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Conservation agriculture (CA) systems represent a set of three soil management principles: minimarbance, permanent soil cover and crop rotations - whereas the CA-based systems in this study add the bed and furrow tillage techniques as integral elements of CA. Studies on the effects of long-term CA-based systems on soil health and crop productivity are rare globally, particularly in Ethiopia. This study aimed at investigating the long-term (2005-2013) influence of CA-based systems on soil health and crop productivity in northern Ethiopia. The treatments we used include two types of CA-based systems (permanent raised bed PRB and contour furrowing CF) and conventional tillage (CT) arranged in a randomized complete block design. Soil samples were collected at 0-10 cm soil depth to assess soil health. Piecewise structural equation modeling (PSEM) was used to analyze linkages between management practices, soil health and crop productivity. Arbuscular mycorrhizal fungi spore abundance and root colonization was higher in PRB followed by CF compared to CT (p < 0.05). Significantly different soil N of 1.4 and 0.9 g kg(-1) and available P of 6.7 and 4.1 ppm were recorded for PRB and CT, respectively. Higher straw and grain yield of 12 and 4.3, 10 and 3.5, 8 and 2.8 t ha(-1) were recorded for PRB, CF and CT, respectively. Outputs of the PSEM highlighted two pathways in which CA-based systems contributed to improved productivity: (a) via higher density of bacteria and improved hydraulic conductivity, and (b) via higher density of fungi and increase soil organic carbon content in the topsoil. The study concludes that CA-based systems have the potential to improve crop productivity through improved soil health.

Conservation agriculture (CA) is believed to contribute to sustainable crop production. However, there are contrasting reports on its short-term effects on soil properties. An experiment was conduc...

This study investigated, soil salinity and moisture content under the exotic Tamarix in the Olifants River, South Africa, where they predominantly occur. Soil electro-conductivity (EC) was mapped u...

Significant research has been conducted on the effects of soil salinity issue on agricultural productivity. However, limited consideration has been given to its critical effects on soil biogeochemistry (e.g., soil microorganisms, soil organic carbon and greenhouse gas (GHG) emissions), land desertification, and biodiversity loss. This article is based on synthesis of information in 238 articles published between 1989 and 2022 on these effects of soil salinity. Principal findings are as follows: (1) salinity affects microbial community composition and soil enzyme activities due to changes in osmotic pressure and ion effects; (2) soil salinity reduces soil organic carbon (SOC) content and alters GHG emissions, which is a serious issue under intensifying agriculture and global warming scenarios; (3) soil salinity can reduce crop yield up to 58 %; (4) soil salinity, even at low levels, can cause profound alteration in soil biodiversity; (5) due to severe soil salinity, some soils are reaching critical desertification status; (6) innovate mitigation strategies of soil salinity need to be approached in a way that should support the United Nations Sustainable Development Goals (UN-SDGs). Knowledge gaps still exist mainly in the effects of salinity especially, responses of GHG emissions and biodiversity. Previous experiences quantifying soil salinity effects remained small-scale, and inappropriate research methods were sometimes applied for investigating soil salinity effects. Therefore, further studies are urgently required to improve our understanding on the effects of salinity, address salinity effects in larger-scale, and develop innovative research methods.

