Net Energy Output Research Articles

Energy Efficiency of Oat:Pea Intercrops Affected by Sowing Ratio and Nitrogen Fertilization

This study analyzed energy input (direct and indirect), energy output, net-energy output, energy use efficiency, energy intensity, and the energy productivity of oat:pea intercrops as affected by sowing ratio (oat:pea (%:%): 100:0, 75:25, 50:50, 25:75, 0:100) and nitrogen (N) fertilization (0, 60, 120 kg N ha−1). The two year field experiment was conducted on a calcaric Chernozem soil in the north-western part of the Pannonian Basin. The results for grain yield showed that pure stands of oat and pea had a higher energy use efficiency and energy intensity than intercrops, indicating that pure stands used the growing factors more efficiently than intercrops. The energy use efficiency was higher in pure pea than pure oat. The energy productivity for the above-ground biomass production was much more affected by the factor N fertilization than by the factor sowing ratio. The highest energy productivity of grain N yield and above-ground biomass N yield was achieved in pure pea stands (0:100). N in plant residues of the zero N fertilization variant required 68% lower technical energy than N from mineral fertilizer. The sowing rate of the intercrops is a management tool to trade-off between the benefits of the in-field biodiversity and energy efficiency.

Linking bioenergy production by agricultural residues to sustainable development goals: Prospects by 2030 in China

Large-scale bioenergy production utilizing agricultural residues (ARs) in multi-paths has potential energy, environmental, economic and social (EEES) impacts. If, how and to what extent these impacts integratively bring sustainability contributions at regional scale remains to be explored. Herein, the EEES impacts quantified based upon a multi-resource-technology-output life cycle framework are reflected as 17 indicators, and linked to the sustainable development goals (SDGs) and their sub-goals to explore the sustainability contributions and trade-offs in 31 Chinese provincial regions by 2030 in three scenarios of ARs availability. Results indicate that the ARs can contribute to 1.86 billion GJ net energy output and 32.1 billion yuan net profit by 2030 in the complete scenario with the highest ARs availability. Attributed to open burning avoidance and fossil energy offset, there are mitigation effects on 11 out of 13 life cycle environmental impact categories, however intensification effects on Freshwater eutrophication and Marine eutrophication. Regional sustainability score closely depends on ARs availability, while does not strictly parallel it. The ARs-abundant regions, such as Heilongjiang, Henan and Jilin, benefit outstandingly from bioenergy production to enhance regional sustainability (especially on SDG1, SDG7 and SDG13). The findings can provide decision-makers with references to soundly boosting agricultural bioenergy development to consolidate regional sustainability.

Herd and animal factors affect the variability of total and differential somatic cell count in bovine milk.

The aim of this study was to quantify some environmental (individual herds, herd productivity, milking system, and season) and animal factors [individual animals, breed, days in milk (DIM) and parity] on the variability of the log-10 transformation of somatic cell count (LSCC) and differential somatic cell count (DSCC) on individual bovine milk. A total of 159,360 test-day records related to milk production and composition were extracted from 12,849 Holstein-Friesian and 9,275 Simmental cows distributed across 223 herds. Herds were classified into high and low productivity, defined according to the average daily milk net energy output (DMEO) yielded by the cows. Data included daily milk yield (DYM; kg/d), milk fat, protein, lactose, SCC, and DSCC, and information on herds (i.e., productivity, milking system). The daily production of total and differential somatic cells in milk was calculated and then log-10 transformed, obtaining DLSCC and DLDSCC, respectively. Data were analyzed using a mixed model including the effects of individual herd, animal, repeated measurements intra animal as random, and herd productivity, milking system, season, breed, DIM, parity, DIM × parity, breed × season, DIM × milking system and parity × milking system as fixed factors. Herds with a high DMEO were characterized by a lower content of LSCC and DSCC, and higher DLSCC and DLDSCC, compared to the low DMEO herds. The association between milking system and somatic cell traits suggested that the use of the automatic milking systems would not allow for a rapid intervention on the cow, as evidenced by the higher content of all somatic cell traits compared to the other milking systems. Season was an important source of variation, as evidenced by high LSCC and DSCC content in milk during summer. Breed of cow had a large influence, with Holstein-Friesian having greater LSCC, DSCC, DLSCC, and DLDSCC compared to Simmental. With regard to DIM, the variability of LSCC was mostly related to that of DSCC, showing an increase from calving to the end of lactation, and suggesting the higher occurrence of chronic mastitis in cows toward the end of lactation. All the somatic cell traits increased across number of parities, possibly because older cows may have increased susceptibility to intramammary infections.

