Economics of intercropping maize with forage crops in small-scale farming systems in western Kenya

A.W. Mukhebi and J.F.M. Onim

Agricultural Economist and Agronomist
Winrock International Institute for Agricultural Development
SR-CRSP P.O. Box 252, Maseno, Kenya

L. Oyugi

Research Officer, Ministry of Agriculture and Livestock Development
P.O. Box 30028, Nairobi, Kenya

Abstract
Introduction
Materials and methods
Results and discussion
Conclusions
References

Abstract

Maize (Zea mays) Hybrid 512, was intercropped with Sudan grass (Sorghum sudanense), pigeon pea (Cajanus cajan) cultivar "Kioko", and sesbania (Sesbania sesban van mubian) in split plot designs at Maseno and the Small Ruminant Collaborative Research Support Programme (SR-CRSP) cluster areas in Kaimosi and Masumbi during the short-rains season of 1983. The main plots were fertilizer treatments (NPK 20-200) at the rate of 40 kg per ha of N, P₂O₅ and the sub-plots were crops and their intercropping combinations. Standard agronomic practice was applied in planting maize and maize-intercrop plots. Sampling for dry matter (DM) yield estimates was done whenever any forage was ready as various forages were ready for feeding at different times in the various treatments and environments. DM yields from each forage crop in one site were accumulated until the last sampling was done. Maize grain and stover DM yields were also estimated when the crop matured at various sites.

A partial budgeting model was applied for economics evaluation of the biological data. Incremental benefits and incremental costs for each crop treatment at each site were calculated. The resultant benefit: cost ratio (BCR was derived as a ratio of net incremental benefits to incremental costs and was used as the choice criterion for ranking the various maize-forage intercrops).

Results indicate that intercropping maize with forages with or without fertilizer application generated greater economic returns than pure-stand maize in Kaimosi Cluster, and with fertilizer application in Masumbi Cluster. There was no economic advantage over pure-stand maize at Maseno Research Station, and in Masumbi Cluster without fertilizer application. In Kaimosi Cluster, maize intercropped with leguminous forages yielded greater returns than maize intercropped with Sudan grass when fertilizer was applied, but the converse results were the case without fertilizer application. For Masumbi Cluster, maize-Sesbania followed by maize-Sudan grass were the most promising intercrops only when fertilizer was applied, otherwise pure-stand maize was economically superior to the maize intercrops without fertilizer application. Overall, fertilizer application was economically more profitable than non-fertilizer application at all the sites for both pure-stand maize and maize intercrops. It is concluded from the results of this one season trial that while intercropping maize with forage crops yields greater economic returns than pure-stand maize in some areas, it may lead to economic loss in other areas depending upon soil fertility and rainfall conditions.

Introduction

Shortage of livestock feed, particularly during dry seasons, is one of the major constraints to increasing livestock production in small-scale farming systems in western Kenya. The Feed Resources Project of the Small Ruminant Collaborative Research Support Programme (SR-CRSP), has conducted various station and on-farm trials on alternative forage producing interventions for relaxing this constraint. Trial interventions have involved intercropping the staple food crop, maize, with leguminous or grass forages with or without fertilizer application.

The objectives of this paper is threefold:

1. To quantify the economic costs and benefits of intercropping maize with selected forage crops;

2. To assess the economic impact of applying fertilizer to maize both in pure stand and intercropped with forage crops;

3. To identify the economically most promising maize-forage intercrops for the SR-CRSP Cluster areas in Kaimosi and Masumbi and for the Maseno Research Station environment.

Two main hypotheses are tested: that intercropping maize with forages yields less economic returns than maize grown in pure stand, and that applying fertilizer to maize in pure stand or intercropped with forage crops yields greater economic returns than non-fertilized pure-stand or forage-intercropped maize.

