Spatial and temporal variability of soil fertility under rainwater harvesting systems: a case study of Makanya river catchment
Loading...
Date
2004
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Sokoine University of Agriculture
Abstract
A study was conducted to assess the spatial and temporal variability of soil fertility
under rainwater harvesting (RWH) systems in three villages along the toposequence
on the Makanya river catchment, Same district, Tanzania. The study aimed at
assessing the soil fertility status and patterns along the toposequence, mapping
spatial patterns of soil fertility under RWH, identifying and determining the nature
and magnitude of the factors causing soil fertility changes under RWH systems along
the toposequence within the cropping seasons, and assessing spatial and temporal
variability of soil fertility within selected fields under RWH systems in Makanya
village. Random soil samples were collected from Makanya, Mwembe and Tae
villages and were used for the characterization of physical and chemical soil
properties on the catchment. Runoff water samples were collected and analysed for
plant nutrients in the runoff. GPS and GIS were used for positioning both soil and
water sampling points and to establish geospatial information database and generate
maps of the study area. Geostatistical analysis was done to carry out soil fertility
surface interpolation. Soil fertility management practice data were collected through
a questionnaire survey and analysed using SPSS software. The study revealed that,
more than 92% of 144 interviewees were practicing RWH systems in the study area.
The soil fertility attributes showed that, total nitrogen was very low to medium level
(0 - 0.5 %). Soil pH ranged from strongly acid to moderately alkaline. Exchangeable
K on the upper zone was very low (0-0.13 cmol(+)/kg) for the majority of samples
(62 %), whereas available P was adequate (39.49 - 81.16 mg P /kg soil) only on the
lower zone. Fertility attribute maps on the mid and upper zone tended to be
systematically distributed following the slope facet, while on the lower zone, maps
showed the patterns distribution to follow availability of harvested rainwater.
Generally, most of the soils under rainwater harvesting in the area had low fertility
status attributable to low organic carbon, total nitrogen and potassium, thus required
improvement for high and sustainable crop yields.
Description
Dissertation
Keywords
Rain water harvesting, Soil fertility, Rainwater harvesting systems