 |
| Figure 1. Mean height of maize |
| Livestock Research for Rural Development 23 (9) 2011 | Notes to Authors | LRRD Newsletter | Citation of this paper |
The effect of intercropping some forage legumes with maize on biomass yield of legumes and the grain yield of maize was determined in the savannah zone using a Completely Randomized Block Design. The legumes included Centrosema pubescens, Lablab purpureus, Stylosanthes guianensis and Macroptilium lathyroides and the maize-legume integrations were sole maize (SM), maize + Centrosema pubescens (MC), maize + Lablab purpureus (ML), maize + Stylosanthes (MS) and maize + Macroptilium (MM).
The results indicted that intercropping forage legumes with maize did not significantly affect the growth and grain yield of maize (P>0.05). The biomass yield of the individual legumes showed that S. guianensis and M. lathyroides were similar but significantly higher than the rest of the other legumes (P<0.05). Total biomass yield of MM was higher than those of other integrations (P<0.05) but sole maize yielded the lowest biomass (4.7 t/ha) (P<0.05). The results suggest that maize grain yield and biomass yields of intercrops can be maximized for both human and livestock feeding by integrating either S. guianensis, C. pubescens or M. lathyroides with maize respectively.
Keywords: crop residues, forage, livestock, mixed cropping, stover
The increasing demand for food has a concomitant increasing demand for animal protein and this calls for increasing provision of animal products (Teye and Gyawu 2002). However production per head of animals in the developing countries is inadequate to provide the required animal protein due to numerous bedeviling factors especially proper nutrition. During the dry season in the sub-saharan region, livestock depend mainly on natural pastures and crop residues which are often limiting in quantity and nutritional quality (Andrea and Pablo 1999). The limiting feed supply to animals results in weight loss and ill-health. The integration of livestock with crops has therefore been suggested as significant in the improvement of livestock output (Rufino 2008).
Crop-livestock farming is commonly practiced in the sub-saharan region but more attention is usually paid to the staple crops, mainly the cereals whose less nutritive residues are left for livestock feeding as well as for firewood. A proper integration of cereals with legumes can improve the nutritive value of crop residues, feed intake and animal production (Rufino 2008).
Farmers practicing cereal-legume intercropping are often concerned with what they will harvest as food and not what the legumes can contribute to livestock nutrition but the integration of food crops and fodder legumes contributes significantly to feed production and to food production through soil fertility improvement (Barnes and Addo-Kwafo 1994a). Nevertheless farmers do not practise it, hence the need for this study. The objective of the study was therefore to determine the effects of cereal-legume integration on total biomass yield and grain yield.
The study was conducted at the Animal Research Institute (ARI) experimental station at Nyankpala in the Northern Region of Ghana. Nyankpala is located between latitude 9º23” N and longitude 0º59” W. The soil in the area is classified as savannah ochrosol under the Ghana system of classification. The soil fertility is low especially for N, P and K and the rainfall ranges from 600 mm to 1000 mm (Owusu-Ansah 2009).
The land was prepared by spraying with sarosate®. After planting, the field was maintained by weeding it in the 2nd and 6th weeks and fertilizer applied at 50 kgN/ha.
The field was divided into four (4) blocks and the five (5) treatments randomly assigned to the plots in each block. The treatments included: sole maize (SM), maize and Centrosema pubescens (MC), maize and Lablab purpureus (ML), maize and Stylosanthes guianensis (MS), and maize and Macroptilium lathyroides (MM). Each plot measured 6 m x 3 m and was spaced 1 m apart. All plants (maize and the legumes) were planted on the same date. Planting distance of maize was 80 cm x 40 cm while that of the legumes was 80 cm x 50 cm.
Data were collected fortnightly on height of the maize and ground cover of the legumes. Harvesting of all plants was done 16 weeks after planting, when the maize cobs were fully matured. At harvest, grain and stover yields of maize and biomass yield of legumes were taken by picking samples from each plot and oven-drying until a consistent weight was achieved. All plants were harvested on the same date. The data collected were subjected to analysis of variance using GenStat (6th edition) and significant differences of means were separated using LSD at 5% probability level.
|
| Figure 1. Mean height of maize |
The introduction of legumes did not significantly influenced the height of maize (P>0.05) (Figure 1). The relatively lower mean height of maize in ML may be due to their suppression by the legume since L. purpureus is a robust and vigorously twining herbaceous plant and so easily outgrows other plants in competition for plant growth factors (Andrea and Pablo 1999).
