Excessive Application Research Articles

Temporal variation in soil quality and carbon sequestration potential of different cropping systems in Arid and Semi-Arid parts of South Eastern Kenya

The use of incorrect agricultural methods and utilization of land, excessive inorganic chemical applications, misguided cultivation, and nutrient mining have all contributed to a considerable deterioration in soil health globally. To meet the requirements of growing inhabitants, farmers have turned to unsustainable methods including monoculture, excessive use of pesticides and fertilizers, and increased agricultural intensification. A study to determine the seasonal variation of soil quality under different cropping systems and carbon sequestration potential was done during the years 2018 and 2019 in Kauwi and Zombe Wards of South Eastern Kenya. Five cropping systems namely, vegetable, cereal, fruit, and agroforestry were selected, whereas uncultivated land was considered as control. During the typical long (MAM) and short (OND) rainfall seasons, composite soil samples were taken from the cropping systems at random, making the treatment combinations ten. Each farming system had surface soil samples obtained from a depth of 0 to 15 centimetres. Two-way ANOVA was used to analyze the results. The results revealed that the influence of cropping systems on seasonal variation of soil quality parameters varied significantly (p<0.05). Further, the interaction between cropping systems and seasons significantly influenced soil pH and soil organic carbon. The short rain season registered lower soil pH values across all cropping systems. Soil Organic Carbon was found to be highest in vegetable-based cropping systems during short and long rain seasons. Electrical Conductivity was highest during the long rain season across all cropping systems. Soil bulk density was lowest during the short rains and under uncultivated land. NPK varied significantly across the cropping systems in the different rain seasons. Higher carbon stock was found in the Zombe ward as compared to the Kauwi ward. Carbon density values were noticed to be highest under Vegetable-based cropping systems in both study locations. This can be ascribed to the heavy application of organic and artificial fertilizers by farmers to increase yields and profits. Based on the results, Vegetable and agroforestry cropping systems were found to contain the highest amounts of soil carbon, and therefore, with the potential to sequester the highest amount of soil carbon. Both tiers of government should promote vegetable and agroforestry cropping systems to minimize the effects of climate change

In-Season Nitrogen Management in the Root Zone of Wheat in a Calcareous Soil Using the Response Index

ABSTRACT Excessive and inappropriate nitrogen (N) fertilizer applications on calcareous soils result in significant losses, necessitating a targeted approach for improved efficiency and yield. Field experiments were conducted over two seasons to develop a strategy for root-zone (RZ) N fertilization for wheat. In the first season, three methods of N fertilizer application were used: surface (SF), in the RZ at a depth of 10 cm (RZF10), and in the RZ at a depth of 20 cm (RZF20). The N fertilizer was applied in a range of 0–280 kg N ha−1. In the second season, another experiment was carried out to validate the results. The data showed that to achieve maximum yield levels, N fertilizer rates of 264 kg ha−1 for SF, 218 kg ha−1 for RZF10, and 183 kg ha−1 for RZF20 were required. The findings also revealed that relocating the application from the surface to depths of 10 and 20 cm resulted in an increase in recovery efficiency by 11.2% and 31.2%, respectively. A linear equation established the relationship between the response index at harvest (RI-Harvest) and the corrective N rate for RZF20. The in-season response index of the normalized difference vegetation index effectively predicted RI-Harvest, leading to the development of an empirical equation to predict the corrective N rate. The validation experiment demonstrated the effectiveness of the proposed strategy in adjusting N rates based on crop-specific needs. This approach allows growers to optimize profits by carefully applying N in the RZ, eliminating both excessive and inadequate use.

Distribution Characteristics and Formation Mechanism of Main Hydrochemical Ions in Qingshui River

