Maize response to nitrogen and phosphorus starter fertilisation in mineral-fertilised or manured systems

Phosphorus(P)is an essential nutrient for maize production,but in temperate areas the P uptake during early growing stages can be limited due to low soil temperature,even though the soil was tested high in P.The objective of this study was to assess the effects of nitrogen and phosphorous(NP)starter fertilisation during early growth stages and its carryover until maize harvest,in mineral-fertilised or manured systems.A field experiment was carried out in north-west Italy during the 2019 and 2020 growing seasons.The trial compared sub-surface placement of NP(diammonium phosphate)or N alone(ammonium nitrate)in bands close to the maize seed furrows,in differing long-term(LT)fertilisation managements:two doses of urea(Min-L and Min-H),two doses of bovine slurry(Slu-L and Slu-H)or two doses of farmyard manure(Fym-L and Fym-H).The two rates,low(L)and high(H),corresponded to 170 and250 kg N ha^(-1)year^(-1) respectively.Compared to N fertilisation,NP starter fertilisation improved early maize growth assessed by leaf area index(LAI)and shoot dry weight(SDW)in all systems.The effects differed between the two years(2019:LAI+63%,SDW+67%;2020:LAI+36%,SDW+38%),as 2019was cool during the first growth.Higher LAI and SDW values were confirmed at crop flowering in the mineral-fertilised systems only.As shoot growth was enhanced by NP starter fertilisation,anthesis occurred 1 day earlier in all systems.However,a response to NP starter fertilisation at harvest was recorded in mineral-fertilised systems only(+1.3 and+3.2 t ha^(-1) in Min-L and Min-H,respectively).The uptake of P,used as a true indicator of soil nutrient availability,increased with increasing soil Olsen P until 39 mg kg^(-1).These results suggest that soil test thresholds should be revised for points above which P fertilisation should be suspended.

A delayed diagnosis of unsuspected retinoblastoma in an in vitro fertilisation infant with retinopathy of prematurity

Dear Editor,I am Dr.Tian Tian,from the Department of Ophthalmology,Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine,Shanghai,China.I write to present a rare case report of a delayed diagnosis of unsuspected retinoblastoma（RB）in an in vitro fertilisation（IVF）infant with retinopathy of prematurity.

An exploratory study of South African women’s experiences of In Vitro Fertilisation and Embryo Transfer (IVE-ET) at fertility clinics

Infertility is considered to be a growing problem worldwide. In sub-Saharan Africa, at least 20%-50% of couples of reproductive age experience a fertility problem and 30% are diagnosed with infertility. This study explores the experiences of women in South Africa who are involuntary childless and explores their psychological and emotional experiences of In Vitro Fertilisation and Embryo Transfer (IVF-ET). Utilising a qualitative methodology, a diverse group of 21 married women diagnosed with infertility and who had undergone at least two cycles of IVF-ET were recruited. Semi-structured, in-depth individual interviews were conducted and the data were analysed using thematic analysis. The results of the study indicated that the women perceived themselves as not conforming to a dominant belief system and as a result felt compelled to explore all the medical options available. They reported emotional turmoil characterised by primary binary emotions of anxiety-excitement and nervousness-optimistic. These emotions were experienced throughout the five stages of the IVF-ET treatment cycles. A synopsis of the psychological and emotional responses to the IVF-ET treatment is discussed. The findings of this study suggest the need for the incorporation of a mandatory psychosocial intervention as part of infertility management. Greater attention to the psychological and emotional repercussions of infertility treatment could lead to a more personalised client-approach which, in turn, would prepare infertile women and couples for the emotional demands of the treatment.

