more mechanical drying It is clear that these changes partly resulted from extension activities conducted

by CARD and extension centres

The statistical t and F tests were used to compare between two groups of respondents,

respondents attending CARD training activities (denoted as CARD-trainees) versus respondents have not taken part in any training activities of CARD project (denoted as non-CARD-trainees) Two groups were compared into two categories: information line and rice knowledge based on their answers in the farming survey The statistical analysis showed that there is no significant difference in ‘information line’ between CARD-trainees and non-CARD-trainees groups (P>0.05) Analysis of percentage of correct answers for rice knowledge questions in the survey given by CARD-trainees and non-CARD trainees show that the difference in rice knowledge between two groups is insignificant (P> 0.05) This emphasizes that there is a so-called spreading effect among smallholder farmers community The awareness of smallholder farmers in terms of rice knowledge is enhanced through training sessions, extension services, demonstration activities and the spreading effect The availability of equipments in cooperatives such as rice dryers, rice harvesters funded by CARD certainly provided more chances for farmers utilising farming machineries This impact resulted in the increase in both percentages of smallholder farmers applying appropriate farming practices and a number of harvesters and dryers installed by the farmers as compared to three years ago before this project started

8 Training activities

8.1 Training of farmers

As a key objective of this CARD project, the demonstrations and training activities for the extension workers and the farmers were undertaken during consecutive crop seasons since February 2007 in Kien Giang Province and Can Tho City These training workshops and demonstrations aimed at disseminating the farmers and extension workers the economic value of correct harvesting time, appropriate harvesting method, and the benefit of mechanical drying against sun drying Table 2 summarises the number of training sessions and number of trained farmers and extension workers conducted by this CARD project

the target of training 1800 farmers and extension workers in this project (520 farmers/year and 39 extension officers/year) has been quite achieved

The content of training session comprised of three lessons on harvesting time, harvesting methods and drying techniques and demonstrations of the dryer and the combined harvester (Figures 6-10) Participants visited the dryer in local sites and discussions were held afterwards Every training session was finished up by related discussions (Figures 11-13) The materials for these extension activities were booklet and pamphlet derived from results

of this project (Figure 14)

Table 2 Number of farmers and extension workers trained in different seasons from Feb 2007

to July 2008

Number of farmers trained

Number of officers/extension workers Province District Date

One day Total One day Total

1 Kien Giang

(Dry season)

Tan Hiep Giong Rieng

25/02/2007 26/02/2007

Phong Dien

Co Do Thot Not Vinh Thanh

28/7/2007 29/7/2007

22/9/2007 23/9/2007 29/9/2007 30/9/2007

1 Kien Giang Giong Rieng 12/07/2008 82 13

(Wet season) Chau Thanh 13/07/2008 76 158 07 20

2 Can Tho Vinh Thanh 23/07/2008 81 15

(Wet season) Thot Not 24/07/2008 75 20

Total:

Wet season 2007-2008: 2312 300

Figure 6 Full of the participants in the

meeting hall at the training lesson in 25 th

February 2007

Figure 7 Visit the combine-harvester at Tan Phat A co-operative, after training lesson (25 th Feb 2007)

Figure 8 Harvesting lessons taught by Dr

Truong Vinh in An Bien District, Kien

Giang 08 th March 2008

Figure 9 Visiting the 8-ton-reversible air-flow flat bed dryer (Tan Phat A cooperative) after training lesson

Figure 12 Discussion during training workshop in Co Do District 24 th July 2008

Figure 13 Discusion after the demonstration of dryer and combine harvester

Figure 15 Study tour on 15/12/07

(discussion)

Figure 16 Study tour on 15/12/07 (dryer demonstration)

Figure 17 Study tour on 16/12/07 (Hoang

Thang Combined-harvester Factory)

Figure 18 Study tour on 16/12/07 (Hoang Thang Combined-harvester demonstration)

8.3 Demonstrations

During the last three years, postharvest machineries such as reaper, thresher, harvester and driers were installed in partner cooperatives to demonstrate the benefits of improved harvesting and drying methods against conventional methods Figs 19-22 illustrate some harvesting and drying equipment funded by this CARD project These equipments have been used in demonstration session after each training workshop and approached by smallholder farmers under the management of partner cooperatives It was felt that the availability of equipment strengthened the impact of using appropriate postharvest technology whereby the smallholder farmers can apply

combine-Figure 19 SDG-4 (reversible, 4-ton/batch) dryer with a solar collector (a new development at NLU in early 2007) This unique drying system has been installed in Go Gon farmers’

cooperative in Long An province

Figure 21 One-ton reversible experimental dryer: Airflow upward (left figure) and