Qingshui River is a vital source for human life and industrial production in Zhangjiakou City. Determination of the formation mechanism of the main hydrochemical ions is important for the sustainable development and utilization of surface water resources in the Qingshui River. In view of this, 20 surface water samples were collected from the agricultural and urban reaches of the Qingshui River in July 2022. Based on the detection of hydrochemical ions and stable isotopes （δ2H-H2O and δ18O-H2O）, the hydrogeochemical methods, multivariate statistical analysis, and positive matrix factorization model （PMF） were used to comprehensively understand the chemical formation mechanism of surface water from qualitative to quantitative perspectives. The results showed that the average pH value in the Qingshui River was 8.66, indicating weakly alkaline water. The average concentrations of cations and anions decreased in the orders of Ca2+ > Na+ > Mg2+ > K+ > NH4+ and HCO3- > SO42- > NO3- > Cl- > F- > NO2- in the river water, respectively. The main hydrochemical type was identified as HCO3-Ca·Mg water. For the natural background, surface water was mainly controlled by rock weathering and evaporation crystallization and rock weathering was identified as the primary driving factor. The main hydrochemical compositions in the Qingshui River were derived from the dissolution of carbonate rocks and silicate rocks. Regarding anthropogenic activities, the portions of river water in the agricultural reaches were mainly affected by the excessive application of chemical fertilizers. Furthermore, the concentration of NO3- （1.88-47.4 mg·L-1） exceeded the standard for drinking purposes （10 mg·L-1）. The concentration of F- （0.38-1.92 mg·L-1） was above the acceptable limit for drinking purposes （1.0 mg·L-1） in the southern urban reaches portion of the river water, which could have been attributed to the industrial sewage discharge. The obtained results from the PMF model showed that the hydrochemical compositions in the river water of agricultural reaches were mainly controlled by four factors, namely synthetic fertilizers （29.6%）, livestock manure （16.4%）, rock weathering （17.4%）, and natural geology （13.7%）, while hydrochemical compositions in the river water of urban reaches were mainly affected by the domestic pollutants （30.5%）, industrial discharges （20.1%）, natural geology （18.4%）, and rock weathering （16.7%）.

Effect of biological additives to a putting green with low plant‐available phosphorus

AbstractThe use of phosphorus fertilizers on managed turf has become discouraged, if not restricted, in many places because of the risk of pollution of surface waters posed by excessive phosphorus application. Therefore, nontraditional options to increase phosphorus availability to turf are worthy of investigation. The objectives of this study were to evaluate the effect of additions of arbuscular mycorrhizal fungi and an N‐fixing bacterium, Methylobacterium symbioticum, on the nutritional status of a mature bentgrass putting green on a sand root zone with low plant‐available phosphorus status. The biological amendments were added at various intervals after aerification, and turfgrass responses were recorded over two field seasons. Mycorrhizae did not result in increased turfgrass visual quality, clipping yield, or clipping P content. Additions of the N‐fixing bacterium resulted in increased mid‐season clipping N content and increased visual turfgrass quality, but the overall effect was relatively small. It appears that applications of M. symbioticum to turfgrass hold promise for improving nutrient use efficiency and visual turfgrass quality and deserve future exploration.

EFFECTS OF POULTRY LITTER ON SOIL PHYSICO-CHEMICAL PROPERTIES FOR CROP PRODUCTION IN KAURU LOCAL GOVERNMENT AREA, KADUNA STATE, NIGERIA

Poultry litter is an important source of soil nutrients that supports beneficial soil bacteria by serving as a substrate, however, its excessive have adverse effects that lead to soil pollution, contamination and acidification of soil and groundwater. This study analyzed the effects of poultry litter on soil physico-chemical properties for crop production in Kauru Local Government Area, Kaduna State, Nigeria. Data on soil properties at the control and poultry littered sites were collected by sampling four farmlands in Barwa, Ungwan Noma, Kurmin-Shado and Dan-Daura and analyzed in the laboratory. Results were subjected to ANOVA and Correlation analyses tools. The findings revealed significant changes in soil physico-chemical properties due to excessive poultry litter application. Compared to the control site, treated soil showed increased pH (6.26 to 6.89), decreased organic carbon (4.29 to 3.63), increased organic matter (5.92 to 6.99), increased total nitrogen (0.49 to 0.58), altered particle size distribution (clay, silt, sand), reduced aggregate, stability (0.818 to 0.715) and increased CO2 (64.8 to 65.88%). Also, Correlation analysis revealed a significant relationship between poultry litter application and soil physico-chemical properties (Sig. value >0.05), indicating that poultry manure significantly alters soil parameters. The study concludes that while some of the soil properties identified were within safe limits, application of poultry manure altered other properties of the soil. Thus, the study recommends that farmers should use poultry litter in conjunction with other fertilizers and soil amendments to balance nutrient inputs.

