Time filter

Source Type

Tiwari R.,Environmental Defense Fund | Kritee K.,Environmental Defense Fund | Adhya T.K.,Environmental Defense Fund | Loecke T.,University of Lincoln | And 10 more authors.
Carbon Management | Year: 2015

We describe a modified manual closed-chamber approach with detachable lid and vertically stackable chambers for sampling followed by simultaneous analysis of nitrous oxide (N2O) and methane (CH4) for measuring greenhouse gas flux from rice and upland cropping systems in peninsular India. A meta-analysis of leading internationally/regionally recommended approaches to monitor agricultural GHG emissions is presented to put our sampling choices (e.g., chamber design, sampling intensity, sample storage and analytical corrections) into perspective. Given our set-up, the sample retention capacity of polypropylene syringes and crimped glass vials with grey butyl-rubber septa was ∼6 hours and 10 days, respectively; and temperature correction of N2O and CH4 concentrations was essential but plant volume correction did not affect the flux rates substantially. Optimization of gas flow rates, pre-column sample retention period, oxygen venting and temperature/current were found to reduce run time from >14 to 7 min per sample and enhance sensitivity by 30-40% while improving analytical precision from 15-30% to < 2% relative standard deviation (RSD). We suggest an alternative to the linear interpolation approach of integrating the area under the N2O peak because linear interpolation can overestimate the cumulative seasonal N2O emissions by 50-100%, especially after fertilization and/or rain events. © 2015 Taylor & Francis.

Kritee K.,Environmental Defense Fund | Nair D.,Environmental Defense Fund | Tiwari R.,Environmental Defense Fund | Rudek J.,Environmental Defense Fund | And 6 more authors.
Nutrient Cycling in Agroecosystems | Year: 2015

Studies reporting agricultural greenhouse gas (GHG) emission data from tropical upland crops or the climate adaptation and mitigation potential of farming practices that involve nutrient management and/or organic farming are very limited in number. We developed alternate groundnut (Arachis hypogaea L.) farming practices for rainfed kharif (South-west monsoon) and irrigated rabi (winter) cropping seasons for agro-ecological region 3.0 in semi-arid peninsular India; and compared their yields, farm income as well as nitrous oxide (N2O) emissions with current baseline practices among regional small scale farm-holders. At the study farm, alternate practices including application of locally prepared fermented manures along with a 40–60 % reduction in application of total N increased pod yield by 50 and 35 % and net profit by ~120 and ~70 % in a drought-hit kharif and an irrigated rabi, respectively. High resolution field measurements of N2O flux indicate that the seasonal emission factors for groundnut cultivation using baseline and alternate practices were 1.7–2.0 % of applied N. Thus, the average IPCC and Indian national emissions factors of 1 and 0.58 %, respectively, underestimate GHG emissions during groundnut cultivation. Crucially, alternate practices led to (1) a reduction of 0.13 ± 0.07 and 0.24 ± 0.1 tCO2e ha−1 season−1through decreases in direct N2O emissions along with a 50 % reduction in GHG emission intensity (per unit yield) in both seasons; (2) a concomitant average reduction of ~0.1 and 0.24 tCO2e ha−1 season−1through decreased demand for manufactured fertilizers in kharif and rabi seasons, respectively. The positive implications for climate resilience, mitigation and ecosystem services are discussed. © 2015, Springer Science+Business Media Dordrecht.

Loading Accion Fraterna Ecology Center collaborators
Loading Accion Fraterna Ecology Center collaborators