Apparent Recovery Fraction Research Articles

Effect of Cow Manure Biochar on Lettuce Growth and Nitrogen Agronomy Efficiency

This study aimed to produce livestock manure biochar to decrease environmental problems from livestock manure and evaluate its effectiveness as an organic fertilizer by examining the growth and nutrient use efficiency of crops. A plot experiment was conducted to investigate the characteristics of lettuce growth and nitrogen use efficiency in upland soils treated with cow manure biochar. The cow manure biochar was applied at rates of 0, 3, 5, 7, and 10 t ha−1 (referred to as CMB0, CMB3, CMB5, CMB7, and CMB10, respectively), along with inorganic fertilizer (IF, NPK—200-59-12 kg ha−1). The lettuce cultivation test was carried out for 42 days, during which the fresh weight, dry weight, length, and number of lettuce leaves were measured. Nitrogen use efficiency was evaluated by determining the agronomic efficiency of N and the apparent recovery fraction of N. Overall, as the cow manure biochar application rate increased, crop growth and nitrogen uptake improved. Soils treated with CMB5 and CMB7 showed higher lettuce growth, nitrogen content, and nitrogen uptake compared to soils under other treatments. Nitrogen use efficiency followed a pattern similar to that of crop productivity, with cow manure biochar application levels playing a significant role. In particular, the agronomic efficiency of N and the apparent recovery fraction of N, which are both related to crop nutrient utilization, were significantly higher in the CMB5 treatment compared to the IF treatment. These results indicate that nitrogen use efficiency can be enhanced through biochar application when growing crops on agricultural land. Therefore, it is suggested that the appropriate application of cow manure biochar can reduce inorganic fertilizer use and increase crop productivity, thereby enabling sustainable and eco-friendly agriculture.

Effects of nitrogen forms on nitrogen utilization, yield, and quality of two wheat varieties with different gluten characteristics

The assimilation and utilization of different nitrogen (N) forms in wheat are different. Therefore, supplying suitable forms of N may be an effective way to optimize yield, quality, and N use efficiency (NUE) synergistically. A two-year field trial was conducted with Jimai22 (JM22) and Jimai44 (JM44) wheat varieties at differential gluten characteristics, with N form treatments: no nitrogen (N0), and nitrogen supply (225 kg ha−1) as urea (U), ammonium nitrogen (ammonium chloride, A), nitrate nitrogen (calcium nitrate, NI), U + A (1:1, UA), U + N (1:1, UN), and N + A (1:1, NA). The results showed that different N forms significantly affected wheat yield, N utilization, and grain quality. Combined application of urea and nitrate nitrogen (UN) significantly increased the spike number by 3.5% on average over U (conventional fertilization), but with no statistical difference in grain yield. N and A treatments significantly increased the activity of N metabolism enzymes in flag leaves and grains at the early filling stage but rapidly declined at the middle and late filling stages. In contrast, UN treatment significantly increased nitrate reductase and glutamine synthetase activities of wheat flag leaves and grains within 7–28 d after anthesis, which facilitated N assimilation and significantly increased free amino acids content in the middle and late filling stages, thereby significantly promoting the accumulation of gliadin and glutenin in grains, resulting in the highest protein content and the best processing quality of JM22 and JM44. Except for N0, NUE, N uptake efficiency (NUPE), and N apparent recovery fraction (NARF) under UN were the highest, which were significantly increased by 4.3%, 5.8%, and 11.8% on average compared to the U treatment, respectively. Therefore, the combined application of urea and nitrate nitrogen could synergistically improve quality and nitrogen use efficiency while maintaining yield, which is important for the rational application of nitrogen fertilizer and achieving stable yield, high quality and efficient production of wheat.

Synthesis of urea slow-release fertilizer using a novel starch-g-poly(styrene-co-butylacrylate) nanocomposite latex and its impact on a model crop production in greenhouse

Herein, an innovative slow-release fertilizers (SRFs) were developed using a bio-based and waterborne polymeric coating containing starch-g-poly(styrene-co-butylacrylate) latex reinforced with natural char nanoparticles (NCNPs). Several SRF samples were prepared via coating the urea granules with the latex formulations containing different amounts of NCNPs, and their urea release rates were evaluated. The results showed that the presence of NCNPs nano-filler and decreasing the temperature could prolong the urea release time. The performances of the SRF samples were compared to urea granules and a commercial latex coating (SBR, poly(styrene-co-butyl acrylate)) on tomato production in the greenhouse. The results confirmed that NCNPs in coating formulation played an important role in improving plant growth and reducing N-release rate. The efficiencies of all the synthesized SRF samples were higher than the SBR-coated urea confirming the key-role of starch in the coating formulations. In sample containing 1 w% NCNPS (F13), total nitrogen percentage and nitrate content in the aerial parts of tomato plants were increased (21.1%) and decreased (42.1%) compared to the pristine urea, respectively. Particularly, application of F13 formulation could enhance the nitrogen use efficiency (NUE), nitrogen agronomic efficiency (NAE), and nitrogen apparent recovery fraction (NRF), 68.3%, 49.9%, and 29.7%, compared to the urea granules, respectively.