Effect of Acupuncture on Outcomes of in vitro Fertilisation:A Scoping Review

Objectives:To identify,examine and summarize the available evidence on the effectiveness and safety of acupuncture for in vitro fertilisation(IVF)outcomes.Methods:Eight electronic databases,including Pub Med,EMBASE,Cochrane Database of Systematic Review,Cochrane Central Register of Controlled Trials,China National Knowledge Infrastructure,Wanfang Database,Chinese Biomedical Database and VIP Database,were searched,supplemented by manual searches.Two researchers independently conducted the literature screening,data extraction,and methodological quality assessments.A narrative description was provided to show the general information and specific characteristics of the included studies.A bubble plot was used to visually display the overall effects of acupuncture on IVF outcomes.Results:Eighty-two studies were identified,including 64 primary studies and 18 systematic reviews.Transcutaneous electrical acupoint stimulation,electric acupuncture and manual acupuncture were applied in most studies and compared with no acupuncture,sham acupuncture and placebo acupuncture control groups.Sixty-three(98.4%)primary studies reported clinical pregnancy rate,and positive effects of acupuncture were found in 34 studies(54.0%).Live birth rate was reported in only 18(28.1%)primary studies,of which 10(55.6%)showed positive results.In addition,only 8 and 2 systematic reviews showed that acupuncture could increase clinical pregnancy events and live birth events,respectively.However,none of these reviews was of high methodological quality.Conclusions:Available evidence suggests that acupuncture therapy could improve clinical pregnancy rates.However,whether acupuncture could increase live birth events was difficult to determine based on the few studies that have reported this outcome indicator.Furthermore,the methodological quality of most systematic reviews was assessed as critically low or low.Studies with a rigorous design and standardized implementation should be performed to refine the available evidence.

Effect of Modified Biochar with Organic Fertiliser on the Growth and Development of Chinese Rose

In order to reduce the waste of resources and environmental pollution caused by excessive application of chemical fertilizers, improve the utilization rate of fertilizers, and promote the large-scale and high-quality development of the Chinese rose industry. In this experiment, corn stover biochar, phosphoric acid modified biochar and organic fertilizer were used as test materials, and the effects of mixed application of modified biochar and organic fertilizer on the growth and development of Chinese rose as well as soil physicochemical properties were investigated by using the method of pot planting test. The results showed that modified biochar with organic fertilizer had the most significant effect on the enhancement of soil pH, organic matter content and soil carbon-to-nitrogen ratio. After 120 d of planting, modified biochar with organic fertilizer had the most significant effect on the enhancement of plant height and crown width of Chinese rose;both organic fertilizer and modified biochar with organic fertilizer significantly increased the chlorophyll content of Chinese rose. The number of flowers and the number of branches were the highest in the modified biochar with organic fertilizer treatment. In conclusion, the application of modified biochar with organic fertilizer can better improve the soil pH, and increase the soil organic matter content and carbon-to-nitrogen ratio to change the biological traits of Chinese rose. The results of this study provide a theoretical basis for the reduction of chemical fertilizers and the resource utilization of agricultural wastes and guarantee the sustainable development of the cut flower industry.

Complementary effect of zoo compost with mineral nitrogen fertilisation increases wheat yield and nutrition in a low-nutrient soil

