Recovery Of Fertilizer Research Articles

Organic amendments as sustainable tool to recovery fertility in intensive agricultural systems

Intensive agriculture is a farming system characterised by a large use of inputs, causing a large pressure on the environment. As peculiar and efficient example of intensive agriculture cultivation under plastic tunnels provides several advantages for farmers due to improvement of microclimatic conditions coupled with a relatively low investment costs. In the Mediterranean Basin such cultivation systems reach about 200,000 ha mainly in Spain, Turkey, Italy, and Morocco. As downside, intensive agriculture negatively affects soil fertility principally because of a loss in soil organic matter. Sustainable practices providing organic amendments could be a useful tool to maintain or increase organic matter content in agricultural soils, preserving and improving soil fertility. An improved knowledge of management factors affecting soil quality is crucial to plan farming systems that effectively maintain soil fertility. Therefore, this review focuses on the potential value of organic amendments in the recovery of soil fertility, in particular in sites under plastic cover intensive farming system. Following a brief overview of the effects of intensive agriculture on soil, the review describes various organic amendments used in agriculture and their benefits on soil fertility, to conclude with the need, in the future researches, to identify organic amendments able to maximize a recovery of soil fertility.

Uptake efficiency of 15N-urea in flooded and aerobic rice fields under semi-arid conditions

The sustainability of traditional rice (Oryza sativa L.) cultivation in many Asian countries is being questioned due to severe water shortage conditions, envisaging the need for development of water-saving rice production technologies. A 2-year-field study on a typic Haplustalf soil was conducted to compare traditional transplanted rice–maize system with water-saving aerobic rice–maize system, with an overall objective of investigating the fate of fertilizer nitrogen (N) using 15N-labeled urea. Results from the field experiments showed that the rice plants positively responded to N fertilizer application. The average fertilizer N recovery by rice crop over the 2 years in aerobic rice was 26 kg per 100 kg of applied fertilizer N in the main field and 21 kg per 100 kg of applied N in the microplot, while the recoveries were 41 and 32 kg ha−1 per 100 kg of applied N in traditionally cultivated rice under flooded conditions. The fraction of 15N that was found in soil after the harvest of rice crop ranged from 11.4 to 47.1 kg ha−1 in aerobic rice and 14.2–51.4 kg ha−1 in flooded rice. Average recovery of 15N fertilizer in maize after the first growing season was 3.3 %, and the corresponding recovery in soil was 19 %. An additional 1.3 % of the fertilizer was recovered by crops during the two subsequent seasons. This study indicates the need to develop management practices that improve N use efficiency in aerobic rice by reducing losses to improve yields and reduce N export to the environment.

Response of Teff (Eragrostis tef) to Different Rates of Slow Release and Conventional Urea Fertilizers in Vertisols of Southern Tigray, Ethiopia

A field experiment was conducted during the main rainy season of the 2011 at Ofla testing site to determine the optimum rates and overall performance of slow release urea (SRU) fertilizer over conventional urea (CU) fertilizer for teff production. The field experiments comprised of 5 treatments, i.e three rates of slow release urea at 23, 46 and 69 kg N ha -1 , recommended rate 46 kg N ha -1 of conventional urea fertilizer and control (without any N fertilizer) laid down in a randomized complete block design with three replications. All experimental units were supplied with a uniform rate of 46 kg P 2 O 5 ha -1 in the form of triple super phosphate (TSP) at planting time. At harvest, the crop was partitioned in to straw and grain for the determinations of N concentrations, uptakes and calculation of N fertilizer recoveries and use efficiencies. Application of different rates and sources of N fertilizer significantly (P≤0.01) affected most the crop parameters tested. The significantly different and maximum plant height (112.33 cm), fertile tillers per plant (22.67), and panicle length (52.00 cm) were obtained from the application of the highest SRU rate (69 kg N ha -1 ) whereas the lowest records were obtained from the control plot of the teff crops. Similarly, the maximum grain yield (3443.67 kg ha -1 ), straw yield (6208.33 kg ha -1 ), total biomass (9652.00 kg ha -1 ) and 1000 grains weight (0.35 g) were obtained from the application of the highest SRU rate showing a decreasing trend with declining N rate with the lowest obtained from the control plots of wheat. Application of SRU fertilizer has also affected the grain and straw N contents and uptakes. These showed increasing trend with increasing N rate where the maximum record were obtained at the highest rate of SRU (69 kg N ha -1 ). The application of 46 kg N ha -1 of SRU fertilizer has yield advantage of 462.00 kg ha -1