Nitrogen Application Stimulates Methane Emissions.

Nitrogen fertilizer plays a vital role in rice cultivation, yet its excessive application significantly intensifies methane emissions from rice paddies. Therefore, the urgent adoption of effective agronomic interventions is crucial to mitigate methane emissions resulting from nitrogen fertilizer application.

Nutrient efficiency unlocked: Water-soluble fertilizers in horticultural crop production

Horticultural crops are invaluable to the lands of small and marginal farmers across the nation, making a substantial contribution to the national economy. The significant productivity gap in horticulture is mostly attributable to the inefficient utilization of water and fertilizer resources. Soil fertility has been declining, driven by nutrient depletion and excessive fertilizer application with low nutrient-use efficiency, which hampers productivity despite the steady increase in cultivated area. Numerous research has investigated the application of water-soluble fertilizers to enhance the yield of horticulture crops, achieving greater profitability while minimizing environmental effects. Water-soluble fertilizers are closely linked to improvements in growth, yield attributes, and soil fertility in various horticultural crops. These fertilizers offer numerous advantages, such as controlling weed growth, reducing the need for herbicides, and enhancing the quality of vegetables and fruits, leading to widespread adoption. Additionally, drip irrigation systems in horticulture have conserved nearly half of the fertilizers and water resources used. Achieving self-sufficiency and sustainability in food production further supports precision farming through water-soluble fertilizers. Consequently, higher nutrient use efficiency (NUE) can be attained, making water-soluble fertilizers an essential component of precision agriculture and site-specific nutrient management.

Nitrogen, phosphorus and potassium budget in crop production in South-Asia: regional and country trends during the last five decades

Nutrient budgeting for cropland is a crucial tool for assessing nutrient mining or excess application. We estimated the nutrient budget of nitrogen (N), phosphorus (P), and potassium (K) in cropland for South Asia during the last five decades (from 1970 to 2018) using equation-based empirical methods. Nutrient budget for the last five decades shows a negative balance of N (3.94 million tons, Mt), P (23.87 Mt), and K (247.23 Mt). Inorganic fertilizer remained the major input source for N and P, and its decadal average share increased for N (from 27.9% to 72.8%) and P (from 72.1% to 94.5%) from 1970 to 2010s and the share of manure, deposition, and crop residue to N, P and K input decreased. Deposition remained a major source of K input and its share decreased from 64.0% to 35.5% during the period. The share of crop removal to the decadal output of N (58.6% to 53.4%) and P (49.0% to 23.1%) decreased, and K (72.5% to 76.0%) increased from 1970 to 2010s. The higher losses of fertilizer N, and accumulation of P and K fertilizers in soils, resulted in decreasing partial factor productivity of N (from 72.2% to 16.9%), P (from 217.0% to 42.2%), and K (from 480.3% to 113.8%) from 1970 to 2018. Nutrient budget helps in identifying the regional imbalance (mining/accumulation) of the major nutrients, it will provide valuable information on the present status of country-level nutrient use for reorientation of their nutrient/fertilizer use policies.

Occurrence, migration, and assessment of human health and ecological risks of PFASs and EDCs in groundwater of Northeast China

Northeast China as an important base of grain production in China, has been suffering from potential groundwater pollution due to the excessive and prolonged application of fertilizers and pesticides. However, exploration of emerging contaminants pollution in groundwater and assessment of human health and ecological risks caused by large-scale agricultural activities have been relatively scarce. This study collected groundwater samples from typical agricultural areas in Northeast China to investigate the extent of contamination by nitrate, per- and polyfluoroalkyl substances (PFASs) and endocrine-disrupting compounds (EDCs), and then compared the levels of these pollutants with those in other regions of China. Groundwater nitrate pollution caused by strong agricultural activity is widespread in Northeast China, with nitrate-nitrogen (NO3N) concentrations exceeding 10 mg/L in as many as 40.3 % of 429 samples. 8 types of PFASs (3.7–7.1 ng/L) and 11 types of EDCs (18,114.0–62,029.8 ng/L) were detected in the collected groundwater samples. Using the Risk Quotient (RQ) method, this study assessed ecological risk and found that the risk level of perfluorooctane sulfonate (PFOS) was higher than that of other PFASs. The groundwater EDCs risks in Northeast China was higher compared to other regions in China, with dibutyl phthalate (DBP), Di-(2-ethylhexyl) phthalate (DEHP), Bisphenol A (BPA) having high ecological risk levels. Nitrate, PFASs and EDCs have been detected in deep groundwater (70–100 m depth), indicating that the deeper aquifers could be significantly threatened by pollutants due to human activities. Fertilizers, pesticides, domestic wastewater, and industrial discharges are major sources of groundwater pollutants in the agricultural regions. Industrial-sourced EDCs were widely detected in groundwater of agricultural area, suggesting that the transport of these pollutants is very active in groundwater system. Groundwater monitoring and pollution prevention are extremely urgent, especially for emerging contaminants. This study can provide important warnings and water resource management references for other agricultural areas affected by intensively agricultural activities in the world.