Excess nitrogen(N) fertiliser use in agriculture is associated with water pollution and greenhouse gas emissions.While practices and programs to reduce N fertiliser application continue to be developed,inefficient fertiliser use persists.Practices that reduce mineral N fertiliser application are needed in a sustainable agricultural ecosystem to control leaching and gaseous losses for environmental management.This study evaluated whether fully or partially replacing mineral N fertiliser with zoo compost(Perth Zoo) could be a good mitigation strategy to reduce mineral N fertiliser application without affecting wheat yield and nutrition.To achieve this,a glasshouse experiment was conducted to assess the complementary effect of zoo compost and mineral N fertiliser on wheat yield and nutrition in a sandy soil of southwestern Australia.Additionally,a chlorophyll meter was used to determine whether there was a correlation between chlorophyll content and soil mineral N content,grain N uptake,and grain protein content at the tillering(42 d after sowing(DAS)) and heading(63 DAS) growth stages.The standard practice for N application for this soil type in this area,100 kg ha^(-1),was used with a soil bulk density of 1.3 g cm^(-3) to calculate the amount of mineral N(urea,46% N) and Perth Zoo compost(ZC)(0.69% N) for each treatment.Treatments comprised a control(no nutrients added,T1),mineral N only(100 kg N ha^(-1),T2),ZC only(100 kg N ha^(-1),T7),and combinations of mineral N and ZC at different rates(mineral N at 100 kg N ha^(-1)+ ZC at 25 kg N ha^(-1)(T3),mineral N at 75 kg N ha^(-1)+ ZC at 25 kg N ha^(-1)(T4),mineral N at 75 kg N ha^(-1)+ ZC at 50 kg N ha^(-1)(T5),and mineral N at 50 kg N ha^(-1)+ ZC at 50 kg N ha^(-1)(T6)).The T6 treatment significantly increased grain yield(by 26%) relative to the T2 treatment.However,the T7 treatment did not affect grain yield when compared to the T2 treatment.All treatments with mineral N and ZC in combination significantly improved the 1 000-grain weight compared to the T2 treatment.Chlorophyll content was better correlated with soil mineral N content(r = 0.61),grain N uptake(r = 0.62),and grain protein content(r = 0.80) at heading(63 DAS) than at tillering(42 DAS).While ZC alone could not serve as an alternative to mineral N fertiliser,its complementary use could reduce the mineral N fertiliser requirement by up to 50% for wheat without compromising grain yield,which needs to be verified in the field.Chlorophyll content could be used to predict soil mineral N at the heading stage,and further studies are warranted to verify its accuracy in the field.Overall,the application of ZC as part of integrated nutrient management improved crop yield with reduced N fertiliser application.

Reducing potassium deficiency by using sodium fertilisation

Potassium(K)is the most abundant cation in the vast majority of plants.It is required in large quantities which,in an agronomic context,typically necessitates application of K in the form of potash or other K fertilisers.Recently,the price of K fertiliser has risen dramatically,a situation that is paralleled by increasing K deficiency of soils around the globe.A potential solution to this problem is to reduce crop K fertiliser dependency by replacing it with sodium(Na)fertiliser which carries a much smaller price tag.In this paper we discuss the physiological roles of K and Na and the implications of Na fertilisation for crop cultivation and soil management.By using greenhouse growth assays we show distinct growth promotion after Na fertilisation in wheat,tomato,oilseed and sorghum.Our results also show that up to 60%of tissue K can be substituted by Na without growth penalty.Based on these data,simple economic models suggest that(part)replacement of K fertiliser with Na fertiliser leads to considerable savings.

Russian Collaborative Development of Reproduction Technologies for the Sustainable Management of Amphibian Biodiversity

Reproduction technologies(RTs)can provide for the reliable reproduction of amphibians,as well as perpetuation of species genetic variation with the use of biobanks.In 1982,in anticipation of the biodiversity conservation crisis,major Russian institutions collaborated in a dynamic program to develop and implement RTs for the sustainable management of amphibian biodiversity.An initial primary focus was the captive breeding of threatened Russian endemic anuran and caudate species,using RTs that varied from environmental manipulation to the use of exogenous gonadotropic hormones to stimulate reproduction.These species were mostly from Palearctic or cool mountain regions,but also included a wide range of species from warm regions.Other early achievements included the successful cryopreservation of anuran spermatozoa and anuran diploid pluripotent cell nuclei,in order to store both the matrilineal and patrilineal genomes in biobanks,with their subsequent development to the blastula stage after implantation into enucleated oocytes.After the turn of the 21st Century,in support of the priorities of the Amphibian Conservation Action Plan(2007),we developed RTs for the refrigerated storage of testicular or urinary spermatozoa for days to weeks at 4℃,the cryopreservation of urinary spermatozoa using anovel cryoprotectant,the in vitro fertilisation of hormonally induced oocytes either fresh or after refrigerated ex situ or in situ storage,and the artificial insemination of salamanders with fresh spermatozoa.In this article,we describe previously unpublished techniques and techniques from obscure Russian sources.