Comparison between solar utilization of a closed microalgae-based bio-loop and that of a stand-alone photovoltaic system

This study compared the solar energy utilization of a closed microalgae-based bio-loop for energy efficient production of biogas with fertilizer recovery against that of a stand-alone photovoltaic (PV) system. The comparison was made from the perspective of broad life cycle assessment, simultaneously taking exergy to be the functional unit. The results indicated that the bio-loop was more environmentally competitive than an equivalent stand-alone PV system, but had higher economic cost due to high energy consumption during the operational phase. To fix the problem, a patented, interior pressurization scheduling method was used to operate the bio-loop, with microalgae and aerobic bacterial placed together in the same reactor. As a result, the overall environmental impact and total investment were respectively reduced by more than 75% and 84%, a vast improvement on the bio-loop.

Analysis of the potential to recover energy and nutrient resources from cattle slaughterhouses in Australia by employing anaerobic digestion

Cattle slaughterhouses contain high strength waste and wastewater streams and are therefore strong candidates for treatment processes that recover energy and nutrients. Analysis of 6 Australian slaughterhouses showed the potential for renewable energy production from a production facility was up to 400GJ or 40MWh per day while the potential for recovery of renewable fertilizer was over 1ton per day as struvite. The composition of individual wastewater streams varied depending on the source within the slaughterhouses. Biochemical methane potential varied from 250 to 300Lkg−1 VS for cattle yard and paunch wastewater to 500Lkg−1 VS for slaughter floor wastewater and over 1000Lkg−1 VS for rendering wastewater. Different anaerobic biodegradability and degradation rates between streams within a slaughterhouse suggests that conventional treatment processes such as anaerobic lagoons are not an optimized treatment strategy. Therefore separate and specialized treatment of red waste (rendering and slaughter floor) and green waste (paunch and offal waste) is recommended. Rendering and paunch wastewater were concentrated resource streams that contribute up to 75% of the methane potential, phosphorus and potassium loads, in only 20% of the volumetric flow. These concentrated streams provide opportunities to enhance the recovery of nutrients using crystallization technologies.

The role of the antisperm antibodies in male infertility assessment after microsurgical varicocelectomy

Antisperm antibodies (ASA) are a cause of male infertility. ASA are often found in varicocele patients. The study objective was to assess the ASA role in fertility recovery after varicocelectomy. The longitudinal study involved 99 patients with varicocele. Patients were examined according to the WHO recommendations; ASA level was measured using the direct method of Sperm MAR test: 66 patients were ASA-negative, 33 had MAR-IgG ≥ 10%. All patients underwent microsurgical varicocelectomy. Student's t-test, Wilcoxon test, Chi-squared test and signed rank test were used for data analysis. The retrospective analysis of all operated patients data showed that the patients without spermiogram improvement after varicocelectomy had higher ASA levels. 3 months after the surgery, the initially ASA-negative varicocele patients demonstrated 2.5 times increase in number of progressive motile spermatozoa in the ejaculate (p < 0.001), accompanied by 6% decrease in abnormal sperm count (p < 0.05); the spermiogram parameters improved in 77% of cases (p < 0.01). After the surgery, ASA developed in 16% of cases (Max--MAR-IgG = 12%). The patients who were initially ASA-positive demonstrated ASA decrease only in half of the cases (16 of 33; p > 0.05). The main outcome in this group was a favourable response to the surgery (ASA level decrease) vs. no reduction in autoimmune process. The improvement in the ASA-positive group was demonstrated in the patients with higher varicocele grade (median--2 vs. 1; p < 0.05) and lower ASA level (MAR-IgG = 48% vs. 92%; p < 0.01). The pregnancy rate within a year after surgery was 2.8 times more frequent in couples with ASA-negative men: 39% (25 of 65) in the ASA-negative group compared to 14% (4 of 28) in the ASA-positive group (p < 0.05). Thus, antisperm immune response decreases the varicocelectomy efficacy for reproductive function recovery: the higher percentage of ASA and lower grade of varicocele are associated with an unfavourable prognosis.

