MSc

A study entitled ‘Organic manure seed pelleting for enhancing soil health and productivity of rice’ was conducted from 2017 to 2019 in the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani, with the objective to develop seed pellets of rice using organic manures and microbial inoculants and to study its effect on soil properties, seedling vigour, growth and yield of rice var. Uma. The study consisted of two parts namely preparation and characterization of organic manure seed pellets and pot culture experiment to evaluate the organic manure seed pellets.
Organic manure seed pelleting materials used were FYM + Azospirillum + Phosphobacteria (T2), vermicompost + Azospirillum + Phosphobacteria (T3), bioslurry flakes + Azospirillum + Phosphobacteria (T4), charcoal powder + Azospirillum + Phosphobacteria (T5), fly ash + Azospirillum + Phosphobacteria (T6), pongamia leaf powder + Azospirillum + Phosphobacteria (T7) and bioslurry + plant extracts + Azospirillum + Pseudomonas (T8: Farmer practice). Seeds alone without pelleting (T1) was used as control. Carrier based inoculum of Azospirillum and Phosphobacteria were used at the rate of 5 g kg-1 and fenugreek paste was added at the rate of 25 g kg-1 as adhesive.
Pelleting materials were analysed for their physical, chemical and nutritional properties as well as enzymatic activity and organic acid content. The results on characterization of pelleting materials revealed that T6 recorded the highest bulk density of 1.07 Mg m-3. Highest water holding capacity was recorded by T7
(380.8 %). All treatments had near neutral to slightly alkaline pH. T4 recorded the highest EC of 3.502 dS m-1. Regarding the nutritional properties, there was no significant difference among the treatments for ammoniacal and nitrate nitrogen. T4 had the highest content of P (1.36 %), Ca (3.46 %), Mg (2.57 %), S (1.03 %),
Mn (398.6 mg kg-1), Zn (128.6 mg kg-1) and Cu (57.00 mg kg-1) while K content was highest in T7 (1.18 %), Fe content in T6 (1.62 %) and B content in T3
(4.80 mg kg-1). T7 recorded the highest urease and acid phosphatase activity and T3, the highest dehydrogenase activity (312.0 µg of TPF g -1 soil 24h-1). Humic and fulvic acid content were maximum in T3 with 28.52 % and 23.76 %, respectively.
Seedlings raised from pellets were separated after 15 days and pellets were analysed. pH and EC were highest in T3. Availability of nutrients were highest in T4 except for Mg and B where T3 recorded the highest Mg content and T6 the highest B content. Enzymatic activity and organic acid content followed similar trend as initial. Germination per cent in all treatments except T7 were 100 per cent. T5 took few days to attain 50 per cent germination while it took more days for T7 to achieve 50 per cent germination. Seedling studies revealed that T2 was superior to all other treatments for mean root length, mean shoot length, seedling length and vigour indices.
The second part of the experiment was conducted to find the effect of organic manure seed pelleting on growth and yield of rice. At active tillering stage, T4 registered the highest root length (33.05 cm) which was on par with T3 and T2. It also recorded maximum root and shoot biomass. Maximum plant height was recorded in T4 at active tillering, panicle initiation and harvest stages with values of 64.85 cm, 86.63 cm and 92.33 cm, respectively. Maximum number of tillers were observed in T4 at active tillering stage and in T3, at panicle initiation and harvest stages. Leaf Area Index (LAI) was highest for T4 (5.09) which was on par with T6, T2 and T3. With respect to chlorophyll content, there was no significant difference among the treatments. The yield attributes, namely, number of productive tillers (16.50), number of spikelets per panicle (159.7) and filled grain per cent
(94.16 %) as well as grain yield (54.84 g pot-1) and straw yield (66.10 g pot-1) were highest in T3. T4, T5, T6 and T8 recorded same values (0.47) and were comparable with T7 and the lowest was recorded by T1 and T2 (0.44). There was no significant difference in length of panicle and 1000 grain weight.
T4 registered the maximum period of retention of flag leaf. However, the treatments had no significant effect on length of panicle and 1000 grain weight.
The post-harvest analysis of soil revealed that pH and EC varied significantly among the treatments. Ammoniacal nitrogen was highest in T2 while nitrate nitrogen showed no significant difference. The highest available P
(76.97 kg ha-1), K (190.4 kg ha-1), Ca (285.0 mg kg-1) and S (16.50 mg kg-1) were observed in T4. Available Mg was not significantly influenced by treatments. The available micronutrients Fe, Mn and Zn were significantly influenced by the treatment T3 recording the highest value of 41.08 mg kg-1, 11.31 mg kg-1 and
5.26 mg kg-1, respectively. There was no significant influence on available Cu. The treatments had a significant influence on available B with T4, T2 and T3 recording highest value of 0.22 mg kg-1. T4 recorded the highest starch and amylose content in grain whereas there was no significant influence of treatments on amylopectin content. Regarding the uptake of nutrients, T3 registered the highest uptake of N, K, Ca, S, Zn, Cu, B and Si in grain and shoot. P uptake in grain was highest in T4 while T3 had the maximum uptake in shoot. Mg uptake in grain and shoot were not significant.
From the study, it can be concluded that organic manure seed pelleting material prepared using bioslurry flakes, Azospirillum and Phosphobacteria (T4) contained significantly higher quantities of nutrients compared to others. Enzyme activity (dehydrogenase) and organic acid content (humic and fulvic acid) were highest in the pellets prepared using vermicompost, Azospirillum and Phosphobacteria (T3). Organic manure seed pelleting significantly increased the growth characters of rice compared to conventional dibbling method. Among the various treatment combinations, organic manure seed pelleting with bioslurry flakes, Azospirillum and Phosphobacteria (T4) and vermicompost, Azospirillum and Phosphobacteria (T3) were found to be effective in improving growth characters of rice such as plant height, number of tillers and LAI. The yield, yield attributes and nutrient uptake were highest in the treatment where vermicompost, Azospirillum and Phosphobacteria (T3) were used as the pelleting material. Seed pelleting using vermicompost, Azospirillum and Phosphobacteria (T3) and bioslurry flakes, Azospirillum and Phosphobacteria (T4) were able to maintain significantly higher quantities of available nutrients in the post-harvest soil. The beneficial effect of organic manure seed pelleting may be due to enrichment of rhizosphere region of seeds thereby promoting seed and soil relationship aiding in better growth and development.