Priorities for Sustainable soils fertility management for Rwanda

Presentation by Dr. Rushemuka N. Pascal (PhD) Agri-Environmental soil scientist

A brief overview of the Rwanda biophysical and socio-economic environment

A small country in central Africa 28 M of KM2 with 11M of the population A very diversified biophysical

environ with 3 main natural regions: oHigh altitude: red> 2000m oMedium altitude: yellow:1600-

2000m o Low altitude: Bleu: 900-1600m

Same language: Kinyarwanda: national language

Relief/topography: country of thousand hills

Orthophotos (5 x 5 m) showing major land units of Akavuguto watershed: From left (West) to East (right): the gradual evolution is from hills and valleys, to mountainous and boxed-valley land units. Source: Swedesurvey (2008).

Rwanda Agro-Ecological Zones (AEZ) and suitable crops

• Each AEZ has a number of suitable crops

• However soil fertility vary significantly within one AEZ

• Within one EAZ soil fertility vary in different land units along the slope (upper hill, back slope, down slope and valley battom)

• This means that the same hill has different units of different suitability

AEZ and their major limitations to agriculture development

Natural regions AEZs Elevation (m)

Relief Temperature (C°)

Rainfall (mm)

Dry season (month)

Major limitation

Highlands Birunga* > 1900, Mountainous 15- 17 1250-2000 1 to 2 Slope+++ Acidity+++ Buberuka

CNWD

Midlands Impala 1,600-1,900 Dissected Plateaus

17-20 1000- 1250 3 to 4 Slope++ Acidity++ Kivu lake borders

Central Plateau Granitic Ridge

Lowlands Imbo < 1,600 Pediplains 20-21 700 – 1000 4 to 5 Slope+ Erratic

rainfall+++ Mayaga Bugesera

Eastern Plateau Eastern Savanna

Cause of poor soil productivity in Rwanda

Inherently poor soils (acidic and depleted) in the West (50%):

old parent materials: gneiss, micaschist, quartzite Steep slopes Heavy rains

Erratic rainfall in the east (50%)

Rwanda soil fertility classes, their characteristics, their proportion and the required type of inputs

Fertility classes

Limitation level

pH (water) Al Sum of Exchangeable

bases

proportion Type of input

(Cmol/Kg soil) (%)

Fertile soils Low > 5.5 < 1.5 > 3.0 27.4 Manure

Medium fertility soils

Medium to high

5.2 - 5.5 1.5-3.0 1.0-3.0 29.5 Manure + fertilizers

Infertile soils Very strong to extremely

strong

< 5.2 > 3.0 < 1.0 43.1 Lime + Manure + fertilizers

Current Initiatives 2002: Rwanda elaborated its long term planning document: vision

2020. The Agriculture is recognize as the engine of Rwanda economic growth

2004: Rwanda elaborated its National Agriculture policy The motto was transforming the Rwanda agriculture from subsistence to

competitive modern agriculture Intensive use of fertilizers High yielding crop varieties Irrigation Mechanization

2007-20014: EDPRS1 (Economic Development for Poverty Reduction Strategy) Erosion control

bench terraces Progressive terraces

Soil fertility management Land consolidation Subside of fertilizers for key crops Subside of high yielding varieties

Irrigation valley bottom irrigation

Mechanization Introduction of heavy machines

2014-2020: EDPRS2: same approach with attempt to leave the subdivide system

Outputs • Crop yields have remained low (poor response to fertilizers, erratic rains, crop

diseases) • The adoption of the new system is low • The contribution of the agriculture sector to Rwanda economic growth has

remained low • After the Phase1 of subside period farmers return to their ancient systems

Our interpretation Ignorance of the role and the place of the soil resource in different

strategic documents of Rwanda Yet we have a comprehensive medium scale soil map for Rwanda

(1:50,00) under Soil Taxonomy classification system (since 1990) How one can promote intensive use of fertilizers bypassing the soil

resource information? How soil laboratories can work when the soil resource information is

overlooked Is the existence of soil data the really problem or we need to look

even beyond?

Priorities areas Land use planning Characterize and delineate urban, arable and forestry lands for sustainable land use

Agricultural research and extension: Improving communication between local soil scientists with farmers and local scientists

with the international soil science community by: Establishing a national soil classification system based on farmers’ soil nomenclature Linking the national soil classification system to the international soil classification systems (Soil Taxonomy,

WRB).

Improvement of the crop productivity Compare the bench terraces and hedgerows along the contour lines about sustainable soil fertility

management and adoption by farmers. Determine soil fertility management recommendations for specific soils and specific crops in different AEZs of

Rwanda

Improvement of the water use efficiency by: Increase productivity of irrigated areas (marshlands) Intensive production and use of organic matter on hillsides

Research policy and research approach Identify the role and contribution of the soil science to improve existing research policies Promote Integrated Watershed Management as a conducive research and extension

approach of conducting sustainable management: It is the interaction between the biophysical and the socio-economic environments that can make the difference.

Investment in the agriculture sector Mechanization

Small equipment and machinery Use of animals

Travertine production for liming acidic soils of Rwanda Organic matter production for fertilizer use efficiency Laboratory equipment and facilities

Capacity building Support national soil laboratories to ensure quality results (ISO), soil fertility

management modeling, land system soil survey /geomophopelogical approach and , DSM) Training of Rwanda soil scientists to master Soil Taxonomy, WRB and Farmers

soil classification

National Policies Mainstream soil into long and mid-term planning documents

Poverty reduction and macro-economic growth Linking soil conservation and soil fertility management to poverty reduction and national

macro-economic growth

Education • Support the teaching system to elaborate adapted teaching programs, curricula,

modules and approaches • Support student during their BSc., Msc and PhD thesis to undertake relevant

studies that aim to contribute the societal problems.

Concluding Remarks • It is one thing to have soil resource information • It is another thing to have it effectively used (Wielemaker et al., 2001;

Bui, 2004; Rushemuka, 2014). • Soil scientists need to be more influential in the development circles They need to ease their communication language: more user friendly They need to interact with scientific from other disciplines (policy makers,

economists, agronomists, extensionists) They need to communicate with farmers in their own soil language

• Soil scientists need to play a leading role in crop selection and fertilizers recommendations

Thank you for your attention