Levels Of Nitrogen Fertilization Research Articles

Response of Pasture Nitrogen Fertilization on Greenhouse Gas Emission and Net Protein Contribution of Nellore Young Bulls.

This study aimed to evaluate the greenhouse gas (GHG) emission and net protein contribution (NPC) of Nellore young bulls grazing marandu palisade grass (Urochloa brizantha cv. Marandu) under three levels of pasture nitrogen (N) fertilization during backgrounding and finished on pasture or feedlot, based on concepts of sustainable intensification. The treatments were: System 1: pastures without N fertilizer during backgrounding, and animals finished on pasture supplemented with high concentrate at a rate of (20 g of concentrate per kg of body weight; P0N + PS); System 2: pastures fertilized with 75 kg N ha-1 year-1 during backgrounding and animals finished on feedlot fed a total mixed ration (TMR; P75N + F); and System 3: pastures fertilized with 150 kg N ha-1 year-1 during backgrounding, and animals finished on feedlot fed a TMR (P150N + F). During backgrounding, all pastures were managed under a continuous and put-and-take stock grazing system. All animals were supplemented with only human-inedible feed. Primary data from systems 1, 2 and 3, respectively, in the field experiment were used to model GHG emissions and NPC (a feed-food competitiveness index), considering the backgrounding and finishing phases of the beef cattle production system. Average daily gain (ADG) was 33% greater for the N fertilizer pastures, while carcass production and stocking rate (SR) more than doubled (P75N + F and P150N + F). Otherwise, the lowest GHG emission intensity (kg CO2e kg carcass-1) was from the P0N + PS system (without N fertilizer) but did not differ from the P75N + F system (p > 0.05; pastures with 75 kg N ha-1). The main source of GHG emission in all production systems was from enteric methane. Moreover, NPC was above 1 for all production systems, indicating that intensified systems contributed positively to supply human protein requirements. Moderate N fertilization of pastures increased the SR twofold without increasing greenhouse gas emissions intensity. Furthermore, tropical beef production systems are net contributors to the human protein supply without competing for food, playing a pivotal role in the food security agenda.

Effects of micro‐nano bubble aerated irrigation and levels of nitrogen fertilizer on nitrogen accumulation and metabolism in super rice

AbstractMicro‐nano bubble aerated irrigation (MNBI) is an innovative technology that generates nano‐diameter bubbles in irrigation water via a micro‐nano bubble device. In this study, pot experiments with three different nitrogen level treatments under conventional irrigation and MNBI were conducted to investigate the effects of MNBI and nitrogen application levels on rice yield, nitrogen accumulation and utilization. The results showed that MNBI promoted rice yields by increasing the seed setting rate compared to conventional irrigation, and nitrogen accumulation was positively correlated with nitrogen application but significantly increased by MNBI due to the increased root growth and activity. Furthermore, the activity of key enzymes involved in nitrogen metabolism, nitrate reductase and glutamine synthetase, significantly increased under MNBI at a nitrogen level of 225 kg ha−1. In conclusion, with the elevation of nitrogen application, MNBI improved rice yields and nitrogen accumulation and utilization, indicating that nitrogen and MNBI synergistically enhanced rice yields. Thus, the results provide the basis for efficient and high‐yielding super rice cultivation.

Nutritional and Polyphenolic Composition of Agrimonia procera Wallr. from Experimental Cultivation with Different Levels of Nitrogen Fertilization.

Plants of the genus Agrimonia, including fragrant agrimony Agrimonia procera Wallr., mainly used as pharmaceutical raw material, perfectly fit into the current trends in nutrition and food technology that are searching for organic raw materials with high contents of bioactive compounds, such as dietary polyphenols and fiber. The aim of the research was to determine the nutritional and polyphenolic composition of fragrant agrimony Agrimonia procera Wallr. from experimental cultivation with varying levels of nitrogen fertilization in the nitrate, ammonium, or amide forms. In the experimental cultivation of fragrant agrimony in a seeding medium with a moderately high level of mineral content, the aerial parts, especially the leaves, were characterized by contents protein, dietary fiber, fat, and polyphenols at levels of 11.5, 58.0, 3.0, and 10.5% of dry matter, respectively, and an energy value of about 260 kcal/100 g of dry matter. The effect of additional nitrogen fertilization, in the form of ammonium nitrate and urea, on the content and yield of nutrients and polyphenol in fragrant agrimony depends both on the dose and the form of nitrogen, as well as the morphological part, of the plant.