Downward reverse (right figure)

Figure 20 A 1.3m wide reaper provided

to Tan Thoi cooperative (Can Tho)

Figure 22 Nhut Thanh combined harvester in field at Tan Phat co-operative

8.4 Mill installation and training of mill owners/operators

To carry out the milling experiments, the rubber-roll dehusker provided by this CARD project was installed at Hung Loi milling line (Figure 23) To make the farmers, service providers, millers and extension workers aware of various factors responsible for harvesting and milling losses and degradation of rice quality, about 70 milling plant owners and milling service provider, machinery companies’ representatives took part in a milling workshop

‘Current situation of milling system in the Mekong River Delta and methods to improve the

milling quality of rice’ to be held on 6th Dec 2008 at the Meeting Hall of People’s Committee Tan Hiep District, Kien Giang Province

Figure 23 Prof Bhesh Bhandari and A/P Dr Truong Vinh at the meeting with Hung Loi milling plant owner at Tan Hiep district of Kien Giang province for collaboration on milling experiment

A workshop ‘Current situation of milling system in the Mekong River Delta and methods to

improve the milling quality of rice’ emphasized on current situation of the milling system in

Kien Giang Province based on results of survey conducted during two years (2006-2008), introducing various milling lines and equipments, and evaluating the investment efficiency, industrialization planning of milling system in MRD (Figures 24-28) This workshop gathered participations, reports, and experiences from experts including milling plant owners, service providers, extension staff and Nong Lam University Participants presented and discussed current situation of the milling system in MRD, particularly at Tan Hiep district which possesses a large number of milling units in Kien Giang Province A brief report of this workshop was submitted to CARD program in the MS11 report

Figure 24a Milling line of 7 ton/hour capacity used for milling experiment

Figure 24b The rubber-roll dehusker installed in the milling line supported by CARD

Figure 25 Milling workshop held in Tan Hiep

district, Kien Giang on Dec 2008

Figure 26 Discussions in the workshop

Figure 27 Participants of the workshop Figure 28 Visit of Tan Hiep milling plant

9 Physical and Financial Benefits

To achieve the physical and ultimately financial benefits to the farmers by the way of controlling rice cracking we propose that the measures listed in Table 3 should be implemented from farmers and extension centres of the government

Table 3 Implemention from stakeholders to achieve the physical and financial benefits in rice

Install roller milling system millers Establish more pilot cooperatives for training Provincial government Extension

Disseminate the information to control the rice cracking through the co-operatives

Extension workers

Financial Facilitate to acquire the harvester and dryers

for the farmers

Provincial government

9.1 Integrated data on harvest and post-harvest losses of rice and information on the

use of harvesters and dryers

From the experiments and surveys undertaken under the project CARD026/VIE05, the data

presented in Table 4 shows the average grain and value losses at each step of the whole

process from harvesting to milling By the application of new technologies such as

combine-harvester, mechanical dryer and modified milling system, the total losses of rice can be

reduced dramatically as analysed and presented below

Table 4 Overall evaluation of total harvest and post – harvest losses (converted into grain losses

– kg/100 kg dried paddy)

Harvesting

time Harvesting method Threshing Sun drying Drying Milling losses Total

(%) Line

Yes (VL=1.5%)

Improved system (0%)

7.9 7 Panicle(V=8.7%) 20.6 8

Manual/

Reaper (GL=2.9%)

Yes (VL=1.5%)

Normal system (4%)

15.2 14 Note: VL= Value losses, GL= Grain losses

Harvesting

time Harvesting method Threshing Sun drying Drying Milling Total (%) Line

Panicle(VL=8.7%) 17.1 15 Yard(VL=4%) 12.4 16 Correct(0%) 8.4 17

Manual/

Reaper (GL=2.9%)

Yes (V=1.5%)

Incorrect (V=5%) 13.4 18 Yard(VL=4%) 10.7 19

Incorrect (V=5%)

Normal system (4%)

