Soil degradation and depletion of soil nutrients are among the major factors threatening sustainable cereal production in the Ethiopian highlands. However, although knowledge on soil fertility status plays a vital role in enhancing production and productivity of the agricultural sector on sustainable basis, little information is available in Southern parts of Tigray. Hence, Mekelle University CASCAPE project has been involved in generating information on soil fertility and nutrient status of the Sothern Zone of the region.
As part of this effort, in 2012 and 2014, CASCAPE project (known as BENEFIT-CASCAPE since 2016) conducted a survey using Monitoring for Quality Assessment (MonQI) tool to assess the soil nutrient balance in the southern zone of the region. The survey result indicates that partial nutrient balance at field level was negative for nitrogen and potassium, and positive for phosphorus. The nutrient balance of the southern Tigray gives strong warning on the status of soil fertility and nutrient management of the area. Moreover, the soil survey to assess the nutrient status, conducted in 2013 and 2014 depicted that the soil nutrient level was below critical level except for phosphorus. The amount of organic amendment applied into the soil is insufficient to offset nutrient losses. Among others, loss of soil organic matter (SOM) in area of low input agriculture is one of the challenges. If the nutrient depletion and land degradation continue at the current rates, farmers will be unable to grow enough food crops for the ever increasing population in the area.
To solve the soil fertility and plant nutrition problems in southern zone of Tigray, Mekelle University CASCAPE Project along with its partners in the region have conducted various survey and experiments during the period of 2012 to 2019, which includes characterization of agricultural soils, MonQI survey for nutrient balance, use of inoculants, use of gypsum amendment, use of compost, farm yard manure (FYM) (Slurry) and soil-crop based fertilizer rate development and others on major crops grown in the southern zone of Tigray.
This document is intends to share experiences and lessons that the project has generated over the last 9 years to its stakeholders in the region and beyond. We believe the document will provide information on soil nutrient status and management practices and serve as reference to the extension system and other actors involved in soil fertility management in Southern zone of Tigray. Read the working paper here.
A B S T R A C T
Geospatially explicit information of soil-landscape resources of Ethiopia is lacking or fragmented for much of the country. Recently, massive soil data were collected, however these are limited to properties related to soil fertility and valid for the topsoil only. Understanding the country’s soil-landscape resources, including their qualities and constraints beyond the topsoil, remains key information for systematic and reliable scaling up of evidence-based agricultural best practices including soil fertility management recommendations. The objective of this study was to produce a coherent dataset of the major soil-landscape resources of 30 highland woredas (districts), contributing to the Agricultural Growth Program of the Government of Ethiopia. The study started with an exploratory survey to identify the major (most common) soils occurring across the landscapes followed by a full survey to assess the distribution of the identified major soils. Representative soil profiles were characterized from soil pits and classified as Reference Soil Groups (RSGs), with prefix qualifiers (PQs), according to the World Reference Base for soil resources (WRB). A large number of soil profiles were classified from auger observations. Observed soil classes at both RSG and RSG + PQ level were combined with spatial explanatory variables (covariates), representing the soil forming factors in the landscapes, and their relationships were modeled and validated by random forest. A multitude of tree models was trained using each profile for calibration in approximately two third and cross-validation in approximately one third of the models. Cross-validation showed that RSGs were predicted with a reasonable overall purity of 0.58 and RSGs +PQ were predicted with a purity of 0.48. The most relevant covariate in the models was the Geomorphology and Soils map of Ethiopia at 1: 1 M scale disaggregated into soil-landscape facets. Next models were used to predict soil classes across woredas which resulted in a 250 m resolution raster map of the most probable major soils. This raster map was generalised into a polygon map of major soil-landscape resources. The purity of this final map was estimated to be 0.54 for RSGs and 0.45 for RSGs + PQ. Soil properties relevant for agricultural interpretation, such as depth, drainage, texture, pH, CEC and organic carbon and nutrient contents, were mapped according to the RSGs depicted on the soil-landscape resources map with a RMSE/mean ratio of on average 42%. We conclude that soil expert knowledge and conventional soil-landscape survey combined with random forest modelling results in an attractive hybrid approach. The approach proves cost-effective and sufficiently accurate and can be used to inform scaling up of evidence-based agricultural best practices. Read the full report here.