Photosynthetic characteristics, soil nutrients, and their interspecific competitions in an apple–soybean alley cropping system subjected to different drip fertilizer regimes on the Loess Plateau, China

Imprecise irrigation hinders the sustainable development of the fruit tree–crop intercropping system in the Loess Gully Area of China. Drip fertigation was applied for two years as part of an apple–soybean intercropping system to optimize local water and nutrient management patterns. The effects of different drip irrigation and fertilizer levels on photosynthetic characteristics, soil nutrients, and their interspecific competitions were studied. The treatments were four irrigation levels, namely 60% (W1), 70% (W2), 80% (W3), and 90% (W4) of field capacity (Fc), and three nitrogen fertilization levels, namely 59 (F1), 92 (F2), and 124 kg∙ha–1 (F3). The control (CK) was a rain-fed (neither irrigation nor fertilizer) crop. The net photosynthetic rate (Pn), transpiration rate (Tr), and soybean yield (GY) increased at first, but then decreased as irrigation and fertilizer application levels rose. The partial factor productivity (PFP) decreased as fertilization increased, but the soil available nitrogen content showed the opposite trend. The soil nutrients, and soybean Pn and Tr were positively correlated with distance from the apple tree row. The interspecific competition intensity for light and soil water decreased from 2018 to 2019, while root and soil nitrate nitrogen (NN) increased. The interspecific competition correlation between the aboveground and belowground parts was weak and varied between the two intercropping years. A principal component analysis showed that treatment W3F2 had the highest comprehensive score. Thus, a combination of irrigation at 80% Fc and 92 kg∙ha–1 nitrogen fertilizer application is optimal for the system. A multiple regression analysis indicated a water input range of 4624.49–4795.75 m3·ha−1·a−1 combined with 84.10–107.27 kg·ha−1·a−1 fertilizer application was suitable for optimal irrigation and fertilization management based on the integrated benefits to root length density, GY, Pn, and PFP during the first 4–5 years of the intercropping system.

The Application of Machine Learning Models Based on Leaf Spectral Reflectance for Estimating the Nitrogen Nutrient Index in Maize

Non-destructive acquisition and accurate real-time assessment of nitrogen (N) nutritional status are crucial for nitrogen management and yield prediction in maize production. The objective of this study was to develop a method for estimating the nitrogen nutrient index (NNI) of maize using in situ leaf spectroscopy. Field trials with six nitrogen fertilizer levels (0, 75, 150, 225, 300, and 375 kg N ha−1) were performed using eight summer maize cultivars. The leaf reflectance spectrum was acquired at different growth stages, with simultaneous measurements of leaf nitrogen content (LNC) and leaf dry matter (LDW). The competitive adaptive reweighted sampling (CARS) algorithm was used to screen the raw spectrum’s effective bands related to the NNI during the maize critical growth period (from the 12th fully expanded leaf stage to the milk ripening stage). Three machine learning methods—partial least squares (PLS), artificial neural networks (ANN), and support vector machines (SVM)—were used to validate the NNI estimation model. These methods indicated that the NNI first increased and then decreased (from the 12th fully expanded leaf stage to the milk ripening stage) and was positively correlated with nitrogen application. The results showed that combining effective bands and PLS (CARS-PLS) achieved the best model for NNI estimation, which yielded the highest coefficient of determination (R2val), 0.925, and the lowest root mean square error (RMSEval), 0.068, followed by the CARS-SVM model (R2val, 0.895; RMSEval, 0.081), and the CARS-ANN model (R2val, 0.814; RMSEval, 0.108), which performed the worst. The CARS-PLS model was used to successfully predict the variation in the NNI among cultivars and different growth stages. The estimated R2 of eight cultivars by the NNI was between 0.86 and 0.97; the estimated R2 of the NNI at different growth stages was between 0.92 and 0.94. The overall results indicated that the CARS-PLS allows for rapid, accurate, and non-destructive estimation of the NNI during maize growth, providing an efficient tool for accurately monitoring nitrogen nutrition.