11.9 21 Panicle(VL=8.7%) 16.6 22 Yard(VL=4%) 11.9 23 Correct(0%) 7.9 24

Manual/

Reaper (G=2.9%)

Yes (VL=1.5%)

Incorrect (VL=5%) 12.9 25 Yard(VL=4%) 10.2 26

Incorrect (VL=5%)

Improved system (0%)

11.2 28

Table 4 presents 28 possibly matching lines of which conventional methods are maintained

or innovative methods are applied in one step or the whole process from harvesting to milling

stages The total losses is the accumulation of losses of every step, namely harvesting time,

harvesting method, threshing, drying (sun drying or mechanical drying), and milling For

example, the highest losses goes to line 8, at 20.6% total losses, which practices late

harvesting (3.5%), manual cutting (2.9%), threshing (1.5%), field drying (8.7%), and normal

milling system (4%) In contrast, in case the new technologies are applied to the whole

process, total losses can be reduced to 2.7% as demonstrated by line 6 (using correct

harvesting, combine-harvester, no threshing, correct drying technique and advanced milling

system) The total losses can be reduced significantly if any intervention opportunity is

introduced to any step For instance, sun drying in line 8 is replaced by correct mechanical

drying can reduce the total losses to 15.9% When smallholder farmers and cooperatives want

to upgrade rice production technology, Table 3 can be used as a reference tool to estimate the

percentage of losses that can be prevented

- Harvesting time: The data from our experiments and surveys at two cooperatives (Tan

Phat A – Kien Giang and Tan Thoi 1 – Can Tho) showed that late harvesting contributed to a

value loss of 3.5% in average About 70% of farmers in the MRD were harvesting late (MS 7

– Report of CARD026/VIE05)

- Harvesting method: Mechanical harvesting in MRD until the year 2009 can be estimated

from the data of Can Tho, Dong Thap and Long An provinces In Can Tho, about 165 reapers

and 170 combine-harvesters contribute to mechanical harvesting approximately 30% of rice

cut by machine in Dong Thap was 233ha/machine/year In Long An province, the number of reapers and combined-harvesters were 1846 and 756 (Nhut Thanh company 2009), respectively, mechanically harvested 70% of rice field in which 35% was harvested by reapers The average rice field cut by machine in Long An was 180ha/machine/year which is equivalent to machine capacity of 4ha/day The data of Long An is reasonable and close to the actual capacity of standard combine-harvester (SCH = 4ha/day) currently used in the MRD and was selected for estimation of the percentage of rice field cut by machine in the MRD as shown in Table 5

Table 5 Number of harvesters and dryers and the harvesting mechanization in MRD

2006 2008(2009)

Location Area

(km 2 )

Rice planting area, 2008-

2009, (1000ha)

Rice field cutting by machine

2009 a , % Reaper

Harvester Dryer

- Drying: with the total of more than 6600 flat-bed dryers currently used in the MRD, about

33% of the rice is dried mechanically (CARD026/VIE05 drying report 2009) From 2006 to

2008, the number of flat-bed dryers increased by only 400 units The impact of CARD project was not necessarily only on the number of dryer units, but on the drying technology

in order to improve the dryer efficiency and promote the mechanical drying The dryers were installed in various cooperatives for experiments and demonstrations and used to train the farmers how to dry correctly to reduce rice cracking

9.2 Assessment of benefits gained by Tan Phat A cooperative region

In total, Tan Phat A cooperative has 478 ha of rice field cultivating 2 crops in a year Thus, total rice planting area in a year is 956ha For an operation time of 45 days/year of a harvester (180ha/year/harvester), this planting area can be harvested by only 5.3 combined-harvesters However, the harvesting time in a place such as cooperative is normally lasting 5 days per season as shown in Table 6, which are surveyed and experimental data by our project For instance, Tan Phat A cooperative in dry season planted OM2517, IR50404 and AG24, the optimum harvesting time was 86-88 days Similarly in other dry season with OM2517 and OM4498, the time was 86-91 days The practice in MRD now is sowing rice at

the same time to avoid brown back rice plant hopper (Nivaparvata lugens)

Table 6 Optimum harvesting time (day) of various rice varieties in different seasons

Variety Season Harvesting time

according to farmer

Harvesting time according to recommendation

of extension centre

Optimum harvesting time according to experiment

be necessary for the cooperatives to install all the required SCH units, but they can hire the outside ones to do this task

