Effectiveness of Selected Soil Conservation Practices on Soil Erosion Control and Crop Yields in the Usambara Mountains, Tanzania

S Mwango,J Poesen,I Massawe,P Mtakwa,J Deckers,D Kimaro,B Msanya,J Samwel

doi:10.9734/jaeri/2015/13636

S Mwango, J Poesen + Show 6 more

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https://doi.org/10.9734/jaeri/2015/13636

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Abstract

Indigenous soil conservation measures such as miraba have been widely used in Usambara Mountains for controlling soil erosion but with little success. On-farm runoff experiments were set from 2011–2014 on Acrisols in Majulai and Migambo villages with contrasting agro-ecological Original Research Article Mwango et al.; JAERI, 2(2): 129-144, 2015; Article no.JAERI.2015.014 130 conditions in the Usambara Mountains, Tanzania. The aim was to investigate the effectiveness of miraba and miraba with various mulching materials in reducing runoff, soil and nutrient losses and improving productivity of maize (Zea mays) and beans (Phaseolus vulgaris). Results show that mean annual runoff coefficients (mm mm) ranged from 0.72 for cropland with no soil conservation measure (control) to 0.15 for cropland with miraba and Tithonia (Tithonia diversifolia) mulching in Majulai village and respectively from 0.68 to 0.13 in Migambo village. Soil loss was significantly (P = .05) higher under control than under miraba with either Tughutu (Vernonia myriantha) or Tithonia mulching e. g. 184 vs. 20 in Majulai and 124 vs. 8 Mg ha -1 year -1 in Migambo village in 2012. The Pfactors were significantly (P = .05) higher under miraba sole than under miraba with mulching in Majulai village (0.18 vs. 0.11) and in Migambo village (0.10 vs. 0.05).The annual nutrient losses in kg hayr were significantly (P = .05) higher under control than under miraba with mulching 367 vs. 37 total N, 0.8 vs. 0.1 P and 14 vs. 4 K for Majulai village; 474 vs. 26 total N, 0.7 vs. 0.1 P and 20 vs. 1.2 K for Migambo village in 2012. Maize and bean yields were significantly (P = .05) higher under miraba with Tughutu mulching than under control (e.g. 2.0 vs. 0.7 Mg ha for maize in Majulai in 2012). Thus miraba with Tughutu mulching is more effective in improving crop yields than miraba with Tithonia and miraba sole.

Highlights

Soil erosion has been reported as a serious problem facing agricultural production all over the world [1,2,3,4,5]
To overcome the problem of soil deterioration, the Usambara farmers have developed local soil and water conservation (SWC) measures such as miraba,micro-ridges and stone bunds as an integral part of their farming systems [7,9,10]
Similar observations were reported by Kabanza et al [32], where soil losses in Makonde plateau were much higher than in in land plains and rainfall depth was spotted as the main contributing factor

Summary

Introduction

Soil erosion has been reported as a serious problem facing agricultural production all over the world [1,2,3,4,5]. To overcome the problem of soil deterioration, the Usambara farmers have developed local soil and water conservation (SWC) measures such as miraba (rectangular grass bound strips that do not necessarily follow contour lines [9]),micro-ridges and stone bunds as an integral part of their farming systems [7,9,10]. Miraba as a SWC measure is traditionally characterized by a wide spacing of grass strips across the slope and usually the spacing depends on the size of farm plots. For decades these SWC technologies were never a subject of scientific writing to allow improvements be made to effectively address problems of soil degradation and low crop productivity [10]. Farmers have not been able to adjust these indigenous SWC techniques to rapidly changing farming systems and increasing intensity of land use [11,10]

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