Parametric study of a novel air-based photovoltaic-thermal collector with a transverse triangular-shaped block

This study discusses the effects of various parameters on the energy output and efficiency of a novel air-based photovoltaic-thermal collector with a transverse triangular-shaped block using numerical analysis. The transverse triangular-shaped block, designed by the authors, enhances heat transfer in the collector by accelerating the air velocity and mixing hot and relatively cold air in an air duct. Using energy balance equations, a mathematical model for the collector with a transverse triangular-shaped block was developed and validated with experimental data obtained from a previous study. The selected parameters were height, air mass flow rate, length, solar intensity, and wind velocity. The highest energy output was achieved at a height of 0.03 m for a solar intensity of 1000 W/m2 and an air mass flow rate of 0.13 kg/s. This study also compared the daily energy output of a previously experimented photovoltaic-thermal collector with that of a collector at a height of 0.03 m. The results showed that daily thermal, electrical, and thermally equivalent net energy outputs were increased by 36.97%, 2.59%, and 8.64%, respectively, and confirmed that the proper selection of design and operating parameters can provide improved performance of the collector.

Artificial intelligence-based modeling and optimization of microbial electrolysis cell-assisted anaerobic digestion fed with alkaline-pretreated waste-activated sludge

Microbial electrolysis cell-assisted anaerobic digestion (MEC-AD) is a promising emerging strategy to enhance simultaneously waste treatment and biomethane recovery from various biowastes, particularly waste-activated sludge (WAS). However, MEC-AD is still in the early stages of development, with numerous experimental studies but no modeling or optimization. Thus, to provide an effective modeling and optimization tool for this process, this study proposed applying artificial intelligence for the first time. The literature-based experimental data of MEC-AD fed with alkaline-pretreated waste-activated sludge (al-WAS) were used for this purpose. Accordingly, a two-hidden-layer artificial neural network (ANN) with topology 2–25–34–6, obtained from the response surface methodology, showed the best agreement between actual and predicted data with a low mean squared error of 0.0579 and a high R-value of 0.9870. This best ANN model was then optimized by particle swarm optimization. As a result, an Eapp of 0.63 V was found to be optimal for al-WAS-fed MEC-AD with a highest net energy output of 41.3 KJ/L-reactor (∼2.6 MJ/kg-WAS) and highest net monetary value of 0.72 $/L-reactor (∼45 $/kg-WAS), which enhanced around 160 % and 300 % compared to AD alone. These findings can support decision-making for managers and operators in wastewater treatment, biomass waste management, and renewable energy sectors.

Two-Phase improves Bio-hydrogen and Bio-methane production of anaerobic membrane bioreactor from waste activated sludge with digestate recirculation