Responses of N2O, CO2, and NH3 Emissions to Biochar and Nitrification Inhibitors Under a Delayed Nitrogen Application Regime

Greenhouse gas and NH3 emissions are exacerbated by the inappropriate timing and excessive application of nitrogen (N) fertilizers in wheat cultivation in China. In this study, the impacts on N2O, CO2, and NH3 emissions of a delayed and reduced N application regime on the Huang-Huai-Hai Plain were investigated. The treatments comprised the control (N0), conventional N at 270 kg N ha−1 (N270) and optimized N application of 180 kg N ha−1 (N180), N180 + biochar at 7.5 t ha−1 (N180B7.5), N180 + biochar at 15 t ha−1 (N180B15), N180 + DMPP (a nitrification inhibitor; N180D), N180D + biochar at 7.5 t ha−1 (N180DB7.5), and N180D + biochar at 15 t ha−1 (N180DB15). Reduced N application (N180) lowered N2O and NH3 emissions. Biochar application resulted in a 4–25% and 12–16% increase in N2O and NH3 emissions, respectively. Application of DMPP significantly decreased N2O emissions by 32% while concurrently inducing a 9% increase in NH3 emissions. Co-application of DMPP and biochar significantly reduced the activity of nitrification enzymes (HAD, NOO), resulting in a reduction of 37–38% in N2O emissions and 13–14% in NH3 emissions. No significant differences in CO2 emissions were observed among the various N treatments except the N0 treatment. Application of DMPP alone did not significantly affect grain yield. However, biochar, in combination with DMPP, effectively increases grain yield. The findings suggest that the N180DB15 treatment has the potential to reduce emissions of N2O and NH3 while concurrently enhancing soil fertility (pH, SOC) and wheat yield.

Effect of Nano-fertilizers in Wheat Crop Nutrition: A Review

The use of nano - fertilizers in wheat cultivation represents a promising approach to overcoming some of the inefficiencies and environmental challenges associated with conventional fertilizer practices. Traditional fertilizers often suffer from low nutrient use efficiency, leading to excessive application, nutrient runoff, and environmental harm. Nano fertilizers, due to their nano-scale size and enhanced reactivity, improve nutrient uptake by plants, leading to better growth, higher yields, and reduced nutrient wastage. Studies show that Nano formulations of both macronutrients (such as nitrogen, phosphorus, and potassium) and micronutrients (like zinc and iron) can significantly enhance wheat productivity. Nano fertilizers not only increase crop yield but also reduce the overall cost of fertilizer application by minimizing nutrient loss and improving absorption by the plants.

The Aftermath Of Diapers Absorbents On Soil PhysioChemical Properties And Its Influence On The Performance Of Crops (Maize) Yield In Obubra Local Government Area Of Cross River State, Nigeria