Ammonium Fertilizers Production from Manure: A Critical Review

Excessive livestock production in small areas poses a risk of nitrogen release to the environment and thus air and water contamination. Recovery of ammonia is necessary to avoid overfertilization, but manure management of untreated slurry is costly and complex. The authors discuss ammonium fertilizer recovery from manure using membrane processes and physicochemical methods including technology and energy assessments. Currently, nanofiltration, reverse osmosis, membrane distillation combined with ultrafiltration, and air stripping are the best choices. The processes rely highly on selection of appropriate pretreatment, as residual particulates will lead to fouling of membranes and stripping towers hence affect the performance greatly.

Reclamation of soil polluted by gas condensate using peat compost

An approach to the reclamation (the recovery of fertility) of soil polluted by gas condensate in the territory of a boosting compressor station using peat compost was developed. The efficiency of soil reclamation was evaluated by an analysis of catalase and dehydrogenase enzyme activities and by the sowing and cultivation of perennial grasses in the area.

Development and evaluation of a full-scale spray scrubber for ammonia recovery and production of nitrogen fertilizer at poultry facilities

Significant ammonia emissions from animal facilities need to be controlled due to its negative impacts on human health and the environment. The use of acid spray scrubber is promising, as it simultaneously mitigates and recovers ammonia emission for fertilizer. Its low pressure drop contribution on axial fans makes it applicable on US farms. This study develops a full-scale acid spray scrubber to recover ammonia emissions from commercial poultry facilities and produce nitrogen fertilizer. The scrubber performance and economic feasibility were evaluated at a commercial poultry manure composting facility that released ammonia from exhaust fans with concentrations of 66–278 ppmv and total emission rate of 96,143 kg yr−1. The scrubber consisted of 15 spray scrubber modules, each equipped with three full-cone nozzles that used dilute sulphuric acid as the medium. Each nozzle was operated at 0.59 MPa with a droplet size of 113 μm and liquid flow rate of 1.8 L min−1. The scrubber was installed with a 1.3-m exhaust fan and field tested in four seasons. Results showed that the scrubber achieved high NH3 removal efficiencies (71–81%) and low pressure drop (<25 Pa). Estimated water and acid losses are 0.9 and 0.04 ml m−3 air treated, respectively. Power consumption rate was between 89.48 and 107.48 kWh d−1. The scrubber effluents containing 22–36% (m/v) ammonium sulphate are comparable to the commercial-grade nitrogen fertilizer. Preliminary economic analysis indicated that the break-even time is one year. This study demonstrates that acid spray scrubbers can economically and effectively recover NH3 from animal facilities for fertilizer.

Wheat leaf properties affecting the absorption and subsequent translocation of foliar-applied phosphoric acid fertiliser

Although foliar fertilisation using liquid forms of phosphorus (P) is not a new concept, its adoption has been hindered by a limited understanding of the variability in performance of fluid forms of foliar P applied to broadacre crops. There is a need to identify how the surface structure of leaves influences the absorption and subsequent translocation of foliar-applied P in above ground plant parts. This study examined the surface properties of wheat leaves using scanning electron microscopy and measured the recovery of foliar-applied fertiliser that was labelled with either 32P or 33P from both the adaxial (upper) and abaxial (lower) leaf sides into untreated plant parts. We found that the adaxial leaf surface absorbed and translocated more foliar-applied P away from the treated leaf than the abaxial surface, likely related to the higher abundance of trichomes and stomata present on that side of the leaf. The recovery of the foliar-applied fertiliser varied with rate and timing of application; ranging from <30 % to as much as 80 % of the adaxial-applied fertiliser translocated from the treated leaf into the wheat ear. This study demonstrated that the differences in surface morphological features between leaf sides influenced the combined absorption and subsequent translocation of foliar-applied P in the above ground plant parts. This is due to a direct effect on the foliar pathway and/or due to differences in wettability affecting both the leaf coverage and drying time of fertilisers on the leaves. Although foliar fertilisation in this study contributed less than 10 % of the total P in the plant, it provided a more efficient pathway for P fertilisation than soil-applied P.

