Required Energy Input Research Articles

Impairing photorespiration increases photosynthetic conversion of CO2 to isoprene in engineered cyanobacteria

Photorespiration consumes fixed carbon and energy generated from photosynthesis to recycle glycolate and dissipate excess energy. The aim of this study was to investigate whether we can use the energy that is otherwise consumed by photorespiration to improve the production of chemicals which requires energy input. To this end, we designed and introduced an isoprene synthetic pathway, which requires ATP and NADPH input, into the cyanobacterium Synechocystis sp. 6803. We then deleted the glcD1 and glcD2 genes which encode glycolate dehydrogenase to impair photorespiration in isoprene-producing strain of Synechocystis. Production of isoprene in glcD1/glcD2 disrupted strain doubled, and stoichiometric analysis indicated that the energy saved from the impaired photorespiration was redirected to increase production of isoprene. Thus, we demonstrate we can use the energy consumed by photorespiration of cyanobacteria to increase the energy-dependent production of chemicals from CO2.

Two Dimensional CFD Analysis and Flow Optimization of Transmission Cooling Scoop for Longitudinal Powertrain Applications

Two dimensional finite area method simulation was conducted to optimize the convective cooling performance of a transmission cooling scoop for longitudinal vehicle powertrain applications. Cooling of the transmission in an automobile is important to prevent premature wear or sudden failure caused by prolonged overheating of internal transmission components. The most common method for transmission cooling requires a small energy input for powering a pump to cool the transmission by circulating transmission fluid through a heat exchanger. An alternative cooling method was designed utilizing a simple scoop geometry to induce forced convection from ambient air to cool the transmission with no energy input requirement. Two dimensional simulation of this alternative cooling method was conducted in ANSYS Fluent. Fluid flow and heat transfer performance were analyzed for three proposed cooling scoop designs. Further flow optimization was achieved with parametric study regarding angle at which the cooling scoop is positioned relative to the transmission. Three dimensional simulation was conducted for improved observation of the physical model. Based on the simulation results, optimal geometry and future design improvements have been determined. A peak simulated heat transfer of 11.14 kW/m^2 was achieved with scoop angle of 45 degrees. Future research investigating the effects of induced turbulence to improve convective heat transfer would be beneficial.

Pyrolysis of heavy hydrocarbons in weathered petroleum-contaminated soil enhanced with inexpensive additives at low temperatures

Pyrolysis is a promising technology for the remediation of soil contaminated with petroleum hydrocarbons. However, for weathered petroleum-contaminated soil (WPCS) with massive recalcitrant heavy hydrocarbons, pyrolysis still has the drawback of high energy consumption. To reduce energy consumption, commonly used inexpensive additives, including Fe2O3, Al2O3, K2CO3, CaO, HZSM-5, and red mud, were selected to strengthen the pyrolysis of heavy hydrocarbons in WPCS. The removal of the total petroleum hydrocarbon (TPH) content from WPCS increased as the dosage of additives increased from 1% to 5% at 400 °C for 30 min, and increased slightly or even decreased when the additive dosage was further increased to 10%. The reduction rates of the TPH content in soil treated with 5% additives of K2CO3, CaO, Fe2O3, red mud, HZSM-5, and Al2O3 increased by 26.16%, 25.65%, 25.53%, 23.93%, 23.15%, and 20.75%, respectively. Among these additives, CaO exhibited the best performance for the removal of aromatics (73.00%) and asphaltenes (72.44%), while Fe2O3 exhibited the best performance for the removal of resins (52.25%). The removal mechanisms of heavy hydrocarbons using additives during WPCS pyrolysis were proposed based on a combination of thermogravimetric analysis and the iso-conversional Flynn–Wall–Ozawa method. The reduction in the activation energy when additives were included during WPCS pyrolysis was closely related to whether the additives participated in the reaction and to the type of pyrolysis product. The soil characterization results demonstrated that the investigated additives would not severely impact further soil cultivation. The additive-assisted pyrolysis of WPCS is expected to reduce the required energy input by 34.71% compared to the traditional pyrolysis method, thus providing an energy-efficient and cost-effective method for treating petroleum-contaminated soil in future engineering applications.