Using the SCOPE model for potato growth, productivity and yield monitoring under different levels of nitrogen fertilization

Most applications of remote sensing in agricultural crop monitoring use multispectral imaging techniques, but with upcoming hyperspectral missions, the opportunity arises to better estimate pigment absorption and crop structure by exploiting the full solar reflective spectrum. In this study, we demonstrate how hyperspectral time series can be used with the Soil Canopy Observation of Photochemistry and Energy fluxes (SCOPE) model to estimate crop yield variability among fields, crop varieties and nitrogen treatments generically, i.e. without a calibration with in situ , data. Field experiments were conducted in two potato fields in the Netherlands between May and September 2019. The fields were planted with five varieties of potato, under three nitrogen fertilization treatments. By fitting the model to the full VNIR-SWIR spectrum of measured hyperspectral reflectance, we retrieved the model input parameters of Leaf Area Index (LAI), leaf chlorophyll content (Cab) and leaf water content (Cw) and simulated the photosynthesis throughout the season using data of local Automatic Weather Stations (AWS). Statistical analysis of measured and retrieved traits of LAI, Cab and canopy water content showed that two fields responded differently to the treatments, exhibiting fewer classes than were expected based on the experimental design. Potato yield, which was estimated as the sum of photosynthesis flux multiplied by the harvest index of 0.64, correlated with the measured tuber dry weight with R 2 0.36 and RMSE 2.5 t ha −1 . This study demonstrates that even in the absence of crop or variety specific information, hyperspectral reflectance and local weather data ingested into SCOPE can explain a substantial part of the observed variability in yield among fields. • Time series of hyperspectral canopy reflectance were recorded in two potato fields. • The variation in traits was created by nitrogen fertilization treatments. • SCOPE model retrieved plant traits contained information about treatments. • SCOPE-simulated accumulated photosynthesis correlated with the final dry yield. • SCOPE model is more generic than dimensionality reduction methods.

Effect of Nitrogen Fertilizer on the Quality of Rhodes Grass (Chloris gayana. L. kunth.) Cultivars

A field experiment was conducted in the Demonstration Farm of the Faculty of Agricultural Studies, Sudan University of Science and Technology, during the season (2006/2007) to investigate the effect of nitrogen fertilizer on crude protein, fiber, ash content, ether extract, nitrogen free extract and metabolizable energy of Rhodes grass (Chloris gayana L.) cultivars. Four cultivars of Rhodes grass (Katambora, Callide, Boma and Finecut) were used in this study. Four levels of Nitrogen fertilizers (0, 40, 60 and 80 kg N/ha) were used. The treatments were arranged in a split-plot with four replications. Nitrogen applications lead to insignificant increase in crude protein for all cultivars except for Katambora cultivar. The results revealed that, crude fiber insignificantly affected by nitrogen applications for the cultivars Callide and Boma. Whereas; the cultivars Katambora and Finecut were significantly affected. Ether extract significantly affected by nitrogen application in all cultivars. The results showed that, ash was not affected by nitrogen levels for all cultivars except for cultivar Callide. Nitrogen free extract was significantly affected by nitrogen levels for all cultivars. Moreover, the metabolizable energy was significantly affected by nitrogen applications in all cultivars except cultivar Katambora. It can be concluded that, the best cultivars in the terms of forage Dry Weight, Crude Protein and Nitrogen Free Extract were Finecut, Callide, Katambora and Boma respectively with added fertilizer (80 kg N /ha).

