Effect of planting method on biomass yield of New Cocoyam (Xanthosoma sagittifolium)

Lylian Rodríguez and T R Preston

TOSOLY, Morario, AA48 Socorro, Colombia
lylianr@utafoundation.org

Abstract

A  randomized block design was employed to compare the effect of choice of planting material on the biomass yield of New Cocoyam (Xanthosoma sagittifolium). The sources of planting material were suckers taken from the base of the root or sections of the disk taken from the PGF2alpha. There were 4 replications of each treatment arranged in 2 blocks in each of the two locations in the “Finca Ecologica, Santander, Colombia. Plant spacing was 70cm between rows and between plants in the row. Establishment of the plants was experiment was on 15 September 2006. Harvesting of leaves and petioles began on 18 February 2007 and continued at approximately 30 day intervals until 3 October 2007.

Fresh biomass (leaves and petioles) yields were 50% greater when the plants were established from suckers than from disks. The yields from plants established from suckers were  equivalent to 128 tonnes/ha/yr fresh biomass, 14.5 tonnes DM and 1.90 tonnes crude protein/ha/year. More leaves were produced from plants established from disks than from suckers but they were much smaller.  More suckers were produced by plants established from disks than from suckers, but the overall development of the plants was in favour of those established from suckers. On a DM basis, the leaves accounted for 60% of the biomass and 87% of the crude protein.

Key words: Alocacia, colocacia, disks, leaves, petioles, suckers, taro

Introduction

Research in our laboratory/farm has shown that the foliage from the New Cocoyam (Xanthosoma sagittifolium) is one of the most appropriate locally available sources of protein to partially replace soybean meal in diets of growing pigs in Colombia (Rodríguez et al 2006, 2009a,b). Similar conclusions have been made concerning other members of the  Araceae family (eg: Alocasia macrorrhiza in Vietnam [Pham Sy Tiep et al 2006, 2008; Ngo Huu Toan and Preston 2007; Hoang Nghia Duyet et al 2008]; and  Colocacia esculenta in Vietnam [Du Thanh Hang and  Preston 2008], in Cambodia [Chhay Ty et al 2007, Pheng Buntha et al 2008a] and  in Laos [Chittavong Malavanh et al 2008]).  

Surveys in Vietnam (Ngo Huu Toan and Preston 2007) and in Cambodia (Pheng Buntha et al 2008b) have shown that it is traditional farmer practice in these countries to use both the leaves and the petioles of different varieties of “Taro” (Alocacia macrrorhiza and Colocacia esculenta) as “vegetables” in pig feeding. Surprisingly there appear to be no agronomic studies on any of the species mentioned above.

The objective of the present study was to measure the biomass production of New Cocoyam and to compare two sources of plant material: the ‘suckers” derived from the root zone of the plant and “disks” obtained by cutting sections of the PGF2alpha.

Materials and Methods

Location

The study was carried out in the "Finca Ecológica", TOSOLY, Morario, Guapota, Department of South Santander, Colombia (6° 18" N, 73° 32" W, 1500 msl) between 15 September 2006 and 17 Decedmber 2007. Air temperature ranges between 19 and 28°C in the day, falling to around 12°C during the night. Rainfall is between 2700 and 3000 mm/year and is relatively evenly distributed (Annex 1).

Treatments and design

A  randomized block design was employed to compare the effect of choice of planting material on the biomass yield of New Cocoyam (Xanthosoma sagittifolium). The sources of planting material were suckers (Photo 1) taken from the base of the root or sections of the disk taken from the PGF2alpha (Photo 2). There were 4 replications of each treatment arranged in 2 blocks in each of the two locations “A” and “B” (Photos 3 and 4). Planting was on 15 September 2006.

Photo 1. Sucker taken from the base of the root	Photo 2. Disks taken from the corm
Photo 3. Location “A” near bamboo grove	Photo 4. Location “B” 100m distant from Location “A”

Planting and fertilization

 Individual plots measured  5.6*3.5m, with 0.7m spacing between plants and 0.7m between rows, equivalent to 22408 plants/ha. The plant material was situated in holes 20cm diameter and 20cm deep (Photos 5 and 6). Loose soil was put at the bottom of the hole at a depth of 5 cm followed by the plant material which was then covered with loose soil to which had been added 300 g poultry manure (from broilers raised in deep litter system). On 12 December 2006, 20 g urea were mixed into the surface of the soil surrounding each plant. A further 20 g urea with 690 g poultry deep litter manure was applied on 14 May 2007.