Process-property correlations in laser-induced graphene electrodes for electrochemical sensing

Laser-induced graphene (LIG) has emerged as a promising electrode material for electrochemical point-of-care diagnostics. LIG offers a large specific surface area and excellent electron transfer at low-cost in a binder-free and rapid fabrication process that lends itself well to mass production outside of the cleanroom. Various LIG micromorphologies can be generated when altering the energy input parameters, and it was investigated here which impact this has on their electroanalytical characteristics and performance. Energy input is well controlled by the laser power, scribing speed, and laser pulse density. Once the threshold of required energy input is reached a broad spectrum of conditions leads to LIG with micromorphologies ranging from delicate irregular brush structures obtained at fast, high energy input, to smoother and more wall like albeit still porous materials. Only a fraction of these LIG structures provided high conductance which is required for appropriate electroanalytical performance. Here, it was found that low, frequent energy input provided the best electroanalytical material, i.e., low levels of power and speed in combination with high spatial pulse density. For example, the sensitivity for the reduction of K3[Fe(CN)6] was increased almost 2-fold by changing fabrication parameters from 60% power and 100% speed to 1% power and 10% speed. These general findings can be translated to any LIG fabrication process independent of devices used. The simple fabrication process of LIG electrodes, their good electroanalytical performance as demonstrated here with a variety of (bio)analytically relevant molecules including ascorbic acid, dopamine, uric acid, p-nitrophenol, and paracetamol, and possible application to biological samples make them ideal and inexpensive transducers for electrochemical (bio)sensors, with the potential to replace the screen-printed systems currently dominating in on-site sensors used.Graphical abstract

Cyanobacterial inoculation as resource conserving options for improving the soil nutrient availability and growth of maize genotypes.

Harnessing the benefits of plant-microbe interactions towards better nutrient mobilization and plant growth is an important challenge for agriculturists globally. In our investigation, the focus was towards analyzing the soil-plant-environment interactions of cyanobacteria-based formulations (Anabaena-Nostoc consortium, BF1-4 and Anabaena-Trichoderma biofilm, An-Tr) as inoculants for ten maize genotypes (V1-V10). Field experimentation using seeds treated with the formulations illustrated a significant increase of 1.3- to 3.8-fold in C-N mobilizing enzyme activities in plants, along with more than five- to six-fold higher values of nitrogen fixation in rhizosphere soil samples. An increase of 22-30% in soil available nitrogen was also observed at flag leaf stage, and 13-16% higher values were also recorded in terms of cob yield of V6 with An-Tr biofilm inoculation. Savings of 30kgNha-1season-1 was indicative of the reduced environmental pollution, due to the use of microbial options. The use of cyanobacterial formulations also enhanced the economic, environmental and energy use efficiency. This was reflected as 37-41% reduced costs lowered GHG emission by 58-68 CO2 equivalents and input energy requirement by 3651-4296MJ, over the uninoculated control, on hectare basis. This investigation highlights the superior performance of these formulations, not only in terms of efficient C-N mobilization in maize, but also making maize cultivation a more profitable enterprise. Such interactions can be explored as resource-conserving options, for future evaluation across ecologies and locations, particularly in the global climate change scenario.

Cold air ventilation for cooling and drying of poplar wood chips from short rotation coppice in outdoor storage piles in Germany