The conventional recirculated two-phase anaerobic digestion (R-TPAD) equipped with two continuous stirred tank reactors (CSTR) usually shows poor water quality, insufficient bioconversion degree and low methane productivity. In this study, a new R-TPAD with CSTR as acidogenic phase and anaerobic membrane reactor (AnMBR) as methanogenic phase was constructed to digest waste activated sludge (WAS) for renewable energy recovery (H2 and CH4). The effects of recirculation ratio (R) on start-up time, long-term performance, membrane fouling behaviors, microbial community evolution, and energy recovery efficiencies were investigated systematically. Result showed that the R-TPAD possessed high H2 (6.1 mL/g-COD) and CH4 (67.9 mL/g-COD) yields with the corresponding COD removal of up to 96.1% at R0.2. During the whole process, the transmembrane pressure was lower than −3.3 kPa with negligible membrane fouling observed. The 16S rRNA gene analysis revealed that the synergistic role of membrane separation and recirculation system promoted the proliferation of fatty acids-producing and organics-degrading bacteria (i.e. Coprothermobacteraeota, Bacteroidetes, etc.) in acidogenic phase and CH4-producing methanogens (i.e. Methanobacterium, Methanosaeta, etc.) in methanogenic phase, thus accelerating the biodegradation of WAS. This positive stimulation sustained the high diversity and the dynamic balance of key microorganisms in the R-TPAD process. Energy balance analysis further indicated that the R-TPAD with R0.2 could increase net energy output by 77.9% compared to the control TPAD without recirculation. This work provides a fundamental data base for the scientific management of WAS and push forward the real-world application of R-TPAD technology in the real-world scenarios.

Grid-connected hybrid PV-wind system simulation in urban Java

This research proposes optimizing the energy harvesting system based on solar and wind energy, using the enhanced PV-Wind Turbine hybrid power grid to supply electrical energy somewhere in the city of Yogyakarta, Indonesia. The analysis was conducted by researching the possibilities of wind and solar energy and gathering data from numerous sources. To examine the available data and the economic feasibility of the proposed hybrid power system, the Hybrid Optimization Model for Electric Renewable (HOMER) program was employed. The scheme was simulated and optimized using the National Renewable Energy Laboratory's Hybrid Optimization System for Electric Renewables model (NREL). Various analyses are examined, such as Net Present Value (NPV), Energy Expenditure, Energy Output, Usage, and Excess Energy created by each component of the resultant system. The results gained via the installation of this hybrid system are fairly excellent due to monthly production optimization and minimal maintenance costs with potential investments.

Energy Consumption Connection of Industrial Sector Based on Industrial Link Theory: A Case Study of China

China’s energy consumption and its growth trend determine the domestic energy production and supply pattern. The understanding of energy consumption and its changes will help to enhance urban resilience. Based on the improved input-output model and hypothesis extraction model, this paper aims at constructing the energy-industry connection model, analyzing the energy transfer implied in the economic activities of various industrial sectors, and examining the energy transfer effect between the supply-side (SS) and demand-side industry sectors of the Shaanxi Province. The results showed that, in 2017, the energy industrial sector was the most energy consumption industry in Shaanxi Province. The industrial energy sector belonged to the net energy output industrial sector, and the energy products were transferred to other industrial sectors. This paper can provide a scientific basis for the energy SS reform, adjusting the industrial layout of regions in the Yellow River Basin.

Subsurface waste heat recovery from the abandoned steam assisted gravity drainage (SAGD) operations

A considerable fraction of the energy injected during the thermal recovery of oil remains in the subsurface and wasted in the surrounding geological formations after the profitable life of oil wells is over. This work studied the concept of thermal energy extraction from the abandoned SAGD operations in oil sands reservoirs for generating electric power. The cold water is injected as a working fluid to extract heat after the oil production is ceased, and the produced hot water is fed to a surface binary cycle to generate electric power. The results show that an oil sands reservoir after SAGD operations could be regarded as an artificial geothermal system suitable for thermal energy extraction. It is demonstrated that a total net electric energy output of 57 GWh could be achieved based on a single SAGD well pair during a ten-year heat-extraction time, indicating the huge heat extraction potential at full field scale. The results show that the thermal energy conversion efficiency to electricity for the abandoned SAGD wells can reach as high as 12%. The demonstrated subsurface waste heat recovery from the abandoned SAGD sites revealed that between 15 and 36% reduction in CO2 emission could be achieved.