ECONOMIC EFFICIENCY OF SPRING TRITICALE PRODUCTION WITH DIFFERENT LEVELS OF INTENSITY

The aim of the study was to evaluate the economic efficiency of spring triticale varieties at different levels of production intensity. Three-year field results for the years 2017, 2018 and 2020 were used for the calculations. Factors such as tillage methods (conventional and reduced tillage), varying levels of nitrogen fertilisation (0, 70 and 100 kg N/ha) and varieties – Sopot and Milewo – were included in the analysis. Direct surplus was used as a measure of economic efficiency. The economic efficiency of spring triticale cultivation was assessed taking into account the use of one of the main production factors, i.e. land. For individual variants of the experiment, the gross profitability index was calculated as the ratio of production value to direct costs. The analysis of the production-economic indices showed that the technology with the use of traditional tillage (plough) and a nitrogen fertilisation rate of 70 kg N/ha were the more favourable variant for spring triticale cultivation. It was also found that the level of obtained direct surplus was more influenced by the level of obtained yields and purchase prices of triticale than by the level of direct costs incurred for tillage and sowing operations.

Response of some bread wheat cultivars to nitrogen fertilizer levels in newly reclaimed sandy soils

Response of some bread wheat cultivars to nitrogen fertilizer levels in newly reclaimed sandy soils

Genetic variation in nitrogen-use efficiency and its associated traits in dryland winter wheat (Triticum aestivum L.) cultivars released from the 1940s to the 2010s in Shaanxi Province, China.

Improving the nitrogen-use efficiency (NUE) of wheat can help mitigate the problems of poor soil fertility under dryland conditions. We conducted field experiments using three nitrogen (N) fertilization levels (0, 120, and 180 kg ha-1 ) applied to eight dryland wheat cultivars to assess NUE and its associated traits. The grain yield significantly increased with the improvement in variety, mainly as a result of a substantial increase in 1000-grain weight and harvest index. Modern wheat varieties have stabilized at an optimal plant height and exhibited improved performance in terms of NUE, partial N productivity, N harvest index, and grain protein content compared to older varieties. The NUE of wheat gradually increased with variety replacement. The net photosynthesis rate of the flag leaves in the filling stage improved with the year of cultivar release; Increasing soil-plant analysis development (SPAD) values of flag leaves in the flowering and filling stages were observed over time, with the flag leaves of modern varieties showing a high chlorophyll content in the filling stage. Additionally, the principal component analysis showed that the SPAD value, grain number per unit area, transpiration rate, leaf area, and grain protein content positively contributed to the clustering of the N180 and modern cultivars (from the 2000s to 2010s). Overall, high levels of N application did not significantly improve the NUE of wheat. However, modern wheat varieties can optimize N distribution, increase flag leaf photosynthetic capacity, and improve photosynthesis ability, thus enhancing NUE to achieve high yields under a suitable level of N supply. © 2022 Society of Chemical Industry.

A review of the determination of nitrogen fertilizer levels for maize in different ethiopian agro-ecologies

A review of the determination of nitrogen fertilizer levels for maize in different ethiopian agro-ecologies

Yield Potential of Machine-Transplanted Rice and Correlation of Crop-Growing Rate during Grain-Filling Stage

Not enough attention has been paid to the comparison in yield performance and N responsiveness between hybrid rice and inbred rice using the large number of new cultivars released after 2000 under machine transplanting. Field experiments were conducted in 2017 and 2018; 48 widely planted rice cultivars included four groups, namely indica hybrids (IHs), japonica inbreds (JIs), indica-japonica hybrids (IJHs), and indica inbreds (IIs) that were transplanted by machine with three nitrogen fertilizer levels (0, 150, 300 kg ha−1). The average yield of the hybrids (IHs, IJHs) was higher than that of JIs or IIs with a higher crop-growing rate (CGR) during the total growth duration, regardless of the N application level; moreover, longer total growth duration was responsible for the higher yield in IJHs than in IHs. The IHs had a large gap yield which mainly came from the genetic improvement in the CGR during the grain-filling stage. The yield gap was relatively small in JIs, and longer growth duration combined with optimal daily mean temperature during the grain-filling stage was the critical factor for high yield. The JIs or IJHs had higher yield under the N300 level, while the response of IHs to nitrogen varied with different cultivars. Cultivars with higher CGR during the grain-filling stage had higher yield under the N300 level. In conclusion, this study suggests that high CGR during the grain-filling stage may be a vital trait for the development of rice with high yield and high N responsiveness at machine transplanting.