The storage and natural drying of wood chips from short rotation coppices (SRC) in open-air piles can be related to high dry matter losses (DML) of more than 20%. Thus it should be researched, whether such loss can energy efficiently be reduced using cold air ventilation (CAV). Respectively, a dedicated channel system for sensor controlled ventilation and drying of wood chips was developed and tested in the drying process of two storage piles of poplar chips (2 × 90 m³). The ventilation of the storage piles was facilitated in two consecutive program phases: a cooling program, subsequent to the harvest in the month of March, and a drying program under more favorable weather conditions in the month of April. The characteristically high temperature rise typical for wood chip storage immediately subsequent to storage intake could be limited to an average storage pile temperature of 6.3 °C with just 41 blower operation hours due to the cooling program in the month of March. Due to the subsequent drying process in April, the storage pile could be dried further from 51.5% to 11.9% in 196 blower operation hours. The required energy input for the process of CAV, consisting of cooling and drying, amounted to 456 MJ t−1 (dry matter). At a total demand of electric energy of 5332 MJ per storage pile, a more than six times higher thermal energy advantage of 35,233 MJ was achieved. DML of 11% were measured at the end of wood chip drying using CAV.

An acceleration of microwave-assisted transesterification of palm oil-based methyl ester into trimethylolpropane ester

Microwave-assisted synthesis is known to accelerate the transesterification process and address the issues associated with the conventional thermal process, such as the processing time and the energy input requirement. Herein, the effect of microwave irradiation on the transesterification of palm oil methyl ester (PME) with trimethylolpropane (TMP) was evaluated. The reaction system was investigated through five process parameters, which were reaction temperature, catalyst, time, molar ratio of TMP to PME and vacuum pressure. The yield of TMP triester at 66.9 wt.% and undesirable fatty soap at 17.4% were obtained at 130 °C, 10 mbar, sodium methoxide solution at 0.6 wt.%, 10 min reaction time and molar ratio of TMP to PME at 1:4. The transesterification of palm oil-based methyl ester to trimethylolpropane ester was 3.1 folds faster in the presence of microwave irradiation. The total energy requirement was markedly reduced as compared to the conventional heating method. The findings indicate that microwave-assisted transesterification could probably be an answer to the quest for a cheaper biodegradable biolubricant.

Towards a recuperative, stationary operated thermochemical reformer: Experimental investigations on the methane conversion and waste heat recovery

In this article, stationary operated, thermochemical recuperation (TCR) based on internal reforming of methane, using oxy-fuel exhaust gases as both heat source and as reactants, is considered. TCR is a promising technology for effective heat recovery from exhaust gases of oxy-fuel furnaces, which could deliver significant increases in combustion efficiency. In order to quantify and validate the potential of TCR, the influence of the main operational parameters on methane conversion and waste heat recovery was experimentally investigated. The experimental investigations presented here differ from previously published work in the following aspects: (I) A stationary, recuperative lab-scale reformer unit filled with industrial nickel catalyst was used to investigate the influence of the oxy-fuel exhaust gas temperature, the exhaust gas recirculation rate and the addition of oxygen to the reactants on the methane conversion and waste heat recovery. (II) The required energy input for the endothermic reforming reaction is provided solely by the thermal energy of the oxy-fuel exhaust gases. (III) The reactants for fuel reforming were exclusively taken from oxy-fuel exhaust gases, resulting in so-called bi- and tri-reforming of methane, depending on the addition of oxygen. The results showed that a maximum CH4 conversion rate of 65.6% was achieved, with a substantial increase in the combustion efficiency of 17.9%, confirming the ability of TCR to improve the combustion efficiency of oxy-fuel furnaces. In addition, the effects of different reactor configurations on the methane conversion were investigated.

Increasing the Energy Efficiency of NiTi Unimorph Actuators With a 3D-Printed Passive Layer

This work demonstrates two strategies to reduce the energy required for actuation of thin film NiTi unimorph actuators with 3D printed polymeric passive layers. First, by taking advantage of 3D printing, a low mass and high stiffness passive layer can be used to achieve faster heating/cooling rates. This ultimately reduces the time and energy required to achieve a threshold temperature. The second approach uses higher currents for shorter periods of time to reach a predefined operational temperature with less energy. Using a well-designed 3D printed passive layer combined with pulsed actuation results in a decrease in the required input energy per cycle of approximately 83 % while improving the mechanical work output by about 50 % when compared to actuators with a solid passive layer driven at a lower current. The actuators were tested using currents up to 19 mA, aiming for a 95 °C change in the temperature of the NiTi layer. The proposed strategies have been shown to enhance the energy efficiency of the electrothermally heated NiTi unimorph microactuators by up to 803 %. [2020-0204]

