Effects of liming and phosphorus application on the growth and nodulation of soybeans (glycine max (l.) merr.) cv "hill" in acid soils
Abstract
A study on the effects of lime and phosphorus
application on the growth and nodulation of soybeans
(Glycine max (L.) merr.) cv "Hill" was conducted in
a factorial experiment under greenhouse conditions
using two strongly acid soils (a umbric andosol from
Gituamba and a humic nitisol from Kisii) The soils
were limed with calcium carbonate (CaC03) based on the
levels of exchangeable Al present in the soil. The
phosphorus levels were 0, 50, 100 and 150 kg P/ha,
applied as triple superphosphate (TSP). Half the
seeds were inoculated with Rhizobium strain, NUM 508
before planting and half were not. The plants were
harvested 51 days after planting and the variables
measured were nodule number and nodule dry weight,
total dry matter yield and uptake of N, P, K, Ca and
Mg.
Inoculating the seeds significantly increased
nodulation. The nodule numbers and nodule dry weights
increased significantly with initial liming. The
application of 100 Kg P/ha significantly increased
nodulation. There was no interaction between lime and
phosphorus with respect to nodulation.
Initial liming (3 meq CaC03/100g) increased the
shoot dry matter yield significantly (P=O.OS) in
Gituamba soil. Further increases in lime application
did not affect the yield significantly. In Kisii
soil the application of 3 and 6 meq CaC03/100g
increased the shoot dry matter yield significantly
(P=O.OS). Application of 9 meq CaC03/100g decreased
the yield but not significantly.
The highest shoot dry matter yield occurred at
the highest level of phosphorus (150 kg P/ha). There
was a positive interaction between lime and
phosphorus with respect to dry matter yield in Kisii
soil. The application of P increased the dry matter
yield significantly at lime levels 3 and 6 meq
CaC03/100g. At the highest level of lime application
(9 meq CaC03/100g) the yields decreased though not
significantly.
The application of phosphorus significantly increased
the uptake of N, P, K, Ca and Mg. The growth response
to liming and phosphorus application was attributed
to the reduction of exchangeable. Significant
increases of dry matter yield with increasing levels
of P application suggest that further investigations
with regard to optimum P level would be advisable.
Citation
Master of Science in Soil SciencePublisher
University of Nairobi Department of Soil Science