This study investigates the environmental impacts of disposable diaper absorbents on soil physico-chemical properties and their subsequent effects on maize (Zea mays L.) yield in Obubra Local Government Area, Cross River State, Nigeria. The increasing use of disposable diapers, particularly in regions with inadequate waste management, poses significant challenges to soil health due to the non-biodegradable nature of superabsorbent polymers (SAPs) and other materials contained within these products. We conducted a controlled experiment on sandy soil, analyzing various treatments with different levels of diaper absorbents (0g, 40g, 80g, 120g, 160g, and 200g per 10kg of soil). Soil samples were collected and subjected to standard physico-chemical analyses, including texture, pH, organic matter content, and nutrient availability. Our findings reveal that moderate levels of diaper absorbents can maintain beneficial sand content while increasing silt levels, which may enhance soil fertility and moisture retention. However, excessive application (beyond 80g) leads to diminished sand percentages and potential long-term soil health issues, such as reduced aeration and root growth inhibition. The pH of the soil across treatments ranged from 6.26 to 6.88, indicating a generally favorable environment for maize cultivation. This research highlights the need for sustainable waste management strategies to mitigate the adverse effects of disposable diaper waste on agricultural land. By providing insights into the complex interactions between diaper absorbents and soil properties, our findings contribute to the broader discourse on agricultural sustainability and environmental health in developing regions. Further studies are recommended to explore the long-term ecological implications of diaper absorbents in agricultural contexts

Biodiversity-safeguarding threshold for urea-fertilizer application on paddy fields: Protozoa-based toxicity tests

Urea is a widely applied fertilizer to enhance crop yields. Ecological risks associated with the excessive application of urea fertilizer threaten the paddy fields' sustainable agriculture and biodiversity preservation. There are no practical thresholds based on proven data on microbial communities. Protozoa are nitrogen-sensitive organisms. For the first time, this study conducted acute and chronic urea toxicity tests on eight species of organisms. The results indicate that Blepharisma sp. is the most sensitive species to urea exposure and is a suitable indicator for determining the safe threshold of urea. This study estimated the predicted no-effect concentration using species sensitivity distribution curves. Subsequently, it established the threshold for urea application in rice fields based on the fields' area and the surface water's height. The short-term safety threshold for urea in the studied paddy field with black soil is 87.7mg/L, equivalent to 43.85kg of urea per hectare for a single nitrogen fertilizer application. The long-term safety threshold is 5.02mg/L, representing the concentration for re-applicating urea. The biodiversity-safeguarding application threshold provides the basis for developing a urea fertilizer reduction protocol to safeguard the paddy fields' biodiversity.

From Flourish to Nourish: Cultivating Soil Health for Sustainable Floriculture.

Despite its rapid growth and economic success, the sustainability of the floriculture industry as it is presently conducted is debatable, due to the huge environmental impacts it initiates and incurs. Achieving sustainability requires joint efforts from all stakeholders, a fact that is often neglected in discussions that frequently focus upon economically driven management concerns. This review attempts to raise awareness and collective responsibility among the key practitioners in floriculture by discussing its sustainability in the context of soil health, as soil is the foundation of agriculture systems. Major challenges posed to soil health arise from soil acidification and salinization stimulated by the abusive use of fertilizers. The poisoning of soil biota by pesticide residues and plastic debris due to the excessive application of pesticides and disposal of plastics is another significant issue and concern. The consequence of continuous cropping obstacles are further elucidated by the concept of plant-soil feedback. Based on these challenges, we propose the adoption and implementation of several sustainable practices including breeding stress-resistant and nutrient-efficient cultivars, making sustainable soil management a goal of floriculture production, and the recycling of plastics to overcome and mitigate the decline in soil health. The problems created by flower waste materials are highlighted and efficient treatment by biochar synthesis is suggested. We acknowledge the complexity of developing and implementing the proposed practices in floriculture as there is limited collaboration among the research and operational communities, and the policymakers. Additional research examining the impacts the floriculture industry has upon soils is needed to develop more sustainable production practices that can help resolve the current threats and to bridge the understanding gap between researchers and stakeholders in floriculture.

Maize biomass yield variations due to diverse nitrogen applications using Aquacrop

AbstractIn the quest to increase crop yields and production intensity to meet the demands of a growing global population, the responsible use of nitrogen (N) applications is paramount. Excessive application of these fertilizers results in economic losses, environmental pollution and reduced N‐use efficiency. To address this challenge, precision agriculture techniques offer promising solutions. This study explored the relationships among applied N, maize crop parameters and the nitrogen nutrition index (NNI) to optimize N application usage and crop performance. The AquaCrop model was used to simulate water productivity and plant parameters accurately. The research establishes equations between the NNI and maize parameters, enabling the use of AquaCrop to simulate crop responses to varying N levels. The results demonstrate that AquaCrop effectively simulates more than 95% of the biomass changes. The findings suggest that applying N based on presented equations optimized the use of N applications, thereby mitigating economic losses and environmental impacts.

