Meetu Jain

Effect of rice cultivars on methane emission

Abstract A field experiment was conducted with six different cultivars of rice (Oryza sativa L.) under similar soil and water environments to study their effect on methane emission from intermittently flooded plots. In addition to gas analysis for methane, soil environment parameters in terms of temperature, redox potential and pH, plant biomass and the number of tillers were also measured. It was observed that the average methane flux varied significantly with different cultivars ranging between 0.65 and 1.12xa0mgxa0m−2xa0h−1. Seasonal emission was maximum for `Pusa 933 (27.2xa0kgxa0ha−1) and minimum for `Pusa 169 (15.6xa0kgxa0ha−1) with intermediate values decreasing in the order of `Pusa 1019 `Pusa Basmati `Pusa 834, `Pusa 677. The relative per cent decrease in methane emission among the cultivars was found to be in the range of 1–42.6%. Soil redox potential was negatively correlated with methane flux.

Methane emissions from irrigated rice fields in northern India (New Delhi)

Methane (CH4) emission fluxes from rice fields as affected by water regime, organic amendment, and rice cultivar were measured at the Indian Agricultural Research Institute, New Delhi, using manual and automatic sampling techniques of the closed chamber method. Measurements were conducted during four consecutive cropping seasons (July to October) from 1994 to 1997. Emission rates were very low (between 16 and 40 kg CH4 m−2 season−1) when the field was flooded permanently. These low emissions were indirectly caused by the high percolation rates of the soil; frequent water replenishment resulted in constant inflow of oxygen in the soil. The local practice of intermittent flooding, which encompasses short periods without standing water in the field, further reduced emission rates. Over the course of four seasons, the total CH4 emission from intermittently irrigated fields was found to be 22% lower as compared with continuous flooding. The CH4 flux was invariably affected by rice cultivar. The experiments conducted during 1995 with one cultivar developed by IRRI (IR72) and two local cultivars (Pusa 169 and Pusa Basmati) showed that the average CH4 flux from the intermittently irrigated plots without any organic amendment ranged between 10.2 and 14.2 mg m−2 d−1. The impact of organic manure was tested in 1996 and 1997 with varieties IR72 and Pusa 169. Application of organic manure (FYM + wheat straw) in combination with urea (1:1 N basis) enhanced CH4 emission by 12–20% as compared with fields treated with urea only. The site in New Delhi represents one example of very low CH4 emissions from rice fields. Emissions from other sites in northern India may be higher than those in New Delhi, but they are still lower than in other rice-growing regions in India. The practice of intermittent irrigation--in combination with low organic inputs--is commonly found in northern India and will virtually impede further mitigation of CH4 emissions in significant quantities. In turn, the results of this study may provide clues to reduce emissions in other parts of India with higher baseline emissions.

Methane emissions from rice fields amended with biogas slurry and farm yard manure

In an experiment on methane-emission measurements from rice fields amended with urea, biogas spent slurry (BSS) + urea, and farm yard manure (FYM) + urea, three distinctive peaks in the methane emissions were observed at 15, 46, and 69 days after transplanting (DAT) due to the availability of readily degradable C-sources. In all cases, the highest peak was at 69 DAT. The steepest Eh drop to a minimum of -320 mV was reached within two weeks of submergence. pH ranged between 7.5 and 8.5. The combined fertilization (FYM + urea) plot showed the maximum emission rate of 4.86 mg m−2 h−1 with a total load of 49.44 kg ha−1 and was 2.3 times higher than (BSS + urea)-treated plot (22.08 kg ha−1). Grain yields in urea, (BSS + urea) and (FYM + urea) plots were 3.34, 2.94, and 2.85 t ha−1 respectively, suggesting that biogas slurry is a preferred source over FYM causing lesser environmental pollution without any significant reduction in grain yield.