Even though there was no significant difference in growth rate of maize, the range of heights observed for plots of maize intercropped with legumes in this study was higher than those observed by NAES (1992) in the same environment for sole maize. This may be attributed to increased nutrients availability in the soil fixed by the legumes because of the legumes’ rhizobium association property. Since the legumes did not significantly affect the growth of maize, farmers can practise food crop-forage legume intercropping without adverse effects on the yield of their food. Besides, such intercrops have the added advantage of enriching the soil nutrient base through the fixation of atmospheric nitrogen into the soil (Cook et al 2005).
 |
| Figure 2. Grain and stover yields of maize |
From Figure 2, the mean grain yield of SM (4.35 t/ha) was the least but not significantly lower than those of the maize-legume intercrops (4.86-6.13 t/ha) (P>0.05). NAES (1989) reported a similar pattern but lower yields of 3.68 t/ha and 4.75-5.43 t/ha for sole maize and maize-groundnut (i.e. cereal-legume) intercrop respectively. Since the two experiments were conducted in the same location but different years, it is possible that changes in environmental conditions and time accounted for the variations in the yields. Nevertheless, the results suggest that legumes (forage legumes in this case), when intercropped with maize, improve the grain yield of the maize. Most farmers in northern Ghana are already intercropping maize (or other cereals) with edible legumes (Karbo et al 2003), and so they can introduce forage legumes into the mixed cropping systems to provide not only better grain yields for human consumption but also fodder with an improved biological value for livestock. Such farmers have double gains (maize grain and livestock feed) compared to those practising mono cropping.
The 1000-grain weight of maize in the following treatments, SM, MC, ML, MS and MM were 0.29 kg, 0.35 kg, 0.33 kg, 0.41 kg and 0.32 kg respectively. The introduction of legumes did not influence grain weight significantly although MS appeared to have more impact on dry grain weight followed by MC (P>0.05). The low influence of ML on grain weight may be attributed to the late emergence of L. purpureus. Also the robust and twining nature of L. purpureus did not seem to suppress grain yield. The low influence of MM may be due to severe insects’ attack on M. lathyroides that resulted in its lower stands. Generally the 1000-grain weight of 0.29-0.41 kg observed in this study was higher than 0.25-0.35 kg reported by Guy (1987), which may be an indication that legumes improve soil fertility.
The stover yields in all the treatments were statistically similar (P>0.05) although MM had the highest value of 5.18 t/ha while ML (4.65 t/ha) was the least (Figure 2). The grain and stover yields were almost the same in all the treatments (Figure 2). The legumes did not improve stover yield of maize. Other studies in the same environment revealed that when grain yield of maize was high, the average stover yield was nearly twice as high as the average grain yield, but when grain yield was low, the average stover yield became 3–3.5 times higher than the grain yield (NAES 1992). The results of this study suggested that the legumes did not suppress maize yield. Even though farmers’ primary target is often the grain and not the stover, they could practise cereal-legume intercropping to produce livestock feed without compromising grain yield (Barnes and Addo-Kwafo 1994a).
The percentage ground cover were significantly different (P<0.05). Lablab purpureus had the highest ground cover (77.6%). L. purpureus is a robust climbing broad leafy legume which accounts for its higher ground coverage (Lenné 1994). The ground cover for C. pubescens was 53.2%. This was 12% higher than the coverage reported at the coastal region of Ghana (Barnes and Addo-Kwafo 1994b). S. guianensis had the least soil coverage of 38.0%, which is in conformity with an average of 38.3% reported by Barnes and Addo-Kwafo (1994b). Lenné (1994) have recommended these legumes for green manure and as cover crops against erosion. In this study L. purpureus showed the greatest potential as a cover crop followed by C. pubescens. However, the soil cover percentage did not reflect in biomass productivity (Table 1). This may be due to the growth pattern of the legumes used for the intercrop as well as the amount of leaves and twigs remaining on each plant at the time of harvest. Hence the best cover crop may not be the best crop for livestock feed production in mixed cropping.
|
Table 1. Percentage ground cover and biomass yields of legumes |
||
|
Treatment |
Ground cover (%) |
Biomass (t/ha/year) |
|
MC |
53.20b |
1.01b |
|
ML |
77.60a |
1.29b |
|
MS |
38.00c |
1.97a |
|
MM |
42.90bc |
1.97a |
|
LSD |
14.98 |
0.26 |
|
CV |
4.1% |
13.7% |
|
Within a column, means following by different letters are different at P<0.05 |
||
From Table 1, the biomass yields of C. pubescens and L. purpureus differed significantly from those of S. guianensis and M. lathyroides (P<0.05). This could be attributed to the differences in the performance by the different legume species as there were no blocking effects. The least yield of C. pubescens (1.01 t/ha/year) was higher than 0.83 t/ha/year reported by Barnes and Addo-Kwafo (1994b), but far lower than 7.6 t/ha/year and 12.8 t/ha/year reported for the same species in Colombia and Queensland respectively (Cook et al 2005). There was drought at the time of germination and this affected the emergence and establishment of the seedlings of the legumes, particularly C. pubescens, which probably lead to its poor growth performance.
Stylosanthes guianensis and M. lathyroides were outstanding in biomass production. They did not have adverse effects on both grain and stover yields of maize and so would be suitable for intercropping with maize for livestock feed production.