Experimental Investigation and Comparison of the Net Energy Yield Using Control-Based Solar Tracking Systems

As the world trend is going towards renewable energy, solar photovoltaic (PV) energy shines the most due to the low generation cost especially by using the latest PV cell technologies and materials, although the conventional silicon cell has an efficiency in the range of 15-16%. A PV tracking system (PVTS) could be a considerable method to increase electrical PV efficiency. In this study, the performance enhancement of the daily output power and energy has been experimentally investigated using single- and dual-axis tracking mechanisms for flat-plate conventional PV panels under the insolation conditions of the Eastern province of Saudi Arabia (SA). In the current study, the active PVTS has been designed and implemented with PID controllers and controlled in real-time with an embedded system. The fixed-tilt (FTPV), single-axis solar tracking system (SAST), and dual-axis solar tracking system (DAST) were tested simultaneously under clear-sky conditions. The PV electrical energy balance has revealed that the energy consumed by the electrical controllers of the SAST and DAST is 3.4% and 3.9%, respectively. In addition, the energy losses due to the actuators of the SAST and DAST are 7.8% and 13.0%, respectively, where they contributed mainly to the energy losses. However, the PV energy production by the DAST was high enough to compensate for the higher actuating mechanism losing rate compared to the SAST and performed incremental net energy output of around 8.64%. On other hand, the DAST and SAST were more efficient than the FTPV recording higher net energy increase by 28.98% and 18.73%, respectively.

A comparison of bio-crude oil production from five marine microalgae – Using life cycle analysis

Marine microalgae biomass could offer a viable feedstock for sustainably producing biofuel by hydrothermal liquefaction. In this study, five promising marine microalgae (i.e., Tetraselmis, Picochlorum, Synechococcus, Chroococcidiopsis, and Dunaliella), having different characteristics, were studied for biocrude oil production. The overall microalgal biocrude oil production process was divided into six unit operations: water supply, CO2 supply, nutrient supply, cultivation, harvesting, and HTL process. Models were developed for these unit processes such that once the key parameters of any unit process are known, the corresponding energy consumption could be determined. While the selection of the cultivation site influenced the energy requirements for sourcing seawater and CO2, the characteristics of the strain influenced energy requirements for the other four-unit operations. A cradle-to-grave concept was assumed to compare the life cycle assessment of the five strains. Among these strains, Tetraselmis sp. provided the most favorable energy balance with a net energy gain of 1.77 GJ/barrel of biocrude, an energy return on investment value of 2.81, and GHG reduction potential of 129 kg CO2 equivalent/barrel of biocrude. Further investigation with sensitivity analysis confirmed that the net energy yield for Tetraselmis sp. was least affected by a ±10% variation of the parameters of the unit processes.

Breakthrough in hydrolysis of waste biomass by physico-chemical pretreatment processes for efficient anaerobic digestion

Anaerobic digestion (AD) is the most comprehended process to stabilise the waste biomass efficiently and to obtain bioenergy. The AD starts with the hydrolysis process, where the major liability is the action of inhibitors during the hydrolysis process. The biomass pretreatment preceding anaerobic digestion is obligatory to improve feedstock biodegradability for enhanced biogas generation. It can be prevailed by the application of various pretreatment processes. This review explains the major inhibiting compounds and their formation during hydrolysis that affect the efficiency of anaerobic digestion and the benefits of the physico-chemical pretreatment (PCP) method for enhancing hydrolysis in the digestion of waste biomass. The synergistic effect of PCP on macromolecular release, liquefaction and biodegradability were presented. The feasibility of the pretreatment process was evaluated in terms of energy and cost assessment for pilot scale implementation. The outcome of this review reveals that the physico-chemical process is one of the best pretreatment methods to enhance anaerobic digestion by optimising various parameters and increasing the solubilization by about 90%. The thermochemical pretreatment at lower temperature (<100) increases the net energy yield. The solubilization of waste biomass in terms of macromolecular release and liquefaction cannot describe the pretreatment potential. The effectiveness of pretreatment was evaluated by the substrate pre-treatment followed by anaerobic digestibility of pretreated substrate.