The exotic Tamarix species, T. ramosissima and T. chinensis, were introduced into South Africa in the early 1900s reportedly either for ornamental or soil wind erosion control purposes in the mines. They are, however, currently invading several riparian ecosystems in the country and threatening its biodiversity and proper functioning. The objective of this study was to assess the effects of the exotic Tamarix species on the soil physicochemical properties vis-à-vis the indigenous Tamarix at the Leeu River in the Western Cape Province, of South Africa where they are purvasive. Three transects were laid from the riverbank towards the outer land, where the exotic followed by the native Tamarix species predominantly occurred. Soil was sampled from three points per transect and three soil depths (0–10, 10–20 and 20–30 cm) per point in winter and summer to determine selected soil physicochemical properties. The results showed that total nitrogen (TN), total carbon (TC), Sodium (Na), Potassium (K) and Magnesium (Mg) concentrations under the native and exotic Tamarix species were significantly higher than those in the open land without Tamarix species. The salinity under the native and exotic Tamarix species was greater (P −1 and 4.73 mS cm−1, respectively. Soil electrical conductivity (EC) was higher (P Tamarix species (5.05 mS cm−1) followed by the native species (4.73 mS cm−1) and it was the lowest in the control (0.16 mS cm−1) at 0–10 cm soil depth. Similarly, sodium and sodium absorption ratios (SAR) under the native and exotic Tamarix species were significantly greater than those in the control. The highest levels (P Tamarix species (1.17%), followed by the native Tamarix (1.07%) with the control recording the lowest (0.53%). There were no significant differences (P Tamarix species. The soil bulk density was lower under the exotic Tamarix followed by native Tamarix species than the control soils. The soil volumetric water content was higher under the exotic Tamarix species compared to the control. This study concludes that the invasion of the exotic and native Tamarix species altered the soil properties underneath and created conducive soil conditions for their predominance.

The distribution and relative importance of lepidopteran stem borers attacking maize and sorghum were investigated in farmers’ fields during the main cropping seasons of 2015 and 2016 across three ...

This study investigated, soil salinity and moisture content under the exotic Tamarix in the Olifants River, South Africa, where they predominantly occur. Soil electro-conductivity (EC) was mapped using the electromagnetic induction (EMI) device (EM38 sensor), in three transects laid along the river from as close to the water source outward towards the bank of the River at 50 m apart. This was supported by three soil EC and moisture measurements from each of the three transects at a soil depth of 0-100 cm at intervals of 10 cm using soil EC meter and Amplitude Domain Reflectometry (ADR) sensor, respectively. The highest salt concertation (3,000 mS/m or 19,500 ppm) was found at a depth of 30-40 cm under the dense Tamarix species. The highest soil moisture (20-40%) was also found at the same depth under the Tamarix, suggesting a hydraulic lift of water to the top 30-40 cm, where the Tamarix fine roots for water absorption occur. It also confirms that the distance from water point and Tamarix plant density affect salt leaching depth and amount of litter decomposition, respectively, which is the main source of salt deposition in soil.

SUMMARYA major problem faced by small-scale farmers in northern Ethiopia is reduced crop yield due to increasing soil degradation resulting from repeated tillage and inadequate agronomic management practices. These practices have left soils and rainfed crops susceptible to hazardous climatic events such as droughts. Sustainable farm practices such as minimum tillage and surface residue retention have been shown to improve soil health and crop productivity. The objectives of this field study were thus to evaluate the impacts of conservation agriculture (CA) practices on crop yield and economic productivity over 6 years in the eastern Tigray region of northern Ethiopia. Using a barley–wheat rotation from 2010 to 2016, the applied treatments were (i) permanent raised beds (PRB); (2) semi-permanent raised beds (SPB) and (3) conventional tillage (CT). Average barley and wheat biomass and grain yields in PRB and SPB treatments were consistently greater than yields under CT each year. In addition, the highest marginal rate of return was obtained in PRB and SPB compared to CT in all years (2010–2016). These results suggest that the CA practices of PRB and SPB can improve crop yield and profit compared to CT practices in the Tigray region.

