Effect of zinc and microbial inoculation on soil enzyme activities for maize (Zea mays L.) in red soil

Abstract

A Field experiment was conducted in red soils
in order to study the soil enzyme activities viz.,
Dehydrogenase, Urease and Phosphatases for maize using
Arbuscular mycorrhizal (AM) fungi and Zinc Solubilizing
Bacteria (ZSB) in combination with graded levels of ZnSO4.
Treatment consisted of two factors viz., Microbial
inoculation (M1
: control, M2
: AM fungi, M3
: ZSB and M4
:
M2 
+ M3
) and graded levels of ZnSO4
 (S1
: 0, S2
: 12.5, S3
:
25, S4
: 37.5, S5
: 50 kg ha-1 and S6
: 0.5 % foliar spray @
45 and 65 DAS) replicated three times in FRBD. The
combination of AM and ZSB had enhanced the soil
enzyme activities viz., Dehydrogenase, Urease and
Phosphatases at vegetative, tasselling and harvest stage
of crop growth. However, the Dehydrogenase, Urease
and Phosphatases activity was quantitatively increased
during tasselling stage due to microbial population, root
activities and root exudates higher during tasselling stage.
Increased doses of ZnSO4
 application had positive effect
on the soil enzyme activities viz., Dehydrogenase, Urease
and Phosphatases. Combined application of AM and ZSB
along with 50 kg of ZnSO4 
ha-1 had recorded the highest
soil enzyme activities at vegetative, tasselling and harvest
stages. However, the dehydrogenase, urease and harvest
stage was slightly increased at tasselling stage than
vegetative and harvest stage. The application of graded
doses of ZnSO4 
in combination with AM and ZSB had also increased the soil enzyme activities viz.,
Dehydrogenase, Urease and Phosphatases, which in turn
increased the fertility status of soil.