Photo 5. The holes situated in undisturbed soil	Photo 6.  Planting distances were 70cm between plants and between rows

Harvesting

The first harvest was made on 18 February 2007, 156 days after planting and subsequently at intervals ranging from 25 to 35 days until 3 October 2007. All the mature leaves and petioles were removed leaving the two youngest leaves to facilitate the regrowth.

Measurements

The plants harvested from each plot were counted, weighed and separated into leaves and petioles, each of which was weighed separately. DM, crude protein and sugars were determined on representative samples of leaves and petioles from the last harvest. DM was determined by micro-wave radiation (Undersander et al 1993), crude protein according to AOAC (1990) and sugars from the “Brix” readings taken with a hand refractometer.

Statistical analysis

The data were analysed using the GLM option in the ANOVA program of the MINITAB (2000) software. Sources of variation were: Blocks, plant material, harvest date, interaction of plant material*harvest date and error.

Biotest characterization of the soils

The maize “biotest” (Boonchan Chantaprasarn and Preston (2004) was used to assess (i) the relative fertility of the soils from the two locations; and (ii) the response curve to fertilization with poultry litter. In each test a completely randomized design was used with 4 replications of the treatments applied to samples of soil/substrate held in one litre capacity plastic bags (Photo 7a). Three maize seeds were planted in each bag. After germination one or two plants were removed to leave only plant for the growth period of 30 days when the maize plant was  harvested (Photo 7b) and the above ground fresh biomass was weighed.

Photo 7a. The plastic bags were placed in holes in the soil	Photo 7b. The maize plants ready for harvesting after 32 days growth

The treatments were:

Test 1

Soils from location “A” and location “B”, casts from worms fed with cattle manure (WC), sand and a 50:50 mixture (by fresh weight) of sand and WC. The quantities put in the bags are shown in Table 1. Weights of soil/substrate (g/bag) were 800 for soils from locations A and B, 600 for WC, 1075 for sand and 840 for sand:WC.

Test 2

Levels of poultry litter (g/bag) of  0, 10, 20, 40, 70 and 100 mixed with 800 g soil taken in equal amounts from locations A and B.

In Test 1 the statistical analysis was by the GLM option in the ANOVA program of the Minitab (2000) software. Sources of variation were: treatments and error. In test 2, a polynomial function was applied to the data, the independent variable (X) being the level of poultry litter and the dependent variable (Y) the fresh weight of the maize plant.   

Results

Biomass yield of New Cocoyam

Fresh biomass (leaves and petioles) yields over a 255 day period following the first harvest (which was made at 155 days) were 50% greater for New Cocoyam planted from suckers compared with disks (Table 1; Figure 1). These yields are equivalent to 128 and 85 tonnes/ha/yr. With an average DM content of 11.4% and crude protein of 13.1% in DM (Table 2), the predicted yields are 14.5 tonnes DM and 1.9 tonnes crude protein per ha/yr for planting by suckers. Biomass yield increased linearly up to 164 days following the first harvest and then declined, probably reflecting a need for further fertilization.

The difference between the biomass yields for each type of planting material decreased linearly with increasing maturity of the plants (Figure 2); however, even at 409 days after planting the yield from plants established from disks was still only 45% of the yield from plants derived from suckers.

The proportion of fresh biomass accounted for by the leaves was higher for plants established from disks (Table 3; Figure 3). On a DM basis, the leaves accounted for 60% of the biomass and 87% of the crude protein (Table 2).

Figure 3. Effect of harvest number on proportion of leaves in harvested biomass from New Cocoyam plants planted as suckers or disks

More suckers were produced by plants established from disks than from suckers, but the overall development of the plants was in favour of those established from suckers (Table 4

More leaves were produced from plants established from disks than from suckers but they were much smaller (Table 5; Figure 4).