Poor land use management and practice inhibit the growth and establishment of tree seedlings in dryland areas. We assessed arbuscular mycorrhizal fungi (AM) status of Faidherbia albida (Del.) A. Chev. trees grown on different land uses. We quantified the growth and nutrient uptake of F. albida seedlings inoculated with AM from different sources. These efforts were based on soil and fine root samples from the rhizosphere soils of F. albida trees. AM root colonization was determined using the gridline intersect method. Spores were extracted by the wet sieving and decanting method and identified to genus level. The seedling experiment had a completely randomized one-factorial design with four treatments and five replications. Faidherbida albida seedlings were grown in a greenhouse. All in situ F. albida trees were colonized by AM fungi. AM root colonization of F. albida trees was significantly higher (P

Many regions in the world are suffering from agricultural droughts and floods, two sides of the same coin. They result in shortage of available water for plant growth or accumulation of water on farm land that is normally not submerged, respectively. The incidence of droughts and floods is not only caused by extreme weather events, but also by an imbalanced partitioning of rainfall, with higher blue water flows at the expense of green water, i.e. soil moisture generated from infiltrating rain. This chapter suggests that poor partitioning of rainwater and an unbalanced water regime is associated with soil structural degradation, lack of physical structures or evapotranspiration controlling measures, among others. Appropriate soil-water management practices could be a first step in building resilience against agricultural droughts and floods. Such practices refer to the management of soil (in whatever way) with the purpose of enhancing the quantity and flow of soil water. They range from improving physical soil quality, i.e., increasing rainwater infiltration capacity and plant-available water capacity through the use of soil amendments, conservation agricultural practices and other field water conservation practices, over farming practices such as use of mulches and cover crops, to soil conservation practices, and runoff and flood water harvesting techniques. In this chapter, two examples from semi-arid zones in Kenya and Ethiopia are given that demonstrate that soil-water management practices lead to more water being conserved and thus reduce drought and flood risk, resulting in at least 40% higher maize and wheat yields when rainfall was lower than normal. On a Vertic Phaeozems in Kenya, best results were obtained when applying three conservation agriculture practices (minimal disturbance, soil cover, diversified cropping). On a Vertisol in Ethiopia, conservation agriculture-based soil-water management practices with narrow raised beds and furrows outperformed other tested practices. Though not demonstrated with data, this chapter also suggests that soil-water management practices can affect the incidence of hydrological and meteorological droughts and floods as well.

Farm productivity and food security in the coming years is undermined by intensive and repeated tillage (Chap. 26), complete crop residue removal at harvest, aftermath grazing in croplands, biomass burning, use of crop straw and animal dung for fuel, deforestation and monocropping. Recurrent food production shortages are commonly linked to periodic drought and insufficient rainfall (Photo 29.1) on the one hand and, periodical waterlogging and high runoff rates under wet conditions in clay-dominated soils (e.g. Vertisols) on the other hand (Chaps. 21, 22, and 23). Conservation agriculture (CA) can improve soil and water management and thus, food production. Despite its promise, CA has not been adopted by farmers in the highlands of Ethiopia mainly due to lack of locally adapted CA systems. CA adoption in this region is largely dependent on the provision of lasting solutions to challenges of livestock interference, lack of residues for surface mulch, lack of smallholder CA equipment, inputs and training. This chapter addresses the importance of CA-based systems to reduce land degradation and minimize the effects of drought on crop yield at Dogu’a Tembien in the highlands of Ethiopia.

Understanding the impacts of agricultural practices on carbon stocks and CO2 emission is imperative in order to recommend low emission strategies. The objective of this study was to investigate the effects of tillage, crop rotation, and residue management on soil CO2 fluxes, carbon stock, soil temperature, and moisture in the semi-arid conditions in the Eastern Cape of South Africa. The field trial was laid out as a split-split-plot design replicated three times. The main plots were tillage viz conventional tillage (CT) and no-till (NT). The sub-plots were allocated to crop rotations viz maize&ndash, fallow&ndash, maize (MFM), maize&ndash, oat&ndash, maize (MOM), and maize&ndash, vetch&ndash, maize (MVM). Crop residue management was in the sub-sub plots, viz retention (R+), removal (R&minus, ), and biochar (B). There were no significant interactions (p &gt, 0.05) with respect to the cumulative CO2 fluxes, soil moisture, and soil temperature. Crop residue retention significantly increased the soil moisture content relative to residue removal, but was not different to biochar application. Soil tilling increased the CO2 fluxes by approximately 26.3% relative to the NT. The carbon dioxide fluxes were significantly lower in R&minus, (2.04 &micro, moL m&minus, 2 s&minus, 1) relative to the R+ (2.32 &micro, 1) and B treatments (2.36 &micro, 1). The carbon dioxide fluxes were higher in the summer (October&ndash, February) months compared to the winter period (May&ndash, July), irrespective of treatment factors. No tillage had a significantly higher carbon stock at the 0-5 cm depth relative to CT. Amending the soils with biochar resulted in significantly lower total carbon stock relative to both R+ and R&minus, The results of the study show that NT can potentially reduce CO2 fluxes. In the short term, amending soils with biochar did not reduce the CO2 fluxes compared to R+, however the soil moisture increases were comparable.

