INFLUENCE OF RICE STRAW COMPOST AND MICROBIAL CONSORTIUM ON ZINC AVAILABILITY IN SOIL AND FORTIFICATION IN MAIZE (Zea mays L.)
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Date
2017
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Acharya N.G. Ranga Agricultural University
Abstract
The continued investigations on yield maximization of maize are much progress
throughout Asian countries. Although much work has been carried out on all the macro and
micronutrients based on needs for sustaining maize productivity, the work related to the
biofortification of Zn utilizing rice straw compost and microbial consortium is very much
limited in our country, in spite of escalating costs and adulteration of Zn mineral fertilizers.
Keeping in view the scenario, incubation and field experiments were conducted for two
consecutive years (2014-15 and 2015-16) on sandy loam and sandy clay loam soils of
Agricultural college farm, Bapatla, India. The experimental soil and rice straw compost was
analysed for available nutrients prior to imposing treatments.
Initially, an incubation study was laid out in a factorial completely randomized design
for determining the release rate of zinc in the sandy loam and sandy clay loam soils. The
treatments consisted of six levels of ZnSO4.7H2O at 0, 6.25, 12.5, 18.8, 25 and 31.3 mg kg-1
under four factors viz., control (F1), rice straw compost (RSC) (F2), microbial consortium
(MC) (F3), RSC+MC (F4) replicated thrice. Soil was incubated at 30±1°C for 90 days by
maintaining moisture at field capacity level. DTPA extractable Zn was analysed at each 15
days interval up to 90 days.
Field experiments were laid out in split plot design, keeping three zinc solubilizers viz.
RSC, MC and their combination (RSC+MC) and control as main-plot treatments with six
graded levels of ZnSO4.7H2O viz. 0, 12.5, 25.0, 37.5, 50.0 and 62.5 kg ha-1
in sub-plots and
replicated thrice. Popular cultivar of maize, 30 v 92 used as test crop. The experimental soils
(0-15cm) was slightly alkaline in reaction, low in organic C and available nitrogen and
medium in available phosphorus and potassium. Other standard package of practices was
followed uniformly for all the plots.
Results showed that rice straw compost and microbial consortium in combination
maximized the release of Zn at all the periods of incubation in both the soils. Maximum
release of Zn was observed at 60th day of incubation in sandy loam soils and at 45th day of
sandy clay loam soils when applied with Zn solubilizers. Without Zn solubilizers, Zn release
increased only up to 30 days after incubation in both the soils. The performance of microbial
consortium was more pronounced in sandy clay loam soils. Whereas, application of rice
straw compost showed a consistent release of DTPA extractable Zn in sandy loam soils.
Irrespective of Zn solubilizers the increase in Zn release was significant up to 50 kg ha-1
in
sandy loam soils whereas in sandy clay loam soils it was up to 37.5 kg ZnSO4.7H2O ha-1
.
Though the interaction was not significant in early stages of incubation (15 DAI), significant
interactions were recorded from 30 DAI onwards in both the soils.
Growth parameters, yield attributes, kernel and stover yield of maize were
significantly higher with the application of ZnSO4.7H2O @ 37.5 kg ha-1
in combination with
RSC+MC during both the years of study. It also ensured the availability of DTPA-extractable
Zn in soil at all the crop growth stages and elevated the Zn content in kernel and stover of
maize. Whereas, sole application of either microbial consortium or rice straw compost with
50.0 kg ZnSO4.7H2O ha-1
in sandy loam soils performed on par with the RSC+MC.
Magnitude of increase in Zn content of kernel and stover was more distinct during second
year of the study on comparison with first year.
The improvement in physical, chemical and biological parameters of the soil at harvest
of maize was higher in the RSC incorporated plots. Incorporation of RSC followed by
inoculation of microbial consortium just before sowing not only improved concentration and
uptake of macronutrients (N, P, K and S) and micronutrients (Fe, Mn, Zn and Cu) of maize
but also economise use of costly fertilizer inputs. The results further showed that 37.5 kg
ZnSO4.7H2O ha-1
as basal + rice straw compost with microbial consortium has been proved
to be superior treatment for the best management of Zn in rabi maize under sandy loam and
sandy clay loam soil conditions.
Description
D5456
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