Optimization of seed rate and nutrient management levels can reduce lodging damage and improve yield, quality and energetics of subtropical flax

Subtropical flax crop often faces an acute problem of lodging owing to having medium to severe winds coupled with occasional rains during its maturity time. To address this problem an experiment was conducted with three different seed rates and six different nutrient managements for two consecutive years during 2019–20 and 2020–21 at Pantnagar. From this two-year study, it was observed that the higher seed rate of 100 kg ha−1 resulted in the maximum plant population, plant height, fibre yield as well as quality among the different seed rate levels. However, lower stem diameter, higher fresh weight of the stem, centre of gravity and poor tensile performance with higher seed rate exhibited lower values of lodging safety indicators. Considering the different nutrient managements, application of 90 kg ha−1 nitrogen (N), 30 kg ha−1 phosphate (P2O5) and 45 kg ha−1 potassium (K) was found to be the best in terms of reduction of lodging vulnerability with better yield, quality and net energy output of fibre production with saving about 25% of the N input. The seed rate of 100 kg ha−1 when combined with 90 kg ha−1 N, 30 kg ha−1 P2O5 and 45 kg ha−1 K2O resulted in optimum crop performance and the lowest lodging under subtropical humid region. The calculated lodging indicators were found exponentially related with actual lodging. The experiment further reveled that lodging damage directly impacts fibre quality and proportion of long fibre in the total fibre yield.

Effect of foliar application of potassium nitrate on yield and energy of garden pea (Pisum sativum L.)

Field experimentation was conducted during Rabi season of 2021 at Central Farm, College of Agriculture, Central Agricultural University, Imphal, India to evaluate the “Effect of foliar application of potassium nitrate on growth, yield and economics of Garden pea (Pisum sativum L)”. Experiment was laid out in Factorial Randomized Block design (FRBD) with three replications consisting of different times of foliar application (A1: Flower initiation stage, A2: Pod development stage and A3: both stages) and four different levels of KNO3 foliar application (F1:0.5 % KNO3, F2:1 % KNO3, F3:1.5 % KNO3 and F4:2 % KNO3) and one control with a total 13 treatments. The results of the study revealed that, among the various treatment combinations, the treatment (A3F4) foliar spray of 2% KNO3 at both flower initiation and pod development stage recorded significantly highest yield components like number of pods per plant, number of seeds per pod, green pod yield, seed yield and Stover yield but non-significant in pod length and harvest index. It was followed by 1.5 % KNO3 application at both flower initiation and pod development stage. The assessment of the energy requirement of foliar application of potassium nitrate, the results revealed that the total input energy utilization was highest in 2 % KNO3 application at both flower initiation and pod development stage (A3F4) followed by 1.5 % KNO3 at both flower initiation and pod development stage (A3F3). Maximum output energy (75.726 GJ/ha), net energy output (68.839 GJ/ha), energy productivity (0.3885 kg/MJ) and minimum specific energy (2.57 MJ/kg) were found in same treatment (A3F4). But in case of energy use efficiency (11.328 %) was found highest in 2 % KNO3 application at flower initiation stage (A1F4).

