Adaption, Productivity and Return on Investment of Integrated Soil Fertility Management Technologies among Sorghum Farmers in Tharaka Nithi County, Kenya
Abstract
Declining soil fertility poses a serious threat to food production and food security to most
farming households. Integrated Soil Fertility Management (ISFM) comprising the
combination of organic and mineral fertilizer and other practices such as cereal-legume
intercropping, diversified crop rotation and farmers’ knowledge has been promoted in
various countries in Sub-Saharan Africa (SSA) including Kenya. This study aimed at
evaluating adoption, productivity and return to investment of ISFM technologies among
sorghum farmers in Tharaka-Nithi County, Kenya. Cross-sectional data was obtained
from a sample of 370 sorghum farmers through multistage stratified random sampling
technique. The study employed a semi-structured questionnaire that was administered to
the respondents to obtain relevant data. The SPSS and STATA softwares were used to
analyze data and results presented using descriptive and inferential statistics. Cragg`s
Double Hurdle model was used to assess the influence of socioeconomic and institutional
factors on the adoption intensity of ISFM technologies among sorghum farmers.
Propensity Score Matching (PSM) and (Inverse Probability Weighting Regression)
IPWRA models were applied in determining the effect of selected ISFM technologies on
sorghum productivity among farmers. Budgetary technique was used to evaluate return
on investment while Endogenous switching regression (ESR) model was used in
determining the effect of selected ISFM technologies on return on investment (ROI) of
sorghum. The results revealed that gender, dependents, farming goal for subsistence
purpose, decision on information use, farm size, extension services, research awareness,
ISFM awareness and ISFM access, significantly affected household decision on adoption
of ISFM technologies. On the other hand, gender of household head, farm size, main
source of agricultural information and formal agricultural training had significant
influence on adoption intensity of ISFM technologies. The first stage results of PSM
shows that extension services and ISFM awareness was significant in influencing adoption
of the ISFM technologies positively while farming goal for subsistence, decision on
information use and cost of ISFM affected adoption negatively. The second stage
determined average treatment effect on adopters of ISFM and the results was 1.268, 1.120
and 1.192 bags of sorghum for nearest neighbor, kernel based and radius matches
respectively. The results reveal that farmers who use ISFM technologies would produce
4.696 bags of sorghum compared to 1.424 bags obtained from not using the technologies.
The expected ROI of farmers growing sorghum under ISFM technologies was reported to
be 1.945 while that of non-adopters was 0.783. Based on the counterfactual outcomes ROI
would have was 2.409 for adopters and 0.734 for non-adopters. It was therefore concluded
that socio-economic and institutional characteristics continue to influence the choice to
adopt ISFM technologies. The performance of adopted technologies on productivity and
returns on investment as well remains high compared to non-adoption. There is a thus a
crucial need for integration of determinants surrounding adoption and adoption intensity
of ISFM technologies in policy making and planning processes to enhance decision on
pro-adoption, which will improve sorghum productivity and returns in Tharaka-Nithi County.