Natural Resource Management Research

An Overview

It is well known that the vision and mission of Agricultural Research and Development in most developing countries is to ensure food self-sufficiency, production of raw materials for domestic industries, production of export commodities to maximize foreign exchange earnings and increase competitiveness in the world market by improving both quantity and quality of agricultural produces in a sustainable way. To make this vision realistic and to bring about sustainable economic development, we have to address the major and priority challenges threatening the agricultural sector in general and food production in particular.

In countries like Ethiopia, where agriculture takes the lion share of the national economy and agricultural-led industrialization is supposed to be the pillar for sustainable development, natural resources management, particularly soil and water management, appears to be the major area of interest. In line with this, decline in soil fertility status and crop productivity as a result of depletion of plant nutrients and soil organic matter due to deforestation, continuous cropping without replenishing adequate soil nutrients, application of sub optimum fertilizer levels and land degradation in the form of soil erosion, acidity, salinity, alkalinity and water logging, are among the main challenges threatening agricultural development in general and food production in particular, especially in most developing countries. 

As the case with other developing countries, in Ethiopia, the wide spread of land degradation, decline in soil fertility status, increasing population growth and climate changes brought about shortages of farmland and water resources, which are becoming the greatest challenges of food security to feed the ever increasing population. On the other hand, most developing countries, including Ethiopia, have Avery large area of suitable land for crop production. But, productivity of most crops is far lower than the potential.

A number of reasons can be listed down for the low level of crop productivity and food insecurity. But, as most part of the food directly or indirectly comes from plants and since soils are basic media to supply water and nutrients for plant growth and food production, factors associated with soil fertility and water productivity need due emphasis tonsure food security and economic growth in a sustainable way.

At this point and time, it seems important to know the root causes of problems related with soil fertility to design appropriate strategies to alleviate the problems and achieve the desired goal. Therefore, what are the causes for the declining soil fertility status and continuous depletion of plant nutrients, making crop production so difficult to feed the growing population and realize fast economic growth? Our research and development agenda should focus on these key questions and should be geared towards generating, adopting and disseminating improved technologies, knowledge and information according tithe need of the users, especially small scale farmers. To this effect and as a spring board for continuous development process, several research and development attempts have been made in soil and water management to improve soil fertility, land, water and crop productivity, food availability and cash income of the smallholder farmers.

However, the information generated so far and lessons learnt from those activities have not been well organized, documented and scaled-up in most cases. Therefore, besides generating and/or adopting new technologies, information and knowledge, demonstration and dissemination of the existing improved and available best practices to the end users also needs due emphasis to enhance water use efficiency, soil fertility and soil health management for increased agricultural productivity in Ethiopia. 

In line with this, the land and water resources research process has a number of research activities being carried out in the areas of inorganic and organic soil fertility management, acid, vertical and salt affected soils management, agricultural water/irrigation and drainage management and integrated watershed management or biological and physical soil and water conservation. These research activities are being conducted in the various agro ecological zones of the country.

 Soil Fertility Improvement 

An overview of Ethiopia’s fertilizer sub sector shows that fertilizer was introduced in the 60s by higher learning institutions through limited laboratory and research activities. In the early 70s nationwide on-farm demonstrations trials were conducted and as a result of these works a blanket rate of 100 kg ha-1DAP or 50 kg ha-1Urea + 100 kg DAP ha-1 were recommended irrespective of crop and soil types. Therefore, efforts have been made to draw crop, soil type and agro-ecology based nutrient(N and P) recommendation for major crops such as wheat, tef, malt barley, food barley, maize, etc in the major growing areas. Accordingly, the following recommendations were drawn for the major crops mentioned above. 

Table 1: N and P recommendation 

Time of N application

N is recommended to be applied in split (for wheat and tef) where 1/3 rdat plating and 2/3 rdat tillering stage; but 2 to 3 split application is recommended for maize at different growth stage of the crop. Split application is useful because under severe water logging conditions and at higher N rates it helps to enhance grain and total N uptake, and for improved apparent recovery and agronomic efficiency of N.

P calibration works

According to experiments conducted through 2012 to 2014 on P calibration for major cereal and pulse crops on different agro-ecology and soil types, critical P values and P-requirement factor has been developed as indicated in the table below. Therefore, the critical P values can be used by soil analytical laboratories to give need based recommendations for different crops and soil types indicated in the table after analyzing the soils coming from the producers. 

Critical P concentrations and P requirement factors determined for different crops and soils at various locations.Table 2: P-Calibration


Micro-nutrient status

According research findings in major zones of the country there is no deficiency of Fe and Mn, on major crops such as wheat, tef, maize and citrus whereas the deficiency of Zn and Cu were severe.