Soil organic carbon estimation with topographic properties in artificial grassland using a state-space modeling approach

She, D., Xuemei, G., Jingru, S., Timm, L. C. and Hu, W. 2014. Soil organic carbon estimation with topographic properties in artificial grassland using a state-space modeling approach. Can. J. Soil Sci. 94: 503–514. Knowledge of the distribution of soil organic carbon (SOC) in artificial grasslands in semiarid areas is helpful in optimizing management for soil fertility recovery and carbon sequestration. Accurate estimation of SOC with easy-to-obtain topographic properties can save considerable labor and cost as well as protect the grassland from being disturbed by intensive soil sampling. In our study, a total of 113 sampling points were setup within a patch of artificial grassland in a small catchment located in the north Loess Plateau of China. State-space modeling and traditional linear regression were used to estimate the localized variation of SOC in the 0- to 20-cm surface soil layer using five selected topographic properties (elevation, slope, aspect, plan curvature, and surface soil roughness). Soil surface roughness and plan curvature were identified as the most effective variables for SOC estimation in state-space models. Soil surface roughness and plan curvature explained 92.5% and 84.5% of the total variation of SOC, respectively. The best state-space model was the one using both plan curvature and surface soil roughness, explaining 94.5% of the total variation of SOC, whereas the best linear regression model could only explain 15.9% of the total variation of SOC. The results indicate that all the derived state-space models performed better than the equivalent linear regression models. Our study provides an insight into the possibility of accurate estimation of SOC only using one or two easy-to-obtain topographic properties with state-space modeling approach.

Potential spermatogenesis recovery with bone marrow mesenchymal stem cells in an azoospermic rat model.

Non-obstructive azoospermia is the most challenging type of male infertility. Stem cell based therapy provides the potential to enhance the recovery of spermatogenesis following cancer therapy. Bone marrow-derived mesenchymal stem cells (BMSCs) possess the potential to differentiate or trans-differentiate into multi-lineage cells, secrete paracrine factors to recruit the resident stem cells to participate in tissue regeneration, or fuse with the local cells in the affected region. In this study, we tested whether spermatogenically-induced BMSCs can restore spermatogenesis after administration of an anticancer drug. Allogeneic BMSCs were co-cultured in conditioned media derived from cultured testicular Sertoli cells in vitro, and then induced stem cells were transplanted into the seminiferous tubules of a busulfan-induced azoospermatic rat model for 8 weeks. The in vitro induced BMSCs exhibited specific spermatogonic gene and protein markers, and after implantation the donor cells survived and located at the basement membranes of the recipient seminiferous tubules, in accordance with what are considered the unique biological characteristics of spermatogenic stem cells. Molecular markers of spermatogonial stem cells and spermatogonia (Vasa, Stella, SMAD1, Dazl, GCNF, HSP90α, integrinβ1, and c-kit) were expressed in the recipient testis tissue. No tumor mass, immune response, or inflammatory reaction developed. In conclusion, BMSCs might provide the potential to trans-differentiate into spermatogenic-like-cells, enhancing endogenous fertility recovery. The present study indicates that BMSCs might offer alternative treatment for the patients with azoospermatic infertility after cancer chemotherapy.

Subcritical hydrothermal treatment for the recovery of liquid fertilizer from scallop entrails

Scallop entrails are organic wastes containing abundant proteins and minerals but are considered difficult to recycle because of high cadmium concentrations. In this work, the current problem of scallop entrails recycling was investigated and a subcritical hydrothermal treatment (SCHT) was examined for the recovery of liquid fertilizer from scallop entrails. Scallop entrails are mainly recycled for composting and feedstuff production. However, the dilution by mixing scallop entrails with other feed waste was the sole countermeasure to reduce the cadmium concentration of compost. For feedstuff production, whole product derived from scallop entrails was exported to other countries instead of domestic utilization. Temperature, retention time (RT) at given temperature, and liquid-to-solid (LS) ratio were examined as SCHT conditions for scallop entrails processing. The extraction ratio of each constituent mainly depends on the temperature rather than the RT or the LS ratio. Upon the SCHT of scallop entrails at 200°C, an RT of 20 min, and an LS ratio of 10, the extraction of fertilizer constituents such as nitrogen, phosphorus, and potassium from the liquid product was optimum, whereas the release of cadmium was suppressed. The concentrations of heavy metals in the liquid product obtained using the above-mentioned SCHT conditions were below the maximum permissible concentration stipulated by the Fertilizer Control Law. SCHT is considered to be a feasible recycling method for scallop entrails to recover fertilizer components with a concomitant separation of cadmium from the product.

Safety and usefulness of cryopreservation of ovarian tissue to preserve fertility: a 12-year retrospective analysis.