Humphreys (1987) reported that when sheep were fed with 1:5 mixture (7.2% CP) of legume and grass respectively, they consumed 1.24kg of feed per sheep per day. From Table 2, if a farmer practises this feeding regime with 10 sheep, he could feed the 4.71t, 7.12t, 7.23t, 8.96t and 9.12t of biomass of SM, MC, ML, MS and MM for 453, 685, 695, 862 and 877 days respectively (based on the formula below).
TBM is total biomass, X is quantity of feed/animal/day and Y is number of animals.
The cereal-legume intercrop could therefore provide enough feed for livestock in a year and also minimize the occurrences of sole grass feeding related problems such as mycotoxicoses, ryegrass staggers, phyto-oestrogenic effects, photosensitization and/or nitrite poisoning. In this case animals receiving stover-legume mix are likely to perform better as a result of a balanced nutrition than those receiving only the stovers because of the crude protein provided by the legumes in the feed mixture (Karbo et al 2003).
|
Table 2. Estimation of feeding of sheep with the total biomass |
||||
|
Treatment |
TBM (kg/ha) |
Quantity/ani/day (X kg/day) |
Number of animals (Y) |
Duration (days) |
|
SM |
4710 |
1.04 |
10 |
453 |
|
MC |
7120 |
1.04 |
10 |
685 |
|
ML |
7230 |
1.04 |
10 |
695 |
|
MS |
8960 |
1.04 |
10 |
862 |
|
MM |
9120 |
1.04 |
10 |
877 |
The study showed that the forage legumes, especially S. guianensis and C. pubescens, did not adversely interfere with the growth and productivity of maize. L. purpureus and C. pubescens are therefore potential cover crops for farmers. S. guianensis and M. lathyroides recorded the highest biomass yields. Regarding biomass yields of the intercrops, those of MM and MS were statistically the highest. Farmers practising cereal-legume intercropping could gain more in terms of food and animal feed than those practising monocropping.
This study thus recommends that legume species for such intercrops are S. guianensis and M. lathyroides. Feeding trials should also be done to select palatable and acceptable species for livestock.
Andrea M M and Pablo E C 1999 A tropical forage solution to poor quality ruminant diets: A review of Lablab purpureus. Livestock Research for Rural Development. Volume 11, Article # 2. Retrieved July 8, 2011July 8, 2011, http://www.lrrd.org/lrrd11/2/colu112.htm
Barnes P B and Addo-Kwafo A 1994a Under-sowing maize with Stylosanthes: Effects of spacing, time of planting, and fertilization on maize grain and stylo herbage yields. African Crop Science Conference Proceedings, Vol. 1:174-176.
Barnes P B and Addo-Kwafo A 1994b Initial evaluation of some introduced forage plants for herbage productivity at two sites in Ghana. Ghana Journal of Agricultural Science. 24:139-144.
Cook B G, Pengelly B C, Brown S D, Donnelly J L, Eagles D A, Franco M A, Hanson J, Mullen B F, Partridge I J, Peters M and Schultze-Kraft R 2005 Tropical Forages: An Interactive Selection Tool. [CD-ROM], CSIRO, DPI&F (Qld), CIAT and ILRI, Brisbane, Australia.
Guy R 1987 MAIZE. The Tropical Agriculturalist Series. Macmillan Press LTD. London and Basingstoke. 102pp.
Humphreys L R 1987 Tropical Pastures and Fodder Crops (2nd ed). ELBS ed. Longman Singapore Publishers Pte Ltd. 155pp.
Karbo N, Clottey V, Bruce J, Addo-Kwafo A, Kombiok J, Alebekiya M, Faalong J, Lawson I, Honya G, Abunyewa A and Aligebam B 2003 Intensification of integrated crop-livestock systems in the dry savannahs of West Africa. Collaborative Research between ILRI-IITA-ICRISAT and the NAES. 99pp.
Lenné J M 1994 Diseases of other Pasture Legumes. In: Lenné, J. M. and P. Trutmann (eds). Diseases of Tropical Pasture Plants. CAB Int. Cambridge, UK. 129-54.
NAES (Nyankpala Agricultural Experiment Station) 1989 Nyankpala Agricultural Research Report /6/1989. Annual Report.
NAES (Nyankpala Agricultural Experiment Station) 1992 Nyankpala Agricultural Research Report /8/1992. 303pp.
Owusu-Ansah D 2009 "Ghana." Microsoft® Student 2009 [DVD]. Redmond, WA: Microsoft Corporation, 2008.
Rufino M C 2008 Quantifying the contribution of crop-livestock integration to African farming. PhD Thesis, Wageningen University, The Netherlands.
Teye G A and Gyawu P 2002 A guide to guinea fowl production in Ghana. A handbook. Department of Animal Science, University for Development Studies. Tamale, Ghana. 14pp.
Received 14 August 2011; Accepted 20 August 2011; Published 1 September 2011