Effect of association with of Flemingia (Flemingia macrophylla) on chemical composition of cassava foliage, total yield of foliage and yield of cassava roots

Duong Nguyen Khang and Thomas R Preston^*

Department of Animal Physiology and Biochemistry,
Faculty of Animal Husbandry and Veterinary Medicine, Nong Lam University, Vietnam
duongnguyenkhang@yahoo com
^*University of Tropical Agriculture Foundation, UTA - TOSOLY - Finca Ecológica,
Morario - Guapota - AA # 48, Socorro, Santander, Santander del Sur, Colombia
trpreston@mekarn org

Abstract

A 4*2 randomized complete block design with 4 replications was conducted from June 2002 to March 2003 at the experimental farm of the Nong Lam University, Ho Chi Minh City, Vietnam, to determine effect of association of Flemingia with cassava on yield and chemical composition of the foliage, and cassava roots. Cassava of the variety KM 94 was grown in plots of 10 m x 20 m at a planting distance of 30 cm x 50 cm and was hand-harvested according to respective treatments, starting 100 days after planting.  All roots were collected at the final harvest 280 days after planting.

 Total dry matter and crude protein yields increased in Fleminia treatment compared to the control.  Mean dry matter foliage yields were 4 77 and 4 33 tonnes per ha with or without Flemingia, respectively. The leaf dry matter proportion in the foliage was high, ranging from 60 to 63%.  The proportion of leaf increased and the stem decreased in the association of Flemingia with cassava.  Crude protein content in cassava foliage ranged from 18 7 to 20 5% and was higher in cassava in association with Flemingia. The ADF and NDF contents of foliage varied between 25 2 and 28 4%, and 36 3 and 37 6% of DM, respectively.  The association of Flemingia with cassava had significant negative effect on root yield, which was reduced by 42% in the association of Flemingia with cassava.

It is concluded that the association of Flemingia with cassava has positive effects on cassava foliage yield and composition but negative effects on yield of roots.

Key words: Flemingia, cassava, foliage, roots
 

Introduction

Supply of protein-rich supplements is a problem in Vietnam as the area planted to oilseeds is small.  There is therefore a need to develop alternative sources, especially those which can be grown by the farmer.  Cassava is an important crop in the hilly and mountain areas of Vietnam as it grows under rain fed conditions on sloping ground, not suitable for rice production.  It is usually cultivated for production of roots but it can also be managed as a perennial forage, in which case the roots are not harvested.  The disadvantage of cassava is that when grown in monoculture it is exploitive of soil nutrients, especially nitrogen and soil fertility decreases.  Preliminary results in small plots showed that cultivating the shrub legume Flemingia macrophylla in association with cassava gave sustainable yields of biomass and reduced the need for fertilizer compared with growing the cassava in monoculture (Ngo Tien Dung et al  2005).  Up to the present time, most of the experimental work reported has been focused on the production potential of cassava root for human and animal food, and only a few published reports have focused on cassava foliage production as a protein feed for livestock, together with root production (Tung et al  2001; Hong et al  2003; Khang et al 2005;  Duong Nguyen Khang et al 2005).  The objectives of this experiment were to study the effects of association with Flemingia on yield and chemical composition of cassava foliage and root yield.

Materials and methods

Location, land and climate

The study was conducted from June 2002 to March 2003 at the experimental farm of Nong Lam University, Ho Chi Minh City, Vietnam.  The soil contained 54% sand, 39% silt, 7% clay and 0 62% organic carbon, with 6,87, 76.2, 3.69, 1.13 and 0.13 meq per 100 g of N, P, K, Ca and Mg, respectively, and a pH _KCl of 5.79 at 15 cm depth (Soil Chemistry Lab Data, Nong Lam University, Ho Chi Minh City, Vietnam, 2002)

	Figure 1.  Monthly rainfall and temperature at the time of the experiment

The climate in the area is a tropical monsoon, with the rainy season between May and December and the dry season from February to April The monthly mean temperatures ranged from about 27  to 34 ^°C with minima in December and February and maxima during the dry season (Figure 1)

The land was first cleared from weeds, and then ploughed by tractor to a depth of 20 - 25 cm to loosen the soil. Weeds were also removed twice during the establishment period.

Experimental design and treatments

The plots were each 10*20 m (200 m²) arranged in a randomized complete block design with 4 replications.  Allocation of treatments is shown in Table 1.  The experiment was set up in a field of 1940 m², of which 1600 m² was used for planting and 340 m² was border areas

Establishment and management

Cassava, variety KM 94, was planted early June 2002 and the final harvest was 280 days after planting. Cassava stems were planted in continuous rows with 50 cm between rows, 30 cm between stem cuttings. The length of stem was 20 - 25 cm and the planting depth 15 cm.  For the treatment of cassava and Flemingia, a row of Flemingia (5 cm spacing between seeds) was planted midway between the rows of cassava The cassava was planted first followed 14 days later by Flemingia.  Cattle manure was applied to all the plots prior to planting at 20 tonnes/ha.  No further manure was applied.

