MSc

The research work entitled “Bio recycling for nutrient management and yield
enhancement of rice (Oryza sativa L.)” was conducted at College of Agriculture,
Vellayani during 2020-2022 with the objective to identify a suitable crop nutrition
package integrating bio resources and inorganic fertilizers for yield enhancement in
rice.
The study was carried out as two experiments at the Integrated Farming System
Research Station (IFSRS), Karamana. The first experiment included production of
composts using different organic substrates viz., rice chaff, water hyacinth, salvinia and
wild taro found associated with rice-based cropping systems. The experiment was
carried out from September to December, 2021. The statistical design followed was
Completely Randomized Design (CRD) with eight treatments and three replications.
From treatments T1 to T4, different substrates (rice chaff, water hyacinth, salvinia and
wild taro) were co-composted using cow dung and poultry manure in the ratio 4:1:1
(v/v). The substrates were co-composted using cow dung and goat manure in T5 to T8.
The time taken for compost maturation, percentage recovery of composts and
quality parameters of different composts were found to vary significantly with different
co-composting methods. Co-composting of wild taro with cow dung and goat manure
(T8) recorded significant earliness in maturity of compost (64 days) and was comparable
to T6 (water hyacinth + cow dung + goat manure). Rice chaff co-composted with cow
dung and poultry manure (T1) recorded highest recovery of compost (29.85%).
Treatment T8 recorded a narrow C:N ratio (12.33) and was comparable to T6 (12.58).
The different composts varied in their nutrient contents also. Compost generated from
T6 recorded higher N (2.28 %), P (1.08 %) and K (2.7 %) contents. T2 (co-composting
water hyacinth with cow dung and poultry manure) recorded significantly higher micro
nutrient contents and was comparable to T6. Co-composting of salvinia with cow dung
and goat manure (T8) recorded the highest boron content. The content of silicon was
significantly higher in T5 (rice chaff + cow dung + goat manure) and was comparable
to T6. Content of plant nutrients was the lowest in T5.

Different composts generated from Experiment I were used for crop nutrition of
rice var. Uma. The field experiment was conducted from last week of January to first
week of June, 2022 and was laid out in Randomized Block Design with 9 treatments
and three replications. Following the recommended dose of nutrients (90:45:45
kg ha-1
) for rice and based on soil test data, the NPK dose decided for the experimental
field was 70.2: 16.6: 42.3 kg ha-1
. For treatment T1 (control), the KAU Package of
Practices Recommendation for crop nutrition was followed on soil test data basis. From
treatments T2 to T9, respective composts generated under Experiment I were provided
as basal dose @ 2.5 t ha-1
. This was followed by 75 per cent of the recommended
nutrients as chemical fertilizers and 25 per cent through respective composts, on N
equivalent basis. Full phosphorus was given as basal; whereas N and K were provided
in equal splits as basal and at PI stage.
The results revealed that treatments had significant influence on the growth,
yield and physiological parameters of rice. Basal application of compost 6 @ 2.5 t ha-1
followed by 25 per cent of the recommended nutrients through compost and the rest
through chemical fertilizers (T7) recorded taller plants at PI and harvest, tiller count at
all the growth stages and dry matter production at harvest. Physiological parameters
like leaf area index and SPAD Chlorophyll Meter Reading were also the highest with
T7. Application of different composts significantly influenced the weed dry weight at
20 and 40 DAT and significantly lower weed dry weights were recorded with T6. Grain
yield (2933 kg ha-1
) as well as yield attributes were significantly higher with T7.
Soil nutrient status after crop harvest was significantly influenced by different
treatments. The P and K status of soil was significantly higher in T7 (35 and
167 kg ha-1
) and was comparable to T1. Different treatments could not significantly
influence the soil pH, EC, soil organic carbon and available nitrogen after the
experiment. Nutrient uptake by crop was significantly higher in T7 and remained
comparable with T8 and T1. Regarding economics, T7 recorded the highest net income
(₹ 67, 476 ha-1
) and B:C ratio (1.59). This was followed by T1 with net returns
₹ 55, 837 ha-1
and B:C ratio 1.58.
The present study revealed that bio resources like aquatic weeds and rice chaff
associated with rice-based system could be value added through co-composting using

locally available organic manures to generate quality composts. Application of water
hyacinth compost (water hyacinth + cow dung + goat manure in 4:1:1 ratio v/v) @
2.5 t ha-1
as basal dose followed by 75 per cent of RDN as inorganic and 25 per cent as
water hyacinth compost on N equivalent basis could be recommended as a prospective
bio recycling option for higher yield and economics of rice during the summer season.