J.G.B. Leenaars a, E. Elias b, J.H.M. Wöstenc, M. Ruiperez-Gonzáleza, B. Kempena
a ISRIC – World Soil Information, PO Box 353, Wageningen 6700 AJ, The Netherlands
b College of Natural and Computational Sciences, Centre for Environmental Science, Addis Ababa University, Addis Ababa, Ethiopia
c Wageningen Environmental Research, PO Box 47, Wageningen 6700 AA, The Netherlands
Continuous use of only N and P fertilisers that depletes secondary and micronutrients has been presented as a major cause for low wheat yields (2.2 t/ha) in the Ethiopian highlands. In this study, on-farm trials were conducted to compare the effects of multi-nutrient blended fertilisers on the wheat yield on Nitisols in southern Ethiopia. Five quantities of fertiliser blend (50, 100, 150, 200, 300 kg NPS + ZnB kg/ha) were compared against a newly introduced compound fertiliser (150 kg/ha NPS) and the conventionally used NP (Di-Ammonium Phosphate DAP) fertiliser at 150 kg/ha. Treatments were arranged in a randomized complete block design (RCBD) and replicated five times using farm fields as replicates. Results revealed that application of 200 and 300 kg/ha of NPS + ZnB blend fertiliser produced significantly (p < 0.01) higher biomass (16.9 t/ha) and grain yield (3.7 t/ha) than the lower amounts. However, the marginal rate of return was highest for 100 kg NPS + ZnB/ha, but compared with DAP, the blend fertiliser did not produce significantly higher yield. Conversely, the agronomic nutrient use efficiency was significantly higher for NPS + ZnB blend suggesting the importance of balanced fertilization. Read the journal here.
Eyasu Elias1* , Beyene Teklu2 and Tewodros Tefera3
- Centre for Environmental Science, College of Natural and Computational Sciences, Addis Ababa University and BENEFIT-CASCAPE Programme Manager, Addis Ababa, Ethiopia
- Wondogenet College of Forestry and Natural Resources, Hawassa University, Shashemene, Ethiopia
- School of Environment, Gender and Development Studies, Hawassa University, Hawassa, Ethiopia
*Corresponding author email: Eyuelias@gmail.com
A B S T R A C T
Ethiopia faces major food security challenges. In spite of a modest level of fertilizer use, the percentage of wheat that is imported is substantial. The Ethiopian government has invested in the fertilizer sector, thereby also moving away from di-ammonium phosphate (DAP) to multi-nutrient blends (NPSZnB). Wheat fertilizer experiments were established in seven locations (three replications) in the highlands that represented the wide range of soils found in this area. The crop was exposed to DAP, NPS and to five levels of NPSZnB (50–300 kg/ha). All treatments included 100 kg/ha urea. The average wheat grain yield at the experimental sites, when all fertilizer treatments were averaged, ranged from<2 to>7 tons/ha. Soil sampling revealed that organic carbon (28%), total nitrogen and pH, and on the negative side, Fe and Mn concentrations, were significant drivers of yield differences. Fertilizers alone (when averaged for all experimental sites) could only explain 8% of yield difference proving the ineffectiveness of blanket fertilizer recommendations. Blend fertilizers including micronutrients (NPSZnB) performed slightly but not significantly better than NPS alone or DAP alone. However, since the NP contents in the blend are slightly below those in NPS and DAP (particularly for P), a slight positive effect of Zn or B can be observed. On the other hand, Zn concentration in soils did not correlate significantly to wheat yields. Hence, determining the added effects of Zn and B remains subject for further research. Maximum yield gains to fertilizer application can only be achieved when fertilizers and soil property differences are analyzed jointly. In that case, 79% of yield differences were explained. Grouping soils into ‘recommendation windows’ then helps to come up with relevant and cost-effective fertilizer strategies. A simple calculation comparing the cost of wheat import with the cost of fertilizers needed to reach the current wheat consumption level in Ethiopia shows that the latter is by far the most cheaper option, but in need of smooth functioning of the entire value chain. Read the journal here.