Soil acidification is a serious challenge and a major cause of declining soil and crop productivity in the Eastern parts of South Africa (SA). An incubation experiment investigated effects of different maize residue biochar rates on selected soil properties and soil loss in acidic Hutton soils. Biochar amendment rates were 0%, 2.5%, 5%, 7.5%, and 10% (soil weight) laid as a completely randomized design. Soil sampling was done on a 20-day interval for 140 days to give a 5 &times, 7 factorial experiment. Rainfall simulation was conducted at 60, 100 and 140 days after incubation to quantify soil loss. Relative to the control biochar amendments significantly improved soil physicochemical properties. After 140 days, biochar increased soil pH by between 0.34 to 1.51 points, soil organic carbon (SOC) by 2.2% to 2.34%, and microbial activity (MBC) by 496 to 1615 mg kg&minus, 1 compared to control. Soil aggregation (MWD) changes varied from 0.58 mm to 0.70 mm for the duration of the trial. Soil loss significantly decreased by 27% to 70% under biochar amendment compared to control. This indicates that maize residue biochar application has the potential to improve the soil properties and reduce soil loss in the degraded acidic Hutton soil.

SUMMARYLong-term in situ soil and water conservation experiments are rare in sub-Saharan Africa, particularly in Eastern Africa. A long-term experiment was conducted (2005–2013) on a Vertisol to quantify the impacts of resource-conserving agriculture (RCA) on runoff, soil loss, soil fertility and crop productivity and economic profitability in northern Ethiopia. Two RCA practices were developed from traditional furrow tillage practices: (i) derdero+ (DER+) and terwah+ (TER+). DER+ is a furrow and permanent raised bed planting system, tilled once at planting time by refreshing the furrow and 30% of crop residue is retained. TER+ is ploughed once at planting, furrows are made at 1.5 m intervals and 30% crop residue is retained. The third treatment was a conventional tillage (CT) with a minimum of three tillage operations and complete removal of crop residues. Wheat, teff, barley and grass pea crops were grown in rotation. Runoff, and soil and nutrient loss were measured in plastic sheet-lined collector trenches. Significantly different (P < 0.05) runoff coefficients (%) and soil losses (t ha−1) averaged over 9 yrs were 14 and 3, 22 and 11 and 30 and 17 for DER+, TER+ and CT, respectively. Significant improvements in crop yield and gross margin were observed after a period of three years of cropping This study demonstrated that RCA systems in semi-arid agro-ecosystems constitute a field rainwater conservation and soil fertility improvement strategy that enhances crop productivity and economic profitability. Adoption of RCA systems (DER+ and TER+) in the study area requires further work to improve smallholder farmers’ awareness on benefits, to guarantee high standards during implementation and to design appropriate weed management strategies.