Static output feedback stabilization of discrete time linear time invariant systems based on approximate dynamic programming

This study proposes a method for the static output feedback (SOF) stabilization of discrete time linear time invariant (LTI) systems by using a low number of sensors. The problem is investigated in two parts. First, the optimal sensor placement is formulated as a quadratic mixed integer problem that minimizes the required input energy to steer the output to a desired value. Then, the SOF stabilization, which is one of the most fundamental problems in the control research, is investigated. The SOF gain is calculated as a projected solution of the Hamilton-Jacobi-Bellman (HJB) equation for discrete time LTI system. The proposed method is compared with several examples from the literature.

Solar syngas production via methanothermal reduction of strontium oxide

A solar methanothermal reduction of strontium oxide for the co-production of Sr and syngas is thermodynamically explored. The data required for the equilibrium and efficiency analysis is taken from a commercial HSC Chemistry 9.9 software. The efficiency analysis is conducted by investigating a) Sr-Syn open process and b) Sr-Syn semi-open process as a function of the rise in the CH4/SrO ratio from 0.1 to 1. As per the results allied with the equilibrium analysis, a temperature of 2230 K is needed for the complete conversion of SrO into Sr and CH4 into a mixture of H2 and CO (syngas). As expected, a rise in the CH4/SrO ratio is responsible for a higher yield of Sr and syngas. The process efficiency is also enhanced from 24.5% to 38.7% due to the escalation in the CH4/SrO ratio from 0.1 to 1. Application of heat recuperation considerably decreased the requirement of solar energy input, and hence the process efficiency is further amplified. The Sr-Syn open process and Sr-Syn semi-open process can attain process efficiencies equal to 42.5% and 49.8% when 50% heat recuperation is applied.

Microwave treatment of municipal sewage sludge: Evaluation of the drying performance and energy demand of a pilot-scale microwave drying system

Sewage sludge management and treatment can represent up to approximately 30% of the overall operational costs of a wastewater treatment plant. Microwave (MW) drying has been recognized as a feasible technology for sludge treatment. However, MW drying systems exhibit high energy expenditures due to: (i) unnecessary heating of the cavity and other components of the system, (ii) ineffective extraction of the condensate from the irradiation cavity, and (iii) an inefficient use of the microwave energy, among others issues. This study investigated the performance of a novel pilot-scale MW system for sludge drying, specifically designed addressing the shortcomings previously described. The performance of the system was assessed drying municipal centrifuged wasted activated sludge at MW output powers from 1 to 6 kW and evaluating the system's drying rates and exposure times, specific energy outputs, MW generation efficiencies, overall energy efficiencies, and specific energy consumption. The results indicated that MW drying significantly extends the duration of the constant rate drying period associated with the evaporation of the unbound sludge water, a phase associated with low energy input requirement for evaporating water. Moreover, the higher the MW output power, the higher the sludge power absorption density, and the MW generation efficiency. MW generation efficiencies of up to 70% were reported. The higher the power absorption density, the lower the chances for energy losses in the form of reflected power and/or energy dissipated into the MW system. Specific energy consumptions as low as 2.6 MJ L−1 (0.74 kWh L−1) could be achieved, well in the range of conventional thermal dryers. The results obtained in this research provide sufficient evidence to conclude that the modifications introduced to the novel pilot-scale MW system mitigated the shortcomings of existing MW systems, and that the technology has great potential to effectively and efficiently drying municipal sewage sludge.