Acrosome reaction： relevance of zona pellucida glycoproteins

During mammalian fertilisation, the zona pellucida （ZP） matrix surrounding the oocyte is responsible for the binding of the spermatozoa to the oocyte and induction of the acrosome reaction （AR） in the ZP-bound spermatozoon. The AR is crucial for the penetration of the ZP matrix by spermatozoa. The ZP matrix in mice is composed of three glycoproteins designated ZP1, ZP2 and ZP3, whereas in humans, it is composed of four （ZP1, ZP2, ZP3 and ZP4）. ZP3 acts as the putative primary sperm receptor and is responsible for AR induction in mice, whereas in humans （in addition to ZP3）, ZP1 and ZP4 also induce the AR. The ability of ZP3 to induce the AR resides in its C-terminal fragment. O-linked glycans are critical for the murine ZP3-mediated AR. However, N-linked glycans of human ZP1, ZP3 and ZP4 have important roles in the induction of the AR. Studies with pharmacological inhibitors showed that the ZP3-induced AR involves the activation of the Gi-coupled receptor pathway, whereas ZP1- and ZP4-mediated ARs are independent of this pathway. The ZP3-induced AR involves the activation of T-type voltage-operated calcium channels （VOCCs）, whereas ZP1- and ZP4-induced ARs involve both T- and L-type VOCCs. To conclude, in mice, ZP3 is primarily responsible for the binding of capacitated spermatozoa to the ZP matrix and induction of the AR, whereas in humans （in addition to ZP3）, ZP1 and ZP4 also participate in these stages of fertilisation.

Heat shock protein family D member 1 in boar spermatozoa is strongly related to the litter size of inseminated sows

Background:Sperm quality evaluation is the logical first step in increasing field fertility.Spermatozoa contain cytoplasmic organelles and biomolecules known as sperm-intrinsic factors,which play key roles in sperm maturation,sperm-oocyte fusion,and embryo development.In particular,sperm membrane proteins[e.g.,arginine vasopressin receptor 2,beta-actin,prohibitin,and heat shock protein family D member 1(HSPD1)]and RNA could be used as functional indicators of male fertility.We sought to clarify the effects of differential mRNA expression of selected genes on several fertilisation parameters,including sperm motility,motion kinematics,capacitation,and litter size,in a porcine model.Results:Our results demonstrated that HSPD1 expression was significantly correlated with male fertility,as measured by the litter size of inseminated sows.The expression of HSPD1 mRNA was linked to sperm motility and other motion kinematic characteristics.Furthermore,HSPD1 had a 66.7%overall accuracy in detecting male fertility,and the high-litter size group which was selected with the HSPD1 marker had a 1.34 greater litter size than the lowlitter size group.Conclusions:Our findings indicate that HSPD1 might be a helpful biomarker for superior boar selection for artificial insemination,which could boost field fertility.

Effects of acut and chronic doses of methoxy acetic acid on hamster sperm fertilising ability

Aim: To evaluate the effects of acute and chronic doses of methoxy acetic acid (MAA) on in vitro fertilisation byhamster sperm and to correlate the data with the testicular damage. Methods: Adult male hamsters were gavagedwith 3 single doses (0, 80, 160 and 650 mg/kg) and 3 chronic doses (0, 8, 32 and 64 mg/kg daily for 5 weeks) ofMAA in distilled water. After treatment hamsters were killed at weekly intervals and spermatozoa recovered from thedistal cauda epididymides were used to assess the fertilising capacity in vitro. The testes were processed for histologicalexamination. Results; Acute doses showed a significant reduction in sperm fertilising ability from week 3 and 4 af-ter treatment and with the chronic doses, the effects were more extensive and persistent. The results were in correpon-dence with the testicular damages observed. Conclusion: It is evident that both acute and chronic doses of MAAcan impair the sperm function by damaging one or more cell populations in the testis.(Asian J Androl 2001 Sep; 3: 209- 216)

Context dependent song-flight performance and timing in the Black-headed Bunting(Emberiza melanocephala)