Wind Energy Data Analysis and Resource Mapping of Dangla, Gojjam, Ethiopia

Energy is one of the most important factors in socio-economic development. The rapid increase in energy demand and air pollution has increased the number of ways to generate energy in the power sector. Currently, wind energy capacity in Ethiopia is estimated at 10,000 MW. Of these, however, only eight percent of its capacity has been used in recent years. One of the reasons for the low use of wind energy is the lack of accurate wind atlases in the country. Therefore, the purpose of this study is to develop an accurate wind atlas and review the wind resources using Wind Atlas Analysis and Application Program in Dangla so that the best sites used for the installation of wind farms can be easily identified. Wind climatology data, vector maps, and wind turbine data were used to model the Wind Atlas Analysis and Application Program. The wind data collected from National Meteorology Survey Agency over three years were used for the analysis. Besides, vector data for the survey area was prepared using Global Mapper V20.1. In this study, the Wind Atlas Analysis and Application Program tool was used to estimate wind resources. The wind resource map was developed at an altitude of 80 m above ground level, and a horizontal axis type wind generator called (i.e., GridStreamer Vestas V100 1.8 MW) was selected from the Wind Atlas Analysis and Application Program catalog to mimic the wind farm. The results obtained from the analysis of actual wind data showed that the minimum wind speed was 0.12083 m/s while the maximum wind speed was 9.96389 m/s. At a height of 10 m a.g.l., the mean wind speed and wind power density were 1.8 m/s and 9 w/m2, respectively. The most common wind direction was also discovered to be 210 degrees. The maximum wind speed and capacity factor were available around hills, according to the wind resource map, and the net annual energy output of the Dangla wind farm at a turbine height of 80 m a.g.l. was found to be 282.726 GWh (or, 32.27 MW). The farm’s capacity factor was also discovered to be 9.54 percent, indicating that the site is rated as low potential.

Efficient methane production from waste activated sludge and Fenton-like pretreated rice straw in an integrated bio-electrochemical system

Integrated microbial electrolysis cell-anaerobic digestion (MEC-AD) systems have demonstrated potential advantages for methane production in the presence of small amounts of residual inhibitors. In this study, a series of tests were conducted to analyse the acidification and methanogenesis performance of pretreated rice straw (RS) in anaerobic digestion (AD) and MEC-AD systems after the addition of Fenton-like reagents. The results indicated that the short-chain acids (SCFAs) accumulations reached 2284.64 ± 21.57 mg COD/L with a dosage ratio of 1/4 (g RS/g VSS sludge) in the MEC-AD system and that methane production increased by 63.8% compared with that of an individual AD system. In the interim, the net energy output reached 1.09 × 103 J/g TCOD, which was 1.23 times higher than that of the AD system. The residual Fe3+/Fe2+ in the pretreatment reagent was capable of promoting acidification and methanogenesis in sludge and RS fermentation. The RS hydrolysis products could constrain methanogenesis, which can be mitigated by introducing an MEC. The microbiological analyses revealed that the MEC strongly increased the enrichment of hydrogenotrophic methanogens, especially Methanobacterium (61.16%). Meanwhile, the Syntrophomonas and Acetobacterium abundances increased to 2.81% and 2.65%, respectively, which suggested the reinforcement of acetogenesis and methanogenesis. Therefore, the enhanced hydrogenotrophic methanogens might have served as the key for enhancing the efficiency of methanogenesis due to the introduction of an MEC.

Crop sequence effects on energy efficiency and land demand in a long-term fertilisation trial

The effect of crop sequences (CR – continuous winter rye; CropR – three-field crop rotation of winter rye-spring barley-bare fallow) and fertilisation systems (unfertilised control, mineral fertiliser (NPK), farmyard manure (FYM)) on crop yield, energy efficiency indicators and land demand were analysed in a long-term experiment under Pannonian climate conditions. Due to lower fuel consumption in the bare fallow, the total fuel consumption for CropR was 27% lower than in CR. It was for NPK and FYM fertilisation by 29% and 42% higher than in the control. Although the energy output was lower in CropR than CR, the energy use efficiency for grain production increased by 35% and for above-ground biomass production by 20%. Overall crop sequences, the NPK treatment had higher crop yields, energy outputs and net-energy output with a lower energy use efficiency than the unfertilised control. CropR increased the land demand just by 20% in comparison to CR, although one-third of the land was not used for crop production. The land demand could be decreased with fertilisation by 50% (NPK) or 48% (FYM). A bare fallow year in the crop rotation decreased the crop yield, energy input and increased the energy use efficiency and land demand.

