MSc

The study entitled “Bio recycling of paddy straw for quality manure production” was undertaken during 2017-2019, at College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, with the objectives to find out an effective technology for composting paddy straw and to assess the effectiveness of paddy straw composts as potting media component on the growth, yield and quality of bhindi and to work out the economics.
The research work was carried out as two experiments, which were conducted at Integrated Farming System Research Station (IFSRS), Karamana. Under Experiment I, composts were generated from paddy straw through different methods of composting. The experiment was laid out in completely randomized block design with eight treatments and three replications during the period March to August, 2018. The treatments included vermicomposting (using earthworm species Eudrillus euginea) of paddy straw with cowdung in the ratios 8:1, 6:1 and 4:1 (T1, T2 and T3 respectively), co - composting of paddy straw with poultry manure in the ratios 8:1, 6:1 and 4:1 (T4, T5 and T6 respectively), co - composting of paddy straw with cowdung and poultry manure in the ratio 8:1:1 (T7) and microbial composting using the fungus Pleurotus (T8).
The time taken for maturation of composts, percentage recovery, quality parameters, microbial and enzymatic activity varied significantly with different composting methods. Paddy straw co - composted with cowdung and poultry manure in the ratio 8:1:1 (T7) recorded significant earliness (97.67 days) with respect to generation of mature compost. Co - composting of paddy straw with poultry manure in the ratio 4: 1 (T6) recorded significantly higher recovery (44.59 %). The treatment T6 registered a lower C: N ratio (9.54:1) and was on par with T5 and T7. It also recorded a higher CEC of 77.91 c mol kg-1 but was comparable with most of the treatments except T1, T2 and T8. The treatment T6 was found rich in plant nutrients and recorded higher N (2.67 %), P (0.93 %) and K (3.15 %) content and was comparable with T7. Co - composting treatments T5, T6 and T7 also recorded higher micro nutrient status.
The total microbial population was higher with the treatments T6 and T7. The fungal population was the highest with T6 whereas that of actinomycetes was for T7. Enzymatic activity with respect to dehydrogenase was higher with T7 (27.55 µg TPF hr -1 g-1), which was comparable to T5 and T6.
Different paddy straw composts generated from Experiment I were used as potting media component in Experiment II. The pot culture experiment was laid out in completely randomized block design with nine treatments and three replications during August to December, 2018. Potting media used was a mixture of soil, rock sand, coir pith compost and different paddy straw composts in the ratio 1:0.5:0.5:1 on volume basis (T1 to T8). In treatment T9 (control), FYM was substituted for paddy straw composts in the potting medium. The KAU hybrid variety of bhindi, Manjima (Gowreesapattom local × IC 282257) was the test crop.
The results indicated that paddy straw composts as potting media component had significant influence on growth, yield attributes, yield and quality parameters of bhindi. Potting media with co - composted paddy straw (T6 and T7) produced taller plants at all stages of crop growth. These treatments also resulted in higher and comparable leaf area at 30 DAS and 60 DAS.
Number of fruits per plant, length and weight of fruit as well as fruit yield were higher with the treatments T6 and T7. The treatment T7 also recorded earliness in flowering and attained 50 per cent flowering in 48.67 days, which was comparable to all other treatments except T8 and T9. All the quality parameters viz., crude protein, crude fibre and ascorbic acid content were favourably influenced by T7. Higher and comparable dry matter production and nutrient uptake were recorded with the treatments T6 and T7.
Organic carbon content of the potting media observed before the pot culture study was higher and comparable in all the treatments except control. The treatments T4, T5, T6 and T7 recorded higher availability of plant nutrients before the pot culture study. However, after the pot culture study, organic carbon content was higher and comparable in all the treatments in which co - composted paddy straw was used as a component (T4, T5, T6 and T7). Microbial population was higher in the treatments T6 and T7, before and after the experiment.
The net returns and benefit cost ratio were significantly higher and comparable with the treatments T7 and T6.
The results of the study revealed that co - composting is an efficient technology for producing quality manure from paddy straw. Co - composting of paddy straw with poultry manure (4:1) or with cowdung and poultry manure (8:1:1) were identified as the best methods for production of nutrient rich compost with high recovery within a short period of time (97.67 days and 108 days respectively), compared to vermicomposting and microbial composting. Substituting these composts instead of FYM in potting medium (T6 and T7) resulted in better growth, yield attributes, yield and net income for bhindi. With respect to quality parameters, paddy straw co - composted with cowdung and poultry manure in the ratio 8:1:1 as potting media component was found superior.