Materials and methods

Biological Trials

During the short-rain season of 1983, maize (Zea mays) Hybrid 512, was intercropped with Sudan grass (Sorghum sudanense), pigeon pea, (Cajanus cajan) cultivar "Kioko", and sesbania (Sesbania sesban var. nubian) in split plot designs at Maseno and in cluster areas. The main plots were fertilizer treatments (NPK 20-20-0) at the rate of 40 kg per ha of N, P₂O₅ and the sub-plots were crops and their intercropping combinations.

Maize was-planted at the standard spacing of 90 cm between rows and 30 cm between plants in the row. Pigeon pea and Sesbania were then planted between these rows but only 45 cm from the maize rows and with inter-row spacing of 30 cm. Sudan grass was drilled between maize rows at the same inter-row spacing as the other forage crops. Fertilizer was applied only once at planting time.

Maize, pigeon pea and Sesbania were thinned to single plants per hill at the second weeding. The thinnings were oven-dried at 80 for 24 hours. Because various forages were ready for feeding at different times in the various treatments and environments, sampling for dry matter (DM) yield estimates was done whenever any forage was ready. DM yields from each forage crop in one site were accumulated until the last sampling was done at the end of the second rainy season in February 1984. Dry matter maize grain and stover yields were also estimated when the crop matured at the various sites between the middle and end of February 1984.

Dry maize grain and DM forage yields obtained per hectare are summarized in Table 1. There was a complete crop failure for maize grain yield in Masumbi Cluster due to a severe drought. However, DM stover yields for maize and forage crops were measured.

Table 1. Dry maize grain and dry-matter forage yields from station and on-farm trials at Maseno Station and in Kaimosi and Masumbi Clusters, Western Kenya, short-rain season, 1983

Intercrop	Without fertilizer		With Fertilizer		Intercrop (Mean)
	Dry grain	Forage dry matter	Dry grain	Forage dry matter	Dry grain	Forage dry matter
	Maseno Station
Maize-pure stand	2.49	40.20	2.47	48.10	2.48	44.15
Maize-Sudan grass	1.38	28.00	1.87	38.90	1.63	33.45
Maize-Sesbania	1.64	28.50	1.75	39.40	1.70	33.95
Maize-Pigeon peas	1.67	26.60	2.32	40.60	2.00	33.60
Fertilizer treatment
Mean	1.80	30.83	2.10	41.75	1.95	36.29
	Kaimosi Cluster
Maize-pure stand	1.66	10.10	2.03	23.10	1.85	16.60
Maize-Sudan grass	0.72	17.20	2.78	34.10	1.75	25.65
Maize-Sesbania	2.47	17.50	1.58	30.20	2.03	23.85
Maize-Pigeon pea	2.34	21.70	3.33	23.50	2.84	22.60
Fertilizer treatment
Mean	1.80	16.63	2.43	27.73	2.12	22.18
	Masumbi Cluster
Maize-pure stand	0	4.80	0	10.00	0	7.40
Maize-Sudan grass	0	2.90	0	13.80	0	8.35
Maize-Sesbania	0	4.50	0	13.80	0	9.15
Maize-Pigeon pea	0	4.00	0	11.30	0	7.65
Fertilizer treatment
Mean	0	4.05	0	12.23	0	8.14

^a There was no maize grain yield due to a severe drought
Source: Onim, et al, 1984

Economic Analysis

A partial budgeting model was applied for economic-evaluation of the biological data in Table 1 (Mukhebi and Onim, 1985). Maize grain yields were valued at farm-gate prices. Forage DM yields were converted into SR-CRSP dual-purpose goat products (liveweight and milk) using the Kenya Dual Purpose Goat Model (Ruvuna and Blackburn 1984). The animal products were then valued at farm-gate prices (Mukhebi and Onim 1985).

Incremental benefit and incremental cost for each crop treatment at each site were calculated. The resultant benefit cost ratio (BCR) was derived as the ratio of net incremental benefit to incremental cost. It is the absolute marginal rate of return (or loss, if negative) to incremental cost. BCR is the choice criterion for ranking the alternative maize-intercrops against respective control practices. A positive BCR implies that a particular crop treatment is economically superior (yields positive marginal return) to the control treatment or practice, and vice versa. The higher the positive BCR, the more economically superior the crop treatment vis-a-vis the control treatment. The converse is also true.