9.3 Benefits from improvement of harvesting methods:

There were no harvesters belonging to Tan Phat A cooperative of Kien Giang province in 2006 However, in 2008 this cooperative had 4 reapers and 16 combine-harvesters including 1 unit supported by CARD project The cooperative’s farmers were

previously This meant for each season, within 5 days of harvesting time, the cooperative’s harvesters can cover 75% (=18/24) rice field of the cooperative, and the rest 25% rice field either can be harvested by outside cooperative’s harvesters or manually It can also be said that at least 75% of cooperative’s field harvested at correct harvesting time According to a survey of CARD026/VIE05 project in 2007 (CARD026/VIE05 workshop 2008) that 70% of farmers in MRD were harvesting late For a situation of before project activities (no harvester), Tan Phat A cooperative was also harvesting late at the rate of 70% In other words, there was an improvement of the cooperative in harvesting capacity that it was from 70% late harvesting become 75% correct harvesting This improvement mainly impacted by CARD026/VIE05 project in terms of improved perception of the farmers via experiments, demonstration and training activities of this project The benefits from improved harvesting methods are shown in the following calculation (referring to Table 1) resulted from correct harvesting and using combine-harvester This consists of 1) Benefits from reduction of harvesting losses; 2) Benefits from reduction of harvesting cost in comparison to manual harvesting; and 3) Benefits from service activities Until the use of combine-harvester will become popular, benefits from service activities will be removed because they can hire the outside ones to do this task

+ Benefits from reduction of harvesting losses:

Let rHL = reduced harvesting losses; Lh1 = losses for the case of before project activities (no

harvesters, late harvesting; Lh2 = losses for the case of after project activities (improved

number of harvesters, correct harvesting); where rHL = Lh1 – Lh2 , and

Lhl = (70% * 3.5% + (2.9%+1.5%)) = 6.85% and

Lh2 = (25% Lhl + 75% * (1.2%+1.5%)) = 3.74%

Thus, reduced harvesting losses is rHL = 3.11%

Assuming the average yield of rice is 5 ton/ha, the total reduced harvesting losses (RHL) of the cooperative in a crop for 1 ha is:

RHL = rHL * 5 ton/ha = 0.156 tons of dried paddy/ha

For the price system in 2008-2009, 1kg of dried paddy is 4500 VND, the reduced harvesting losses of 956ha/year of cooperative will be:

RHLM = RHL * 4500 * 1000 = 700300 VND/ha = 38.9 USD/ha

RHLMT = 956*RHLM = 669.5 million VND/year = 37194 USD/year (= 3.7 SCH)

+ Benefits from reduction of harvesting cost in comparison to manual harvesting

Manual harvesting required 40 labours to cut, gather and service for threshing of 4 ha

in one day costing 2.15 million VND based on the price system of the year 2008 Whereas, combine-harvester required only 3 workers to do the same work costing only 1.17 million VND as shown in the following Table 7 using Kien Giang and Can Tho data

Table 7 Calculation of harvesting cost of a standard combine-harvester

Harvesting cost 1170000

Note: standard combined-harvester (SCH) is a harvester with price of 180 million VND (10000 USD), capacity of 4ha/day, working 10hrs/day

Benefits from reduction harvesting cost will be:

RHCM = 2.15 – 1.17 = 0.98 million VND/ha = 54.4 USD/ha

RHCMT = 0.75*956* RHCM = 702.7 million VND/year = 39036 USD/year (= 4 SCH)

+ Benefits from service activities:

In the total operation time of 45 days, after 10 days of service their own rice fields, the cooperative’s combined-harvesters can serve other rice fields outside the cooperative One combined-harvester can serve 140ha/year (35day/year * 4 ha/day) to earn an amount of 70 million VND/year (3889 USD/year) The benefits from service activities of cooperative will

be RHSMT = 1.26 billion VND or 70000 USD/year (18*3889 USD/year) (7 SCH)