Harvesting

The first harvest was made when the cassava plants reached 100 cm in height (about 100 days after planting). All the foliage was cut at 30 cm above the ground. The same pattern was followed for the re-growth at 60 days interval.  In the associated plot,  the Flemingia was harvested at the same time as the cassava at 30 cm above ground level.  Cassava foliage (comprising young stems, leaves and petioles) was hand-harvested.  Cassava foliage was harvested between 08:00 h to 10:00 h to avoid fluctuation in cyanogenic glucosides, which occurs later during the day due to the hot sun (Yeoh and Oh 1979).  Cassava roots from all treatments were collected at the final harvest.

Measurements

All cassava foliage and roots from each plot were weighed to determine the fresh yield.  The fresh foliage was sampled and pooled from the 3 replicates (1.5 kg fresh weight each), and was placed in a porous paper bag for dry matter determination and chemical analyses.  A similar sample was collected to determine the ratio of leaf, petiole and stem, on a DM basis.  The contents of crude protein (CP), ether extract (EE) and total ash in the samples were determined according to the procedure of AOAC (1990).  The contents of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were determined according to the procedure of Van Soest et al (1991).  Total condensed tannin was determined by the butanol-HCl method (Terrill et al 1992).  The HCN content was determined by the alkaline titration method (AOAC 1990).

Statistical analysis

Data were statistically analyzed by using the General Linear Model Procedure of Minitab Statistical Software version 13 31. When the F-test was significant (P<0 05), the Tukey's test for paired comparisons was used to compare means.  The relationship between foliage yields or root yield, respectively, and cutting intervals were determined using the linear or quadratic responses in the Fitted Line Plot procedure of Minitab 13 31.

Results

Yields of foliage and roots

Yield of cassava foliage was reduced by approximately the same amount as was produced by the Flemingia, with total foliage yield being similar for the two treatments(Table 2). The mean fresh weight of roots was 42% lower in the association of Flemingia with cassava.

Fresh and dried weight proportions of cassava foliage

On a DM basis the cassava grown in association with Flemingia has a higher proportion of leaf and less stem than cassava grown in monoculture (Table 3).

Table 3  Fresh and dried weight proportions of cassava foliage grown in monoculture or in association with Flemingia
	Flemingia
	Without	With	SE	P
Fresh proportion, %
Leaf	60 5	61 0	0 34	0 25
Petiole	20 5	21 2	0 21	0 03
Stem	19 1	17 8	0 51	0 09
Dried proportion, %
Leaf	60 1	63 0	0 49	0 001
Petiole	20 1	19 9	0 1	0 11
Stem	19 7	17 2	0 47	0 001

Chemical composition of foliage

The crude protein content was similar, but ash, NDF, ADF and condensed tannins, were lower in the foliage of cassava grown with Flemingia.  The mean HCN content of fresh foliage increased, while the mean tannin and ash contents decreased with Flemingia.  There were no differences in the content of ether extract.

Table 4.   Chemical composition of cassava foliage grown in pure stand or in association with Flemingia
	Flemingia		SE	P
	Without	With
Dry matter, %	18 7	18 2	0 390	0 390
% in DM
Crude protein	18 6	20 5	0 450	0 390
Ether extract	7 46	7 55	0 100	0 490
Ash	5 68	5 06	0 060	0 001
NDF	37 6	36 3	0 460	0 050
ADF	28 4	25 2	0 390	0 001
Tannin	3 98	3 67	0 110	0 050
HCN #	84 3	91 6	0 530	0 001
# mg 100 g-1 fresh weight

Discussion

The foliage yields in 280 days of 4.3 and 4.7. tonnes per ha (without and with Flemingia) were proportionately lower than reported by Ngo Tien Dung et al (2005), in an experiment in which cassava, and cassava associated with Flemingia, produced 10 tonnes of DM as foliage in the first year (365 days) after planting. Flemingia accounted for 20% of the total foliage in the present experiment compared with 30% in the experiment of Ngo Tien Dung et al (2005).  However, there were major differences in root yields, which in the present experiment were 25.5 and 14.9 tonnes fresh weight per ha, without and with Flemingia, compared with 7 and 5 tonnes in the experiment of Ngo Tien Dung et al (2005), admittedly at the end of the second year from planting. 