BCRs were computed in two ways. First, pure stand maize was taken as the control practice against which incremental benefits and costs for intercrops were measured, both with and without fertilizer application. This was to determine the effect of intercropping maize with forages with or without fertilizer application. Second, maize and maize intercrops without fertilizer application were regarded as the control practice against which the same crop treatments, but with fertilizer application, were compared. This was to assess the effect of fertilizer application to maize in pure stand or intercropped with forages.

Results and discussion

Intercropping Maize with Forages

Benefit cost ratios from intercropping maize with various forage crops with or without fertilizer application at the various sites are shown in Table 2. The ratios are summarized from partial budgeting results presented in Appendix 1, Table A1 for Maseno Station, Table A2 for Kaimosi Cluster and Table A3 for Masumbi Cluster.

Figures in Table 2 demonstrate clearly that there were no incremental economic benefits generated by intercropping maize with Sudan grass, Sesbania or pigeon pea with or without fertilizer application at Maseno station. BCR is negative unit for each maize intercrop indicating zero incremental benefits. This implies that pure-stand maize is the economically superior practice for the site whether fertilizer application is undertaken or not. This result is apparent from the biological data in Table 1 which show that for Maseno station both grain and dry-matter yields for each maize intercrop were less than those of pure-stand maize.

Table 2. Economics of intercropping maize with forage crops with and without fertilizer application in station and on-farm trials at Maseno Station, Kaimosi and Masumbi Clusters, Western Kenya, short rains season, 1983

Intercrop	Benefit: Cost ratios
	Without Fertilizer	With Fertilizer	Intercrop Mean
Maize-pure stand	Control
	Maseno Station
Maize-Sudan grass	-1.0	-1.0	-1.0
Maize-Sesbania	-1.0	-1.0	-1.0
Maize-Pigeon peas	-1.0	-1.0	-1.0
	Kaimosi Cluster
Maize-Sudan grass	0.1	5.3	2.7
Maize-Sesbania	11.9	1.0	6.5
Maize-Pigeon pea	16.2	3.0	9.6
	Masumbi Cluster
Maize-Sudan grass	-1.0	0.3	-0.4
Maize-Sesbania	-1.0	1.2	0.1
Maize-Pigeon pea	-1.0	-0.3	-0.7

For Kaimosi Cluster Table 2 shows that without fertilizer application the maize-pigeon pea intercrop yields the highest BCR of 16.2, followed by the Maize-Sesbania intercrop with a BCR of 11.9. The maize-Sudan grass has the lowest BCR of 0.1. On the other hand, with fertilizer application, the maize-Sudan grass intercrop yields the greatest BCR of 5.3, followed by the maize-pigeon pea intercrop with a BCR of 3.0, and lastly by the maize-Sesbania mixture with a BCR of 1.0. Each intercrop with or without fertilizer is economically superior to the pure-stand maize control as indicated by positive BCRs.

Results for Kaimosi Cluster also show that when fertilizer is not applied, maize-legume (pigeon peas and Sesbania) intercrops generate significantly greater marginal returns (higher BCRs) than the maize-grass (Sudan grass) intercrop. The explanation for this is that when fertilizer is not applied, maize benefits from the nitrogen fixation by the legumes, while it competes with a grass intercrop for available nitrogen in the soil. On the other hand, when fertilizer is applied, the maize-grass intercrop for available nitrogen in the soil. On the other hand, when fertilizer is applied, the maize-grass intercrop generates higher marginal returns than the maize-legume intercrop. In this case, the yield response to fertilizer application is greater for the maize-grass intercrop which does not fix any nitrogen than for the maize-legume intercrops which fix some nitrogen of their own.