In situ water and soil conservation (WSC) practices are a promising intervention to improve rainwater management particularly in the semi-arid to dry sub-humid tropics. This study applies a fully coupled surface–subsurface process-based model (HydroGeoSphere) to simulate in detail rainwater partitioning as affected by two in situ WSC practices [terwah+ (TER+) and derdero+ (DER+)] currently under study on Vertisols in Tigray, Ethiopia and to evaluate the treatments in terms of rainwater partitioning. In the TER+ practice, contour furrows of 0·2 m wide and 0·1 m deep are created at 1·5 m intervals between permanent broad beds, whereas in DER+, permanent raised beds 0·6 m wide with furrows 0·2 m wide and 0·1 m deep are created, to minimize runoff and water logging. The model accurately reproduced measured surface runoff (e.g. in DER+: Nash–Sutcliffe model efficiency E = 0·6 for calibration and 0·7 for verification) and soil moisture content (DER+: E = 0·6 for calibration and 0·8 for verification). Runoff depth was lowest under DER+ (50 mm) followed by TER+ (67 mm) and significantly higher in conventional tillage (CT) (160 mm). Simulated transpiration, evaporation and drainage out of the root zone were all higher under DER+ and TER+ compared with CT. The effects of DER+ and TER+ practices on rainwater partitioning were more pronounced in wet years than in dry years. The model proved to be a promising and versatile tool to assess the impact of WSC practices on rainwater partitioning at the field scale. Copyright © 2014 John Wiley & Sons, Ltd.

Tree seedling establishment, survival and growth in dryland areas is greatly impacted by water, land use effects and soil nutrient availability. Arbuscular mycorrhizal fungi (AMF) can have a substantial effect on water and nutrient uptake by seedlings and are affected by nutrient application, water availability and inoculum source. In this study, we examined the effect of AMF inoculation, phosphorus application levels, soil water status, and inoculum source on the growth of Faidherbia albida seedlings. Two greenhouse experiments were conducted on F. albida seedlings: to compare (a) ±AMF inoculation, at three levels of volumetric soil water content (field capacity (FC), 60% of FC and 20% of FC), and three AMF inoculum sources (derived from cultivated land, grazing land and area exclosure); (b) ±AMF inoculation, at four levels of phosphorus application (0, 25, 50 and 100 mg kg−1) and three AMF inoculum sources. Inoculation with AMF, higher soil water and higher P application significantly increased the growth of seedlings (P

Resource-conserving agriculture (RCA) aims at improving soil quality and crop yield whilst maintaining or improving soil health by minimizing soil disturbance, retaining crop residue, using crop rotations and adding in situ soil and water conservation tillage practices ( terwah and derdero ) in crop fields. In Ethiopia, intensive mining of soil resources using repeated tillage, complete crop residue removal at harvesting, overgrazing and biomass burning in croplands have aggravated soil degradation. We studied the impact of two RCA ( derdero + (DER+) and terwah+ (TER+) on long-term soil quality and crop productivity in permanently kept plots in northern Ethiopia 7 years after its inception. The two RCA practices: (i) DER+ is a bed and furrow planting system, where beds remain unploughed, furrows are tilled once at planting time and 30% of crop residue is retained. (ii) TER+ is ploughed once at planting, furrows are made at 1.5 m intervals, creating fresh broad beds, and 30% crop residue is retained. These RCA practices were compared against conventional tillage (CT) characterized by a minimum of three tillage operations and complete removal of crop residues. Among the several assessed soil properties, soil organic C (SOC), total soil N, available P, soil microbial biomass C (SMBC), time of ponding, aggregate stability index (SI), consistency index (CI), cone index, air capacity and macroporosity were shown to increase significantly in soils subjected to DER + planting system compared to CT. On average, crop yields under DER+ and TER+ increased by 30 % and 16 %, respectively, as compared to CT. Thus, from an agro-ecological point of view, adopting improved local practices such as DER+ and TER+ planting systems that employ conservation agriculture principles proved to be sustainable, resource conserving alternatives and incentives should be provided to facilitate larger adoption by farmers in Ethiopia.