Integrated nutrient management

  • Integrating inorganic fertilizers with organic sources such as FYM and compost have been identified as environmentally sound and economically profitable approach for sustainable soil fertility improvement and thereby increasing crop yield.
  • Incorporation of the green manure plant species such as dolichos lablab, mucuna prureins, lupin, crotolaria have been identified as effective to improve soil fertility and enhance the efficiency of applied fertilizer and thus increase crop yield.
  • From the research findings obtained over the past few years, rotations of wheat after faba bean, rape seed, and barley have been identified as the best rotation system in wheat dominated Arsi province.
  • Two common bean varieties (Nasir and Dimitu) have identified as suitable pulse crops for inter-cropping with Maize in high rain fall areas. They can increase the income of the farmers by up to 30% as compared to growing sole maize and moreover they improve the fertility status of the soil.
  • In the moisture stress areas, growing of common bean as an inter-crop with maize integrated with tie-ridging technique to conserve moisture has been identified as effective system to improve the yield of maize by 20-30%.
  • Growing of common bean with sorghum in rotation and inter-cropping system has been identified as most the effective strategy to increase the yield of sorghum by four fold and land intensification of about 40-50%.
  • Dekeko (low land field pea) has been found effectively produced when panted at the soil moisture of between 20 to 30% and 40 and 15 cm inter and intra row spacing respectively.
  • In melka Worer area, the recommended seed rate of sesame has been identified as 80 kg/ha.
  • Suitable coffee pruning and training system that can boost the yield of the crop has been identified
  • Using desmodium as mulching (being harvested twice per year) in coffee plantation has been identified as effective system to improve the yield of coffee, soil fertility status and controlling weed.
  • Relay Inter-cropping of coriander with coffee has been found effective in land intensification and hence it is economical to grow the two crops altogether.
  • New biofertilizers strains that can boost the yield of Faba bean and soya bean and increasing the yield of the crops up to 30% have been identified.
  • A strain called CP-5 has been identified for chick pea and it can boost the yield of the crop by about 60% 

Vertisols and Acid Soils Management

  • According to the research results conducted on highland Vertisols areas, black cumin and white cumin and coriander have been identified as highly economical and alternative crops as compared to other field crops such as teff, wheat, chick pea and lentil. The result indicated that one can produce 990, 1081 and 4185 kg/ha black and white cumin and coriander respectively. This means the monetary advantage of these high value crops is 34,855.0, 19,587.0 and 13,295.9 in that order as compared to the popular crop on Vertisols i.e teff.
  • It was found that barely yield can be increased from 2.5 ton/ha to 4.5 ton/ha by applying 1.5 to 3.5 ton/halime (according to the exchangeable acidity level of the soil) and 46 kg/ha P2O5. On the other hand, the yield of the same crop has increased to 3.7 ton/ha by applying compost and lime altogether.
  • Split application of liming i.e. 1/3 of the recommended rate for the crop (maize, soybean, and barley) has-been found effective as compared to the application of the full rate once. This also gives an opportunity for the resource poor farmers.
  • Low pH and associated low P availability is major limiting factor for the production of highland pulse son Nitisols where faba bean and field pea are mainly grown. Therefore, liming has been found as effective reclamation option where the rate is determined based exchangeable acidity level of the soil.
  • Impeded drainage is the major constraint affecting productivity of cereals and pulses on Vertisols. Therefore, using BBF (broad bed and furrow) system has been found effective to drain excess water from the field and boosting productivity.

Agricultural Water andSoil Salinity Management

Irrigation and Drainage commodity

  • Irrigation interval, depth of water application andwater use efficiency (WUE) has been determined foralfalfa and banana in Werer and middle Awash areas
  • Seasonal crop water requirement (CWR), WUE andirrigation has been determined for
  • Haricot bean, sorghum and pepper in Melkasa area,
  • Chickpea in Debrezeit and Gerado/Desse areas, forcotton in middle Awash, Gewane, lower Awash andArbaminch areas,
  • Groundnut in middle Awash and Gode areas and forkenaf in middle Awash area,
  • Maize in middle Awash, central rift valley includingMelkassa, in Gerado/ Dessie and Dire Dawa areas,
  • Sesame in middle Awash and Gode areas,
  • Teff in Gerado/Dessie area,
  • Wheat in middle Awash, Melkassa, and Debre-Zeitareas,
  • Rice at Melka werer and tomato Melkassa
  • Tomato, onion, pepper, maize and sorghum in Mohoniareas
  • Optimum supplemental irrigation regime has beendetermined for maize in Melkassa and middle Awashareas.
  • Optimum deficit irrigation scheme has been determinedfor tomato in Malkassa, for supermint in Koka and forsesame in Melka Werer areas.
  • The influence of water deficit stress at various growthstages on crop growth and yield has been identified foronion in Melkassa area and for maize in Koka, and foronion and sesame in in Melka Werer areas
  • Seasonal CWR of onion has been determined atdifferent growth stages and in different seasons formiddle Awash, central rift valley
  • Similarly, CWR of tomato in different seasons has beendetermined for central rift valley and Dire Dawa areas
  • CWR of established citrus (orange) orchard has beendetermined for upper Awash (Nura Era), middle Awashand central rift valley areas
  • Similarly, seasonal CWR and gross irrigation requirementhas been determined for mandarin in upper Awash(Nura Era), for mango in central rift valley and forbanana in upper Awash (Nura Era) and middle Awashareas
  • On the other hand, optimum irrigation regime(application depth, time, method and interval) hasbeen determined for onion in Ziway Dugda, DireDawa, Melkassa and Melka Werer areas
  • Similarly, optimum irrigation regime has beendetermined for tomato in Melkassa, Dire Dawa, andMelka Werer areas.
  • Optimum irrigation regime has also been determinedfor pepper in middle Awash and Bako areas and forsweet potato in middle Awash area
  • Optimum irrigation regimes have been determined fororange and mandarin in upper Awash, for banana inmiddle Awash and for coffee nurseries and establishedstands in Jimma areas.
  • About six to eight Arabica coffee genotypes relativelytolerant to drought stress have been identified orscreened at seedling stage under controlled rainoutshelter condition in Jimma and Sidamo areas.
  • Drip irrigation method also showed promising resultsin increasing water use efficiency and yield. The highestcrop yield and WUE have been achieved with dripirrigation as compared to furrow irrigation.