Do the benefits of ovarian tissue cryopreservation outweigh the risks for patients seeking to preserve fertility before gonadotoxic treatment in various indications? In >90% of the patients undergoing cryopreservation of ovarian tissue, oncological treatment was associated with a reduced ovarian reserve and in 30% of patients, premature ovarian failure (POF) occurred within 5 years. Ovarian tissue cryopreservation is an effective fertility preservation option, especially for pre-pubertal patients and patients who have a short time between diagnosis of a disease and gonadotoxic treatment. This study retrospectively analysed ovarian function and fertility recovery rates, as well as ovarian tissue characteristics, of patients who underwent ovarian tissue cryopreservation at Erasme Hospital between 1999 and 2011. A total of 225 patients referred from 15 Belgian oncological units underwent cryopreservation of ovarian tissue before gonadotoxic therapy for malignant or benign diseases. There were 28 patients (12.4%) who died during follow-up due to recurrence of disease. One severe adverse event occurred during anaesthesia for ovarian tissue collection, leading to the death of the patient. Ovarian function and fertility outcomes were available for 114 patients including 13 girls who were pre-pubertal at the time of the procedure. Eight patients had undergone ovarian tissue transplantation in order to restore their fertility after remission of the disease. Breast cancer and haematological disease were the most frequent indications for ovarian tissue cryopreservation. Overall, 90% of post-pubertal patients were diagnosed with poor ovarian reserve (AMH < 0.5 ng/ml) after a mean of 50 months of follow-up (11-125 months), including 30% with POF (FSH > 40 IU/ml). Breast cancer patients had a lower rate of POF than did post-pubertal patients with haematological diseases (11 versus 34.5%, respectively), despite the older age (mean 31 versus 23.5 years old, respectively) of the breast cancer patients. Ovarian function returned in 71 post-pubertal patients without the need for grafts of cryopreserved tissue. Spontaneous pregnancies were reported for 33 of them, leading to 34 live births. Among the 13 pre-pubertal patients who reached pubertal age during the follow-up, 10 had POF. Eight patients received cryopreserved ovarian grafts to reverse POF and three of them have already become pregnant. This study is a retrospective analysis. The cohort was not compared with a control group of patients who did not undergo the procedure. After careful evaluation of the surgical risks, ovarian tissue cryopreservation can be proposed as an efficient option to preserve the fertility of children and young adults facing gonadotoxic therapies. However, alternative procedures such as oocyte or embryo cryopreservation should be considered as first options especially for older patients or if there is high risk of neoplastic cells within the ovaries. This study was supported by the Télévie, FNRS-FRSM and Fondation Belge contre le cancer. There are no competing interests to report.

Fertility restoration in three CMS systems of eggplant by the Rf genes of each other's systems and their SCAR marker

Three pollen non-formation type cytoplasmic male sterility (CMS) systems of eggplant (Solanum melongena L.) were developed in our previous study, through repeated backcrossing, by using wild Solanum species Solanum aethiopicum L. Aculeatum Group, Solanum anguivi Lam. and Solanum grandifolium C. V. Morton as the cytoplasm donor and eggplant ‘Uttara’ as the recurrent pollen parent. Each CMS system has male fertile (MF) line which carries the fertility restorer (Rf) genes for the pollen non-formation type sterility. In the present study, fertility restoration ability in three CMS systems of eggplant by the Rf genes of each other's systems was evaluated. The male sterile (MS) line of each CMS system was pollinated with the pollen of MF lines of other CMS systems as well as its own CMS system. Among the nine cross combinations, six groups were obtained from crossing MS lines with MF lines of other CMS systems and three groups were obtained from crossing MS lines with MF lines of their own CMS system. The segregation of MF and MS plants was fitted well with a 3:1 ratio in almost all cross combinations. The segregation patterns revealed that two independent dominant Rf genes restore fertility in each CMS system. Pollen stainability and in vitro pollen germination rate of the progenies obtained from different cross combinations were varied from 61.0 to 89.8% and 0.7 to 8.0%, respectively. Each Rf gene of three CMS systems restores fertility of other CMS systems as well as its own CMS system. Moreover, fertility recovery action in these three kinds of CMS is similar. DNA markers linked to Rf genes were screened by bulked segregant analysis (BSA) using random amplified polymorphic DNA (RAPD). A total of 420 primers were used, and more than 65% of the primers yielded a considerable number of RAPD fragments in both MF and MS bulks. Only one Operon primer OPAB10 gave a reproducible polymorphic band of 1.9kbp (OPAB101900) between bulks and was identified as linked to the Rf genes. Additionally, the RAPD marker OPAB101900 was converted to sequenced characterized amplified region (SCAR) marker designated as SCAB101900 by nucleotide sequencing. Findings of the present study may give us a potential way to explore CMS and the corresponding Rf genes from wild Solanum resources for the breeding program of eggplant.

