Biochar Effects on Carbon Stocks in the Coffee Agroforestry Systems of the Himalayas

Coffee agroforestry is an emerging agricultural practice in the mid hills of Nepal. Smallholder farmers of low-income strata have progressively adopted coffee as a perennial crop over seasonal crops. A multi-year study was conducted to test effects of locally produced biochar derived from coffee wastes, e.g., pulp and husks, on carbon stocks of: i) coffee trees, and, ii) soil organic carbon (SOC) in selected coffee growing pockets. We conducted on-farm experimental trials in three different physiographical locations of the Nepal mid-hills, namely, Chandanpur (Site I at 1475masl), Panchkhal (Site II at 1075masl), and Talamarang (Site III at 821masl) where smallholders grow coffee together with other cereal crops and vegetables. We applied biochar to the soil at a rate of 5 Mgha-1 , then, monitored the SOC and biomass growth of the coffee trees in the three treatment plots at sites I, II and III over two years beginning in 2013. The average stocks of aboveground carbon in coffee trees increased from 6.2±4.3 Mgha-1 to 9.1±5.2 Mgha-1 over the trial period of two years in biochar treated plots. The same in control plots increased from 5.6±2.8 Mgha-1 to 6.7±4.7 Mgha-1 . In the biochar plots, the average increments of ABG carbon was 0.73 Mgh-1 while in the control it was 0.29 Mgh-1 . Analysis of soil organic carbon of the plots indicated overall incremental change in carbon stocks in the coffee farms. During the base year, the average SOC stocks in the top 0-15cm layer of the soil at sites I, II, and III were estimated 74.88 ± 15.93; 63.96 ±16.71 and 33.05 ±4.42 Mgha-1 respectively. Although both the biochar treated and control plot registered incremental change in SOC stocks, the volumes were remarkably higher in the former than the latter. Compared to the baseline data, the changes in SOC stocks in the three biochar treated plots were 19.8, 49.8 and 45.3 Mgha-1 , respectively, whereas in the control plots these were 8.3, 29.3 and 11.3 Mgha-1 , respectively. The higher incremental rates of C-stocks in all the biochar treated plots in comparison to the corresponding control plots of the coffee agroforestry implies that application of biochar can enhance accumulation of carbon in the form of aboveground biomass and soil organic carbon

A Discourse on Agricultural Intensification in the Mid-Hills of Nepal

Agricultural intensification is not as simple as the Boserupian process of agricultural change; rather it is a complex evolutionary process involving several interacting drivers. This article attempts to identify the gaps in the social, economic, and environmental effects of agricultural intensification in the mid-hills of Nepal by reviewing agricultural intensification, which emerged as a major subject of development discourse in livelihood improvement and environmental degradation in Nepal. Intensification of agriculture has provided improved economy, food security, employment opportunities, decision making, labor division, local institutions, and leaderships. However, with the aim of increasing production, the intensification process has almost overlooked essential environmental factors -- soil acidification, fertility decline, and greenhouse gas emissions have been accelerated. A path towards sustainable intensification would be possible through improvements in agricultural extension programs such as integrated pest management (IPM) and farmers’ field schools. Indeed, good institutional systems make sustainable agricultural intensification economically feasible. Thus, such measures will probably encourage farmers and likely ensure economically- and environmentally-sound production, with the promise of sustainable agricultural intensification