Many songbirds produce song-flights;however,the function,vocal and motor characteristics,as well as the diel and seasonal variation of song-flight in songbirds remain not well understood.Here,we studied two types of song-flight in male Black-headed Buntings(Emberiza melanocephala),the Moth—a standard,i.e.,perch song produced during a horizontal flight,and the Towering—a specifically structured song produced during a complex ascending and descending flight.While perch song,used during Moth flight,has already been described,here we provide the first description and sonogram representation of the more elaborate and less stereotyped Towering song.While males started to perform Moth song-flights as soon as they arrived at the breeding site,Towering did not start before the female arrival.Males usually delivered spontaneous Moth song-flights before chasing rivals or undertaking aerial fights,suggesting Moth is directed towards conspecific males and serves as a threat display.Furthermore,playback of conspecific perch songs triggered males to approach the loudspeaker with Moth song-flights.The Towering started after females arrived at the breeding site,suggesting the Towering is directed towards conspecific females.We detected a seasonal difference in the peak Towering rate between forenoon and afternoon,suggesting that Towerings performed at different times of the day have different functions.Forenoon Towerings were strongly positively related to the number of fertile females at the breeding site,while afternoon Towerings peaked very early in the breeding season and coincided with the number of females at the breeding site before the onset of nest-building.These results provide evidence that birds can direct different types of song-flight towards different receivers and suggest the possibility that time of the day determines the context of the display,namely to attract social mates or solicit copulation.Further work is needed to account for the effect of between male variability in song-flight rate,as well as in height/steepness of flight or song quality.

Biomass Accumulation and Nutrient Uptake of Jerusalem Artichoke (<i>Helianthus tuberosus</i>L.)

The dynamics of biomass accumulation during the growing period, the yield of leafy stalks and tubers, and the nutrient concentration and nutrient uptake of the yield were investigated for two Jerusalem artichoke varieties (Tápiói Korai and Tápiói Sima) in a field experiment involving mineral fertilisation. Considerable differences were observed between the dynamics of leafy stalk and tuber development in Tápiói Korai which has a short vegetation period and Tápiói Sima where the vegetation period is long. The maximum dry matter ratio between the tuber yield and the leafy stalk yield was 1:1 for Tápiói Korai and 1:4.5 for Tápiói Sima. During the period when the maximum aboveground biomass developed in Tápiói Korai, 100 kg.ha-1 N and P fertiliser resulted in the highest leafy stalk yield (38.34 t.ha-1), while for Tápiói Sima, which developed a much greater leafy stalk mass, the highest aboveground biomass yield (78-80 t.ha-1) was given in response to 200 kg.ha-1 N supplemented by P and K fertiliser. Both artichoke varieties produced the great-est tuber yield at a N rate of 200 kg.ha-1, supplemented with P and K fertiliser. The nutrient concentration in the leafy stalks was highest on the 85th day of the vegetation period, prior to intensive dry matter accumulation in the leafy stalks and before tuber formation began. In both varieties the maximum nutrient uptake was recorded on the 155th day. Great differences were observed between the varieties in terms of specific nutrient uptake. For a tuber yield of 10 t, together with the corresponding leafy stalk yield, the specific nutrient uptake of the Tápiói Korai variety amounted to 48 kg N, 10 kg P, 83 kg K, 30 kg Ca and 10 kg Mg, while for Tápiói Sima these figures were 162 kg N, 30 kg P, 300 kg K, 84 kg Ca and 45 kg Mg.

Lazzaro Spallanzani: pioneer of artificial insemination, multidisciplinary research, and scientific dissemination

Lazzaro Spallanzani(1729-1799)was a father of modern biology,with peculiar traits such as a multidisciplinary approach and penchant for scientific dissemination.Spallanzani consistently contributed to modern reproductive medicine by implementing experimental methods for the first historically successful artificial insemination.Nevertheless,he participated in discoveries pertaining to blood circulation,digestion,and respiration.Widely known in Europe in the eighteenth century,his fame prolonged to the following century,not exclusively through scientific acknowledgments,but even in literature.Nowadays,the figure of Spallanzani experience a kind of neglect and it would appear essential to maintain his work in the light of the history of medicine.

