当前世界环境

Introduction

The population of buffalo, sheep, goat and cattle in 2012 in India is 105, 71.6, 140.5, and 199.1 Million.¹They produce a huge amount of dung per day which is a good fertilizer but it is not managed in a scientific manner. Use of raw dung as such or in the form of farm yard manure causes nutrients loss. The nutrient’s content of this dung can be increased by composting. Composting is a process in which the microflora and macroflora of dung degrades the material used for composting and causes nutrients transformation by which nutrients are converted into plant available forms. When this compost is applied to soil as fertilizer then plants absorbs easily the nutrients from it and hence nutrients loss can be saved. The micro- and macroflora of composting obtains their nutrients through degradation of composite materials of composting material.Calotropis giganteais a shrub of Family- Apocynaceae and Order- Gentianales. Although the plant has many medicinal properties and used to treat fever, cough, cold, diarrhea etc but its leaves and stem produces toxic milky juice due to which it remains unutilized. In India the plant is grown at almost each and every type of lands in its wild form and its leaves has no use due to toxicity.

Based on above facts we decided to utilize the leaves ofC. giganteafor composting with mixed dung obtained from buffalo, cow, goat and sheep with the aim to obtain a good quality of compost.

Materials and Methods

Compost Preparation

Pits (2x2x2 feet) of bricks were prepared on cemented floor under shed at Biogas Research and Extension Centre, Gujarat Vidyapith, Sadara. Composting mixture comprises 10 kg mixed dung (2.5 kg dung each of buffalo, cow, goat and sheep) and 2 kg green leaves ofCalotropis gigantea．堆肥混合物was mixed well and then added into the pit. Sufficient amount of water was sprinkled during mixing of composting mixture so that no portion of material should remain dry. Filling of material in pit was recorded as zero days. After every 15 days the composting material was mixed thoroughly. Watering was done in pit to make the composting material moist.

Analysis

At 30, 60 and 90 days composting mixture was mixed well and a composite sample was taken to laboratory for its chemical analysis to determine pH (by pH meter); electrical conductivity (by conductivity meter), calcium and magnesium (EDTA titration method²), chloride (Mohr’s method²), total organic carbon,³total nitrogen,⁴available phosphorus⁵and available potassium.⁶

Results and Discussion

The results of present study showed that values of pH and electrical conductivity, decreased at 30, 60 and 90 days of composting whereas the content of calcium and magnesium remains almost same (Table 1). Degradation of organic matter produces various types of acids which results into decreased value of pH. Reduction in pH of composting material is observed by a number of workers.^7、8Decreased value of EC is related with increased concentration of various form of nitrogen like nitrate and nitrite.⁹Presence of various salts like sodium, chloride, potassium, nitrate, sulphate and ammonia in compost are reported earlier.^10，11

With composting time the content of phosphorus and potassium increased and at the end of composting the phosphorus and potassium content increased by 189.66 and 118.18%, respectively compared to their values before composting (Table 1). Transformation of minerals during composting and vermicomposting is reported earlier also.¹²

Table 1: Changes in various Physico-chemical characteristics before and after composting

Total organic carbon is lost by 58.04% at maturity compared to before composting (Table 1). Carbon of composting material is lost by mineralization.^13,14Microbial-oxidation of carbon produces carbondi oxide and mineralization occurs. The results showed that total nitrogen content increased during composting. Before composting its content was 0.9% which increased by 215.56% and reached to 2.84% at maturity of compost (Table 1). Higher loss of nitrogen through volatilization is reported at higher pH¹⁵so these results support our findings and with decreased pH, losses of nitrogen decreased at maturity of compost. Increased nitrogen during microbial decomposition of wastes is also reported earlier.⁹

Table 2: Changes in C:N with composting time

The outcome of increased nitrogen and decreased carbon content during composting is decreased C:N ratio at the end of composting than before (Table 1 and 2). Results are in tune with.¹¹

Conclusion

The present study concluded that leaves ofC. gigantea可以成功地转化成营养丰富吗compost along with mixed dung from cow, buffalo, goat and sheep. During composting ofC. gigantealeaves its pH becomes neutral and content of major nutrients (nitrogen, phosphorus and potassium) increased whereas organic carbon and C:N decreased.

Acknowledgement

Necessary financial help to conduct the present experiment was received from our University Gujarat Vidyapith, Ahmedabad through Career Oriented Programme at UG level for which authors are highly thankful to University.

References

1. Anonymous, http://www.nddb.org/English/Statistics/Pages/Population-India-Species.aspx, (retrieved on February, 08, 2015)
2. APHA, American Public Healh Association. (1985).Standard methods for the examination of waste and waste water．16^thEdition, Washington, DC.
3. Walkley, A and Black, I.A. (1934). An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method.Soil Science, 34: 29-38.
4. Bremner, J.M. (1996). Nitrogen-total. InMethods of Soil Analysis. Part 3-Chemical methods, ed. D.L. Sparks, 1085-1122. SSSA Inc., ASA Inc., Madison, WI, USA.
5. Olsen, S.R., Cole, C.V., Watanabe, F.S. and Dean, L.A. (1954).Estimation of available phosphorus in soils by extraction with sodium bicarbonate．U.S. Department of Agriculture Circular, 939.
6. Hanway, J.J. and Heidel, H. (1952). Soil analysis methods as used in Iowa state college soil testing laboratory.Iowa Agric, 57:1-31.
7. Garg, P., Gupta, A., and Satya, S. (2006). Vermicomposting of different types of waste usingEisenia foetida:A comparative study.Bioresoure Technology, 97: 391–395.
8. Hartenstien, R. and Hartenstein, F. (1981). Physicochemical changes in activated sludge by the earthwormEisenia foetida．J. Environ. Qual.,10: 377–382.
9. Pathak, A. K., Singh, M. M., Kumara, V., Arya, S. and Trivedi, A. K. (2012). Assessment of physico- chemical properties and microbial community during composting of municipal solid waste (Viz. KItchen waste) at Jhansi City, U.P. (India).Recent Research in Science and Technology,4(4):10-14
10. Benito, M., Masaguer, T.O., Moline T.O., Arrigo, N. and Palmmm M. (2003). Microbiological Chemical and parameters for the characterization of the stability and maturity of pruning waste compost.Biol.Fertil. Soils,37:184 – 189.
11. Chaudhuri, P.S., Pal, T.K., Bhattacharjee, G. and Dey, S.K. (2000). Chemical changes during vermicomposting (Perionyx excavatus) of kitchen wastes.Tropical Ecology. 41: 107-110.
12. Ghosh, M., Chattopadhyay, G.N. and Baral K. (1999). Transformation of phosphorus during vermicomposting. Bioresource Technology, 69: 149-154
13. Bernal, M. P., Sanchez–Monedero, M.A., Paredes, C. and Roig, A. (1998). Carbon mineralization from organic wastes at different composting stages during their incubation with soil.Agriculture, Ecosystems and Environment,69 (3): 175-189.
14. Fang, M., Wong, M.H. and Wong, J.W.C. (2001). Digestion activity of thermophilic bacteria isolated from ash-amended sewage sludge compost,Water Air Soil Pollution, 126 (1-2):1-12.
15. Bishop, P.L. and Godfrey, C. (1983). Nitrogen variations during sludge composting.BioCycle,24:34-39.