In the northern Ethiopian highlands, croplands yield extremely high volumes of storm runoff and are the major contributor to sediment load in the rivers. A medium-term tillage experiment was carried out (2005–2010) on a Vertisol to quantify changes in runoff, soil loss and crop yield due to Conservation agriculture (CA) in the sub-humid May Zegzeg catchment. A randomized complete block design with 3 replications on permanent plots of 5 m by 14 m was used for three tillage treatments, (i) derdero + (DER+), permanent raised beds with 30% standing crop residue retention and no-tillage on the top of the bed, (ii) terwah+ (TER+), ploughed once at sowing with 30% standing crop residue retention and furrows made at 1.5 m interval, and (iii) conventional tillage (CT) with a minimum of three tillage operations and removal of crop residues. Tillage operations in the three treatments were done using the local ard plough mahresha. Local crop rotation practices followed during the six years sequentially from the first to the sixth year included wheat-grass pea-wheat- hanfets (wheat and barley sown together)-grass pea-wheat. Glyphosate was sprayed starting from the third year (2007) at 2 L/ha before planting to control pre-emergent weed in DER+ and TER+. Runoff and soil loss were measured in collector trenches at the lower end of each plot. Soil organic matter was determined at two depths (0–15 cm) and (15–30 cm). Local farmers evaluated crop stands. Significantly different ( p

McConnachie AJ, Strathie LW, Mersie W, Gebrehiwot L, Zewdie K, Abdurehim A, Abrha B, Araya T, Asaregew F, Assefa F, Gebre-Tsadik R, Nigatu L, Tadesse B & Tana T (2011). Current and potential geographical distribution of the invasive plant Parthenium hysterophorus (Asteraceae) in eastern and southern Africa. Weed Research 51, 71–84. Summary Parthenium hysterophorus (Asteraceae), of South American origin, is considered to be one of the world’s most serious invasive plants, invading Australia, Asia and Africa. As part of an international collaborative project, this study attempted to improve the understanding of the geographical distribution of P. hysterophorus in eastern and southern Africa. The climate modelling program CLIMEX was used to assist in the selection of survey localities. Roadside surveys of the distribution of the weed were conducted in Botswana, Ethiopia, South Africa, Swaziland and Uganda. Prior to these surveys, only limited P. hysterophorus locality records existed; substantially more records were obtained from surveys. Most infestations were high density (>3 plants m−2). Distribution records were used to validate the CLIMEX model, which proved a useful tool. This study increased current understanding of the distribution of P. hysterophorus and developed a baseline from which to monitor future spread and abundance of P. hysterophorus. Additional surveys are required in other countries in Africa which are predicted by CLIMEX to be at risk. This will enhance integrated management decisions for the control of a weed which has implications for food security and human health.

Sorghum (Sorghum bicolor (L.) Moench) is an important cereal crop and stable food for the semi-arid small scale farming communities in the third world. Even though, it is highly adapted to different agro-ecological conditions, its yield is constrained by different factors including declining soil fertility and improper utilization of fertilizer. Results of the research conducted in Shire-Mytsebri Agricultural Research Center at Sheraro sub-site during the main cropping season of 2016 are presented in the paper. The aim was to investigate the effect of NPK; and blended fertilizer on nitrogen, phosphorus, and potassium uptake; and nutrient use efficiency of selected sorghum varieties. The treatments are comprised of factorial combination of ten levels of fertilizers including the recently recommended [N, P, Blanket recommendation (NP), NPK, NPS, NPKS, NPKSZn, NPKSZnB, NPKSZnB (after Agricultural Transformation Agency, ATA) and Control (0)]. Two sorghum varieties (Melkam and Dekeba) were tested in a Factorial Randomized Complete Block Design with three replications. The data were computed using four agronomic indices, which are commonly used to describe nutrient (N, P and K) uptake and use efficiency. The results indicate that there is a significant interaction effect of fertilizer treatments and sorghum varieties on majority of the parameters studied. Application of NPKSZn blended fertilizer significantly enhanced nutrient uptake and use efficiency. The highest total N (78.70 kg ha-1), P (51.19 kgha-1) and K (74 kg ha-1) uptake and use efficiency in Melkam variety treated by fertilizer contained NPKSZn brought higher yield (5541 kg ha-1). Increasing uptake of the major nutrient elements ensured ample nutrient availability for normal growth and high yield of sorghum. Thus, application of macronutrients in combination with micronutrients increased sorghum yield and concomitantly improved N, P and K uptake, and nutrient use efficiency for the sorghum varieties used in the study. Therefore, it is recommended that in the study area and other similar areas blended fertilizer 41N-46P-13.7K-9.25S-1.72Zn kg ha-1 be used to achieve higher yields.Keywords: Blended fertilizer, Nutrient uptake, Nutrient use efficiency, Sorghum, Ethiopia.