The mean dry leaf proportion of the foliage (63%) was higher than found in an earlier study by Meyrelles at al (1977) where the leaf proportion of cassava foliage on DM basis was almost 52% of foliage yield. The crude protein content of the cassava foliage ranged from 18 6 to 20 5% in DM and was similar to the result of 22 8% reported by Khang and Wiktorsson (2000), and 18 8% reported by Man and Wiktorsson (2001), but much higher than reported (17% in DM) by Ngo Tien Dung et al (2005). The estimated protein yield in the present study (from 0 8 to 0 88 tonnes per ha) was lower than the levels of 1 to 1 5 tonnes per ha with five cuts at 45 day interval for three cassava varieties reported by Tung et al (2001).

The marked reduction in cassava root yield in the association with Flemingia (about 4 tonnes of DM), was not compensated by the increase in foliage yield which was only 0.44 tonnes of DM. By contrast, Ngo Tien Dung et al (2005) found that although root yield in the Flemingia-cassava association was reduced (from 2.81 to 1.93 tonnes DM), total foliage yield increased from 6.8 to 11.9 tonnes/ha, with a net gain of 4 tonnes DM/ha (from 9.6 to 13.8 tonnes DM). There is no obvious explanation for these differences, other than location and the cassava variety since fertilization was similar.is
 

Conclusions

• Inter-cropping cassava with Flemingia provided no major benefits in foliage yield, other than slight improvements in nutrient composition of the cassava foliage.

• There was a major negative effect on yield of roots after 280 days which was reduced by 42% by inter-cropping with Flemingia.

Acknowledgments

The authors are grateful to the Swedish International Development Cooperation Agency, Department for Research Cooperation (Sida/SAREC) for funding this study and Mr Tuan and Mr Thanh for their technical help.

References

AOAC 1990 Official methods of analysis of the Association of Official Analytical Chemists (15^th Ed ) Washington, DC 1: 69-90

Duong Nguyen Khang and Preston T R 2005: Effect of  effluent from low-cost plastic film biodigester on yield and chemical composition of cassava foliage and tuber yield.  Workshop-seminar "Making better  use of local feed resources" (Editors: Reg Preston and Brian Ogle) MEKARN-CTU, Cantho, 23-25 May, 2005. Article #6. Retrieved, from http://www.mekarn.org/proctu/khan6.htm

Hong N T T, Wanapat M, Wachirapakorn C, Pakdee P and Rowlinson P 2003 Effects of timing of initial cutting and subsequent cutting on yields and chemical compositions of cassava hay and its supplementation on lactating dairy cows Asian-Aus J Anim Sci 16: 1763 - 1769

Khang D N and Wiktorsson H 2000 Effects of cassava leaf meal on the rumen environment of local yellow cattle fed urea-treated paddy straw.  Asian-Aus J Anim Sci 13: 1102-1108

Khang D N, Wiktorsson H and Preston T R 2005 Yield and chemical composition of cassava foliage and tuber yield as influenced by harvesting height and cutting interval.  Retrieved 17 December 2005 from http://diss-epsilon.slu.se/archive/00000640/01/Agraria471.pdf

Man N V and Wiktorsson H 2001 Cassava tops ensiled with or without molasses as additive effects on quality, feed intake and digestibility by heifers Asian-Aus J Anim Sci 14: 624-630

Meyrelles L, MacLeod N A and Preston T R 1977 Cassava forage as a source of protein: effect of population density and age of cutting. Tropical Animal Production 2: 18-26 http://www.fao.org/ag/aga/AGAP/FRG/TAP21/2_1_3.pdf

Ngo Tien Dung, Ledin Inger and Nguyen Thi Mui  2005: Intercropping cassava (Manihot esculenta Crantz) with Flemingia (Flemingia macrophylla); effect on biomass yield and soil fertility. Livestock Research for Rural Development. Vol. 17, Art. #6. Retrieved , from http://www.cipav.org.co/lrrd/lrrd17/1/dzun17006.htm

Terrill T H, Rowan A M, Douglas G B and Barry T N 1992 Determination of extractable and bound condensed tannin concentrations in forage plants, protein-concentrate meals and cereal grains J Sci Food Agric 58: 321-329

Tung C M, Liang J B, Tan S L, Ong H K and Jelan Z A 2001 Foliage productivity and growth persistency of three local cassava varieties Asian-Aus J Anim Sci 14: 1253-1259

Van Soest P J, Robertson J B and Lewis B A 1991 Methods for dietary fiber, neutral detergent fiber and non-starch polysaccharides in relation to animal nutrition J Dairy Sci 74: 3583-3597

Yeoh H H and Oh H Y 1979 Cyanide content of cassava, Malayan Agri J 52: 24-28

Go to top