PSXII-17 The Effects of N Fertilization on N2O Emissions from Urine or Fecal Samples from Nellore Bulls

Abstract Better understanding of N2O emissions from interactions between urine or feces, with different levels of nitrogen (N) fertilization on tropical pastures would be helpful in developing strategies to mitigate emissions and improve N2O inventories. The objective of this study was to evaluate N2O emissions from feces or urine samples collected from Nellore young bulls, isolated or in association with different levels of N fertilizer. Study was designed as completely randomized block design with five replications per treatment. Treatments were two levels of excreta (Feces or Urine) and three levels of N fertilizer (0, 75 and 150 kg N ha-1). Ammonium nitrate was used as source of N (32% of N). One liter of urine or 1.5 kg of feces was used per chamber with the respective N dose directly applied on excreta sample. Gas emissions were evaluated using the static chamber closed method and quantified using gas chromatography. Chambers were closed for 40 min and gas samples were collected at 0, 20 and 40 min. After treatment imposition, gas was sampled three times during week 1, twice during week 2, 3, and 4 and once during week 5, 6, 7 and 8, and subsequently every 2 weeks for two consecutive years. Type of excreta samples did not affect N2O emissions. Additionally, associative effects of N fertilizer onto feces or urine was similar. Cumulative N2O emissions linearly increased with increasing levels of N regardless of source, and ranged from 5.95, 32.1 to 74.7 mg of N2O/m2, for 0, 75 and 150 kg/ha/year of N. Similarly, emissions factor of N2O were linearly increased with increased N fertilizer (0.15, 0.36 and 0.73%, for excreta, excreta + 75 kg N and excreta + 150 kg N). Therefore, the interaction between N fertilizer and excreta on N2O emissions in tropical pastures was additive.

Impact of Compost Tea and Spirulina platensis Algae on Sugar Beet Grown under Different Levels of Inorganic Nitrogen Fertilizer.

<b>Background and Objective:</b> Nitrogen is an essential macronutrient for plant growth, improving the absorption and utilization of some other nutrients and controlling total plant development. Compost tea (CT) is an aqueous extract of compost that contains high organic matter levels necessary for plants and aerobic soil microorganisms. <i>Spirulina platensis</i> is a multi-cellular blue-green micro-alga that contains green pigments, high levels of nutrients and plant growth regulators. This work was designed to study the possibility of using CT and <i>S. platensis</i> algae culture filtrate (ACF) in improving plant growth, yield and quality of sugar beet grown under different nitrogen fertilizer levels. <b>Materials and Methods:</b> Two field experiments were conducted at Ismailia Research Station, Ismailia Province, Egypt, during the 2019/2020 and 2020/2021 seasons. The study involved two N levels (90 and 120 kg/fed), three CT rates (without, 30 and 60 l/fed) and three ACF levels (without, 1 and 2 l/fed) three times. A split-plot design was used. <b>Results:</b> Adding 120 kg N/fed increased crop growth rate (CGR), root yield/fed (RY) and sugar yield/fed (SY), while, sucrose (%) and quality index (QI) decreased. Soil drench with 60 l CT/fed incremented leaf area index (LAI), CGR, sucrose (%), RY and SY. Increasing ACF level up to 2 l/fed increased LAI, sucrose (%), QI, RY and SY. Root yield was positively correlated with SY and negatively with QI. <b>Conclusion:</b> Applying 90 kg N/fed combined with a soil drench of 60 l CT/fed and foliar spraying with 2 l ACF/fed thrice can be recommended to attain economical root and sugar yields.

Response of tuberose to different levels of nitrogen, phosphorus and potassium fertilizers

Response of tuberose to different levels of nitrogen, phosphorus and potassium fertilizers

Nitrogen Fertilization Increases Soil Microbial Biomass and Alters Microbial Composition Especially Under Low Soil Water Availability.