Closing the nitrogen use efficiency gap and reducing the environmental impact of wheat-maize cropping on smallholder farms in the Guanzhong Plain,Northwest China

A high crop yield with the minimum possible cost to the environment is generally desirable.However,the complicated relationships among crop production,nitrogen(N) use efficiency and environmental impacts must be clearly assessed.We conducted a series of on-farm N application rate experiments to establish the linkage between crop yield and N_2 O emissions in the Guanzhong Plain in Northwest China.We also examined crop yield,partial factor productivity of applied N(PFPN) and reactive N(Nr) losses through a survey of 1 529 and 1 497 smallholder farms that grow wheat and maize,respectively,in the region.The optimum N rates were 175 and 214 kg ha^(-1) for winter wheat and summer maize,respectively,thereby achieving the yields of 6 799 and 7 518 kg ha^(-1),correspondingly,with low N_2 O emissions based on on-farm N rate experiments.Among the smallholder farms,the average N application rates were 215 and 294 kg ha^(-1) season^(-1),thus producing 6 490 and 6 220 kg ha^(-1) of wheat and maize,respectively.The corresponding PFPN values for the two crops were 36.8 and 21.2 kg N kg^(-1),and the total N_2 O emissions were 1.50 and 3.88 kg ha^(-1),respectively.High N balance,large Nr losses and elevated N_2 O emissions could be explained by the overdoses of N application and low grain yields under the current farming practice.The crop yields,N application rates,PFPN and total N_2 O for wheat and maize were 18 and 24% higher,42 and 37% less,75 and 116% higher,and 42 and 47% less,correspondingly,in the high-yield and high-PFPN group than in the average smallholder farms.In conclusion,closing the PFPN gap between the current average and the value for the high-yield and high-PFPN group would increase crop production and reduce Nr losses or the total N_2 O emissions for the investigated cropping system in Northwest China.

Effects of organic mineral fertiliser on heavy metal migration and potential carbon sink in soils in a karst region

Heavy metal pollution in karst mountainous area of Guizhou has spread due to the long-term exploitation of mineral resources and the improper disposal of environmentally hazardous waste. Heavy metals are characterised by non-degradation, strong toxicity, and constant accumulation, posing a grave threat to karst mountain fragile soil ecosystem. To reduce the harm caused by heavy metal pollution and damage to agricultural products, research was undertaken on the basis of previous work by simulating pot experiments on pak choi cabbage(Brassica rapa chinensis)planted in Cd-contaminated soil: different amounts of organic mineral fertilisers(OMF) compared with chemical fertiliser(CF) were used and by detecting the amount of heavy metal in the mature vegetable, a better fertilisation strategy was developed. The results showed that the Cd content in vegetables grown with CF was 23.70 mg/kg,while that of vegetables grown with OMF and bacterial inoculant was the lowest at 15.13 mg/kg. This suggests that the use of OMF and microbes in karst areas not only promotes plant growth but also hinders plant absorption of heavy metal ions in the soil. In addition, through the collection of pot leachate, the detection of water chemistrycharacteristics, and the calculation of the calcite saturation index, it was found that the OMF method also induces certain carbon sink effects. The results provide a new way in which rationalise the use of OMFs in karst areas to alleviate soil heavy metal pollution and increase soil carbon sequestration.

Growth response of broom (Cytisus scoparius) growing with and without radiata pine (Pinus radiata) seedlings to different P levels in soils

A study was carried out to test the effects of three rates of TSP （triple superphosphate） （0, 50, and 100 mg·kg^-1 P） on growth of broom with and without radiata pine seedlings and to determine the relationships between P concentrations in the broom shoot and dry matter yields with soil plant-available P （Bray-2 P）. A bulk sample of soil was collected from Kaweka forest at soil depth of 0-10 cm, in New Zealand on March 11, 2001. The forest area was not supplied with fertiliser at least 30 years. The results show that TSP application increased P avail- ability in the soil. The P availability concentration in soil of broom with radiata pine seedlings was higher than that in soil of broom alone. Bray-2 P concentrations had a significant logarithmic relationship with Pcon- centrations of broom shoot and an exponential relationship with dry matter weight of whole broom plant.