9.4 Benefits from improvement of drying methods:

There were available 2 normal flat-bed dryers (FBD) of 4 ton/h (equivalent to one FBD 8ton/h) and one reversible-flat bed dryer (RFD) of 8 ton/h built by CARD026/VIE05 project

at the cooperative in 2006 In 2008, the cooperative developed further 4 RFD units 8 ton/h In equivalence, the cooperative had 6 RFD units It can be said that before project activities, the cooperative had 1 dryer unit, and after project activities, the cooperative had 6 units Under experimental and training activities, the project has impacted on the perception of the cooperative’s farmers about the benefits of correct drying techniques using mechanical dryer over sun drying The benefits from improved drying technology consists of three components, i.e., 1) Benefits from reduction of drying losses; 2) Benefits from drying cost; and 3) Benefits from service activities

For drying issue, the dry and wet seasons should be considered There is 478 ha of rice field (per season) in the cooperative The required number of dryers to dry the paddy harvested from 478 ha can be calculated based on Table 8

For a yield of 5ton/ha, total paddy of each crop in the cooperative was 2390 tons (=5* 478) So, number of dryers required is 5.7 units (2390/422.4) However, there is only 5 days for harvesting, the required time for dryer to dry the cooperative rice in a season is 4.5 shorter than the operation time Thus, the required dryers are 5.7*4.5 (=25.5) or 26 units This meant

for each season, within 5 days of harvesting time, the cooperative’s dryers before project

activities can cover 3.85% (=1/26) rice field of the cooperative, and the cooperative’s dryers after project activities can cover 23% (=6/26) rice field of the cooperative, the rest rice fields

either can be dried by outside cooperative’s dryers or sun drying The difference of before and after project activities is that after project activities the farmers under the cooperative are

encouraged to have a higher number of dryers and use correct drying technique

+ Benefits from reduction of drying losses:

Firstly, the drying losses caused due to the practice of leaving the panicle in the field for sun drying has been removed completely According to the cooperative report collected in

2008 (CARD026/VIE05 workshop), no farmer of this cooperative used this method any more, demonstrating the impact of this project This benefit avoided 8.7% of value losses The practice of leaving the panicle in the field for sun drying will be excluded in the calculation of drying losses

Let rDL = reduced drying losses; Ld1 = losses for the case of before project activities;

Ld2 = losses for the case of after project activities; where rDL = Ld1 – Ld2 , and

Ldl = sun drying + incorrect drying = (99% * 4% + 1%*5%) = 4.01% and

Ld2 = sun drying = (100%-23%)*4% = 3.08%

Thus, reduced harvesting losses is rDL = 0.93%

Assuming the average yield of rice is 5 ton/ha, the total reduced drying losses (RDL)

of the cooperative in a crop for 1 ha is:

RDL = rDL * 5 ton/ha = 0.0465 tons of dried paddy/ha

For the price system in 2008-2009, 1kg of dried paddy is 4500 VND, the reduced drying losses of 956ha/year of cooperative will be:

RDLM = RDL * 4500 * 1000 = 209250 VND/ha = 11.6 USD/ha

RDLMT = 956*RDLM = 200 million VND/year = 11114 USD/year (= 3 RFD)

+ Benefits from reduction of drying cost in comparison to sun drying

Table 9 is the drying cost from different drying methods currently used in the MRD Mechanical drying using husk as fuel will reduce the drying cost compared to sun drying in wet season Coal fuel is not recommended for drying For normal weather in wet season, mechanical drying saved 61 VND/kg (3.9 USD/ton) dried paddy For 1 ha with the yield of 5ton/ha, the saving will be RDCM1 = 305000 VND/ha (19.5 USD/ha)

Benefits from reduction drying cost in wet season will be:

RDCMT1 = 0.23*478* RHCM1 = 33.6 million VND/year = 2150 USD/year

For the dry season, mechanical drying increase cost compared to sun drying, i.e., lost

9 VND/kg (0.5 USD/ton) The losses will be RDCM2 = 45000 VND/ha (2.5 USD/ha) for the yield of 5ton/ha

Losses from increasing drying cost in dry season will be:

RDCMT2 = 0.23*478* RHCM2 = 4.95 million VND/year = 275 USD/year

Thus, total benefits from drying cost compared to sun drying will be:

RDCMT = RDCMT1 - RDCMT2 = 28.6 million VND/year = 1870 USD/year (1/2 RFD)