Measuring the energy and environmental indices for apple (production and storage) by life cycle assessment (case study: Semirom county, Isfahan, Iran)

Assessment of energy and environmental indices is a common method for estimation the sustainable production in different sectors of agriculture. Considering the area under apple cultivation in Semirom county located in Isfahan province, the present study aimed to investigate the status of energy consumption and emission the environmental pollutants through life cycle assessment for apple production and storage in 2017–2018 cropping season. Required data were collected through questionnaire and interview with apple growers. Based on the results, the average of total required energy input and the yield of apple orchard were obtained as 116,505 ​MJha−1 and 34,951 ​kgha−1, respectively. For post-harvest operations, the average of total energy inputs was estimated as 15,727 ​MJ ​t−1. In apple orchard, the contribution of fuel, pesticides and transportation to total energy input were 58%, 12% and 11%, respectively, while in post-harvest section, the share of apple baskets and electricity in total energy input were 50% and 46%, respectively. Assessment of energy indices showed that energy ratio, energy productivity, specific energy and energy net-added were 0.72, 0.3 ​kgMJ−1, 3.33 ​MJ ​kg−1 and -32621 ​MJha−1, respectively. Based on the results obtained from environmental impact assessment of apple, the highest normalized pollution in apple orchard was related to Eutrophication and Freshwater aquatic ecotoxicity impact categories with the amount of 473×10−9 and 137×10−9, respectively, while in post-harvest operations, Marine aquatic ecotoxicity and Acidification impact categories had highest amounts as 0.0802×10−9 and 0.0121×10−9, respectively. Based on the results, diesel fuel and manure with the share of 97% of total emissions were identified as the environmental hotspots in apple orchard.

Ultrasound-assisted regeneration of zeolite/water adsorption pair.

The use of ultrasound to enhance the regeneration of zeolite 13X for efficient utilization of thermal energy was investigated as a substitute to conventional heating methods. The effects of ultrasonic power and frequency on the desorption of water from zeolite 13X were analyzed to optimize the desorption efficiency. To determine and justify the effectiveness of incorporating ultrasound from an energy-savings point of view, an approach of constant overall input power of 20 or 25W was adopted. To measure the extent of the effectiveness of using ultrasound, the ultrasonic-power-to-total power ratios of 0.2, 0.25, 0.4 and 0.5 were investigated and the results compared with those of no-ultrasound (heat only) at the same total power. To analyze the effect of ultrasonic frequency, identical experiments were performed at three nominal ultrasonic frequencies of ~28, 40 and 80kHz. The experimental results showed that using ultrasound enhances the regeneration of zeolite 13X at all the aforementioned power ratios and frequencies without increasing the total input power. With regard to energy consumption, the highest energy-savings power ratio (0.25) resulted in a 24% reduction in required input energy and with an increase in ultrasonic power, i.e. an increase in acoustic-to-total power ratio, the effectiveness of applying ultrasound decreased drastically. At a power ratio of 0.2, the time required for regeneration was reduced by 23.8% compared to the heat-only process under the same experimental conditions. In terms of ultrasonic frequency, lower frequencies resulted in higher efficiency and energy savings, and it was concluded that the effect of ultrasonic radiation becomes more significant at lower ultrasonic frequencies. The observed inverse proportionality between the frequency and ultrasound-assisted desorption enhancement suggests that acoustic dissipation is not a significant mechanism to enhance mass transfer, but rather other mechanisms must be considered.

Hybrid microbial photoelectrochemical system reduces CO2 to CH4 with 1.28% solar energy conversion efficiency

Artificial photosynthesis is a promising technology to convert CO2 to fuels using solar energy, but it faces significant challenges, such as low Faradaic efficiency, poor selectivity, and the requirement of external electrical energy input. Here, we coupled a TiO2/CdS composite photoanode with a CH4-producing biocathode to construct a visible-light responsive hybrid microbial photoelectrochemical system for CO2-to-CH4 conversion. Owing to the low onset potential of the TiO2/CdS photoanode and the high selectivity and low overpotential of the biocathode, we successfully demonstrated efficient methane production with a high Faradaic efficiency up to 94.4% without any external electrical bias. The visible-light responsive hybrid system yielded a high solar-to-fuel conversion efficiency (SCE) up to 1.28%, which is around 6 times of that of global natural photosynthesis. The successful demonstration of such a visible-light responsive hybrid system provides new opportunities for artificial photosynthesis to produce solar fuels.