Figure 4 . Effect of harvest number on numbers of leaves in harvested biomass from New Cocoyam plants planted as suckers or disks

Figure 5. Weights of  fresh leaves from New Cocoyam plants established from  suckers or disks

Characterization of the soils

As measured by the relative growth of maize the soils from both locations were of inherently low fertility, with no difference in maize yield between the samples of the two soils and sand  (Figure 6).

Figure 6. Growth of maize in soil taken from the two locations compared with negative (sand) and positive (worm casts) control substrates	Figure 7. Response in maize growth from adding poultry litter to the soils taken from locations "A" and "B"

Discussion

The biomass DM and crude protein yields of the New Cocoyam in the present study are encouraging taking account of the low inherent fertility of the soils in which the plants were grown. The fertilization procedure can be criticized in that the quantities applied were large and given in only two applications (equivalent to 97 kg N/ha at planting and a further 410 kg N/ha 280 days after planting) over the overall growing period of some 500 days.  The peak in the yield per harvest some 50 days after the final application of fertilizer and the subsequent decline in yield, are indicative of the need for fertilizer and for this to be applied more frequently. 

The comparative results from the two planting methods indicate the possible strategy to be followed in establishing plantations of New Cocoyam. If established plants are available it is obviously better to take the suckers from these plants for the new plantings. However, in situations where these are not available, a “nursery”could be prepared in which the plants would be established from disks. As each disk produces up to 3 suckers, these could then form the basis for the commercial plantation.

From observations, and the recorded pattern of  biomass yields, it is clear that New Cocoyam responds to fertilization with nitrogen. Subsequent experiments should be directed to measuring biomass yield responses to increasing levels of fertilization from biodigester effluent. The results of the “biotest” (Figure 7) showed a good response in growth of maize on the test soils to applications of poultry litter at N equivalent rates of 20 kg/ha over the 32 day growth period, equivalent to about 250 kg N/ha/year. This annual quantity of N, divided into applications at one or two month intervals, could be taken as a reference point for future agronomic studies with New Cocoyam for forage.  

The harvest interval of about 30 days applied in this study also merits closer study. We have observed that shorter intervals may be more appropriate especially in periods when the rainfall is more intense.

Conclusions

·         Fresh biomass (leaves and petioles) yields of New Cocoyam were 50% greater when established from suckers than from disks.

·         The yields from plants established from suckers are equivalent to 128 tonnes/ha/yr fresh biomass, and 14.5 tonnes DM and 1.8 tonnes crude protein/ha/year.

·         On a DM basis, the leaves accounted for 60% of the biomass and 87% of the crude protein

References

AOAC 1990:  Official Methods of Analysis. Association of Official Analytical Chemists. 15th edition (K Helrick editor). Arlington pp 1230

Boonchan Chantaprasarn and Preston T R 2004: Measuring fertility of soils by the bio-test method. Livestock Research for Rural Development. Volumr 16, Article No. 78. http://www.lrrd.org/lrrd16/10/chan16078.htm

Buntha P, Borin K, Preston T R and Ogle B 2008a:  Survey of taro varieties and their use in selected areas of Cambodia.  Livestock Research for Rural Development. Volume 20, supplement.  http://www.lrrd.org/lrrd20/supplement/bunt1.htm

Buntha P, Borin K, Preston T R and Ogle B 2008b:  Digestibility and nitrogen balance studies in pigs fed diets with ensiled taro (Colocasia esculenta) leaves as replacement for fish meal.  Livestock Research for Rural Development. Volume 20, supplement.  http://www.lrrd.org/lrrd20/supplement/bunt2.htm

Chhay Ty, Borin K, Preston T R and Mea Sokveasna 2007:  Intake, digestiew arebility and N retention by growing pigs fed ensiled or dried Taro (Colocasia esculenta) leaves as the protein supplement in basal diets of rice bran/broken rice or rice bran/cassava root meal. Livestock Research for Rural Development. Volume 19, Article #137.  http://www.lrrd.org/lrrd19/9/chha19137.htm

