MSc.

The research entitled “Evaluation of fortified humic acids from growbag
mixtures as phytotonic in Okra [Abelmoschus esculentus (L.) Moench]” was
undertaken with an objective to study the physicochemical characteristics and
microbial enumeration of different growbag mixtures and the effect of their humic
acids fortified with multinutrient mixture on growth, yield and quality of okra.
The study consisted of two parts, an incubation study and a crop study in grow
bags. Incubation study was carried out for a period of three months maintaining
60% of water holding capacity. Conventional composition of growbag media, soil
+ sand + FYM. The third component FYM was replaced by various composts to
form 6 treatments. T1- soil + sand + FYM, T2 -soil + sand + coirpith compost, T3-
soil + sand + vermicompost, T4- soil + sand + desi cowdung with assorted farm
waste soil, T5- sand + soil+ desi cowdung mixed with straw and Gliricidia, T6-
soil + sand + composted kitchen waste using composting inoculum. Incubated
mixtures were sampled 6 times and analysed for physicochemical properties and
microbial load at fortnightly intervals. Humic acids were extracted from
incubation mixtures and were characterised and fortified with multinutrient
mixture.
The effect of multinutrient fortified humic acids were assessed in the
growbag containing routine potting mixture using okra variety Varsha Uphar as
the test crop during January 2017- April 2017 as per POP recommendations. The
study consisted of eight treatments in which HA1 to HA6, were humic acids
extracted from the incubated growbag media of different composition and
fortified with multinutrient mixture as T1 to T6 respectively, T7- water spray and
T8- extractant spray (0.5 N NaOH). Foliar application of treatments at 0.5 %
concentration were given at fortnightly intervals throughout the crop period. The
plant samples were analysed at fifty percent flowering and at final harvest.
Incubation study recorded neutral to alkaline pH in all media except
coirpith medium (5.49 - 7.5) and kitchen waste inoculum compost (8.75-10.4). EC
of the growing media was non saline in all media except kitchen waste inoculum
compost (7.15 - 8.50 d Sm-1). Available N content was highest in kitchen waste
inoculum compost (703.0 kg ha-1) and all other media were in low to medium
range. Available P content was highest in vermicompost medium (93.9 kg ha-1).
Available K was high in all media except coirpith medium where it was low to
medium and the highest K content was recorded in kitchen waste inoculum
compost (9893 kg ha-1). Ca content was sufficient throughout the incubation in all
media except coirpith during the first fortnight (103.3 mg kg-1). Available Mg
was found to be deficient in coirpith, vermicompost and kitchen waste during the
first fortnight. Available B was highest in kitchen waste compost (6.71 – 3.50 mg
kg-1). Generally, the availability of other micronutrients (Fe, Mn, Cu and Zn) were
not significantly influenced by the composition of the growth media.
Microbial enumeration of incubated samples showed highest bacterial
count from vermicompost (8.88 log cfu /g soil). Fungal population was found to
be maximum in coirpith compost (5.39 log cfu/g soil) and highest count of
actinomycetes was noted in medium with desi cowdung and farm waste. Humic
acids extracted from the vermicompost growth media showed a higher total
acidity of 12 meq g-1 of humic material. Content of humic acids was the highest in
vermicompost media. Time taken for pH stabilization of humic acids was highest
for desi cowdung + farm waste medium.
Crop study in growbag revealed that different humic acids fortified with
multinutrient mixture have significant effect on growth and yield of bhindi.
Application of vermicompost HA (T3) recorded best biometric characters and
yield characters viz., days to flowering (36 days), number of fruits per plant (24
no.), average fruit weight (17.1 g) and a highest yield of (573.15 g plant-1). T3 also
showed maximum keeping quality (9 days) and highest crude protein content
(15.40 %) in fruit. B: C ratio (1.76) was also highest in T3.
The results of plant nutrient analysis indicated that T3 (vermicompost HA)
has the highest content of total N (2.80%) and K (2.52 %), while T6 recorded
highest content of P (0.66%) which was on par with T3. The N, P, K status of T3
was found to be positively correlated with yield. Content of secondary nutrients
was also the highest in T3.
Hence it may be concluded that composition of growth media has
significantly influenced quantity and quality of humic acids. In the incubation
study T6 (kitchen waste compost) recorded the highest nutrient content followed
by T3 (Vermicompost). However, the highest humic acids content was noted in
the medium containing vermicompost comparing the effects of fortified humic
acids, best results in crop study were shown by the vermicompost HA (T3),
followed by the treatment which received HA extracted from medium containing
desi cowdung + assorted farm waste (T4). Hence humic acids extracted from
growing media containing vermicompost, fortified with multinutrient mixture can
be recommended as a phytotonic.