Table A1. Partial budget analysis of intercropping maize with forage crops with and without fertilizer application, Maseno, short rains season, 1983

Intercrop	Without fertilizer			With Fertilizer
	Incrementala
	Benefit	Cost	Marginal Benefit (+) (Ksh/ha)	Benefit cost (-)	Cost	Marginal Benefit (+) cost (-)
Maize-pure stand	Control
Maize-Sudan grass	0	6,878	-6,878	0	7,007	-7,007
			(-1.0)b			(-1.0)b
Maize-Sesbania	0	8,111	-8,111	0	6,588	-6,588
			(-1.0)			(-1.0)
Maize-Pigeon pea	0	9,950	-8,950	0	4,640	-4,640
			(-1.0)			(-1.0)
Maize-Benefit cost	0	7,980	-7,980	0	6,078	6,078
			(-1.0)		(-1.0)

^a. Incremental benefit (gain) or cost (loss) as compared to pure-stand maize used as control practice.

^b. Figures in parentheses are benefit: cost ratios (BCR) computed as a ratio of marginal net benefit (+) or cost (-) to incremental cost: BCR is an absolute marginal rate of return on incremental cost. When multiplied by 100 it yields a percentage return.

Intercrop mean BCRs for fertilizer and non-fertilizer treatments are 9.6, 6.5 and 2.7 for maize-pigeon pea, maize-Sesbania and maize-Sudan grass respectively.

For Masumbi Cluster all the three intercrops are inferior to the pre-stand maize control without fertilizer application, as shown by negative unit BCRs. With fertilizer application, maize-Sesbania and maize-Sudan grass yield positive BCRs of 1.2 and 0.3 respectively, while the maize-pigeon pea intercrop yields a negative BCR of -0.3. Only the maize-Sesbania intercrop has a positive intercrop mean of 0.1 for fertilizer and non-fertilizer treatments.

Table A2. Partial budget analysis of intercropping maize with forage crops with and without fertilizer application, Kaimosi Cluster, short rains season, 1983

	Without Fertilizer			With Fertilizer
	Incrementala
	Benefit	Cost	Marginal benefit (-) cost (-) (Ksh/ha)	Benefit	Cost	Marginal benefit (+) cost (-)
Maize-pure stand	Control
Maize-Sudan grass	3,433	3,138	+295b	7,109	1,129	+5,980
			(0.1)			(5.3)
Maize-Sesbania	5,521	428	+5,093	3,433	1,741	+1,692
			(11.9)			(1.0)
Maize-Pigeon peas	7,215	420	+6,795	2,644	658	+1,986
				(16.2)		(3.0)
Mean benefit or cost	5,390	1,329	+4,061	4,395	1,176	3,219
			(3.1)			(2.7)

^a. Incremental benefit (gain) or cost (loss) as compared to pure-stand maize used as control practice.

^b. Figures in parentheses are benefit: cost ratios (BCR) computed as a ratio of marginal net benefit (+) or cost (-) to incremental cost. BCR is an absolute marginal rate of return on incremental cost. When multiplied by 100 it yields a percentage return.

Fertilizer Application to Maize and Maize-Forage Intercrops

BCRs from applying fertilizer to maize and maize-forage intercrops are reported in Table 3. These ratios are summarized from partial budgeting results presented in Appendix Table A4 for Maseno Station, Table A5 for Kaimosi Cluster and Table A6 for Masumbi Cluster.

Table A3. Partial budget analysis of intercropping maize with forage crops with and without fertilizer application, Masumbi Cluster, short rains season, 1983

	Without Fertilizer			With Fertilizer
	Incrementala
	Benefit	Cost	Marginal benefit (-) cost (-) (Ksh/ha)	Benefit	Cost	Marginal benefit (+) cost (-)
Maize-pure stand	Control
Maize-Sudan grass	0	1,612	-1,612	1,440	1,129	+311
			(-1.0)b			(0.28)
Maize-Sesbania	0	542	-542	1,440	665	+775
			(-1.0)			(1.16)
Maize-Pigeon pea	0	722	-722	493	658	-165
			(-1.0)			(-0.25)
Mean benefit cost	0	959	-958	1,124	917	+307
			(-1.0)			(0.38)

^a. Incremental benefit (gain) or cost (loss) as compared to pure-stand maize used as a control practice.