Higher N2O emission by intensified crop production in South Asia

-Intensification of food production in Nepal has been found to acidify the soils and hence increase their apparent propensity to emit N2O as measured by the N2O/(N2+N2O) product ratio of denitrification during standardized anoxic incubations (Raut et al., 2012). We hypothesized that this would lead to high N2O emission factors (EF), and tested this by measuring N2O emissions from fields on which intensified crop production (IC) had been practiced for the last 20 years, and adjacent fields having traditional crop production (TC) practices. The measurements were done every one to two weeks over a period of 12 months covering two to three cropping periods. On the sites with periodically flooded soils, the cumulated emissions for IC and TC were 15.41 and 7.23 kg N2O/ha, respectively. On the sites with permanently drained soils, the cumulated emissions were 5.43 and 1.46 kg N2O/ha (IC and TC). We used the available data on fertilizer levels to calculate an emission factor for the transition from TC to IC (EFI); i.e. View the MathML sourceΔN2O−N/ΔNfertilizer, where ΔΔN2O-N is the cumulated emission in IC minus that in TC, View the MathML sourceΔNfertilizer is the annual N input to IC minus that in TC. The EF values were 0.08 and 0.02 for the sites with permanently drained and periodically flooded soils, respectively. These factors are 2 to 8 times higher than the EF values used by IPCC to calculate emission as a function of fertilizer level. The high EFI appear to confirm our hypothesis that intensification will lead to higher emission of N2O than that predicted by the increase in nitrogen inputs, and that this is due to the soil acidification

People’s perception of climate change impacts and their adaptation practices in Khotokha Valley, Wangdue, Bhutan

publishedVersio

Vulnerability of Pastoralism: A Case Study from the High Mountains of Nepal

Pastoralism in the Himalayan region of Nepal has undergone significant socio-economic and ecological changes. While there are numerous contributing factors behind these changes, the effect of a changing climate has not been thoroughly studied. This paper adds a significant contribution to the knowledge base through analysis from a survey of 186 herder households, interviews with 38 key participants, and four focus group discussions with individuals from three National Parks and Conservation areas in the high-mountain region of Nepal. Additionally, a review of the existing policies and programs on pastoralism was carried out. Results demonstrate several reasons behind the decline of transhumance pastoralism: Policy focus on the establishment of conservation areas, increasing vulnerability to extreme events (avalanches, snowfall, storms, and disappearing water sources), and ineffective government policies and programs. Hardships involved in herding combined with changing social values and the degradation of pasture quality were identified as contributing factors to the growing challenges facing mountain pastoralism. Similarly, the declining interest among herders to continue their profession can be traced to vulnerability associated with escalating climate change impacts. Considerable knowledge gaps regarding threats to high-altitude pastoralism remain, and continued research on pastureland conservation, capacity development, facilitation for climate change adaptation, and coping strategies for herders in the high mountains is urgently needed. Our analysis suggests that non-climatic variables such as policy and globalization were more influential in eroding pastoralism as compared to climate change. Keywords: range land; livestock farming; transhumance system; livelihoodpublishedVersio

Isotope mixing models require individual isotopic tracer content for correct quantification of sediment source contributions

The use of isotopic tracers for sediment source apportionment is gaining interest with recent introduction of compound-specific stable isotope tracers. The method relies on linear mixing of source isotopic tracers, and deconvolution of a sediment mixture initially quantifies the contribution of sources to the mixture's tracer signature. Therefore, a correction to obtain real sediment source proportions is subsequently required. As far as we are aware, all published studies to date have used total isotopic tracer content or a proxy (e.g., soil carbon content) for this post-unmixing correction. However, as the relationship between the isotopic tracer mixture and the source mixture is different for each isotopic tracer, post-unmixing corrections cannot be carried out with one single factor. This contribution presents an isotopic tracer model structurethe concentration-dependent isotope mixing model (CD-IMM)to overcome this limitation. Herein, we aim to clarify why the conventional approach to converting isotopic tracer proportions to source proportions using a single factor is wrong. In an initial mathematical assessment, error incurred by not using CD-IMM (NCD-IMM) in unmixing two sources with two isotopic tracers showed a complex relation as a function of relative tracer contents. Next, three artificial mixtures with different proportions of three soil sources were prepared and deconvoluted using C-13 of fatty acids using CD-IMM and NCD-IMM. Using NCD-IMM affected both accuracy (mean average error increased up to a threefold compared with the CD-IMM output) and precision (interquartile range was up to 2.5 times larger). Finally, as an illustrative example, the proportional source contribution reported in a published study was recalculated using CD-IMM. This resulted in changes in estimated source proportions and associated uncertainties. Content of isotopic tracers is seldom reported in published work concerning use of isotopic tracers for sediment source partitioning. The magnitude of errors made by miscalculation in former studies is therefore difficult to assess. With this contribution, we hope the community will acknowledge the limitations of prior approaches and use a CD-IMM in future studies