Soil Salinity Management

  • Among the various tree species, Sesbania sesban, Albizialebbeck, Acacia nilotica and Acacia tortilis have been found to be tolerant to soil salinity with potential of ameliorating both physical and chemical properties ofthe soil and lowering the level of ground water table asbio-drainage agents.
  • Two rice varieties, namely NONA BOKRA and IR72593-B-3-2-3-5 have been identified as salt tolerantand as alternative crop in salt affected areas of the riftvalley and middle Awash.
  • On saline affected soils, the use 46 kg N/ha and irrigating 75mm water at 17 days interval was found to be effective for improved production of cotton in the rift valley/Werer areas.

Three wheat varieties, namely Simba, Geleme and Kubsa, have been found to be adaptable to moderate soil Two cotton varieties, Nazil-84 and Acala sj-2, were found to be relatively tolerant to highly saline soils and high yielders under salinity stress condition in middle Awash areas.

  • Four forage grass species, namely Chloris gayana,Cinchrus spp, Panicum antidotale, Sorghum sudaness,and two legume forage species (Medica sativa andSesbania sesban) have been identified as adaptable andtolerant to and high biomass yielding in saline soil areas,and have remarkably reduced the soil salinity content.
  • Intermittent leaching with single application of 20 cmdepth every recession period and continuous pondingwith an application of 15 cm water depth has beenadvised as a proper leaching practice for cotton andrice, respectively, in saline-sodic soils of Melka Sediarea, where subsurface drainage system was alsorecommended to control ground-water table, reducesoil salinity level and increase crop yields.
  • The nature, extent, cause and distribution of .salinesodic soils have been studied in irrigated areas ofAmibara and Fentale, and in lower, middle and upperAwash, Rift valley and northern, southern and easternlow land areas and river basins and information hasbeen generated for the users.

Integrated Watershed Management 

The major objectives of integrated watershed management(IWM) research case team are to rehabilitate degraded lands,control gully formation and land degradation as a result ofdeforestation/loss of vegetation cover , runoff and erosion, andgeneration, adoption/introduction and popularization of improvedbiological and physical soil and water conservation practices in majorwatersheds. 

In line with this, so far different activities have been carried out indifferent parts of the country. But most of the activities have beenfocusing on more of development works, mainly introduction ofvarious improved crop, forestry and/or agro-forestry and livestockproduction technologies, rural energy saving, soil and waterconservation practices, and gully rehabilitation technologies withparticipation of the community in model watersheds.

Currently, the case team has developed short,medium and long term strategies and startedsome research activities to generate technologiesand information in the following areas:

  • Gauging and assessment at different basins(soil, nutrient, water discharge, sediment,economic, yield loss quantification, effectson downstream), mapping risk areas andmodeling for effective soil and waterconservation.
  • Introduction and evaluation of soil andwater conservation practices includinginventory and documentation (practicesincluding IK) of SWC.
  • Inventory and documentation (practicesincluding IK) and Mountain development.
  • Introduction and evaluation of multipurpose(MP) and high value fruits and trees/shrubs.
  • Evaluation of soil - tree - crop -livestockinteraction .
  • Introduction and evaluation of waterharvesting technologies (proper harvesting,storage mechanisms , conveyance,abstraction, utilization).
  • Validation and evaluation of ConservationAgriculture (CA).
  • Inventory and documentation (Practicesincluding IK) of CA.
  • Hillside rehabilitation with enclosure andenrichment Plantation.