^b. Figures in parentheses are benefit: cost ratios (BCR) computed as a ratio of marginal net benefit (+) or cost (-) to incremental cost. BCR is an absolute marginal rate of return on incremental costs. When multiplied by 100 it yields a percentage return.

Table 3. Economics of fertilizer application to maize intercropped with forage crops at Maseno Station, Kaimosi and Masumbi Clusters, Western Kenya, short rains season, 1983

Intercrop	Benefit: Cost ratios of fertilizer application over non-application of fertilizer
	Maseno Station	Kaimosi Cluster	Masumbi Cluster	Inter-Crop Mean
Maize-pure stand	12.4	29.2	7.3	16.3
Maize-Sudan grass	26.1	54.1	16.4	32.2
Maize-Sesbania	22.3	1.6	13.8	12.6
Maize-Pigeon peas	12.7	12.7	10.6	12.0

Table A4. Partial budget analysis of fertilizer application to maize intercropped with forage crops, Maseno station, short rains season, 1983

Intercropped	With Fertilizer
	Incrementala benefit	Incrementala cost	Marginal net benefit (+) cost(-)
Maize-pure stand	3,816	285	+3,531
			(12.4)b
Maize-Sudan grass	6,436	238	+6,198
			(26.1)
Maize-Sesbania	5,528	238	+5,290
			(22.3)
Maize-Pigeon pea	3,247	238	+3,010
			(12.7)
Mean benefit cost	4,757	250	+4,507
			(18.0)

^a. Incremental benefit (gain) or cost (loss) as compared to the same intercrop without fertilizer application.

^b. Figures in parentheses are benefit: cost ratios (BCR) computed as a ratio of marginal net benefit (+) or cost (-) to incremental cost. BCR is an absolute marginal rate of return on incremental cost. When multiplied by 100 it yields a percentage return.

It is quite clear from Table 3 that fertilizer application is economically superior to non-fertilizer application at all sites (Maseno Kaimosi and Masumbi) and for both pure-stand maize and all the maize-forage intercrops. BCRs are all positive and considerably greater than zero for al treatments. For Maseno Station trials, maize-Sudan grass and maize-Sesbania intercrops generate the highest BCRs of 26.1 and 22.3 respectively. For Kaimosi trials, the highest BCRs are recorded from maize-Sudan grass (54.1) and pure-Sesbania with a BCR of 13.8. Overall, the BCRs in Table 3 again demonstrate that the maize-Sudan intercrop generates greater economic response (BCR = 32.2) than maize-legume intercrops (BCR of 12.6 and 12.0 for maize-Sesbania and maize-pigeon pea respectively).

While the results in Table 2 address the first hypothesis, namely that intercropping maize with forage crops yields less economic returns than maize grown in pure stand, the results in Table 3 address the second hypothesis that applying, fertilizer to maize in pure stand or intercropped with forage crops yields greater economic returns than non-fertilized pure stand or forage-intercropped maize. The first hypothesis appears to be acceptable for Kaimosi Cluster, unacceptable for Maseno Station and inconclusive for Masumbi Cluster. This implies that, while intercropping maize with forages is an economically superior practice in some areas, it may lead to economic loss in other areas depending upon soil fertility and climatic conditions of the areas in question. The second hypothesis appears to hold for all sites and for all crop regimes (pure or intercrops), i.e. it is economically beneficial to apply fertilizer whether maize is grown in pure stand or intercropped with forages.