Eyasu Elias a,b, P.F. Okoth c, E.M.A. Smaling d
- a College of Natural and Computational Sciences, Centre for Environmental Science Addis Ababa University, Ethiopia
- b Bilateral Ethiopia-Netherlands Partnership for Food Income and Trade (BENEFIT), Ethiopia
- c New Scape Agrosystems Ltd., PO Box 27303, 00100 Nairobi, Kenya
- d Wageningen University & Research, Wageningen Environmental Research, P.O. Box 47, 6700 AA Wageningen, the Netherlands
This study identified decision variables influencing fertilizer adoption and optimal fertilizer rates among smallholder farmers in the Ethiopian highlands. The fertilizer adoption and fertilizer use were examined in four regional states using a questionnaire survey, which was administered to 2880 farm households. A double hurdle model was used to analyze factors influencing the two independent decisions of adoption of fertilizers and use of fertilizers. The model estimates of the first hurdle revealed that the probability of fertilizer adoption increased by 1.2% as household education status improved, by 1.4% for an increased number of active family members, by 5.6% with improved access to credit, by 3.4% with cooperative membership, by 3.3% with an increase in farm size, by 4.6% when soil and water conservation practices are employed, and by 3.4% when agroecology of the farm is located in the medium to highland zone. Conversely, the probability of fertilizer adoption reduced by 0.9% for an increase in family size, 0.6% with 1 km distance from all-weather road, 1.6% for a kilometer further to farm plots, and 0.9% for an increase in number of parcels. The intensity of use of fertilizers was influenced by education status of the household head, family size, access to credit, membership to cooperatives, use of crop rotation, annual income, number of farm plots owned, use of soil and water conservation, and agroecology. Therefore, a concerted effort is needed to encourage fertilizer adoption and optimum fertilizer use intensity by improving households’ resource endowment, institutional capacity to deliver services, and infrastructure development. Read the research article here
Tewodros Tefera1,*, Eyasu Elias2 and Christy van Beek3,4
- School of Environment, Gender and Development Studies, Hawassa University, Addis Ababa, Ethiopia,
- Centre for Environmental Sciences, College of Natural and Computational Sciences, Addis Ababa University, Addis Ababa, Ethiopia,
- Wageniningen Environmental Research, Wageningen, The Netherlands and
- Present address: AgroCares, Wageningen, The Netherlands
*Corresponding author. Email: firstname.lastname@example.org (Received 26 November 2019; revised 5 June 2020; accepted 31 August 2020)
Continuous use of only N and P containing fertilizers are claimed to be the causes of other secondary and micronutrients depletion, resulting in low crop productivity in Ethiopia. In this study, on-farm trials were conducted to compare the effect of multinutrient blended fertilizer – also called boron blend (NPSB: 18. 1 N – 36.1 P2O5 – 6.7S – 0.71B) on the yield and yield components of food barley grown in Alisols in southern Ethiopia during 2017 and 2018 cropping seasons. Seven treatments involving five levels of bornblend fertilizer (50, 100, 150, 200, and 300 kg NPSB kg ha−1) were compared against a compound fertilizer (100 kgha−1 NPS) and the conventionally used 150 kg ha−1 di-ammonium phosphate (DAP). The seven treatments were replicated five times using farm fields as replicates and arranged in randomized complete block design (RCBD). Results revealed significant yield advantages of applying micronutrient containing fertilizers compared to fertilizers without micronutrients. The marginal rate of return analysis showed that the application of 100 NPSB kg ha−1 was the most profitable and agronomically efficient. Season and the soil fertility variation among farmers had a significant (p < .001) effect on food barley yield. Application of Boron blend fertilizer had 500 kg ha−1 grain yield advantage compared to equivalent amount of DAP that was highly promoted by the extension system. B-blended fertilizer was advantageous when applied during good rainy seasons in Alisols of Ethiopian highlands. For good performances of B-blended fertilizers, taking into account the soil moisture availability is advised for both better productivity and agronomic efficiency. (Read the full journal here)
Eyasu Elias , Beyene Teklu Mellisse , Getachew Agegnehu & Desalegn Ayele (2020): Response of Food Barley (Hordeum Vugarae L.) To Boron Blend Fertilizer Rates on Alisols in Southern Highlands of Ethiopia, Communications in Soil Science and Plant Analysis To link to this article: https://doi.org/10.1080/00103624.2020.1813752
Published online: 02 Sep 2020.
Agriculture is considered as the backbone of Ethiopian economy. The government promotes rural development through policies that enhance intensive and commercially-oriented agriculture. Soil quality may be the bottleneck of these ambitions as more than half of the agricultural land shows signs of land degradation. Soil organic carbon (SOC) contents are a key aspect of soil quality, where relatively high SOC contents indicate better water holding capacity, nutrient retention capacity and better structure of the soil. In this research, SOC balances were used as indicator for short and midterm changes in SOC contents. SOC balances were calculated using data collected from 6914 fields for three years (2012-2014) using a simple input-out approach. On average, SOC balances were three tons per hectare per year. This equals 4 to 7% of the total soil organic carbon stock, which varied according to regions and cropping systems. SOC depletion rates were high in the mountainous and high cultivation intensity sites in central and northern Ethiopia where cereal based cropping systems dominates. Under the current practice, soils will eventually become exhausted and lose their productivity. This alarming trend could be reversed by integrating organic matter and nutrient management strategies and by providing alternative sources for feed and fuel supply of the community.
(read the full publication here)
Christina Laetitia (Christy) van Beek1, Eyasu Elias2, Yihenew G. Selassie3, Girmay Gebresamuel4, Asrat Tsegaye5, Feyisa Hundessa6, Mekonnen Tolla3, Melmuye Munaye7, Gebremeskel Yemane4, Seyoum Mengistu8.
- Alterra, Wageningen University and Research Centre, Wageningen, The Netherlands
- Addis Ababa University and CASCAPE Project, Ethiopia
- Bahir Dar University, Ethiopia
- Mekelle University, Ethiopia
- Hawassa University, Ethiopia
- Haramaya University, Ethiopia
- Jimma University, Ethiopia
- Addis Ababa University, Ethiopia