Evaluation of Plant Nitrogen Use Efficiency in Different Crop Rotations

IntroductionThere is an urgent need to increase per capita food production to compete with high population growth while maintaining environmental sustainability. Because nitrogen plays a vital role in food production for humans and livestock, nitrogen management is essential in food production. In most cropping systems, nitrogen management seems to be a major challenge due to its high mobility and natural tendency for losses from the soil-plant system to the environment. Soil organic carbon plays a key role in improving soil ecological conditions. Adding organic matter to the soil is an excellent tool for improving physical, chemical and biological conditions and is almost always desirable. Soil organic carbon stock of crop ecosystems may be increased by improving farming practices. The application of green manure, fertilizer and the return of crop straw into the soil are known as management operations to increase soil organic carbon. Fertilizers, especially nitrogen, increase crop yield, and organic carbon is returned to the soil through roots and debris, which in most cases leads to increased soil organic carbon.Materials and MethodsThis study was conducted with the aim of utilizing a set of improving farming practices in diverse cropping systems to improve nitrogen efficiency during two crop years. Farming practices including removal of summer fallow were used by importing three crops of mung bean, corn and wild rocket in rotation plus nitrogen supply levels factor. The crop rotation factor was applied in four levels of Fallow-wheat, mung bean-wheat, corn-wheat and wild rocket-wheat and the factor of nitrogen fertilizer (0, 180 and 360 kg.ha-1) in a randomized complete block design as factorial. Soil mineral nitrogen (nitrate and ammonium) were measured before sowing wheat and grain, straw and total plant nitrogen after harvest. Uptake efficiency, utilization efficiency, agronomic efficiency and nitrogen harvest index were calculated.Results and DiscussionThe results of combined analysis of variance showed that the crop rotation and nitrogen were significantly effective (ρ ≤ 0.01) on plant nitrogen, harvest index and nitrogen efficiency. Increasing nitrogen fertilizer up to 360 kg.ha-1 increased grain nitrogen, straw nitrogen, total plant nitrogen and also nitrogen harvest index. While the best uptake, utilization and agronomic efficiency of nitrogen was observed on the treatment without nitrogen fertilizer. Comparison of the means showed that the wild rocket-wheat crop rotation had the best result among all measured traits except utilization efficiency, while the utilization efficiency in the corn-wheat crop rotation showed the best performance. The results clearly show the effect of increasing organic carbon on nitrogen availability and grain nitrogen concentration as well as the role of cover crops and legume, in increasing access to nitrogen. The amount of grain nitrogen was directly affected by the amount of nitrogen fertilizer. The highest correlation coefficient was seen between agronomic and uptake efficiency (r = 0.96**). There was also a significant inverse relationship between nitrogen harvest index and the types of calculated efficiencies. The amount of uptake efficiency and agronomic efficiency in all crop rotations except corn-wheat in the second year improved compared to the first year. The highest increase in efficiency in the second year was related to the wild rocket-wheat crop rotation. In the conditions of 360 and 180 kg.ha-1 nitrogen fertilizer, the nitrogen harvest index increased in the second year compared to the first year. While in conditions without nitrogen fertilizer, nitrogen harvest index has a significant decrease. Therefore, at least in the short term, to increase the nitrogen harvest index, the minimum supply of nitrogen fertilizer should be used, even under improving crop management conditions such as green manure, removal of fallow and introduction of legumes in rotation and return of crop residues.ConclusionContinuous cropping, removal of fallow, use of cover crops and legume and preservation of residues led to increased carbon and nitrogen sequestration in soil and consequently increase biomass and nitrogen concentration in plant tissue. On the other hand, crop rotations that increased soil organic carbon and improved soil fertility quickly improved nitrogen efficiency and nitrogen harvest index

The incidence of transient neurologic syndrome after spinal anesthesia with lidocaine or bupivacaine: The effects of needle type and surgical position: brief report