Table A5. Partial budget analysis of fertilizer application to maize intercropped with forage crops, Kaimosi Cluster, short rains season, 1983

	With fertilizer
	Incrementala	Incrementala cost (Ksh/ha)	Marginal net benefit (+) cost (-)
Maize-pure stand	7,173	238	+6,935
			(29.2)b
Maize-Sudan grass	13,096	238	+12,858
			(54.1)
Maize-Sesbania	6,137	2,365	+3,772
			(1.6)
Maize-pigeon pea	3,247	238	+3,009
			(12.7)
Mean-benefit or cost	7,413	769	+6,644
			(8.6)

^a. Incremental benefit (gain) or cost (loss) as compared to the same crop intercrop without fertilizer application.

^b. Figures in parentheses are benefit: cost ratios (BCR) computed as a ratio of marginal net benefit (+) or cost (-) to incremental cost. BCR is an absolute marginal rate of return on incremental cost. When multiplied by 100 it yields a percentage return.

Conclusions

It should be noted that the above results are based upon biological data from one season only, namely short rains 1983. Nevertheless, several conclusions may be drawn from the results. First, intercropping maize with forage crops with or without fertilizer application has no economic advantage over pure-stand maize at Maseno Station, and in Masumbi Cluster without fertilizer application. Second, intrecropping maize with forage crops yields greater economic returns than pure-stand maize, with or without fertilizer application in Kaimosi Cluster, and with fertilizer application in Masumbi Cluster except for the maize-pigeon pea intercrop. Third, for Kaimosi Cluster, maize intercropped with leguminous forages yields higher economic returns than maize intercropped with Sudan grass when fertilizer is not applied. In this case, the maize-pigeon pea and maize-Sesbania intercrops, in that order, are economically the most promising intercrops for Kaimosi Cluster. Fourth, for Kaimosi cluster, maize-Sudan grass intercrop generates greater economic returns than maize-legume intercrop when fertilizer is applied. In this case, maize-Sudan grass and maize-pigeon pea intercrops, in that order, are economically the most promising intercrops. Fifth, for Masumbi Cluster, maize-Sesbania followed by maize-Sudan grass are the most promising intercrops only when fertilizer is applied. When fertilizer is not applied, pure-stand maize is economically superior to the maize-forage intercrops. Sixth, fertilizer application was economically more profitable than non-fertilizer application at all sites for both pure-stand maize and maize intercrops. Seventh, and lastly, while intercropping maize with forage crops yields greater economic returns than pure-stand maize in some areas, it may lead to economic loss in other areas depending upon soil fertility and climatic conditions of the areas in question.

Table A6. Partial budget analysis of fertilizer application to maize intercropped with forage crops, Masumbi Cluster, short rains season, 1983

	With Fertilizer
	Incrementala benefit	Incrementala cost (ksh/ha)	Marginal net benefit (+) cost (-)
Maize-pure stand	1,971	238	+1,733
			(7.3)b
Maize-Sudan grass	4,130	238	+3,892
			(16.4)
Maize-Sesbania	3,523	238	+3,285
			(13.8)
Maize-pigeon pea	2,766	238	+2,528
			(10.6)
Mean benefit or cost	3,097	238	+2,859
			(12.0)

^a. Incremental benefit (gain) or cost (loss) as compared to the same intercrop without fertilizer application.

^b. Figures in parentheses are benefit: cost ratios (BCR) computed as a ratio of marginal net benefit (+) or cost (-) to incremental cost. BCR is an absolute marginal rate of return on incremental cost. When multiplied by 100 it yields a percentage return.

References

Mukhebi, A.W. and Onim, J.F.M. (1985). Economics of intercropping forage crops with maize in Kaimosi Cluster, Western Kenya. Proceedings of the Fourth Small Ruminant CRSP Kenya Workshop, Kenya, March 11 and 12, 1985.

Onim, J.F.M., Hart, R., Otieno, K. and Fitzhugh, H.A. (1984). Potential of intercropping forages with maize in Western Kenya. Proceedings of the Third Small Ruminant CRSP Kenya Workshop, 5-6 March, 1984, Kabete, Kenya.

Ruvuna, F., and Blackburn, H. (1984). Data from the Kenya dual purpose goat model simulations, SR-CRSP Kenya Systems Analysis Project, Kabete, Kenya (unpublished).