Spatial variation in biodiversity, soil degradation and productivity in agricultural landscapes in the highlands of Tigray, northern Ethiopia

Hadgu, Kiros Meles; Rossing, W.A.H.; Kooistra, L.; Bruggen, A.H.C. van

doi:10.1007/s12571-008-0008-5

Cited by 34 publications

(26 citation statements)

References 32 publications

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“…Additionally, CDA was used to confirm the significance of the explanatory variables that discriminate between the three soil degradation classes. In this study, the threshold (T ) for the selection of variables correlating significantly with the canonical discriminant functions was taken as T = 0.2/ √ (eigenvalue) as suggested by Hadgu et al (2009). Scoring and indexing were performed using Microsoft Excel 2013.…”

Section: Statistical Analyses and Index Developmentmentioning

confidence: 99%

“…It is widely acknowledged that agricultural practices or land use changes in agricultural regions alter key soil properties such as SOM, total nitrogen (TN), cation exchange capacity (CEC), exchangeable cations, water-holding capacity (WHC), bulk density (BD), and total porosity (TP; Lemenih et al, 2005;Awiti et al, 2008;Trabaquini et al, 2015;Dawoe et al, 2010Dawoe et al, , 2014Ameyan and Ogidiolu, 1989;Hadgu et al, 2009;Thomaz and Luiz, 2012;Zhao et al, 2014;Tesfahunegn, 2014). Although many of these soil properties are regularly used as indicators of soil degradation (Trabaquini et al, 2015), the use of single soil characteristics often provides an incomplete representation of soil degradation (De la Rosa, 2005;Puglisi et al, 2005Puglisi et al, , 2006Sione et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Development of a composite soil degradation assessment index for cocoa agroecosystems in southwestern Nigeria

2017

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Abstract. Cocoa agroecosystems are a major land-use type in the tropical rainforest belt of West Africa, reportedly associated with several ecological changes, including soil degradation. This study aims to develop a composite soil degradation assessment index (CSDI) for determining the degradation level of cocoa soils under smallholder agroecosystems of southwestern Nigeria. Plots where natural forests have been converted to cocoa agroecosystems of ages 1-10, 11-40, and 41-80 years, respectively representing young cocoa plantations (YCPs), mature cocoa plantations (MCPs), and senescent cocoa plantations (SCPs), were identified to represent the biological cycle of the cocoa tree. Soil samples were collected at a depth of 0 to 20 cm in each plot and analysed in terms of their physical, chemical, and biological properties. Factor analysis of soil data revealed four major interacting soil degradation processes: decline in soil nutrients, loss of soil organic matter, increase in soil acidity, and the breakdown of soil textural characteristics over time. These processes were represented by eight soil properties (extractable zinc, silt, soil organic matter (SOM), cation exchange capacity (CEC), available phosphorus, total porosity, pH, and clay content). These soil properties were subjected to forward stepwise discriminant analysis (STEPDA), and the result showed that four soil properties (extractable zinc, cation exchange capacity, SOM, and clay content) are the most useful in separating the studied soils into YCP, MCP, and SCP. In this way, we have sufficiently eliminated redundancy in the final selection of soil degradation indicators. Based on these four soil parameters, a CSDI was developed and used to classify selected cocoa soils into three different classes of degradation. The results revealed that 65 % of the selected cocoa farms are moderately degraded, while 18 % have a high degradation status. The numerical value of the CSDI as an objective index of soil degradation under cocoa agroecosystems was statistically validated. The results of this study reveal that soil management should promote activities that help to increase organic matter and reduce Zn deficiency over the cocoa growth cycle. Finally, the newly developed CSDI can provide an early warning of soil degradation processes and help farmers and extension officers to implement rehabilitation practices on degraded cocoa soils.