Conservation agriculture (CA) is often quoted as a beneficial resource-saving technique for dryland agriculture, but its large-scale implementation is frequently hindered by the lack of farmers' acceptance. To date, few studies have investigated the impact of spatial factors, costs and benefits and regional agroecosystem differentiation on adoption of CA. This study, therefore, aims to assess the impact of these factors through a case study in the North Ethiopian Highlands. One hundred eight farmers of 11 villages surrounding an experimental plot were interviewed in order to identify their knowledge and acceptance of the technique. The results show that several spatial factors play a role in CA acceptance. The lack of knowledge on the resource-saving technique proved primarily dependent (R = -0.73) on spatial impedance with the innovation source and on the strength of sociospatial networks. Next, a consumer model showed that perceived costs and benefits seem to balance each other. Finally, some agronomic traditions were identified that are related to the regional agroecosystem, which are not favoring the implementation of zero-tillage practices. Since this study identified acceptance problems related to several spatial and regional factors, future CA adoption schemes must allow better regional differentiation optimized to local contexts and conditions.

Summary This study evaluates the practice of conservation agriculture (CA) in the May Zeg-zeg catchment (MZZ; 187 ha) in the North Ethiopian Highlands as a soil management technique for reducing soil loss and runoff, and assesses the consequences of future large-scale implementation on soil and hydrology at catchment-level. The study of such practice is important especially under conditions of climate change, since EdGCM (Educational Global Climate Model) simulation predicts by 2040 an increase in precipitation by more than 100 mm yr −1 in the study area. Firstly, field-saturated infiltration rates, together with soil texture and soil organic carbon contents, were measured. The relation with local topography allows to generate a pedotransfer function for field-saturated infiltration rate, and spatial interpolation with Linear Regression Mapping was used to map field-saturated infiltration rates optimally within the catchment. Secondly, on several farmlands, CA was checked against plain tillage (PT) for values of field-saturated infiltration rates, soil organic carbon, runoff and soil loss. Results show no significant differences for infiltration rates but significant differences for runoff and soil loss (as measured in the period 2005–2011). Runoff coefficients were 30.4% for PT and 18.8% for CA; soil losses were 35.4 t ha −1 yr −1 for PT and 14.4 t ha −1 yr −1 for CA. Thirdly, all collected information was used to predict future catchment hydrological response for full-implementation of CA under the predicted wetter climate (simulation with EdGCM). Curve Numbers for farmlands with CA were calculated. An area-weighted Curve Number allows the simulation of the 2011 rainy season runoff, predicting a total runoff depth of 23.5 mm under CA and 27.9 mm under PT. Furthermore, the Revised Universal Soil Loss Equation management factor P was calibrated for CA. Results also show the important influence of increased surface roughness on water ponding, modeled with a hydrologic conservation balance. By coupling this model with the infiltration rate map, a ‘ponding map’ of the catchment was established. Finally, a sediment budget for a full future implementation scenario of CA has been estimated, predicting a large impact of CA on sheet and rill erosion rates, since total soil loss due to sheet and rill erosion in cropland would become 581 t yr −1 instead of 1109 t yr −1 , if CA would be practiced in MZZ. Simulation of several policy scenarios shows that especially under a future wetter North-East-African climate, CA would be a beneficial alternative for the current plain tillage, as it will increase infiltration and keep runoff coefficients under control.