Occurrence of unapproved pesticides and their ecotoxicological significance for an agriculturally influenced reservoir and its tributaries in Nepal

Many catchments in Nepal are affected by intensive agricultural activities, leading to extensive pesticide usages. This study aimed to assess pesticide abundance in concurrently collected water, sediment and fish samples for the first time in intensively cultivated catchment (Indra Sarowar) located in the mid-hill region of Nepal during the rice and vegetables growing season. A total of 75 pesticides were analysed, of which 4 pesticides (alachlor, diuron, metalaxyl and pyrimethanil) were present in water with detection frequency (DF) >40%, with alachlor (0.62 - 2.68 mu g L-1) being ubiquitous. In the sediment of tributaries, the pesticides p,p'-DDT, ss-HCH, alachlor and diuron were detected with DF exceeding 40%, where ss-HCH was commonly observed (DF= 92%) with concentration ranging from 6.29 - 99.22 mu g kg(-1). The ecotoxicological risk indicated that herbicides (alachlor and diuron) posed a high risk to aquatic organisms in both tributaries and reservoir water. Such risk in sediment was even more pronounced, with alachlor and diuron showing up to 2.3 and 53.7 times higher risk respectively compared to water samples. However, none of these herbicides were detected in fish muscles. Among the fish species studied, pyrimethanil was the only quantified pesticide in edible tissue of both cage cultured (0.35 - 1.80 mu g g(-1) ww) and open stock fishes (0.06 - 1.12 mu g g(-1) ww). The consumer risk assessment showed very low human health risk associated with fish consumption (HQ< 0.2). Nonetheless, long-term consumption of contaminated fish may pose some risk that cannot be ignored. Overall, this study generated the benchmark data highlighting pervasive presence of banned (DDT, endosulfan, HCH) and unapproved (alachlor, diuron, pyrimethanil) pesticides in the environmental compartments in the mid-hill's streams of Nepal

People’s perception of climate change impacts and their adaptation practices in Khotokha Valley, Wangdue, Bhutan

publishedVersio

Vulnerability of Pastoralism: A Case Study from the High Mountains of Nepal

Pastoralism in the Himalayan region of Nepal has undergone significant socio-economic and ecological changes. While there are numerous contributing factors behind these changes, the effect of a changing climate has not been thoroughly studied. This paper adds a significant contribution to the knowledge base through analysis from a survey of 186 herder households, interviews with 38 key participants, and four focus group discussions with individuals from three National Parks and Conservation areas in the high-mountain region of Nepal. Additionally, a review of the existing policies and programs on pastoralism was carried out. Results demonstrate several reasons behind the decline of transhumance pastoralism: Policy focus on the establishment of conservation areas, increasing vulnerability to extreme events (avalanches, snowfall, storms, and disappearing water sources), and ineffective government policies and programs. Hardships involved in herding combined with changing social values and the degradation of pasture quality were identified as contributing factors to the growing challenges facing mountain pastoralism. Similarly, the declining interest among herders to continue their profession can be traced to vulnerability associated with escalating climate change impacts. Considerable knowledge gaps regarding threats to high-altitude pastoralism remain, and continued research on pastureland conservation, capacity development, facilitation for climate change adaptation, and coping strategies for herders in the high mountains is urgently needed. Our analysis suggests that non-climatic variables such as policy and globalization were more influential in eroding pastoralism as compared to climate change. Keywords: range land; livestock farming; transhumance system; livelihoo