The dynamic relation between fertilization, precipitation and the diffusion of agricultural non-point pollution in Hainan Island

With the increasing demand for crops, the excessive application of fertilizers has gradually become a significant factor affecting water quality. Therefore, studying the relationship between agricultural fertilizer runoff and water quality is crucial for the sustainable development of agricultural production. The present study sets up a new dynamic model of nitrogen fertilizer loss, introducing variables such as precipitation, fertilization application during dry and rainy seasons, and their lagged and interaction terms. The paper analyzed the issue of fertilizer runoff under the complex interactions of various factors, including spatial and temporal scales and climatic conditions, and explored the relationship between agricultural activities and water quality changes in the context of sustainable development. Due to Hainan Island’s independent river system, which is free from transboundary pollution, and its low level of industrial pollution, it provides an excellent sample for assessing the impact of agricultural non-point source pollution on water quality. Based on watershed monitoring data from Hainan Island, this study draws the following conclusions: 1. Precipitation exhibits a pronounced seasonal influence on total nitrogen concentration. 2. Nitrogen fertilizer enters into water bodies through precipitation, resulting in a lag effect on total nitrogen concentration. 3. The influence of grain and tropical crops on nitrogen loss is less significant, while cash crops will trigger the nitrogen overloading of rivers in scenarios where they account for a high proportion of the planting structure of the sown area.

Winter leaf phenology differences facilitate selective control of an invasive plant species by herbicide

Herbicide control of invasive plant species is generally efficient. However, there is a likelihood of the excessive application of non-selective herbicides that kill co-occurring native species and cause environmental toxicity. We present a case study on the control of the invasive exotic Solidago canadensis with photosynthetically active leaves in winter by applying glyphosate. This approach improves herbicide control efficiency, while preventing harm to most co-occurring native plants. We quantified the winter leaf phenology and photosynthetic capacity of S. canadensis and two commonly co-occurring native species. We tested the effects of glyphosate and competition on S. canadensis and native Imperata cylindrica with contrasting winter leaf phenology in both pot and field experiments. Finally, we surveyed the life forms and winter leaf phenology of most co-occurring plant species in eastern China to determine whether most co-occurring species and S. canadensis differ in winter leaf phenology. Old leaves withered much later and new leaves developed much earlier in S. canadensis than in the two co-occurring species. Both the old and new leaves of S. canadensis had high photosynthetic capacity in winter. In summer, glyphosate suppressed the growth of S. canadensis by 20.1–59.5% and growth of I. cylindrica to a greater extent (by 57.6–91.7%), whereas winter application of glyphosate at a certain concentration suppressed the growth of S. canadensis by 91.4–95.6% (the efficiency was higher than summer application), but had no impact on I. cylindrica. Glyphosate application in winter alleviated competition stress from S. canadensis on I. cylindrica. We conclude that winter glyphosate application can increase the selectivity and efficiency of chemical control of invasive S. canadensis, which may shift the competition balance towards native species and favour native vegetation recovery in sites invaded by S. canadensis. The principles of this approach can be applied to any scenario where invasive species and co-occurring species have distinct phenological niche separation.

Effects of Recommended Fertilizer Application Strategies Based on Yield Goal and Nutrient Requirements on Drip-Irrigated Spring Wheat Yield and Nutrient Uptake