Soil microbial biomass and composition are affected by resource supply and water availability. However, the response of soil microbial communities to nitrogen fertilization under different water availability conditions is unclear. Therefore, this study conducted a 6-year pot experiment comprising five watering regimes (40%, 50%, 60%, 80%, and 100% of field capacity (FC)) and three nitrogen fertilization levels (NH4NO3 solution; 0 [N0], 20 [N1], and 40 [N2] g N m-2year-1) to investigate soil microbial biomass, composition, and properties. The results indicated that soil microbial biomass and composition were more strongly affected by nitrogen fertilization compared with water regime. Nitrogen fertilization increased soil microbial biomass and altered soil microbial community composition, especially under low soil water availability. Soil microbial biomass was positively linearly associated with soil water regimes under N0, whereas it responded polynomially to soil water regimes under N1 and N2. The maximal soil microbial biomass was observed at FC80 for N1 and FC60 for N2. Furthermore, the biomass of soil microbial groups with high nitrogen and carbon acquisition ability as well as the enzyme activities of carbon and nitrogen cycling (β-1,4-glucosidase and β-1,4-N-acetyl-glucosaminidase, respectively) were stimulated by nitrogen fertilization. Soil microbial biomass was affected directly by nitrogen fertilization and indirectly by nitrogen and water regimes, via altering soil pH, dissolved inorganic nitrogen (NH4+-N and NO3--N) concentration, and soil organic carbon concentration. This study provides new insights into the effect of interaction between soil nitrogen and water availabilities on soil microbial biomass, composition, and its underlying mechanism.

Yield, nitrogen-use efficiency, and distribution of nitrate-nitrogen in the soil profile as influenced by irrigation and fertilizer nitrogen levels under zero-till wheat in the eastern Indo-Gangetic plains of India

Due to the introduction of zero-till wheat in the Indo-Gangetic plains (IGP) in India, irrigation and fertilizer nitrogen (N) management needs to be modified from that followed under conventionally tilled fields. A field experiment was conducted to study the effect of irrigation and N levels on yield and N uptake by zero-till wheat, fertilizer N-use efficiency, and distribution of nitrate-N (NO3-N) in a soil profile under zero-till conditions in an acidic alluvial soil of the eastern IGP. The experiment was laid out in a split-plot design with four levels of irrigation as main plots (I0-no irrigation, rain-fed, I1-122 mm in one irrigation at 21 days after sowing (DAS), I2-263 mm in two irrigations at 21 and 42 DAS, and I3-386 mm in three irrigations at 21, 42, and 84 DAS) and 4 N levels [0 (N0), 60 (N1), 120 (N2), and 150 (N3) kg N ha−1] as subplots. Grain and straw yields were significantly higher at the irrigation level-I2 and 120 kg N ha−1-N2 over the control (I0 and N0) and were at par with the highest applied levels of irrigation and N (I3 and N3). The nitrogen uptake by wheat followed a trend similar to yield for irrigation levels; however, it increased significantly up to 150 kg N ha−1. After the harvest of wheat crop, more NO3-N was observed in the 60–90 cm subsurface soil layer than in the surface 0–15 cm and/or 15–30 cm and 30–60 cm subsurface soil layers. The highest NO3-N concentration was recorded in the treatment I2N2. Accumulation of NO3-N in the soil increased up to irrigation levels I2 and with increasing doses of fertilizer N application. Combined applications of irrigation and N had a positive and significant influence on agronomic efficiency (AE) and apparent N recovery (ANR) but had no significant effect on physiological efficiency (PE). This study suggests that an appropriate combination of irrigation and N levels in zero-till wheat can lead to not only high-yield levels and N-use efficiency but also adequately control NO3-N leaching under acidic alluvial soils in the eastern IGP.