The Effect of Organo-Mineral Fertilizer Applications on the Yield of Winter Wheat, Spring Barley, Forage Maize and Grass Cut for Silage

Biosolids were applied with urea to produce a granulated organo-mineral fertiliser (OMF) for application by farm fertiliser equipment to a range of agricultural crops. The recommended rates of nitrogen, phosphate and potash were calculated for the test crops using “The Fertiliser Manual”, which assesses the nutrient requirement based on previous cropping, rainfall and soil index. The OMF produced similar crop yields compared to ammonium nitrate fertiliser when applied as a top-dressing to winter wheat, forage maize and grass cut for silage in the cropping years 2010 to 2014. In 2012 the grain yield of spring barley top-dressed with OMF was significantly lower than the conventional fertiliser treatment, due to dry conditions following application. For this reason it is recommended that OMF is incorporated into the seedbed for spring sown crops and The Safe Sludge Matrix guidelines followed. The experimental work presented shows that OMF can be used in sustainable crop production systems as a source of nitrogen and phosphorus for a range of agricultural crops.

The current status of nitrogen fertiliser use efficiency and future research directions for the Australian cotton industry

Fifty years of sustained investment in research and development has left the Australian cotton industry well placed to manage nitrogen（N） fertiliser. The average production in the Australian cotton industry today is greater than two tonnes of lint per hectare due to improved plant genetics and crop management. However, this average yield is well below the yield that would be expected from the amount of N fertiliser used. It is clear from the recent studies that across all growing regions, conversion of fertiliser N into lint is not uniformly occurring at application rates greater than 200-240 kg·hm;of N. This indicates that factors other than N availability are limiting yield, and that the observed nitrogen fertiliser use efficiency（NFUE） values may be caused by subsoil constraints such as sodicity and compaction. There is a need to investigate the impact of subsoil constraints on yield and NFUE.Gains in NFUE will be made through improved N fertiliser application timing, better targeting the amount of fertiliser applied for the expected yield, and improved soil N management. There is also a need to improve the ability and confidence of growers to estimate the contribution of soil N mineralisation to the crop N budget. Many Australian studies including data that could theoretically be collated in a meta-analysis suggest relative NFUE values as a function of irrigation technique; however, with the extensive list of uncontrolled variables and few studies using non-furrow irrigation, this would be a poor substitute for a single field-based study directly measuring their efficacies. In irrigated cotton, a re-examination of optimal NFUE is due because of the availability of new varieties and the potential management and long-term soil resilience implications of the continued removal of mineralised soil N suggested by high NFUE values. NFUE critical limits still need to be derived for dryland systems.

Phosphorus fractions of fertiliser-derived P in an allophanic soil under Pinus radiata seedlings grown with broom and ryegrass

Changes in phosphorus （P） fractions in a P deficient allophanic soil under P. radiata seedlings grown with broom （Cytisus scoparius L.） and ryegrass （Lolium multiflorum） in pots were studied 14 months after the application of triple superphosphate at the rates of 0, 50, and 100 pg.g^-1, to determine the fate of fertiliser-derived P in the rhizosphere soils. Application of P fertiliser increased NaOH-Pi, NaOH-Po, and H2SO4-Pi concentrations in the soil, but decreased the residual-P concentration. The resin-Pi concentration, which is ex- tremely low in this soil （1 to μgg^-1 ）, remained the same. The majority of the added fertiliser P was however recovered in the NaOH-Pi fraction （40%-49%）. This is due to the high P fixation in this soil （92%）. The second highest P recovery was in NaOH-Po fraction （7%-19%）. Under P deficient condition or addition at the rate of 0 μg.g^-6, the NaOH-Pi concentration in the radiata rhizosphere soil was lower than that in the bulk soil and broom and grass rhizosphere soils. This may be due to higher oxalate production by the roots and mycorrhiza under P deficient conditions which released some ＆the P fixed to the soils in the rhizosphere, which needs to be tested in future studies.