Evaluation of the growth response of soybean (Glycine max L.) to some commercial fertilizers in the guinea savannah agro -ecological zone of Ghana
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Date
2015-04-15
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Abstract
Series of field experiments were undertaken in the Guinea Savanna agro - ecological zone of
Ghana to assess the influence of some agricultural commercial products in optimizing
soybean production. The field experiments were carried out using sixteen treatments at
Akukayili, Cheshegu and Ghulahgu during the 2012 and 2013 cropping seasons. The
treatments were replicated four times in a split – plot arranged in randomized complete block
design. Soil chemical properties evaluated in the study areas before trial establishment
indicated that the soil fertility status was below the optimum for soybean growth. The results
showed that the use of starter N (25 kg N ha
-1
) is essential to increase soybean yields in the
study area. Grain yields of 3321 and 3056 kg ha
-1
were recorded respectively for Boost Xtra
(BX) + 25 kg N ha
-1
and BX + 5O kg N ha
-1
at Akukayili where 25 kg N ha
-1
+ BX emerged
as the best treatment in enhancing both Agronomic Efficiency (AE) and Nutrient Use
Efficiency (NUE) of nitrogen. Furthermore, the sole use of Bradyrhizobium japonicum
inoculum did not significantly (P > 0.05) enhance grain yield. At Cheshegu, Fertisoil and
Bradyrhizobium japonicum inoculum treatments increased nodule dry matter accumulation
by 51% and 407% respectively relative to the control. Moreover, P90 + FS, P60 + FS and P30
+
FS produced grain yields of 3588, 3583 and 3524 kg ha
-1
respectively, which were
significantly higher (P < 0.05) than the control. Phosphorus application increased N uptake in
the order, 30 > 60 > 90 kg P ha
-1
. The use of 30 kg P ha
-1
enhanced the AE and NUE of
phosphorus when combined with Bradyrhizobium japonicum inoculum (INO) and /or
Fertisoil (FS). The emphasis on the benefit of combining more than one nutrient at a time was
clearly observed across the study locations, where combined use of the various treatments
(especially FS + N25P30
) led to an increase in nodule dry weight, biomass and grain yield
relative to their sole treatments. Also, the uptake of N and P were enhanced with the
treatment combinations than the sole applications. At Ghulahgu, the application of Boost xtra
iv
resulted in a value cost ratio (VCR) of 5 which was the highest relative to VCR‟s obtained at
Akukayili and Chesshegu.
Description
A thesis submitted to the Department of Crop Science, Faculty of Agriculture, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfilment of the requirements for the degree of Doctor of Philosophy
in Soil Science.