Energy Consumption, Carbon Emissions and Global Warming Potential of Wolfberry Production in Jingtai Oasis, Gansu Province, China

During the last decade, China's agro-food production has increased rapidly and been accompanied by the challenge of increasing greenhouse gas (GHG) emissions and other environmental pollutants from fertilizers, pesticides, and intensive energy use. Understanding the energy use and environmental impacts of crop production will help identify environmentally damaging hotspots of agro-production, allowing environmental impacts to be assessed and crop management strategies optimized. Conventional farming has been widely employed in wolfberry (Lycium barbarum) cultivation in China, which is an important cash tree crop not only for the rural economy but also from an ecological standpoint. Energy use and global warming potential (GWP) were investigated in a wolfberry production system in the Yellow River irrigated Jingtai region of Gansu. In total, 52 household farms were randomly selected to conduct the investigation using questionnaires. Total energy input and output were 321,800.73 and 166,888.80 MJ ha−1, respectively, in the production system. The highest share of energy inputs was found to be electricity consumption for lifting irrigation water, accounting for 68.52%, followed by chemical fertilizer application (11.37%). Energy use efficiency was 0.52 when considering both fruit and pruned wood. Nonrenewable energy use (88.52%) was far larger than the renewable energy input. The share of GWP of different inputs were 64.52% electricity, 27.72% nitrogen (N) fertilizer, 5.07% phosphate, 2.32% diesel, and 0.37% potassium, respectively. The highest share was related to electricity consumption for irrigation, followed by N fertilizer use. Total GWP in the wolfberry planting system was 26,018.64 kg CO2 eq ha−1 and the share of CO2, N2O, and CH4 were 99.47%, 0.48%, and negligible respectively with CO2 being dominant. Pathways for reducing energy use and GHG emission mitigation include: conversion to low carbon farming to establish a sustainable and cleaner production system with options of raising water use efficiency by adopting a seasonal gradient water pricing system and advanced irrigation techniques; reducing synthetic fertilizer use; and policy support: smallholder farmland transfer (concentration) for scale production, credit (small- and low-interest credit) and tax breaks

Change in Characteristics of Soil Carbon and Nitrogen during the Succession of <i>Nitraria Tangutorum</i> in an Arid Desert Area

The shrub Nitraria tangutorum is distributed widely in arid desert areas, and plays a critical role in the desert&#8315;oasis ecosystem. This study quantified varying characteristics of carbon (C) and nitrogen (N) in the soil at four stages&#8212;the initial stage (IS), stable stage (SS), degradation stage (DS), and severe degradation stage (SDS)&#8212;in a steppe ecosystem in the desert of northwestern China. The results indicated that N. tangutorum experienced both expansion and deterioration as a decline of 50.7% occurred in the available soil water due to agricultural utilization, and the plant community transformed from being shrub-dominated to annual herb-dominated. At soil layer depths between 0&#8315;100 cm in the N. tangutorum nebkha dune ecosystem, organic C and total N storage was 1195.84 g/m2 and 115.01 g/m2 during the SDS, respectively, with an increase of 11.13% and 12.59% from the IS. In addition, the storage of C and N in the soil increased during the IS as well as the SS, when most of the C and N were accumulated, and the storage decreased during the DS and SDS, as the N. tangutorum communities declined. At soil layer depths between 0&#8315;100 cm in the desert steppe ecosystem, the highest storage levels of C and N were 8465.97 g/m2 and 749.29 g/m2 during the SS, and the lowest were 1076.12 g/m2 and 102.15 g/m2 during the IS, respectively. The changes and accumulation of C and N were greater in the deeper (40&#8315;100 cm) layer than in the surface layer of soil (0&#8315;40 cm). Lastly, changes in soil organic carbon (SOC) as well as in the total nitrogen (TN) were strongly related to the coverage degree, water content in soil, and the ratio of fine soil particles (silt and clay). To sum up, the intensive development of water resources has vastly reduced the ability of N. tangutorum vegetation to sequester C and N in the desert of Minqin. Efforts to perform ecological restoration and reverse desertification in the Minqin Desert should focus on preventing the unreasonable exploitation of water resources in order to maintain stable N. tangutorum communities

Carbon sequestration of sand-fixing plantation of Haloxylon ammodendron in Shiyang River Basin: Storage, rate and potential

Forest plantation can sequestrate atmospheric CO2 and slow down global warming effectively. However, its carbon sequestration capacity and rate vary significantly across different climate regions and tree species. Haloxylon ammodendron sand-fixing plantation, a unique ecological shelter forest in desert areas of Asia, has not only the ecological functions of reducing wind speed and controlling soil erosion, but also those of improving soil quality and increasing the carbon storage of the desert ecosystem. To reveal the effect of H.ammodendron plantation on carbon sequestration of the desert ecosystem, 3, 10, 25 and 35 a H.ammodendron plantations were selected in the lower reaches of Shiyang River Basin by using a space-for-time method, and their characteristics, rates, and potential of carbon sequestration in the vegetation succession were studied. The results showed that the biomass and ecosystem carbon storage of the H.ammodendron plantations increased first and then decreased with the afforestation years. The average carbon fixation rates of vegetation and its ecosystem in 10 a were 0.274 and 0.434 kg C/m2·a, respectively, which were significantly higher than those of other three successional stages in desert areas. With the increase in plantation ages of H.ammodendron, the soil organic carbon (SOC) density in topsoil continued to increase. SOC density in 3, 10, 25 and 35 a were 1.03, 1.60, 2.27 and 2.48 kg C/m2, accounting for 71.0%, 36.9%, 71.4% and 76.8% of the carbon density in vegetation-soil ecosystem, respectively. Soil carbon pool was the main part of the carbon pool in ecosystem. The results of carbon benefits project (CBP) estimation show that the total carbon storage of H.ammodendron sand-fixing plantations in Shiyang River Basin is 0.18 Tg C, and the maximum carbon sequestration potential is 0.84 Tg C, and the maximum carbon emission potential is 1.95 Tg C on 0–100 a time scale. On the time scale of 0–100 a, the carbon efficiency of H.ammodendron sand-fixing plantations in Shiyang River Basin showed a rapid growth (0–20 a) - slow decline (25–40 a) - rapid decline (50–100 a). In order to increase the organic carbon storage and maintain the stability of the desert ecosystem, the H.ammodendron sand-fixing plantations should be constructed largely and conserved scientifically in Shiyang River Basin

Entropic Ligands for Nanocrystals: From Unexpected Solution Properties to Outstanding Processability

Solution processability of nanocrystals coated with a stable monolayer of organic ligands (nanocrystal–ligands complexes) is the starting point for their applications, which is commonly measured by their solubility in media. A model described in the other report (10.1021/acs.nanolett.6b00737) reveals that instead of offering steric barrier between inorganic cores, it is the rotation/bending entropy of the C–C σ bonds within typical organic ligands that exponentially enhances solubility of the complexes in solution. Dramatic ligand chain-length effects on the solubility of CdSe-<i>n</i>-alkanoates complexes shall further reveal the power of the model. Subsequently, “entropic ligands” are introduced to maximize the intramolecular entropic effects, which increases solubility of various nanocrystals by 10²–10⁶. Entropic ligands can further offer means to greatly improve performance of nanocrystals-based electronic and optoelectronic devices