Search

The broiler production chain (BPC) has associated environmental impacts, costs, and effects that are not compensated by the Brazilian socioeconomy. The objective of this review was to discuss BPC waste composting from a circular economy perspective. Organic solid waste is a negative externality and the agroindustry must contribute to its internalization, especially in countries with significant production, consumption, and export of chicken meat. The BPC has four main stages of significant organic waste production: reproductive poultry, hatchery, broiler growth, and broiler industry. The principal residues of this industry are reproductive poultry litter, hatchery waste, feed waste, carcasses, truck cleaning solid fraction, flotation sludge, sausage casings, charcoal, and ash. These residues have varying characteristics, such as total organic carbon (TOC) from ranging 4.4–56.22% and nitrogen from 0.2 to 9.33%. It is evident that raw materials, nutrients, and energy are misused throughout the BPC; developing countries especially cannot sustain the loss of these valuable resources. Composting has emerged as a method for mitigating the impacts of BPC waste, however, there are some obstacles. The high nitrogen concentration in BPC residues make balancing the C/N ratio complex. This deficit carbon demands residues from other sectors, such as from tree pruning, cotton residues, raw glycerin, and Napier grass. The produced BPC compost has favorable attributes to be reincorporated into the supply chain as an agricultural input. However, little research has been conducted on the short, medium, and long-term impacts of BPC compost application on different crop and soil types. Cultivations close to BPC facilities which grow broiler feed components (e.g., corn) are attractive for a closed cycle strategy and for approaching the principles of the circular economy. [Display omitted] • The broiler production chain (BPC) has four main stages of organic waste production. • Composting mitigates environmental impacts and improves BPC waste management. • The critical obstacle in composting BPC waste is the high nitrogen concentration. • There is no known local organic material used as a carbon source in the BPC. • The organic compost reincorporates into the BPC as an agricultural input. [ABSTRACT FROM AUTHOR]

Currently, the effects of different tillage modes on greenhouse gas (GHG) emissions, carbon footprint (CF), energy budget and net ecosystem economic efficiency (NEEE) in rice fields remain unclear. In the present study, three tillage modes were tested, including rice conventional cultivation with intensive till (CT), conventional flat cultivation with no-till (FNT) and ridge cultivation with no-till (RNT) in Dafasi town, Wuxue city, Hubei province, China. This study for the first time evaluates the effects of RNT on agricultural GHG emissions, grain yield, CF, energy budget and NEEE. Compared with CT and FNT, RNT reduced the soil CH 4 emissions by 29.5% and 9.9%, respectively. CT resulted in 15.8% and 23.1% lower total GHG emissions than FNT and RNT, respectively, due to lower soil CH 4 emissions. Moreover, RNT significant decreased the CF by 35.7% and 18.2% relative to CT and FNT, respectively. The net energy, energy efficiency and energy productivity under RNT were 41.2%, 25.0% and 26.7% higher than those under CT, respectively, while the specific energy under RNT was 24.7% lower than that under CT. The NEEE under RNT was 1.66 and 1.20 folds of that under CT and FNT, respectively. In conclusion, this study recommends that RNT is an environmentally safe tillage mode for reducing GHG emissions and CF, and improving energy use efficiency and NEEE for rice production in China and similar agro-eco-regions elsewhere in the world. [ABSTRACT FROM AUTHOR]

Unreasonable application of nitrogen (N) fertilizers gives rise to agricultural greenhouse gas (GHG) emissions, causing increases in carbon footprint (CF). To solve such problems, scholars have proposed the practice of N deep placement (DPN), which has been proven to be an effective approach to enhance N use efficiency and reduce N loss. However, the effect of DPN on CF and net ecosystem economic benefit (NEEB) from no-tillage (NT) rice fields remains largely unknown. In this work, a field experiment was conducted with a random complete block design to investigate the differences in soil CH 4 and N 2 O emissions, agricultural GHG emissions, grain yield, CF, and NEEB from NT paddy fields between urea deep placement (UDP) and urea broadcasting (UBC) in central China. The CF for the entire rice production chain can be calculated as the ratio of total GHG emissions to grain yield using a life-cycle approach. The novelty of this study lies in the examination of the integrated effects of DPN on GHG emissions, grain yield, CF and NEEB from NT paddy fields. The agricultural GHG emissions varied from 1297.0 to 1420.8 kg CO 2 -eq ha−1. Chemical fertilizers dominated the GHG emissions. UDP resulted in 96.8 kg CO 2 -eq ha−1 more emissions than UBC due to more consumption of diesel by machinery operations. Compared with UBC, UDP significantly reduced soil CH 4 emissions by 36–39% and N 2 O emissions by 29–31%. The mitigation of soil CH 4 and N 2 O emissions under UDP decreased the total GHG emissions by 34% and CF by 46%. Soil CH 4 emissions accounted for 83–88% of the total GHG emissions. The NEEB under UDP was 48% higher than that under UBC. In conclusion, DPN can increase grain yield, reduce CF, and enhance NEEB from NT rice fields, and may be an economic and cleaner approach for rice production. Changes in total greenhouse gas emissions, carbon footprint and net ecosystem economic benefit under different N fertilization methods. Image 1 • N deep placement decreased soil CH 4 and N 2 O emissions from no-tillage rice fields. • N deep placement reduced carbon footprint compared with N broadcasting. • N deep placement enhanced net ecosystem economic benefit relative to N broadcasting. [ABSTRACT FROM AUTHOR]