The aim of conservation agriculture (CA) is to improve soil quality and crop yield whilst reducing runoff and topsoil erosion. An experiment was carried out in a rainfed field using a permanent raised bed planting system for 3 yr (2005–2007) in Adigudem, northern Ethiopia in order to evaluate the effect of CA on runoff, soil loss and crop yield. CA practices were introduced in fields with Vertisols in a randomized complete block design on permanent 5 · 19 m plots. Three treatments were evaluated: (1) conventional tillage (CT) with a minimum of three tillage operations and removal of crop residues, (2) terwah (TER) that was similar to CT except that contour furrows were included at 1.5 m intervals, and (3) derdero+ (DER+), which consists of permanent raised beds with a furrow and bed system, retention of 30% of standing crop residues and zero tillage on the top of the bed. All ploughing as well as the maintenance of the furrows of the permanent raised beds was done using a local ard plough called maresha. Results from monitoring over 3 yr showed that soil loss and runoff were significantly higher (P < 0.05) in CT followed by TER and DER+. Average soil losses of 5.2, 20.1 and 24.2 t ⁄ ha were recorded from DER+, TER and CT, respectively. Runoff was 46.3, 76.3 and 98.1 mm from DER+, TER and CT, respectively. Grain yield was significantly lower (P < 0.05) in DER+ under teff in 2006, probably due to the high sensitivity of teff to weeds. The yield of wheat in 2007 was significantly higher in DER+ followed by TER. The terwah system is recommended as a first measure for wider adoption to reduce runoff and soil loss and to increase crop yield. The long-term goal is to achieve a derdero+ system, i.e. a permanent raised bed planting system along with the application of crop residues.

Metadata only record Indigenous tillage systems are often undervalued in conservation agriculture (CA). In Ethiopia, since the 1970s there have been several attempts to develop and implement often major modifications to the marasha, the traditional ox-drawn ard plough, with the main aim of creating various types of surface depressions. The establishment of furrows and ridges increases soil moisture and grain yield and reduces soil loss. Dissemination of the modified tools, however, remains limited. Recent tendencies are towards testing relatively simple conservation agriculture tools. Major challenges remain, however; the need for capacity building and problems in marketing the tools. From experimental plots, often worked with exotic tools, there is a long road to real adoption by farmers. Rather than developing yet another CA tool, we investigate whether CA-based resource-conserving technologies might be achieved successfully with simple changes to the use of the marasha. On-farm observations on traditional conservation techniques were carried out throughout the northern Ethiopian highlands, and experiments were conducted involving resource-conserving technologies. Farmers traditionally use the marasha ard plough for various types of in situ soil and water conservation by creating surface depressions, either at the moment of sowing (terwah, derdero) or after crop emergence (shilshalo). Building upon this indigenous knowledge, we further developed resource-conserving technologies into a system named derdero+, whereby the traditional ard plough was found suitable for a "bed-and-furrow" system. From the socio-economic point of view, implementation of permanent beds and retention of stubble leads to decreased oxen (and straw) requirements, but also to an increased need for weeding in the first years. To overcome that problem, we introduced glyphosate herbicide into the tillage system. The decreased runoff (-51%) and soil loss (-81%) allow protection of the downslope areas from flooding, but soil nutrient build-up and soil structure improvement are slow processes, and hence the full benefit of the permanent bed system can only be expected after some years. Overall, this type of resource-conserving technology can be part of the ongoing intensification process which includes physical soil and water conservation, slope reforestation and irrigation development. It has, however, its own niche: the cropped land sensu stricto, i.e. the most important part of the land, both for the farmer and for a nation that is striving for long-term food security. (Cab Abstracts)