Copulation without seminal expulsion: the consequence of sexual satiation and the Coolidge effect

The studies of sexual satiety in male rats under the Coolidge effect indicate that males reassume copulation until ejaculation. Recently, it was demonstrated that sexually satiated males preserve the motor patterns of intromission and ejaculation, also penile erection, but not seminal expulsion. The first aim was to investigate if penile erections displayed by sexually satiated males dislodge the seminal plugs from the vagina and its effect on sperm transcervical transport. The second aim was to determine the recovery time of seminal expulsion after sexual satiety and its optimal ability to induce pregnancy. Results show that during the Coolidge effect males were able to dislodge the seminal plugs deposited by others (experiment 1A) disturbing the sperm transport (experiment 1B) then interfering with pregnancy (experiment 1C). After satiation, the ejaculate parameters recover slowly: it starts after 10 days with the seminal plug formation, and continues with an increase in sperm count in the uterus 15 days post-satiety (experiment 2). Sexually satiated males impregnated only 28% of the females during 15 days of cohabitation, whereas, satiated males that rested for 15 days impregnated 89% of the females (experiment 3). We concluded that males with successive ejaculations remain potential rivals, because they may disrupt the sperm transport of other males. The ejaculate features recovery after sexual satiety is gradual, begins with the secretions of the sex accessory glands and is followed by the sperm count. Full fertility recovery is reached after 15 days of sexual abstinence when males are able to impregnate most females.

The mid-twentieth century Baby Boom and the changing educational gradient in Belgian cohort fertility

AbstractBACKGROUNDThe historical transition towards low fertility in many Western countries was interrupted during the period around the 1950s and '60s, called the Baby Boom. This upturn in fertility was completely unanticipated. One of the reasons for expecting continued fertility decline rather than fertility recovery was the expansion of female participation in higher education.OBJECTIVEThis research investigates how the recovery of fertility and declining ages at first birth observed during the Baby Boom era can be reconciled with the expansion of female participation in education. How did the pre-existing negative educational gradient in fertility evolve in the cohorts that produced the Baby Boom?METHODSUsing Belgian 1981 Census data, I estimate retrospective measures of cohort fertility. Potential sources of bias in the retrospective data are discussed. Trends in timing and quantum components are charted by women's levels of educational attainment for cohorts born between 1901 and 1940. A counterfactual simulation is used to delineate the role played by the changing educational gradient in completed fertility.RESULTSThe recovery of fertility was pervasive in Belgium, but there was a clear convergence between educational groups in terms of the quantum of fertility. Both low and high parity births increased: childlessness declined particularly among the highly educated while the share of women with three or more births went up in all educational groups, but most sharply among the highly educated. The educational gradient in completed fertility was strongly reduced. Without this shift, the recovery of completed fertility would have been about 25% less than its actual magnitude. The educational gradient for age at first birth remained stable: ages at first childbirth declined across all levels of educational attainment.CONCLUSIONSConvergence in the quantum of fertility across educational groups suggests a major weakening of the role incompatibility between obtaining a degree in higher education on the one hand and subsequently getting married and having children on the other hand. Declining ages at first marriage and childbirth indicate that this period was generally conducive to family formation. The reduction in the educational gradient was a crucial ingredient of the emergence of today's fertility patterns.(ProQuest: ... denotes formulae omitted.)1. IntroductionIn many Western countries, the transition from medium-high to low fertility that occurred from late nineteenth to the late twentieth century was interrupted during the period around the 1950s and '60s known as the Baby Boom. Increased childbearing during that era remains enormously consequential through its impact on current population aging. Yet, we know surprisingly little about the causes of the Baby Boom. At the time when it occurred, no one was expecting it. Today, most textbooks routinely ascribe the revival of fertility to the air of optimism and economic growth in the wake of the low fertility trough of the Great Depression. Yet, the recovery of fertility was already underway before and during the Second World War in most countries. Significantly, only a small part of the Boom can be explained by the timing mechanisms of postponement (during the Depression era) and recuperation (in times of post-war optimism). It also clearly involved a recovery of cohort fertility (Van Bavel and Reher 2013).The end of the Baby Boom was just as unexpected as its start. Indeed, by the 1960s, pro-cyclical fertility was considered one of the most firmly based empirical findings in the social sciences. Around 1960, mainstream demography was predicting that further fertility increases would accompany continuing economic growth (Butz and Ward 1979: 318). That did not happen, however, and the post-hoc explanations given for subsequent fertility decline were very similar to the ones given for low and declining fertility before the Second World War (Van Bavel 2010). …