Bioelectrocatalytic Conversion from N2 to Chiral Amino Acids in a H2/α-Keto Acid Enzymatic Fuel Cell.

Enzymatic electrosynthesis is a promising approach to produce useful chemicals with the requirement of external electrical energy input. Enzymatic fuel cells (EFCs) are devices to convert chemical energy to electrical energy via the oxidation of fuel at the anode and usually the reduction of oxygen or peroxide at the cathode. The integration of enzymatic electrosynthesis with EFC architectures can simultaneously result in self-powered enzymatic electrosynthesis with more valuable usage of electrons to produce high-value-added chemicals. In this study, a H2/α-keto acid EFC was developed for the conversion from chemically inert nitrogen gas to chiral amino acids, powered by H2 oxidation. A highly efficient cathodic reaction cascade was first designed and constructed. Powered by an applied voltage, the cathode supplied enough reducing equivalents to support the NH3 production and NADH recycling catalyzed by nitrogenase and diaphorase. The produced NH3 and NADH were reacted in situ with leucine dehydrogenase (LeuDH) to generate l-norleucine with 2-ketohexanoic acid as the NH3 acceptor. A 92% NH3 conversion ratio and 87.1% Faradaic efficiency were achieved. On this basis, a H2-powered fuel cell with hyper-thermostable hydrogenase (SHI) as the anodic catalyst was combined with the cathodic reaction cascade to form the H2/α-keto acid EFC. After 10 h of reaction, the concentration of l-norleucine achieved 0.36 mM with >99% enantiomeric excess and 82% Faradaic efficiency. From the broad substrate scope and the high enzymatic enantioselectivity of LeuDH, the H2/α-keto acid EFC is an energy-efficient alternative to electrochemically produce chiral amino acids for biotechnology applications.

Improvement of Ethylene Removal Performance by Adsorption/Oxidation in a Pin-Type Corona Discharge Coupled with Pd/ZSM-5 Catalyst

The adsorption and plasma-catalytic oxidation of dilute ethylene were performed in a pin-type corona discharge-coupled Pd/ZSM-5 catalyst. The catalyst has an adsorption capacity of 320.6 μ mol g cat − 1 . The catalyst was found to have two different active sites activated at around 340 and 470 °C for ethylene oxidation. The removal of ethylene in the plasma catalyst was carried out by cyclic operation consisting of repetitive steps: (1) adsorption (60 min) followed by (2) plasma-catalytic oxidation (30 min). For the purpose of comparison, the removal of ethylene in the continuous plasma-catalytic oxidation mode was also examined. The ethylene adsorption performance of the catalyst was improved by the cyclic plasma-catalytic oxidation. With at least 80% of C2H4 in the feed being adsorbed, the cyclic plasma-catalytic oxidation was carried out for the total adsorption time of 8 h, whereas it occurred within 2 h of early adsorption in the case of catalyst alone. There was a slight decrease in catalyst adsorption capability with an increased number of adsorption cycles due to the incomplete release of CO2 during the plasma-catalytic oxidation step. However, the decreased rate of adsorption capacity was negligible, which is less than one percent per cycle. Since the activation temperature of all active sites of Pd/ZSM-5 for ethylene oxidation is 470 °C, the specific input energy requirement by heating the feed gas in order to activate the catalyst is estimated to be 544 J/L. This value is higher than that of the continuous plasma-catalytic oxidation (450 J/L) for at least 86% ethylene conversion. Interestingly, the cyclic adsorption and plasma-catalytic oxidation of ethylene is not only a low-temperature oxidation process but also reduces energy consumption. Specifically, the input energy requirement was 225 J/L, which is half that of the continuous plasma-catalytic oxidation; however, the adsorption efficiency and conversion rate were maintained. To summarize, cyclic plasma treatment is an effective ethylene removal technique in terms of low-temperature oxidation and energy consumption.