Du Thanh Hang and  Preston T R 2008: Taro (Colocacia esculenta) leaves as a protein source for growing pigs in Central Viet Nam Proceedings MEKARN Regional Conference 2007: Matching Livestock Systems with Available Resources (Editors: Reg Preston and Brian Ogle), Halong Bay, Vietnam, 25-28 November 2007 http://www.mekarn.org/prohan/hang_hue.htm

Hoang Nghia Duyet, Pham Thi Loan and Truong Thi Thuan 2008: Use of Giant taro leaves (Alocasia macrorrhiza) for replacement of soybean meal in diets of Mong Cai sows in Central Vietnam .  Proceedings MEKARN Regional Conference 2007: Matching Livestock Systems with Available Resources (Editors: Reg Preston and Brian Ogle), Halong Bay, Vietnam, 25-28 November 2007 http://www.mekarn.org/prohan/duyet.htm

Malavanh C, Preston T R and Ogle B 2008:  Effect of replacing soybean meal by a mixture of taro leaf silage and water spinach on reproduction and piglet performance in Mong Cai gilts.  Livestock Research for Rural Development. Volume 20, supplement.  http://www.lrrd.org/lrrd20/supplement/mala2.htm

MINITAB 2000. Minitab Reference Manual release 13.31.

Ngo Huu Toan and Preston T R 2007:  Evaluation of uncultivated vegetables for pigs kept in upland households. Livestock Research for Rural Development. Volume 19, Article #150.  http://www.lrrd.org/lrrd19/10/toan19150.htm

Pham Sy Tiep, Nguyen Van Luc, Nguyen Manh Hung, Tran Van Tu and Tran Van Phung 2008:  Study on the processing and use of Alocasia macrorrhiza (Giant taro) leaves in diets for Mong Cai sows and crossbred F1 (Large White x Mong Cai) growing pigs under mountainous village conditionsProceedings MEKARN Regional Conference 2007: Matching Livestock Systems with Available Resources (Editors: Reg Preston and Brian Ogle), Halong Bay, Vietnam, 25-28 November 2007 http://www.mekarn.org/prohan/tiep.htm

Pham Sy Tiep, Nguyen Van Luc, Trinh Quang Tuyen, Nguyen Manh Hung and Tran Van Tu 2006: Study on the use of Alocasia macrorrhiza(roots and leaves) in diets for crossbred growing pigs under mountainous village conditions in northern Vietnam. Workshop-seminar "Forages for Pigs and Rabbits" MEKARN-CelAgrid, Phnom Penh, Cambodia, 22-24 August,  2006. Article # 11. RetrievedJuly 15, 109, from http://www.mekarn.org/proprf/tiep.htm

Rodríguez Lylian, Lopez D J, Preston T R and Peters K 2006: New Cocoyam (Xanthosoma sagittifolium) leaves as partial replacement for soya bean meal in sugar cane juice diets for growing pigs. Livestock Research for Rural Development. Volume 18, Article No. 91. http://www.lrrd.org/lrrd18/7/rodr18091.htm  

Rodríguez Lylian, Peniche Irina, Preston T R and Peters K 2009a:  Nutritive value for pigs of New Cocoyam (Xanthosoma sagittifolium); digestibility and nitrogen balance with different proportions of fresh leaves and soybean meal in a basal diet of sugar cane juice.  Livestock Research for Rural Development. Volume 21, Article #16.  http://www.lrrd.org/lrrd21/1/rodr21016.htm

Rodríguez Lylian, Preston T R and Peters K 2009b: Studies on the nutritive value for pigs of New Cocoyam (Xanthosoma sagittifolium); digestibility and nitrogen balance with different levels of ensiled leaves in a basal diet of sugar cane juice.  Livestock Research for Rural Development. Volume 21, Article #27.  http://www.lrrd.org/lrrd21/2/rodr21027.htm

Undersander D, Mertens D R and Theix N 1993:  Forage analysis procedures. National Forage Testing Association. Omaha pp 154

Annex figure. Monthly rainfall in TOSOLY farm during 2007

Received 13 July 2009; Accepted 21 July 2009; Published 5 August 2009

Go to top