"nBurning Transient Neurologic Syndrome (TNS) which was first described by Schneider et al in 1993, is defined as a transient pain and dysesthesia in waist, buttocks and the lower limbs after spinal anesthesia.1,2 The incidence of TNS after spinal anesthesia with lidocaine is reported to be as high as 10-40%.3,4 This prospective study was designed to determine the incidence of TNS with two different types of drugs, lidocaine and bupivacaine, in lithotomy or supine positions as the primary outcomes and to determine the association between two different types of needles and surgical positions with the occurrence of TNS as the secondary outcome."nThe present study was conducted on 250 patients (ASA I-II), aged 18-60 years old, who were candidates for surgery in supine or lithotomy positions. According to the needle type (Sprotte or Quincke) and the local anesthetic (lidocaine or bupivacaine) all patients were randomly divided into four groups. After establishing standard monitoring, spinal anesthesia was performed in all sitting patients by attending anesthesiologists at L2-L3 or L3-L4 levels. The patients were placed in supine or lithotomy position, in regards to the surgical procedure. During the first three postoperative days, patients were observed for post spinal anesthesia complications, especially TNS. Any sensation of pain, dysesthesia, paresthesia or hyperalgesia in the low back area, buttocks, the anterior or posterior thigh, knees, either foot or both feet were recorded. Moreover, duration of pain, its radiation and its relation to sleep and the patients' position were all carefully considered. Ultimately, the patients' response to opioid (pethidine) for analgesia was determined."nThe incidence of TNS was higher when spinal anesthesia was induced with lidocaine (68% vs. 22%, P=0.003). TNS developed in 85% of the patients in lidocaine group and 58% in bupivacaine group after surgery in lithotomy position (P=0.002). In 77 patients pain was in lumbosacral area that radiated to lower limbs and was aggravated in sitting position but in 22 patients pain was in thighs with no radiation. The mean visual analogue scale (VAS) for the determination of pain severity was six in all patients. Pain was alleviated by the administration of pethidine. With regard to the needle type, there were no significant differences between the two types of needles (P=0.7)."nAccording to the results of this prospective study, it seems that induction of spinal anesthesia by lidocaine combined with surgical lithotomy position increases the risk of TNS. Our study is in concordance with Keld's study.5 Higher neurotoxicity of lidocaine in comparison with bopivacaine may justify the higher incidence of TNS in the lidocaine group. Moreover, natural lumbar lordosis is maintained better in supine position while it is lost in lithothomy position which may lay traction forces on cauda equina or other nerve roots in the lumbar area leading to neuropraxia

Gender Differences in the Role of Positive and Negative Social Interactions on Retirement Satisfaction

Research has examined different domains of social exchanges in relation to adjustment among older adults. Predictably, positive exchanges are associated with positive affect and negative exchanges are associated with negative affect. The current study examined the relationship between different social interactions and retirement satisfaction. The current study was a part of a 1-year-long study with 433 retirees at Concordia University in Montréal, Quebec, Canada. Data utilized for the present study was from the first point of data collection. Participants completed measures of social interactions. We employed structural equation modeling using latent constructs of the social interactions. We regressed retirement satisfaction on all latent constructs. Positive informational and positive emotional interactions were significant, positive predictors of retirement satisfaction. Negative informational interaction was a significant, negative predictor of retirement satisfaction. A revised model trimmed for parsimony tested for gender differences with retirement satisfaction regressed on positive informational, positive instrumental, positive communal, positive emotional, and negative informational interactions. All told, the social interactions accounted for 12.5% of the variability in retirement satisfaction. Some gender differences emerged. Women reported marginally significantly fewer positive instrumental interactions and significantly fewer positive emotional interactions. Negative informational interaction predicted lower retirement satisfaction only for men. The final model accounted for 20.8% of the variability among men, but only 8.9% of the variability among women. The current study illustrates the importance of testing for gender differences in social interactions in older adults. This suggests that we have a better understanding of what predicts retirement satisfaction among men than women

Chemical-specific biosensing through mid-infrared graphene plasmons

Infrared spectroscopy provides chemical information of biomolecules by detecting their vibrational fingerprints. Here, we use graphene plasmons to enhance infrared absorption and to demonstrate a tunable biosensor with high sensitivity for label-free and chemically-specific detection of protein monolayers. We show that the tunability and extreme light confinement of graphene offer great possibilities for biosensing

Graphene as enabling material for infrared plasmonic biosensors

We demonstrate a graphene infrared biosensor for chemical-specific label-free protein detection. Graphene plasmon resonances are dynamically tuned to enhance protein vibrational bands. We show that the extreme light confinement makes graphene plasmons extremely sensitive to nanometric molecules

Ultrabroadband 3D invisibility with fast-light cloaks

An invisibility cloak should completely hide an object from an observer, ideally across the visible spectrum and for all angles of incidence and polarizations of light, in three dimensions. However, until now, all such devices have been limited to either small bandwidths or have disregarded the phase of the impinging wave or worked only along specific directions. Here, we show that these seemingly fundamental restrictions can be lifted by using cloaks made of fast-light media, termed tachyonic cloaks, where the wave group velocity is larger than the speed of light in vacuum. On the basis of exact analytic calculations and full-wave causal simulations, we demonstrate three-dimensional cloaking that cannot be detected even interferometrically across the entire visible regime. Our results open the road for ultrabroadband invisibility of large objects, with direct implications for stealth and information technology, non-disturbing sensors, near-field scanning optical microscopy imaging, and superluminal propagation. © 2019, The Author(s)