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Section: Statistical Analyses and Index Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development of a composite soil degradation assessment index for cocoa agroecosystems in southwestern Nigeria

2017

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“…1) from four sampling strata based on intensity of land use, natural vegetation and altitude derived from a Digital Elevation Model (DEM), aerial photographs and topographic maps. In each substratum, sample farms were selected randomly (Hadgu et al 2009). Every farm, consisting of four fields on average which were mostly adjacent to one another, was surveyed in 2005 including interviews with farmers, and two to three transects were made across farmers' fields.…”

Section: Farm Surveymentioning

confidence: 99%

“…Every farm, consisting of four fields on average which were mostly adjacent to one another, was surveyed in 2005 including interviews with farmers, and two to three transects were made across farmers' fields. For every farm, field locations were recorded using a hand held GPS and crops, farmer's estimates of their yield, tree and shrub species and general management in and around the sampled farms were recorded (Hadgu et al 2009). …”

Section: Farm Surveymentioning

confidence: 99%

Assessing the effect of Faidherbia albida based land use systems on barley yield at field and regional scale in the highlands of Tigray, Northern Ethiopia

Hadgu

Kooistra

Rossing³

et al. 2009

Food Sec.

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Implications of changes in traditional Faidherbia albida based land use systems on productivity were investigated in Tigray, northern Ethiopia. The relation between F. albida based-land use systems and crop productivity was explored in 77 fields and 81 farms at field and regional scales, respectively. Barley yield and soil fertility increased when field locations were closer to a F. albida trunk in the F. albida alone (AA) and F. albida + livestock (AL) land use systems. However, the F. albida + Eucalyptus camaldulensis (AE) land use system showed a decreasing trend in barley yield and soil fertility as distance from a F. albida trunk decreased. At regional scales, higher F. albida tree density per farm and sparsely cultivated land use types were associated with increased potential ecosystem services (barley yield). This study suggests that local biodiversity components (e.g. F. albida trees) can increase crop yield and soil fertility significantly when grown within and around farm lands. This study contributes to the knowledge on agricultural productivity enhancement by developing an approach to scaling up from farm to regional level.

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“…Conversely, there is increasing concern over the land quality as farmers over the time have experienced declining crop production [15]. Agricultural sustainability and soil fertility on smallholder farms are determined by land use and management practices [16].…”

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confidence: 99%

Agrobiodiversity conservation enhances food security in subsistence-based farming systems of Eastern Kenya

et al. 2016

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Background: Globally, there is great concern about expanding agricultural activities due to their impact in the conservation of agrobiodiversity. African continent is known for its richness in biodiversity. In Kenya, there is a continuous unabated expansion of agriculture into natural habitats due to demographic and economic pressures posing a significant threat to biodiversity. Therefore, there is a need to study biodiversity loss and its regain through practices in agricultural landscapes. In this study, we assessed the status of agrobiodiversity and its contribution to food security in four agroecological zones of Eastern Kenya. Sixty households were sampled from two selected agroecological zones (upper and lower midland zones) in Embu and Tharaka-Nithi counties. Structured questionnaires and checklists were used to collect the data.Results: Thirty-nine crop species were identified dominated by vegetables, fruits, legumes and cereals with relative densities of 28.8, 20.5, 18.3 and 8.3 %, respectively. Embu Lower Midland and Tharaka-Nithi Lower Midland zones had relatively higher crop species richness of 243 and 240, respectively, and Shannon-Wiener diversity indices (H′) of 3.403 and 3.377, respectively, compared with Embu Upper Midland and Tharaka-Nithi Upper Midland zones with species richness of 229 and 207, respectively, and H′ of 3.298 and 3.204, respectively. Conclusions:Households from lower midland zones with high crop diversity and richness were more food secure compared with those from the Upper Midland zones with low crop diversity and richness. These findings suggest that farm production systems with high agrobiodiversity contributed more toward food security among smallholder farmers in the selected sites.

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Spatial variation in biodiversity, soil degradation and productivity in agricultural landscapes in the highlands of Tigray, northern Ethiopia

Abstract: Biodiversity, GIS, Productivity, Soil degradation, Spatial scales,

Cited by 34 publications

References 32 publications

Development of a composite soil degradation assessment index for cocoa agroecosystems in southwestern Nigeria

Development of a composite soil degradation assessment index for cocoa agroecosystems in southwestern Nigeria

Assessing the effect of Faidherbia albida based land use systems on barley yield at field and regional scale in the highlands of Tigray, Northern Ethiopia

Agrobiodiversity conservation enhances food security in subsistence-based farming systems of Eastern Kenya

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