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Wiklund, Jonna, 2017. Effects of wood ash on soil fertility and plant performance in southwestern Kenya. Second cycle, A2E. Uppsala: SLU, Dept. of Soil and Environment



A field experiment was conducted in Kisii county, southwestern Kenya from February
to May 2017. The purpose of the study was to examine the effect of wood ash
on soil pH, soil nutrient content and productivity of common bean (Phaseolus vulgaris
L.) and compare it to effects from mineral fertilizer (Diammonium phosphate,
DAP) application and liming using calcium carbonate, CaCO3. Two weeding approaches
with different timings were also included in the study. The experiment
was two-factorial with six fertilizer/lime treatments (recommended dose of mineral
fertilizer, mineral fertilizer dose used by farmers, mineral fertilizer dose used by
farmers with lime, lime only, wood ash and a control where no amendments were
made) and two weeding treatments (early and farmers practice) replicated four
times. Soil samples were collected before experiment establishment and four weeks
after the experiment was established. Data was taken on soil pH, available P, exchangeable
base cation content, CEC and BS. Parameters for plant growth and
development recorded were emergence, days to developmental stage V4 and R1,
number of flowers and pods, bean yield and plant biomass. This was collected
throughout the growing season. Data were analysed using ANOVA and Spearman’s
correlation coefficient.

The soil pH after treatments was found to be significantly higher in the ash
treatment compared to the control and the treatments where only mineral fertilizer
and no lime was applied. Lime application had no significant effect on the soil pH.
However, base saturation was higher in the treatments where lime was applied than
in the other treatments. No significant effects by the different treatments were recorded
on available P or exchangeable base cations. The number of flowers and pods
per plant was higher in plots treated with ash than in those treated with lime. The
harvested plant biomass was lower in the lime treatment than in the other treatments.
No significant differences were found in bean yield. Plant performance did
not differ between weeding treatments, nor were there any significant interactions
between fertilizer/lime treatment and weeding approach. Based on these results ash
successfully increased soil pH. There are also indications that wood ash can provide
other nutrients to meet the requirement of beans when grown under these conditions.
Studies performed over a longer period of time would be required to see long
term effects on soil pH, nutrient status and plant performance.

Main title:Effects of wood ash on soil fertility and plant performance in southwestern Kenya
Authors:Wiklund, Jonna
Supervisor:Dahlin, Sigrun and Onyango, Cecilia
Examiner:Kirchmann, Holger
Series:Examensarbeten / Institutionen för mark och miljö, SLU
Volume/Sequential designation:2017:16
Year of Publication:2017
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:NY003 Agricultural Programme - Soil/Plant 270 HEC
Supervising department:(NL, NJ) > Dept. of Soil and Environment
Keywords:fertilization, lime, nutrient depletion, soil acidification, smallholder farmers, Phaseolus vulgaris, Kenya
Permanent URL:
Subject. Use of subject categories until 2023-04-30.:Fertilizing
Soil science and management
Soil fertility
Deposited On:02 Nov 2017 11:21
Metadata Last Modified:02 Nov 2017 11:21

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