Browsing by Author "Deckers, Jozef"
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Item Effectiveness of mulching under miraba in controlling soil erosion, fertility restoration and crop yield in the Usambara mountains, Tanzania(Wiley Online Library, 2014-09-23) Mwango, Sibaway Bakari; Msanya, B. M.; Mtakwa, Peter W.; Kimaro, D. N.; Deckers, Jozef; Poesen, JeanSoil erosion is a major threat to food security in rural areas of Africa. Field experiments were conducted from 2011 to 2014 in Majulai and Migambo villages with contrasting climatic conditions in Usambara Mountains, Tanzania. The aim was to investigate the effectiveness of mulching in reducing soil erosion and restoring soil fertility for productivity of maize (Zea mays) and beans (Phaseolus vulgaris) under miraba, a unique indigenous soil conservation measure in the area. Soil loss was significantly higher (p < 0·05) under miraba sole than under miraba with mulching, for example, 35 versus 20 and 13 versus 8 Mg ha 1 y 1 for Majulai and Migambo villages, respectively, in 2012. Soil fertility status was significantly higher (p < 0·05) under miraba with Tughutu mulching than under miraba sole, for example, 0·35 versus 0·25% total N, 37 versus 22 mg kg 1 P and 0·6 versus 0·2 cmol(+) kg 1 K for the Majulai village; and 0·46 versus 0·38 total N, 17·2 versus 10·2 mg kg 1 P and 0·50 versus 0·2 cmol(+) kg 1 K for the Migambo village. Maize and bean yields (Mg ha 1 ) were significantly higher (p < 0·05) under miraba with Tughutu mulching than under miraba sole, 2·0 versus 1·3 for maize and 0·9 versus 0·8 for beans in Majulai; and 3·8 versus 2·6 for maize and 1·0 versus 0·8 for beans in the Migambo village in 2012. This implies that Tughutu mulching is more effective in improving crop yield than Tithonia, although both could potentially protect the arable land from degradation caused by water erosion under miraba. Copyright © 2014 John Wiley & Sons, Ltd.Item Effectiveness of selected soil conservation practices on soil erosion control and crop yields in the Usambara Mountains, Tanzania(SCIENCEDOMAIN international, 2014-12-16) Mwango, Sibaway Bakari; Msanya, B. M.; Kimaro, D. N.; Mtakwa, Peter W.; Deckers, Jozef; Poesen, Jean; Massawe, I.; Samwel, J.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 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 -1 ) 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 -1 -1 mulching e. g. 184 vs. 20 in Majulai and 124 vs. 8 Mg ha year in Migambo village in 2012. The P- factors 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 ha -1 yr -1 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 -1 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.Item The influence of selected soil conservation practices on soil properties and crop yields in the Usambara Mountains, Tanzania(SCIENCEDOMAIN international, 2014-12-08) Mwango, Sibaway Bakari; Msanya, B. M.; Mtakwa, Peter W.; Kimaro, D. N.; Deckers, Jozef; Poesen, J.; Nzunda, I.; Ringo, S.The Usambara Mountains in Tanzania are severely affected by soil erosion which has led to deterioration of soil properties and reduced crop productivity. Indigenous soil erosion control measures such as miraba which are widely practised in the area have yielded little success. Field plot experiments were laid down in Majulai and Migambo villages from 2011 – 2014 on typical soils of the area (Acrisols). The aim was to single out soil properties developed under the studied soil conservation practices and their impact on crop productivity with reference to maize (Zea mays) and 2+ 2+ + beans (Phaseolus vulgaris). Results showed that total N, OC, available P, Ca , Mg , K and Ph were powerful (P = .05) attributes that discriminated conservation measures. Magnitudes of the discriminating attributes followed the trend: miraba with Tughutu (Vernonia myriantha) mulching >miraba with Tithonia (Tithonia diversifolia) mulching > miraba sole > cropl and with no ‘Soil and Water Conservation’ (SWC) measures (control). Contents ofmicro-nutrients did not differ significantly with SWC measures except for Zn which was significantly (P = .05) lowin the control. Bulk density and available moisture content (AMC) were also strong discriminators of conservation measures. Maize and bean grain yields differed significantly (P = .05)with the trend: miraba with Tughutu > miraba with Tithonia > miraba sole > control in both villages. Crop yields under miraba were a 2 2+ + 2 function of AMC and pH (R = 0.71); AMC, available P, Ca and K (R = 0.89) under miraba with 2+ + 2 Tithonia mulching; AMC, available P, Ca and K (R = 0.90) under miraba with Tughutu mulching. These findings imply that miraba with Tughutu mulching had greater potential in improving soil properties and crop yields than miraba with Tithonia mulching and miraba sole.Item Plague and the human flea, Tanzania(Emerging Infectious Diseases, 