Table 9 Drying cost (2006) for different drying methods

RFD (SRA-8) (air reversible, 8-ton/batch), husk as fuel 79 4.9

RFD (SRA-8) (air reversible, 4-ton/batch), coal as fuel 130 8.1

Sun drying, wet season, normal weather 140 8.8

Sun drying, wet season, bad weather 210 13.1

Source: Phan Hieu Hien et al 2009, CARD026/VIE05 final workshop 2009

+ Benefits from service activities:

In the total operation time of 45 days, after 10 days of service their own rice fields, the cooperative’s dryers can serve other rice fields outside the cooperative One dryer can serve 133ha/year (35day/year * 3.8 ha/day) to earn an amount of 16.6 million VND/year (924 USD/year) (1 batch earns 200000 VND) The benefits from service activities of cooperative will be RDSMT = 99.7 million VND or 5500 USD/year (6*924 USD/year) (1.5 RFD)

9.5 Summary on the benefits gained by Tan Phat A cooperative from the project

The benefits gained by Tan Phat A cooperative from the improvement of harvesting and drying practices calculated above is summarized in Table 10 The time from 2006 to 2008 is considered as the developing time where the cooperative received the knowledge and experiences from CARD project to improve their own practices on harvest and drying methods to increase the grain quantity and quality From this time onward, i.e., commencing from 2009, the cooperative will gain a benefit every year as shown in Table 10 without further installation of the equipments The current investment can cover 75% cutting by combine-harvesters (18 harvesters) and 23% mechanical drying (6 dryers) of their rice fields using their own equipments within only 5 days harvesting time per crop For the operation time of 22-23 days per crop, 18 harvesters can harvest triple of cooperative rice field

Table 10 Estimated benefits per year from improvement of harvesting and drying technologies

of Tan Phat A cooperative since 2009

11114

1870

5500

3 Dryers 0.5 Dryers 1.5 Dryers

The items in column “Benefits” were defined in section 2 The values in column “Equivalent

machine” were the number of harvesters or dryers can be purchased using the saving money

In these calculated benefits, the cooperative got 100% of benefits from the reduction of

processing cost and service components (RHCMT, RHSMT , RDCMT, and RDSMT) However, the

cooperative didn’t get 100% benefits of the loss component (RHLMT) because most of

reduction of losses was value losses (quality) rather than grain losses (quantity) For the

current trading system in the MRD, whoever possesses the white rice will gain benefits from

reduction of value losses In fact, the traders and millers possess the white rice and farmers

possess the dried paddy Thus, although the improvement on harvesting and drying processes

are done by farmers, the reduction of value losses (more head rice recovery) is benefitted by

the traders and millers This happens because at present there is no clear difference between

good and bad dried paddy in terms of price In 2008, the price for a good dried paddy (correct

drying, moisture content 14%wb) was 50 VND/kg higher than the bad dried paddy (incorrect

drying or sun drying, moisture content of 17%) only This 50 VND/kg is equivalent to the

expense for drying to get 14% moisture This is because of the fact that the service providers

control the price of wet and dried rice in addition to the service fee In other words, farmers

got no benefits by improving the grain quality via advanced technologies

Looking at the Table 4, changing from a conventional system (“late harvesting

(VL=3.5%) => manual harvesting (GL=2.9%) => threshing (VL=1.5%) and sun drying

(VL=4%))” to an advanced system (correct harvesting (VL=0) => combined-harvesting

(G=1.2%, V = 1.5%) => correct mechanical drying (VL=0)”, the losses reduced from 11.9%

to 2.7%) In the reduction of 9.2% losses, there was 7.5% value losses occupied 7.5/9.2 =

81.5% Therefore, the farmers gained only 19.5% of the benefits from reduction of losses

The values of RHLMT and RDLMT in Table 7 will be 7253 USD (< 1 harvester) and USD 2167

(< 1 dryer) Considering this argument, the total benefits of Tan Phat A cooperative is shown

in Table 11

Table 11 Different benefit situations estimated for Tan Phat A cooperative

(1): Theoretical calculation with all components

(2): Theoretical calculation without service component

(3): All components considering current trade system

(4): All components except service considering current trade system

For the farmers to gain the benefits from reduction of losses due to advanced harvest and post-harvest technologies, the farmers should possess the white rice A model so-called

“integrated rice management chain model” from harvesting to milling for a better rice quality and higher farmer income (Figure 29) may help the farmers to possess the white rice, i.e., gain the benefits from reduction of losses

