Agronomic and Financial Benefits of Phosphate Rock Use in Acidic Soils of Upper Eastern Kenya
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Date
2021-07
Authors
Ndeleko-Barasa, Emily Mwake
Mucheru-Muna, Monicah
Ngetich, Felix Kipchirchir
Journal Title
Journal ISSN
Volume Title
Publisher
SSRN
Abstract
A major constraint to crop production in Sub-Saharan Africa is nutrient deficiency, especially
phosphorus deficiency. Phosphorus plays a crucial role in photosynthesis but is usually
deficient in acidic soils since it is converted to less available forms, affecting crop yields. There
is a need to improve phosphorus availability to crops for maximum production. This study
assessed the impact of phosphate rock fertilizer application on maize yields, soil chemical
composition, and cost-effectiveness in Tharaka Nithi County, Upper Eastern Kenya. We set a
field experiment in a randomized complete block design (RCBD) during long rains (SR2017)
and Short rains (LR2018) seasons. The treatments were phosphate rock + manure, Tithonia
diversifolia + phosphate rock, Calcium Ammonium Nitrate (CAN) + Triple Superphosphate
(TSP), and a control. Soil samples were collected at a depth of 0-20 cm before and at the end of
the experiment for pH, P-sorption, and other soil nutrients determinations. Other auxiliary data
collected included labor and input costs besides output prices. The CAN+TSP treatment had
significantly higher grain yields, while phosphate rock on its own had the second-lowest than
the control treatment (p<0.05). We also observed a similar trend in the stover yields. Phosphate
rock combined with either manure or Tithonia diversifolia led to a significant (p<0.05) increase
in the phosphorous levels. Sole application of organics increased soil sodium and calcium while
iron levels decreased. Other than the control, all treatments significantly lowered the p-sorption
levels. However, CAN+TSP had the highest p-sorption while Tithonia diversifolia had the
lowest. During the LR2018 season, a break-even point was arrived at with all the treatments,
and the net benefit was significantly higher at P<0.05. Conclusively, the use of phosphate rock,
either solely or in combination with organic elements, was found to improve yields, soil
chemical composition, P-sorption, and very cost-effective.
Description
research paper in SSRN
Keywords
Phosphate Rock, Agronomic, cost-benefit analysis, maize yields
Citation
Ndeleko-Barasa, Emily Mwake and Mucheru-Muna, Monicah and Ngetich, Felix Kipchirchir, Agronomic and Financial Benefits of Phosphate Rock Use in Acidic Soils of Upper Eastern Kenya. Available at SSRN: https://ssrn.com/abstract=3882380 or http://dx.doi.org/10.2139/ssrn.3882380