2007) Laudson, Anne; Leirs, Herwig; Makundi, Rhodes H.; Dongen, Stefan Van; Davis, Stephen; Neerinckx, Simon; Deckers, Jozef; Libois, RolandDomestic fl eas were collected in 12 villages in the western Usambara Mountains in Tanzania. Of these, 7 are considered villages with high plague frequency, where hu- man plague was recorded during at least 6 of the 17 plague seasons between 1986 and 2004. In the remaining 5 vil- lages with low plague frequency, plague was either rare or unrecorded. Pulex irritans, known as the human fl ea, was the predominant fl ea species (72.4%) in houses. The den- sity of P. irritans, but not of other domestic fl eas, was signifi - cantly higher in villages with a higher plague frequency or incidence. Moreover, the P. irritans index was strongly posi- tively correlated with plague frequency and with the logarith- mically transformed plague incidence. These observations suggest that in Lushoto District human fl eas may play a role in plague epidemiology. These fi ndings are of immediate public health relevance because they provide an indicator that can be surveyed to assess the risk for plague.Item Rodent abundance, stone bund density and its effects on crop damage in the Tigray highlands, Ethiopia(Sokoine University of Agriculture, Tanzania., 2014) Meheretu, Yonas; Sluydtsc, Vincent; Welegerimaa, Kiros; Bauerd, Hans; Yirgaa, Gidey; Mulungue, Loth; Hailef, Mitiku; Nysseng, Jan; Deckers, Jozef; Makundie, Rhodes; Leirsb, HerwigIn areas of subsistence agriculture, a variety of soil conservation methods have been implemented in the last few decades to improve crop yields, however these can have unintended consequences such as providing habitat for rodent pests. We studied rodent population dynamics and estimated crop damage in high and low stone bund density fields for four cropping seasons in Tigray highlands, northern Ethiopia. Stone bunds are physical structures for soil and water conservation, and potentially habitat for rodents. We used a general model to relate the proportion of crop damage to rodent abundance, stone bund density and crop stages. Generally, rodent abundance remained relatively low during the study period, except during the fourth quarter of the 2010 cropping season. We found a positive correlation between rodent abundance and crop damage, and significant variation in rodent abundance and crop damage between high and low stone bund density fields. Furthermore, crop damage also varied significantly between crop stages. We concluded that Mastomys awashensis (Lavrenchenko, Likhnova and Baskevich 1998) and Arvicanthis dembeensis (Ruppel 1842) were the two most important crop pests in Tigray highlands causing significant damage. Fields with high stone bund density (~10m average distance apart) harbor more rodents and endure a significantly higher proportion of crop damage compared to fields with lower stone bund density (~15m average distance 4 apart). The fact that rodent abundances peaked during the reproductive stage of the crop and around harvest implies the need for management intervention before these crop stages are attained.Item Root properties of plants used for soil erosion control in the Usambara Mountains, Tanzania(SCIENCEDOMAIN international, 2014-08-25) Mwango, Sibaway Bakari; Msanya, B. M.; Mtakwa, Peter W.; Kimaro, D. N.; Deckers, Jozef; Poesen, Jean; Massawe, V.; Bethuel, I.Plant roots may have a strong erosion-reducing effect. However, little is known about root characteristics of tropical plants used for erosion control. A study was thus conducted in the Western Usambara Mountains, Tanzania to investigate rooting characteristics of Guatemala grass (Tripsacum andersonii), Napier grass (Pennisetum purpureum) and Tithonia shrub (Tithonia diversifolia), also referred to as wild sunflower, and to evaluate their potential for erosion control. For each plant species, mean root diameter (D), root density (RD), root length density (RLD) and root area ratio (RAR) were assessed for six plants in each species and relative soil detachment rate (RSD) predicted. Mean RD values in the 0 - 0.4 m soil depth for Majulai village and Migambo village respectively 3 3 were 50.9 and 58.6 kg/m for Guatemala grass, 30.4 and 31.3 kg/m for Napier grass and 3 3 22.1 and 23.0 kg/m for Tithonia shrub. RLD values were 35.9 and 45.0 km/m for 3 3 Guatemala grass, 31.3 and 150.0 km/m for Napier grass and 10.5 and 6.4 km/m for -12 -14 Tithonia shrub. Predicted RSD values were 4.43*10 and 1.20*10 for Guatemala -5 -4 -3 -4 grass, 6.10*10 and 2.74*10 for Napier grass and 4.43*10 and 2.24*10 for Tithonia shrub in the 0 - 0.4 m soil depth. The results indicate that Guatemala grass has a higher potential to reduce soil erosion rates by concentrated flow as compared to Napier grass or Tithonia shrub in the 0 - 0.4 m soil depth. These findings have implications on the selection and use of appropriate plants for soil erosion control.