A numerical parametric study on the efficiency of prestressed geogrid reinforced soil

Prestressing geosynthetics offers a rapid and safe method of improving the poor ground conditions. This paper aims to find out the effect of prestressing the geogrid layer on load bearing and settlement performance. This study also takes into account the impact of the size, depth of placement and the adjacency of footing, for unreinforced (UR), geogrid reinforced (GR) and prestressed geogrid reinforced (PGR) soil on the load-bearing and the settlement characteristics by using the finite element program Plaxis 3D. Based on numerical simulation, it appears that PGR soil can enhance the bearing pressure of the UR soil by almost 500% and reduced the settlement by nearly 88 % by reducing the energy consumption. The footing placed at higher depths for PGR soil gives better performance as compared to GR soil. Moreover, placing two adjacent square footing increases the interference zone of PGR soil by 67% as compared to UR soil. This method can be instrumental in reducing the total input energy requirement to achieve a certain settlement during placement of shallow foundation for various important structures while being economic simultaneously.

Design of Discretely Tunable Resonant Actuators Using Additive Inertial Units

Abstract Resonance is known to reduce the input energy requirements of various actuator systems. The favorable effects of resonance, however, are limited to a narrow frequency range. To overcome this limitation, we describe a general framework for using discrete units of inertia that can be activated in a binary sense to move a resonant frequency across a desired frequency range. We also enumerate the generalized physical cases in which actuators can energetically benefit from resonance. We develop closed-form optimal results for the idealized case of two binary additive inertial units and extend this to a general optimization scheme for higher numbers of units that introduce parasitic friction and added stiffness. We illustrate the concept of binary tuning with a representative linear translational system powered by a voice coil motor (VCM). The experimental results show good agreement with the intended theoretical design and show the general utility of the binary additive inertia approach.

Water, Nutrient, and Energy-use Efficiencies of No-till Rainfed Cropping Systems with or without Residue Retention in a Semi-Arid Dryland Area

No-till rainfed cropping systems are being considered by farmers to make farming more profitable by reducing production costs, thereby enhancing resource-use efficiency. Field studies were conducted at the Indian Agricultural Research Institute (IARI), New Delhi during rainy and winter seasons of 2010-2011 and 2011-2012 to examine consumptive use of water (CW), water-use efficiency (WUE), nutrient uptake and balance, and energy-use efficiency (EUE) of nine diverse cropping systems based on three rainy season crops - pearl millet (Pennisetum glaucum (L.) R. Br.), cluster bean (Cyamopsis tetragonoloba L.), and green gram (Vigna radiata L. Wilczek) followed by three winter crops - wheat (Triticum aestivum L.), chickpea (Cicer arietinum L.), and mustard (Brassica juncea L.) in each of those three rainy season crop planted fields under no-till semi-arid rainfed conditions. Three residue treatments [i.e., no residue, crop residue, and Ipil-ipil {Leucaena leucocephala (Lam) twigs}] were examined for both rainy season and winter crops. Retention of crop residues significantly increased soil moisture, CW, and WUE in all cropping systems. Good growth of mustard, chickpea, and wheat after cluster bean, and a large amount of cluster bean green pods resulted in substantially higher CW and WUE of cluster bean-based systems compared to pearl millet- and green gram-based systems. Crop nutrient uptake increased substantially under crop residue and Leucaena twigs treatments compared to no-residue control plots due to enhanced crop growth and augmentation of nutrients. However, nutrient uptake and apparent nutrient balances varied greatly among cropping systems. Energy input requirement increased by approximately 10 times under crop residue and Leucaena twigs treatments. As a result, net energy balance and EUE were substantially higher for no-residue treatments. Leucaena twigs treatments had higher net energy balance and EUE than crop residue treatments, indicating the importance of leguminous residues in crop production. Results indicate the necessity of exercising optimal balance between retention of crop residues and energy inputs for the long-term soil health and sustainability of cropping systems.