We propose a cooperative model where the farmers share the money via cooperatives to run their rice post-harvest chain In this system, the cooperative will be strong enough to invest the dryers and harvesters and run these equipments Thus, benefit from advanced technology will be brought to the farmers via cooperative In this project we have experimented integration of harvesting and drying However, one additional step is required to complete the post-harvest process, e.g., the milling step This step is very important as it produces the final product (white rice) in the chain of post-production of rice The benefit will be higher if farmers can manage also the milling operation to produce white rice This model will work if

a group of cooperatives unitedly invest and run a milling plant

In 2006, the number of dryers in MRD was 6200 units Most of these dryers were installed in the farmers place In 2009, this number was only 6600 units, i.e, there was only 400 units installed in three years (Table 5) Table 9 shows that in the components of benefits from

Figure 29 A proposed integrated rice management chain model

9.6 Assessment of overall benefits to a province or MRD

In Table 4, an improvement at each step was estimated from the actual data For instance, late harvesting can be improved by 3.5% of losses by correct harvesting A popular conventional rice system and an advanced rice system for harvest and post-harvest of rice are shown in the following procedures:

(1) Conventional system: - Late harvesting => Manual/Reaper cutting => Threshing => Sun drying => Milling using normal system

(2) Advanced system: - Correct harvesting => Combined-harvester cutting => Mechanical drying => Milling using modified dehusker

According to the milling experiments undertaken using a 7ton/h milling plant in Kien Giang province, an advanced rice system using modified dehusker increased 12-14% HRY in comparison to conventional rice system Assuming 3% of losses of HRY is equivalent to 1%

of grain losses, then advanced system reduces 4% of grain losses in milling step against conventional system (Table 5) Theoretically, advanced system will reduce the losses from 15.9% of conventional system to 2.7% This is a huge benefit if the whole MRD applied advanced system In addition, 21000 dryers (RFD) and 20000 combine-harvesters (SCH) are required for advanced system Regardless of milling improvement, the reduction of 9% losses from improved harvest and drying methods will save at least 190 million USD/year for

Harvesters -Dryers

Milling plant Storage

Capital line

MRD In other words, costing of 21000 dryers (73,500,000 USD) and 20000 harvesters (200,000,000 USD) can be returned after one and a half year of investment

combine-Among the 13 provinces, the Long An, Can Tho and Kien Giang provinces which were selected by CARD026/VIE05 project for experiments and training activities were the three of four leading provinces in relation to percentage of harvesting mechanization in the MRD in

2009 (Table 5) These provinces have increased the number of combined-harvesters dramatically in three years from 2006 to 2009 Consequently, the number of combine-harvesters in the MRD has increased from 33 units in 2006 to 2300 units in 2009 These results imply the impact of this project on mechanization of rice harvesting Beside CARD project, other programs such as “competition of combined-harvester” organised yearly by MARD since 2007 might have also contributed to the increased number of combine-harvesters in MRD Therefore, it is hard to estimate how much is the impact of CARD project on the mechanization of harvest and post-harvest of rice in MRD However, only the CARD project was involved with demonstrating the farmers the cracking issues (value losses) caused by late harvesting, sun drying and incorrect mechanical drying

Kien Giang is a province where CARD project organised more than 10 training sessions in all the districts Over 1200 farmers have been trained In Kien Giang, the number

of reapers in 2006 was only 16 units and there were no combine-harvesters In 2009, the number of harvesters increased dramatically, i.e., more than 800 combine-harvesters and 168 reapers were installed The mechanization of rice harvesting in Kien Giang increased from 0% in 2006 to 27% in 2009 Calculating in the similar way as in section 9.5 for Tan Phat A cooperative, commencing from 2009 Kien Giang province will possibly gain yearly USD 4.4 million from reduced losses and USD 12.9 million from reduction of harvesting cost in comparison to 2006

10 Conclusion

In our point of view, the target output related to the validation of improved harvesting, drying, and milling methods is satisfactory The actual benefit has been demonstrated to the farmers through cooperatives by training, visits and workshops The quantitative data on the impact of the project based on the farmers’ survey were presented in earlier MS 11 report

We have achieved number of outcomes which are important for the benefit of small holder’s farmers