Evidence for enhanced N availability during switchgrass establishment and seeding year production following inoculation with rhizosphere endophytes

Improvement in sustainable production of switchgrass (SG, Panicum virgatum L), as a purpose-grown biomass feedstock crop, could be realized through investigation of plant–microbe interactions associated with plant growth promoting rhizobacteria (PGPR), capable of biological nitrogen fixation (BNF). The objective of this study is to increase establishment year production of SG biofuels by inoculation with a mixed PGPR inoculum. We isolated pure strains of N2-fixing, and other PGPR, from SG rhizomes. The bacteria were identified as Paenibacillus polymyxa, an N2-fixing bacterium, and other PGPR capable of solubilizing phosphate and/or producing auxins. Field trials utilizing these strains in a mixed PGPR inoculum showed that inoculated plants contained more N in tillers during anthesis but not at senescence, suggesting that more N could be cycled to belowground roots and rhizomes for winter storage. The amount of N removal in biomass and recovery of fertilizer N were also greater for inoculated than uninoculated plants. PGPR inoculation also resulted in positive N balances, suggesting improved access to N from non-fertilizer N sources, possibly through BNF and improved soil N uptake. Overall, inoculation of SG with PGPR enhanced N acquisition and could be an effective strategy to increase the establishment year production of this crop.

P53 activity is selectively licensed in the Drosophila stem cell compartment

Oncogenic stress provokes tumor suppression by p53 but the extent to which this regulatory axis is conserved remains unknown. Using a biosensor to visualize p53 action, we find that Drosophila p53 is selectively active in gonadal stem cells after exposure to stressors that destabilize the genome. Similar p53 activity occurred in hyperplastic growths that were triggered either by the Ras(V12) oncoprotein or by failed differentiation programs. In a model of transient sterility, p53 was required for the recovery of fertility after stress, and entry into the cell cycle was delayed in p53(-) stem cells. Together, these observations establish that the stem cell compartment of the Drosophila germline is selectively licensed for stress-induced activation of the p53 regulatory network. Furthermore, the findings uncover ancestral links between p53 and aberrant proliferation that are independent of DNA breaks and predate evolution of the ARF/Mdm2 axis. DOI: http://dx.doi.org/10.7554/eLife.01530.001.

Fertilizer and Irrigation Management Effects on Nitrous Oxide Emissions and Nitrate Leaching

Irrigation and N fertilizer management are important factors affecting crop yield, N fertilizer recovery efficiency, and N losses as nitrous oxide (N2O) and nitrate (NO3−). Split application of conventional urea (split‐U) and/or one‐time application of products designed to perform as enhanced‐efficiency N fertilizers may mitigate N losses. The objective of this study was to compare the effects of controlled‐release polymer‐coated urea (PCU), stabilized urea with urease and nitrification inhibitors (IU) and split‐U on direct soil‐to‐atmosphere N2O emissions, NO3− leaching, and yield for fully irrigated and minimum‐irrigated corn in loamy sand. Indirect N2O emissions due to NO3− leaching were estimated using published emission factors (EF5). Split‐U increased yield and N uptake compared with preplant‐applied PCU or IU and decreased NO3− leaching compared with PCU. Direct N2O emissions were significantly less with IU or split‐U than with PCU, and there was a trend for greater emissions with split‐U than with IU (P = 0.08). Irrigation significantly increased NO3− leaching during the growing season but had no significant effect on direct N2O emissions. After accounting for significantly increased yields with irrigation, however, N losses expressed on a yield basis did not differ and in some cases decreased with irrigation. Post‐harvest soil N and soil‐water NO3− in spring showed the potential for greater N leaching in minimum‐irrigated than fully irrigated plots. Indirect emissions due to NO3− leaching were estimated to be 79 to 117% of direct emissions using the default value of EF5, thus signifying the potential importance of indirect emissions in evaluating management effects on N2O emissions.