Cotton productivity and fiber quality response to nitrogen fertilization levels under different sowing dates EL-Refaey, R. A.1; M. A. A. Emara2; Hanaa M. Ashri1 and M. A. El-Sawy1 1Agronomy Dept., Fac., of Agric., Tanta University 2Cotton Research Institute, Agricultural Research Center

Cotton productivity and fiber quality response to nitrogen fertilization levels under different sowing dates EL-Refaey, R. A.1; M. A. A. Emara2; Hanaa M. Ashri1 and M. A. El-Sawy1 1Agronomy Dept., Fac., of Agric., Tanta University 2Cotton Research Institute, Agricultural Research Center

Enhanced suppression of saprotrophs by ectomycorrhizal fungi under high level of nitrogen fertilization

Ectomycorrhizal fungi (EMF) are widespread in northern conifer forests. By competing with the free-living saprotrophic fungal and bacterial communities for limited soil nitrogen, EMF are expected to suppress litter decomposition and thus drive soil carbon accumulation. The EMF may also stimulate rhizosphere microbial growth through inputs of labile plant carbon, and subsequently contribute to the soil carbon pool via microbial necromass. Here we examined the relative strength of these two potential EMF effects in a northern conifer plantation of the Saihanba Forest, the largest plantation in China. The soil fungal and bacterial biomass, as well as their respiration, were quantified within the two types of soil cores that either allow or exclude the ingrowth of EMF. We also set up a nitrogen fertilization gradient (0, 5, 10, 15 g N m–2 y–1) in this plantation to quantify the influence of external inorganic nitrogen on the EMF effects. We found evidence that EMF inhibit the overall fungal and bacteria biomass, confirming the suppression of saprotrophs by EMF. In addition, high levels of external nitrogen fertilization (15 g N m–2 y–1) might further enhance the suppression by EMF. In contrast, the presence of EMF consistently increased soil microbial respiration across all nitrogen fertilization levels, indicating that the carbon allocated to EMF could have been largely consumed by microbial respiration and contributed minimally to the accumulation of microbial biomass. Our results also indicated that the suppression of saprotrophs by EMF may play a critical role in driving continuous soil carbon accumulation in this northern pine plantation under atmospheric nitrogen deposition.

Intercropping of Faba Bean with Wheat Under Different Nitrogen Levels Reduces Faba Bean Rust and Consequent Yield Loss.

While intercropping can help control faba bean rust, the ability of intercropping to reduce this disease under different levels of nitrogen fertilization and its contribution to increasing yield is not clear. In this study, two planting patterns of faba bean monocropping and wheat/faba bean intercropping, together with two treatments for disease control and noncontrol, and four nitrogen application levels (N0 [0 kg/ha], N1 [45 kg/ha], N2 [90 kg/ha], and N3 [135 kg/ha]) were tested for 2 years in a continuous field experiment. The results revealed that nitrogen application increased the area under the disease progress curve (AUDPC) of faba bean rust from 41.9 to 47.3%, with the N3 treatment resulting in the largest increase. Nitrogen application decreased the relative control efficacy of intercropping on faba bean rust. Compared with monocropping, N0 to N3 with intercropping significantly reduced AUDPC by 33.1% for the first year and 28.7% for the second year (P < 0.05). Nitrogen application aggravated the faba beans grain yield loss, while the loss of yield components increased in the first year and then declined as the nitrogen application increased; the yield losses of monocropping were higher than those of intercropping. The N1 and N2 application levels significantly increased the total effect (TE) of intercropping yield advantage by 34.3 and 32.9% in the 2 years, respectively. During the 2 years, the overall partial land equivalent ratio of faba bean was greater than 0.33. The average disease control effect (DCE)/TE of intercropping was 56.1 and 49.3% for the 2 years, respectively, indicating that intercropping increased yields and that the contribution of the DCE was close to or higher than that of the other intercropping effects. A regression analysis of the grain yield loss and the AUDPC showed that reducing the nitrogen fertilizer input (N1) could effectively reduce the yield loss caused by rust and enhance the yield. Intercropping of faba bean combined with a suitable nitrogen application (45 kg/ha) is the best treatment to maximize yield by fully utilizing intercropping for managing faba bean rust.