Authors :
Mujanama Erick; Ntwali Didier; Byicaza Prince; Hategeka Emmanuel
Volume/Issue :
Volume 8 - 2023, Issue 4 - April
Google Scholar :
https://bit.ly/43uxUln
Scribd :
https://bit.ly/3Lte2rU
DOI :
https://doi.org/10.5281/zenodo.7861110
Abstract :
In Rwanda more than 745 thousand hectares
of potential agricultural land are eroded annually in
Rwanda. Using the reference year 2021A, more than 3
million tons (six million tons annually) of crop produce
are expected to be lost each season, with severe erosion
affecting 22,000 tons of maize and 15,000 tons of beans.
Each season, severe erosion results in a total economic
loss of 37.9 billion Rwandan francs (RWf) in agricultural
productivity. The research’s overall objective was to
assess the impact of soil erosion on soil fertility on sebeya
catchement. the specific objectives was to analyze to
determine amount of soil loss in Sebeya catchment,
determine the impact soil erosion on soil nutrients loss
and estimate the value of replacement cost of soil
nutrients lost in RWf for period of 2022, To achieve
these objectives RUSLE model & Geographic
Information System (GIS) techniques were combined to
determine soil erosion .Soil mapdatabase was used to
determine the quantinty of soil nutrients, whereas
ministerial price guideline from MINAGRI was used to
determine the value (RWf) of fertlizers (NPK) to replace
the nutrients lost due to soil erosion. This study showed
that amount of soil loss by combining all the five factors
influencing soil erosion. After observation and analysis,
it revealed that the big losses of soil in the sebeya
watershed are only found on the surface covered by
cropland and settlements with an estimated amount
>300 t/ha/year, while other part of the catchment
covered by forest and grasses loose a low quantity of soil
with an estimation of 0 to 50 t/ha/year, which reconfirms
that human activities are well managed and structured
by rules and guidelines given by responsible institutions
in charge such as MINAGRI, REMA, RWB, etc the
sebeya catchment that is facing large amount of soil loss
each year can be protected efficiently. The study has
revealed that erosion is seriously taking place in Sebeya
watershed, the results shows that, In general, the average
soil composition of Nitrogen in the sebeya watershed is
0.378%, 9.051 mg/l of Phosphorous and 1,205 Cmol/kg
of Potassium. Generally, Nitrogen is the soil nutrient
that is highly lost with an estimated amount of 90
kg/ha/y. the highest amount of N lost is found in
cropland about 173.4kg.ha/y while forestland loses the
lowest amount of N estimated about 14.45kg/ha/y. the
highest loss of nutrients amount of P and K are also
observed in cropland with respective amount of
56.82kg/ha/y and 147.89kg/ha/y. These soil nutrients
losses have a huge impact on soil fertility reduction,
because the soil fertility is made at 80% of these three
elements (N, P and K). This average value of soil loss in
the catchment, which is estimated to be about 135t/ha/y,
naturally indicates 90 kg/ha/y of N, 15kg/ha/y of P, and
74kg/ha/y of K. If three or five consecutive years of the
same soil loss amount occur, soil fertility will be gone,
and we will be left with a marginal soil unsuitable for
cultivation. This study recommends the consideration of
soil erosion control measures for all government plans to
increase agricultural productivity through
intensification and commercialization and suggest to
conduct more research for other watershed to know
exactly the amount for of soil and nutrient loss.
Keywords :
Soil loss, Soil Fertility , GIS and Remote Sensing, RUSLE, Sebeya Catchement
In Rwanda more than 745 thousand hectares
of potential agricultural land are eroded annually in
Rwanda. Using the reference year 2021A, more than 3
million tons (six million tons annually) of crop produce
are expected to be lost each season, with severe erosion
affecting 22,000 tons of maize and 15,000 tons of beans.
Each season, severe erosion results in a total economic
loss of 37.9 billion Rwandan francs (RWf) in agricultural
productivity. The research’s overall objective was to
assess the impact of soil erosion on soil fertility on sebeya
catchement. the specific objectives was to analyze to
determine amount of soil loss in Sebeya catchment,
determine the impact soil erosion on soil nutrients loss
and estimate the value of replacement cost of soil
nutrients lost in RWf for period of 2022, To achieve
these objectives RUSLE model & Geographic
Information System (GIS) techniques were combined to
determine soil erosion .Soil mapdatabase was used to
determine the quantinty of soil nutrients, whereas
ministerial price guideline from MINAGRI was used to
determine the value (RWf) of fertlizers (NPK) to replace
the nutrients lost due to soil erosion. This study showed
that amount of soil loss by combining all the five factors
influencing soil erosion. After observation and analysis,
it revealed that the big losses of soil in the sebeya
watershed are only found on the surface covered by
cropland and settlements with an estimated amount
>300 t/ha/year, while other part of the catchment
covered by forest and grasses loose a low quantity of soil
with an estimation of 0 to 50 t/ha/year, which reconfirms
that human activities are well managed and structured
by rules and guidelines given by responsible institutions
in charge such as MINAGRI, REMA, RWB, etc the
sebeya catchment that is facing large amount of soil loss
each year can be protected efficiently. The study has
revealed that erosion is seriously taking place in Sebeya
watershed, the results shows that, In general, the average
soil composition of Nitrogen in the sebeya watershed is
0.378%, 9.051 mg/l of Phosphorous and 1,205 Cmol/kg
of Potassium. Generally, Nitrogen is the soil nutrient
that is highly lost with an estimated amount of 90
kg/ha/y. the highest amount of N lost is found in
cropland about 173.4kg.ha/y while forestland loses the
lowest amount of N estimated about 14.45kg/ha/y. the
highest loss of nutrients amount of P and K are also
observed in cropland with respective amount of
56.82kg/ha/y and 147.89kg/ha/y. These soil nutrients
losses have a huge impact on soil fertility reduction,
because the soil fertility is made at 80% of these three
elements (N, P and K). This average value of soil loss in
the catchment, which is estimated to be about 135t/ha/y,
naturally indicates 90 kg/ha/y of N, 15kg/ha/y of P, and
74kg/ha/y of K. If three or five consecutive years of the
same soil loss amount occur, soil fertility will be gone,
and we will be left with a marginal soil unsuitable for
cultivation. This study recommends the consideration of
soil erosion control measures for all government plans to
increase agricultural productivity through
intensification and commercialization and suggest to
conduct more research for other watershed to know
exactly the amount for of soil and nutrient loss.
Keywords :
Soil loss, Soil Fertility , GIS and Remote Sensing, RUSLE, Sebeya Catchement