A note on stimulation of biogas production from cattle dung by addition of charcoal

Abstract Various forms of carbon were screened for their ability to stimulate biogas production in batch fermenters and the commercial charcoal which was found to be most efficient was tried in a semi-continuous anaerobic digester. The addition of 5% commercial charcoal to cow dung on a dry weight basis resulted in augmentation of gas production by 17% and 34·7% in batch and semi-continuous fermenters, respectively. Analysis of the microbial profile of the fermenters showed that fermenters with charcoal had a higher number of both total anaerobic bacteria and cellulolytics. The decomposition of Volatile Solids increased from 30% to 34% and COD reduction from 55% to 69% on addition of charcoal to the semi-continuous digester. The Volatile Fatty Acid concentrations were similar and within the acceptable limits. Locally-produced wood charcoal was as good as the commercial charcoal in batch digestions, but other forms of carbon were not as efficient.

Gingival crevicular blood: As a non-invasive screening tool for diabetes mellitus in dental clinics

Background: A high number of patients with periodontitis may have undiagnosed diabetes. Self-monitoring devices provide a simple method for rapid monitoring of the glucose level in the blood by utilizing a blood sample from the finger, but this method requires a needle puncture to obtain blood. It is possible that gingival crevicular blood (GCB) from routine periodontal probing may be a source of blood for glucose measurements. Aim: To establish whether GCB can be used as a non-invasive diagnostic aid in screening for diabetes mellitus during routine periodontal examination. Materials and Methods: The study involved 50 diabetics and 50 non-diabetics, with an age range of 26-66 years. Both diabetic and non-diabetic patients had moderate to severe gingivitis with at least one tooth in the maxillary anterior region showing bleeding upon probing. The Gingival Index and Oral Hygiene Index-Simplified were recorded. Blood oozing from the gingival sulcus/pocket following periodontal pocket probing was collected using a capillary tube and transferred to the test stick of a glucose self-monitoring device (Accu-Chek, Roche Diagnostic, Germany) in patients with comparable gingival and oral hygiene status. This value was compared with the peripheral fingerstick blood glucose (PFBG) value, which was obtained by pricking the finger tip at the same visit. Statistical analysis was performed using Pearsons correlation coefficient. Result: There was no statistically significant difference between the gingival crevicular blood glucose (GCBG) values and the PFBG values in both the diabetic (P = 0.129, NS) and the non-diabetic (P = 0.503, NS) groups. Karl Pearsons product–moment correlation coefficient was calculated, which showed a positive correlation between the two measurements in the diabetic (r = 0.943) as well as the non-diabetic (r = 0.926) groups. Conclusion: The results suggest that GCB can be used as a non-invasive diagnostic aid in screening for diabetes mellitus during routine periodontal examination.

Efficacy of xanthan based chlorhexidine gel as an adjunct to scaling and root planing in treatment of the chronic periodontitis

Aim: The aim of this study was to evaluate the clinical effectiveness of locally delivered xanthan-based Chlosite® gel as an adjunctive therapy to scaling and root planing in treatment of chronic periodontitis. Materials and Methods: In a randomized controlled clinical study, 30 patients were selected. Pocket depth between 5 and 7 mm was selected and each patient had two sites on the same side of the mouth. A total of 30 control sites were scaled and root planed and 30 test sites were scaled and root planed and Chlosite® gel was added. The clinical parameters, probing depth (PD), clinical attachment level (CAL), plaque index (PI) and bleeding on probing (BOP), gingival index were recorded at baseline, 6 weeks, 3 months and 6 months. Statistical Analysis: Paired/unpaired t-test was used, significance was placed at 5% level of significance, i.e., P < 0.05 was considered as a significant. Results: From baseline to a period of 6 months, significant difference was found between test and control group for PD, CAL, PI and BOP, P value being PD (P = 0.002), CAL index (P = 0.014), respectively. Conclusion: Subgingival injection of xanthan-based Chlosite® gel adjunct with scaling and root planing appeared to cause significant improvement compared with scaling and root planing alone in persons with chronic periodontitis.