MSc

An investigation entitled ‘Utilization of dairy industry solid waste as an organic waste in soil productivity’ was carried out at College of Agriculture, Vellayani to study the feasibility of using dairy industry solid waste (dsw) as an organic source for improving soil productivity. The experiment consisted of four parts viz., characterization of dsw, vermicomposting of dsw, incubation study to monitor the changes in physical property, nutrient availability and microbial population in soil and pot culture experiment to study the influence of cdsw on amaranthus. The dairy waste collected from TRCMPU Ltd. at Ambalathara, Thiruvananthapuram was used in the present study. The physico-chemical and microbial analysis of dsw were done using suitable analytical procedures.
Vermicomposting was carried out in pits of size 1 m x 0.5 m x 0.5 m using vegetable wastes, ground dsw and cowdung in the ratio 5:3:1 by the activity of earthworm Eudrillus eugeniae. Vermicompost was prepared according to package of practices recommendations of Kerala Agricultural University.
Incubation study was conducted at the laboratory to monitor the nutrient release pattern and changes in physical properties and microbial population in soil. Two kg of soil was taken in plastic containers of uniform size and incubated at 60 per cent field capacity for three months after application of treatments. The experiment was laid out in CRD with seven treatments viz., T0 - absolute control, T1 – soil + 25 g fym, T2 – soil + 25 g dsw, T3 – soil + 12 ½ g fym + 12 ½ g dsw, T4 – soil 12 ½ g fym + 6 ¼ g dsw, T5 – soil + 12 ½ g cdsw, T6 –soil+ 6 ¼ g cdsw. Physico-chemical and microbilogical properties of soil were analysed at an interval of 1, 2, 4, 6, 8 and 12 weeks.
The pot culture experiment was conducted to study the influence of dsw on growth, yield and quality of amaranthus. It was laid out in CRD with a treatments viz., T0 – absolute control, T1 – fertilizers and fym as per POP, T2 – POP fertilizers and 50 t ha-1 cdsw, T3 – POP fertilizers + fym 25 t ha-1 and cdsw 25 t ha-1, T4 – POP fertilizers and fym 25 t ha-1 and cdsw 12 ½ t ha-1, T5 – 2/3 N + full NPK of POP + fym 25 t ha-1 and cdsw 25 t ha-1, T6 – 2/3 N + full PK of POP and fym 25 t ha-1 + cdsw 12 ½ t ha-1, T7 – ½ N + full PK of POP + fym 25 t ha-1 + cdsw 25 t ha-1, T8 – ½ N + full PK of POP and fym 25 t ha-1 and cdsw 12 ½ t ha-1. Observations on various biometric and yield parameters have been recorded and analysis of plant sample were done at three stages of growth of plant viz., 30, 45 and 60 days after transplanting. The nutrient status of soil after the experiment was also analysed.
Analysis of physico-chemical and microbial properties of dsw revealed that it had a near neutral pH (6.5) and it contained 37.5 per cent organic carbon, 5.80 per cent N, 2.04 per cent P, 0.71 per cent K, 1.69 per cent Ca, 1.58 per cent Mg, 1.71 per cent Fe, 159 mg kg 1 Mn and 1084 mg kg 1 Zn. Population of bacteria, fungi and actinomycetes in dsw were 13.3 x 106, 11.6 x 104 and 1.3 x 104 respectively.
The results of the study revealed that vermicomposting can be successfully done in dsw using Eudrillus eugeniae. Vermicompost with a C : N ratio of 11.12 was obtained after 60 days of composting. The final compost contained 3.12 per cent N, 1.97 per cent P, 1.81 per cent K, 2.05 per cent Ca, 3.55 per cent Mg, 0.80 per cent Fe, 230 mg kg-1 Mn, 408 mg kg-1 Zn and 44 mg kg¬-1 Cu. Number of bacteria, fungi and actinomycetes in the compost at maturity stage were 42.6 x 106, 38.6 x 104 and 21.3 x 104 respectively.
From the incubation study, it can be seen that nutrient content of soil increased upto 6-8 weeks in all treatments except T0 followed by a gradual decline. All nutrients except Cu were more on cdsw applied treatment in the initial period. Cu content was more in fym applied treatment. Nutrient availability was more from fym applied treatments during later periods of incubation. Bulk density of soil decreased in all treatments except T0 upto six weeks of incubation followed by a gradual increase in 8 and 12 weeks. Treatment in which cdsw was applied at higher dose showed the lowest bulk density. Upto six weeks the highest water holding capacity was noticed in cdsw applied treatments, after that fym applied treatments showed highest water holding capacity. Bacterial and fungal population reached the peak in sixth week and then declined. Upto eight weeks the effect of treatments was non significant with respect to actinomycete population.
The pot culture experiment indicated the influence of cdsw on growth, yield and quality of amaranthus. Biometric and yield observation have proved the superiority of cdsw over fym. Beta-carotene content was more in cdsw applied treatments. Total yield and B:C ratio were the highest when cdsw was used as a partial substitute for fym.
Physico-chemical properties of soil after the pot culture experiment revealed that pH, EC, organic carbon and available nutrients increased in all treatment except in T0 compared to the initial soil. pH, EC, organic carbon, available P, Ca and Fe were the highest in T2 which received cdsw at higher dose while the available N, K, Mg, Mn, Zn and Cu were the highest in T1 which received fym.
From the results it can be concluded that effective biomanagement of dsw can be carried out using Eudrillus eugeniae. Better availability of nutrients especially nitrogen from cdsw compared to fym immediately after application as evidenced by incubation study is advantageous for short duration leafy vegetables. Use of cdsw can reduce the use of fym partially or fully in amaranthus. Fertilizer N can also be reduced to the extent of 1/3 of POP recommendation.