Excessive application of fertilizers in drip-irrigated wheat production can suppress yields, lower nutrient utilization efficiency, and lead to economic and environmental issues such as nitrogen residues in the soil. Based on a recommended fertilizer application (RF) strategy that takes into account target yield and nutrient requirements, this study explores the responses of wheat plant traits, changes in topsoil and subsoil nutrients, fertilizer utilization, and economic benefits under this strategy. From 2022 to 2023, a field experiment was conducted in a typical oasis spring wheat production area at the northern foot of the Tianshan Mountains in Xinjiang. The treatments included no fertilizer control (CK), the farmer’s conventional practice (FP), recommended fertilizer (RF), RF with nitrogen omission (RF-N), phosphorus omission (RF-P), and potassium omission (RF-K). The results showed that compared with FP, the RF reduced 91 kg N ha−1 (30.3%) and 33 kg P2O5 ha−1 (24.8%) in 2022, and 69 kg N ha−1 (23.0%) and 2 kg P2O5 ha−1 (1.5%) in 2023. The effect in 2023 was better; RF also decreased the NO3−1-N residue in the 0–100 cm soil layer by 40.1 kg N ha−1 compared with FP, with no significant difference in wheat grain yield (RF: 5382.9 kg ha−1) or economic benefit (RF: USD 1613.1 ha−1). Furthermore, there were no significant differences between RF and FP in pre-anthesis NP transport or post-anthesis NP accumulation; however, RF significantly increased pre-anthesis potassium transport volume (15.8%) and transport rate (12.5%). RF led to a 16.3% increase in nitrogen utilization efficiency (NUE), while there was no significant difference in phosphorus utilization efficiency (PUE) compared with FP. The fertilizer yield effect for RF was evaluated as N > P > K. Correlation analysis indicated that grain yield was significantly positively correlated with pre-anthesis NPK transport and post-anthesis NP accumulation. It was also positively correlated with organic matter, alkali-hydrolyzed nitrogen, and Olsen-P content in both the topsoil (0–20 cm) and subsoil (20–40 cm), but not with available potassium in the soil. Therefore, conducting soil tests and determining fertilizer recommendations based on the proposed RF method at harvest can reduce fertilizer usage and achieve a balance between the conflicting objectives of environmental protection, increased crop yields, nutrient utilization efficiency, and improved economic benefits in oasis agricultural areas facing excessive fertilizer application.

Study on Optimal Nitrogen Application for Different Oat Varieties in Dryland Regions of the Loess Plateau.

The present study endeavored to tackle the challenges posed by limited diversity in oat varieties and suboptimal nitrogen fertilizer utilization in the arid landscapes of the Loess Plateau. We selected three oat varieties, including early-maturing oats (E), medium-maturing oats (M), and late-maturing oats (L). In 2022, four nitrogen applications were set up as CK (0 kg N ha-1), N1 (60 kg N ha-1), N2 (90 kg N ha-1), and N3 (120 kg N ha-1). We introduced two additional nitrogen applications, N4 (180 kg N ha-1) and N5 (240 kg N ha-1), in 2023. The two-year study results demonstrated a significant increase in oat yield due to nitrogen application (p < 0.05). The highest grain yield was observed for E oats at 2216.63 kg·ha-1 under the N3 treatment, while M and L oats had the highest grain yields at 2505.43 kg·ha-1 and 2946.30 kg·ha-1 under N4, respectively. The protein content of L oats reached a peak of 14.15% under N4, and the order of protein contents in oat protein components was globulin > gliadin> glutenin > albumin. The β-glucan content of L oats reached a peak of 4.92% under N3. The nitrogen fertilizer utilization efficiency (NFUE) of the three oats was highest under N2. L oats exhibited enhanced NFUE owing to an elevated pre-flowering nitrogen translocation amount (PrNTA), with a 42.94% and 29.51% increase relative to E and M oats, respectively. The pre-flowering nitrogen translocation contribution (PrNTC) in oats surpassed the post-flowering nitrogen accumulation contribution (PoNAC). Therefore, nitrogen application positively impacted oat growth, yet excessive application had an inhibitory effect. There is a significant positive correlation among oat yield, quality, nitrogen accumulation, and utilization efficiency. In summary, oat crops exhibited optimal performance in terms of yield, quality, and nitrogen use efficiency when nitrogen application rates ranged between 90 and 180 kg·ha-1. Late-maturing oats coincide with the rainy and hot season in the northern dryland regions, making them more suitable for planting in the dryland areas of the Loess Plateau.

Neoliberalism and sustainability of higher education in Australia

This paper critically examines the influence of neoliberal policies on the direction of Australian universities in recent years. By examining publicly available sources, including media, court, and parliamentary reports, we contend that the internationalization of higher education in Australia is a strategic response to these neoliberal policies, which have reduced government funding for the sector. However, the excessive application of neoliberalism in funding and cost management of universities has led to notable issues, such as a persistent decline in service quality, unfair treatment of international students, and insufficient pay for casual academics. The paper concludes with recommendations for policy improvements.