TY - JOUR
T1 - Fluxes and retention of sediment and nutrients in valley bottom fish and rice farms and wetlands
T2 - impacts on surface water
AU - Uwimana, Abias
AU - van Dam, Anne A.
AU - Wali, Umaru G.
AU - Irvine, Kenneth
N1 - Funding Information:
This study was conducted as part of a cooperation between the University of Rwanda (former National University of Rwanda) and IHE Delft Institute for Water Education, The Netherlands. Financial support was provided by NUFFIC, The Netherlands through the NICHE programme and the Netherlands Fellowship Programme.
Funding Information:
The Netherlands Fellowship Programme (NFP) provided the research funds through the Nuffic Multi Year Agreement (NUFFIC-MYA).
Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Nature B.V.
PY - 2022
Y1 - 2022
N2 - This study compares nutrient and sediment retention among rice and fish farms and wetlands in valley bottoms in southern Rwanda. Small-scale wetland, rice and fishpond experimental systems were established to measure sediment, nitrogen (N) and phosphorus (P) fluxes during a 9-month period. There were significant differences in the processes contributing to sediment, N and P retention in the three systems related to system characteristics, management practices, and seasons. Overall nutrient retention was higher in the rice and fish systems, but these systems had higher inputs and outputs of sediment and nutrients. In rice plots, resuspension and discharge of sediment and nutrients to the outflow were caused by ploughing and weeding during the first 3 months of the culture period. In fishponds, nutrients and sediment discharge were associated with water renewal and sediment removal during the last 5 months of the farming period. The undisturbed wetland plots had the lowest outflows of sediment and nutrients. Nutrient uptake and accumulation in biomass was much higher in rice and wetland vegetation than in fish biomass. In fishponds and wetlands, nutrients accumulated in soil, whereas rice plots showed a decrease or depletion in nutrient storage. To increase nutrient utilization at the plot level, sediment and nutrient discharge from land preparation and rice transplanting should be reduced by better farm practices. Within a catchment, nutrient flows can be integrated by using fishpond sediments for crop farming, by incorporating natural wetlands in crop rotations or using them as buffer zones.
AB - This study compares nutrient and sediment retention among rice and fish farms and wetlands in valley bottoms in southern Rwanda. Small-scale wetland, rice and fishpond experimental systems were established to measure sediment, nitrogen (N) and phosphorus (P) fluxes during a 9-month period. There were significant differences in the processes contributing to sediment, N and P retention in the three systems related to system characteristics, management practices, and seasons. Overall nutrient retention was higher in the rice and fish systems, but these systems had higher inputs and outputs of sediment and nutrients. In rice plots, resuspension and discharge of sediment and nutrients to the outflow were caused by ploughing and weeding during the first 3 months of the culture period. In fishponds, nutrients and sediment discharge were associated with water renewal and sediment removal during the last 5 months of the farming period. The undisturbed wetland plots had the lowest outflows of sediment and nutrients. Nutrient uptake and accumulation in biomass was much higher in rice and wetland vegetation than in fish biomass. In fishponds and wetlands, nutrients accumulated in soil, whereas rice plots showed a decrease or depletion in nutrient storage. To increase nutrient utilization at the plot level, sediment and nutrient discharge from land preparation and rice transplanting should be reduced by better farm practices. Within a catchment, nutrient flows can be integrated by using fishpond sediments for crop farming, by incorporating natural wetlands in crop rotations or using them as buffer zones.
KW - African wetlands
KW - Eutrophication
KW - Sustainable agriculture
KW - Wetland agriculture
KW - Wetland conversion
KW - Wise use of wetlands
UR - http://www.scopus.com/inward/record.url?scp=85123846908&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85123846908&partnerID=8YFLogxK
U2 - 10.1007/s11273-021-09854-0
DO - 10.1007/s11273-021-09854-0
M3 - Article
AN - SCOPUS:85123846908
JO - Mangroves and Salt Marshes
JF - Mangroves and Salt Marshes
SN - 0923-4861
ER -