Prey diversity constrains the adaptive potential of predator foraging traits

Predators are generally under selective pressure to get better at foraging, leading to steeper functional responses and stronger predator–prey interactions. Yet strong interactions can de‐stabilize food webs, and most interactions across ecological communities are thought to be weak. This conflict between evolutionary and community expectations for the strength of predator–prey interactions represents a fundamental gap in our understanding of how the evolution of foraging plays out in food webs. Here we help to resolve the conflict by showing analytically that the expectation for the evolution of steeper functional responses is relaxed in communities with diverse prey types. We simulate communities with varying prey richness and show that increasing prey richness can indeed constrain the adaptive potential of predator foraging traits, but that at low prey richness predators can evolve to have a stronger interaction with prey that have high net energy yields. Our results also indicate that handling time plays a role in determining whether predators may evolve to have a stronger interaction with abundant prey, suggesting that the evolution of keystone predator modules in food webs is most likely when handling times are negligible. Our results also provide a new mechanism predicting more diffuse interactions in diverse tropical communities relative to more species‐poor communities at higher latitudes.

Economic, energy and environmental consequences of shifting from maize-wheat to forage rotation in the North China Plain

Intensive self-sufficient forage production is one of the dominant challenges for the boosting intensification of livestock production. However, there is limited information on the economic, energy and environmental consequences of converting conventional crop systems with intensive forage production systems. Based on 4-year field experiments, this work proposed a comprehensive assessment of the shift from maize-wheat (M-W) to forage production systems [silage maize-ryegrass (SM-R), sweet sorghum-ryegrass (SS-R), and sorghum-sudangrass hybrids-ryegrass (SH-R)] from economic, energy, and environmental perspectives in the northern part of the North China Plain (NCP). The results revealed that SH-R had the highest yields of dry shoot biomass and crude protein, followed by SS-R, SM-R, and M-W. Similar trends were also found for the net return, ratio of income to costs, net energy output, energy use efficiency, and energy productivity. Furthermore, the environmental assessment through a life cycle assessment suggested that compared with the M-W, the total potential environmental impacts for the product-based indicators were reduced by 50%, 55%, and 72% in SM-R, SS-R, and SH-R, respectively, even if crop protection was based on a prophylactic approach. Thus, shifting from maize-wheat to forage rotation systems, especially the sorghum-sudangrass hybrids-ryegrass system, may be promising for forage production in the northern part of the NCP. This work provides valuable insight into forage production system design and environmental change adaptation for improving food security and achieving green/circular economy.

Yield, Economic Benefit, Soil Water Balance, and Water Use Efficiency of Intercropped Maize/Potato in Responses to Mulching Practices on the Semiarid Loess Plateau

Increasing agricultural productivity without undermining further the integrity of the Earth’s environmental systems such as soil water balance are important tasks to ensure food security for an increasing global population in rainfed agriculture. The impact of intercropping maize (Zea mays L.) with potato (Solanum tuberosum L.) on yield, land equivalent ratios (LER), water equivalent ratio (WER), water use, energy output, and net economic return were examined under seven planting systems: potato grown solely or intercropped on the flat field without mulching, maize grown solely or intercropped with potato on ridges or flat field with or without plastic film mulched. The three intercropping systems had 3–13% less water use than the monocropping. Among the intercropped systems, flat field caused more depletion of soil water than ridged field for both years. Compared to monocultures, intercropping with plastic film mulching and ridging significantly increased LER and WER. Meanwhile, intercropping with mulching and ridging significantly increased net economic return and energy output by 8% and 24%, respectively, when compared to monocropping. These results suggest that maize under plastic film mulched ridge-furrow plot intercropped with potato under flat plot without mulching increased energy output, net economic return, and water use efficiency without increasing soil water depletion, which could be an optimal intercropping system for the semiarid farmland on the western Loess Plateau.