Fodder production potential for zero-grazing systems in the bimodal West Usambara Mountains of Tanzania

Reinhard Pfeiffer
TIRDEP-SECAP-LUSHOTO, P.O. Box 72, Tanzania

Introduction
Materials and methods
Results and discussion
Conclusion
References

Abstract

Overpopulation and increasing land pressure are resulting more and more in the deterioration of the agricultural potential in the hitherto highly productive agricultural areas of the West Usambara Mountains. To counteract this sad development, multiple measures have been applied. This paper presents the production potential data of fodders planted along contourlines and gives an outlook on environmental effects of such fodder lines in zero-grazed systems as part of an integrated approach to resolving the land pressure problems.

Introduction

The Western Usambara highlands are among the highly populated areas in Tanzania. Lundgren (1278) estimated the human population density at 180 people/km². Backeus (1982) predicted that by the year 1990 the population will have risen to 300 people/km². The high population has considerably increased pressure on land for agriculture. In certain areas people keep large herds of cattle which graze freely on the slopes as the communal grazing areas at the valley bottoms are used extensively for horticultural crops.

Free grazing has caused considerable surface runoff and soil erosion resulting in site deterioration with a consequent reduction in crop production. Lushoto district has tried to tackle the problem by implementing a major project on agroforestry throughout the Western Usambara highlands since 1980. The Soil Erosion Control Agroforestry Project (SECAP) applies an integrated extension approach which takes into account forestry, plant production and livestock measures using the macro-contourline approach. This approach integrates livestock production through "cutting and carrying" of fodder, zero-grazing and stall-feeding of livestock. It also integrates plant production through farmyard manure application due to stall-feeding operations, and it has a forestry component for fuel, construction and soil erosion control measures.

Materials and methods

In order to simulate the many site conditions in the West Usambara Mountains, four on-station trial fields covering various ecoclimatic conditions have been established since November 1985. Screening, elimination and management trials have been carried out using the randomised block designs. The macro-contourline is essentially an erosion control barrier consisting of four components, namely: a fodder bushline (preferably a legume), creeping legume line, fodder grass line and an agroforestry-tree line. This has been prepared and planted accordingly. The fodders are subjected to intensive cutting regimes. All the fodder components are cut half a year later after planting as this is what an average farmer would normally do. Thereafter the fodders are cut intermittently throughout the year once there is sufficient amount of regrowth on them.

Detailed ecological and meteorological measurements have been carried out in between the macro-contourlines. These have included:

	Z:	A zero treatment in which no soil control measure has been effected.
	MI:	Sunflower planted along the contourline.
	T:	Grevillea robusta line planted at 2m spacing along the countour.
	GT:	Guatemala grass with Grevillea robusta planted.
	I:	Maize planted as a sole crop.
	II:	Groundnuts planted as a sole crop.
	III:	Maize/groundnut mix stand planted.
	IV:	Maize/oil radish mix stand planted.

Erosion (-) and accumulation (+) of soil was measured in mm at soil erosion measuring stakes in between two contourlines.

Results and discussion

The data in the accompanying pages suggest that the macro-contourlines produced considerable amounts of biomass of both grass and legume species. In Table 1 for instance, the high productivity potential of the macro-contourlines has been demonstrated over sole stands. The average dry-matter (DM) yields are nearly three times higher on macro-contourlines than on sole grasslands in Kenya. The macro-contourlines produced considerably more fodder in subsequent years than the first (Table 2). The grass yields were 22% whereas the yields of fodder bushes were 86% more in the second year. This was most probably due to better established root systems and more intensive cutting regimes after the first year.

Because of the diversity in topography and ecoclimatic conditions the most feasible fodder combinations for zero grazing systems in the West Usambara Mountains are presented in Table 3. The macro-contourlines appear to serve as basic fodder sources for zero grazing systems in the West Usambara Mountains. Due to stall-feeding of dairy cows with macro-contourline fodders the milk yields in the West Usambara Mountains have increased already from 3 liters/day for local farmers to 7 liters/day for SECAP farmers.

Table 1. Fodder DM yields (t/ha) of various grasses.

Species/location	Sole grasses in Kenya		Macro-contourlines in Tanzania
	Kisii	Kakamega	Lushoto
Bana grass	18.2	20.0	51.1
Guatemala grass	3.1	3.1	25.5

Table 2. Fodder DM yields (t/ha) of different fodder types.

Fodder type/year	1st year	Mean of 2nd & 3rd year
Fodder grasses	2.10	3.30
Fodder bushes	1.75	3.25

Table 3. Feasible fodder combinations adapted to ecoclimatic zones/sites.

Site/ecoclimatic	Fodder combinations
Mbwei in warm/dry	Bana grass Desmodium intortum, Calliandra callothyrsus, Leucaena diversifolia, Neonotonia wightii, Stylosanthes guianensis.
Ubiri and Silvici in humid/warm	Napier grass Neonotonia wightii, Desmodium intortum, Desmodium uncinatum, Cajanus cajan, Leucaena leucocephala.
Nywelo in dry/cold	Tripsacum laxum, Desmodium intortum, Sesbania aculeata.

The macro-contourlines also appear to have good environmental attributes based on detailed ecological and meteorological measurements carried out in cropped fields between macro-contourlines. As shown in Table 4, most of the soil was transported from treatments MI, T and GT; these were treatments that offered small erosion control because of poor ground cover. The zero treatment which was densely covered by natural fallow weeds had little soil movement.

Table 4. Soil loss as a result of macro-contourline plantings on a slope inclination of 21° between contourlines.

Decreasing soil movements
MI		G	III	II	IV	I	Z
2.86(+)	2.44(+)	1.60(+)	1.42(+)	1.41(+)	1.17(+)	0.62(+)	0.26(-)

Conclusion

The contourline fodder production studies in the West Usambara Mountains have indicated potential for integrated approach to livestock production, crop production, soil erosion control and agroforestry. It has provided considerable amount of forage for zero-grazing systems by more than doubling the milk production capacity of the small-scale dairy farmers in the area. The contourline fodder and tree plantation also has helped to consolidate the erosion control role of these structures.

References

Backeus, I. 1982. Report on study tour to the indigenous forests of the West Usambara Mountains. Vaxtbiologiska Institutionen, Uppsala.

Lundgren, B. 1978. Soil condition and nutrient cycling under natural plantation forests in Tanzania Highlands. Reports in Forest Ecology and Forest Soils No. 31, Uppsala.