11 Appendix

Appendix 1 Effects of harvesting time around grain maturity on rice cracking and head rice

yield in Mekong River Delta

Appendix 2 Response Surface Method (RSM) experiment for optimum drying condition

Appendix 3 Technical report of milling experiments

3a Data collection of milling losses

3b Experiment on 1 ton/h system

3C Experiment on 7 ton/hr system

APPENDIX 1 Influence of harvesting time around grain maturity on rice cracking and head rice yield in the Mekong River Delta of Vietnam

ABSTRACT

Timely harvesting plays an important role in controlling rice cracking Reduced whole rice grain yield due to cracking causes the value loss and reduces the farmers’ income Field experiments were carried out to study the effect of harvesting time around crop maturity on rice cracking and head rice yield for seven common rice varieties (OM1490, OM2718, OM2517, OM4498, AG24, IR50404 and Jasmine) in three different locations during two cropping years (2006-2008) in the Mekong River Delta, Vietnam The results showed that the rice cracking was strongly influenced

by both the variety and time of harvesting around maturity There was a general trend of increase

in percentage of cracked rice with late harvesting in relation to estimated grain maturity date The head rice yield also followed the same trend in response to delayed harvesting A delay of 4-

6 days reduced the head rice yield by 11.3 % an average and up to 50 % Similar trends were observed in both wet and dry seasons The large varietal difference in percentage of cracked grain (0.9 to 60.5%) on 6 days after maturity date indicated that the level of rice cracking caused

by late harvesting time can be minimized by the selection of suitable varieties

1 INTRODUCTION

Head rice yield, which is defined as the weight percentage of rough rice that remains as head rice (the kernels that are at least ¾ of the original kernel length) after milling, is considered as the main quality indicator because the broken rice has often half the commercial value of whole grain rice It has been shown that timeliness of harvesting can influence milling yield

significantly Harvesting rice at crop maturity can give a maximum head rice yield (Kester et al

1963, Bal and Oiha 1975) Any delay in harvesting time causes reduction of head rice yield (Bal

and Oiha 1975, Ntanos et al 1996, Berrio et al 1989) and extended delay in harvesting can lead

to significant losses in head rice yield Berrio et al (1989) showed that among 16 investigated

rice varieties studied the whole-milled grain was reduced by 18% when harvesting was delayed

by 2 weeks However, it was also found that there was no impact of harvesting time on sensory

perception of rice (Champagne et al 2005, Chae and Jun 2002)

The incidence of rice fissuring in the field has a potentially significant impact on head rice yield Cracking can develop in the field as a result of changes in grain moisture after the rice matures due to hot sunny days followed by humid nights Harvesting time affects proportion of cracked rice and hence head rice yield Large quantities of immature rice kernels can be detected in early

35

Chau and Kunze (1982) showed that cracking can develop in low-moisture content kernels (13%

or 14% wet basis) before harvesting as a consequence of the swings in relative humidity in the atmosphere Furthermore, improper post-harvest practices, such as a delay in threshing when rice stacks are left in the field, can also provide the potential of moisture adsorption due to an uneven moisture content and uneven maturity within the bulk rice (Kunze and Prasad 1978)

Reduced whole rice grain yield due to cracking is one of the major issues that directly reduce income and availability of staple food to the farmers in the Mekong River Delta of Vietnam Mekong River Delta is the largest rice production region in Vietnam The cracking or partial fissuring of rice kernels may occur right in the paddy field due to incorrect harvesting time and improper harvesting practices, and occur also due to adverse post-harvest drying conditions and inappropriate milling operations The weather pattern (temperature and humidity) in Mekong River Delta is unique The rice is grown and harvested in both wet and dry seasons Weather conditions at around harvesting period are different between the two seasons and this can impact the rice fissuring and cracking during milling However, there is no experimental data available

on the impact of harvesting time on rice cracking and head rice recovery on the rice varieties grown at different seasons in the Mekong River Delta This research work is an attempt to systematically collect the rice cracking and head rice yield data based on field experimentations

in four consecutive harvesting seasons between 2006 and 2008 The main factor considered in this study during the collection of data was harvesting time- before and after grain maturity The objective of this experiment was to evaluate the effects of harvesting time of several rice varieties on the level of rice cracking and head rice yield in different seasons This study will assist to determine the optimal harvesting time for various rice varieties grown in the Mekong River Delta