Effect of biochar application on nitrogen use efficiency for sustainable and productive agriculture under different field crops

This study was undertaken to investigate crop productivity, nitrogen use efficiency (AE_N, agronomic efficiency of N; ARF_N, apparent recovery fraction of N), and nitrous oxide (N2O) emission after biochar (BB, bamboo biochar) and nitrogen fertilizer (N) application in paddy and upland agricultural soils. The selected rice and Chinese cabbage were grown in the paddy soil and upland soil, respectively. Each treatment group, comprising N100% (N, 90 kg ha−1 for rice; 320 kg ha−1 for Chinese cabbage), BB + N35%, BB + N70%, and BB + N100%, was separated by a Control treatment. Overall, the increased nitrogen input and uptake resulted in improved crop growth. Under each experimental condition, soils treated with BB + N100% treatment had higher crop growth, nitrogen contents, and nitrogen uptake, as compared to other treatments. Nitrogen use efficiency was investigated independently of crop productivity results, and biochar played an important role in this assessment. In particular, both AE_N and ARF_N related to crop nutrient availability were significantly increased in the BB + N35% and BB + N70% treatments, as compared to the N100% treatment. In addition, N2O emission was reduced by decreasing the N input, and biochar contributed to N2O reduction in paddy and upland conditions. These results indicate that nitrogen use efficiency can be increased in agricultural soils supplemented with biochar application, such as paddy and upland field cultivations in South Korea. Additionally, it is considered good agricultural land management to reduce the use of inorganic fertilizers, and practice sustainable and productive agriculture.

The impact of biogas digestate typology on nutrient recovery for plant growth: Accessibility indicators for first fertilization prediction

In recent years, anaerobic digestion of organic waste (OW) is rapidly appearing as a winning waste management strategy by producing energy and anaerobic digestates that can be used as fertilizers in agricultural soils. In this context, the management of the OW treatment process to maximize agro-system sustainability satisfying the crop nutrient demands represents the main goal. To investigate these traits, two protocols to assess the plant availability of digestate nitrogen (N) and phosphorus (P) were evaluated. With this aim, the N and P availability was determined on 8 digestates and 2 types of digestate-based compost from different OW via sequential chemical extractions (SCE). In addition, the digestates were tested in soil incubations and in plant pot tests with Italian ryegrass and compared with chemical fertilizer and a non-amended control soil. The N extracted from digestates via SCE was related to soil N mineralization and plant N recovery. The C: N ratio had negative impact on mineralized N and its recovery in shoots (ShootsN = −0.0085.(C/N)+0.172, r2 = 0.67), whereas water extractable mineral N was positevely related to the root N apparent recovery fraction (N-ARF) with (RootsN = 5E−5.Nsolublemin+0.0138, r2 = 0.53). The shoot P-ARF was positively correlated with the inorganic water extractable fraction of P (ShootsP =0.1153.H2O-Pi−0.2777.H2O-Po+0.0249, r2 = 0.71) whereas the root P-ARF was positively correlated with the less accessible fractions (RootsP = (b) 0.0955.NaHCO3-Po+0.0955.NaOH-Po-0.0584NaHCO3-Pi+0.0128, r2 = 0.8641). Feedstock digestate typology impacted the N and P recovery results leading to a better description of the typology properties and a first nutrients ARF prediction.

Variability of maize inbred lines in nitrogen use effciency

Nitrogen (N) is an important element for many physiological processes in crops, and grain yield realisation. Nitrogen loss could be significant through leaching and evaporation, and from this reason lower quantities for fertilization are required. A genotype could be an important source for improved N management in crops. Breeding for high yield and nutrient-efficient genotypes is the most important strategy to enable food security, resolve resource scarcity and environmental pollution. Variability of 36 maize lines grown in optimal and low-N (without fertilization) conditions was assessed through grain yield, 1000 kernel weight, N utilization efficiency (NUtE) and N apparent recovery fraction (nitrogen use efficiency - NUE), during seasons 2017 and 2018. The genotype and year are important sources for variation of grain yield, 1000 kernel weight and NUtE, as a factor which defines N utilization efficiency. The lines, such as L1, L6, L13, L16, L26, L27, L32 and L34 are able to achieve higher grain yield when grown on low-N. Furthermore, L16, L22, L24 and L26 have high NUtE values in both experimental years (even in 2017, season with low and unequal precipitation level), especially in low-N treatment. From that point of view, they could be characterized as efficient N users, even in low-N conditions, as well as tolerant to stressful conditions. Nevertheless, L1, L6 and L27 are the lines with negative NUE, what gives them attribute as the best N users in low-N conditions. Based on the similarity of NUtE values, the genotypes such as L2, L3, L4, L8, L11, L12, L14, L15, L16, L18, L19, L24, L26, L32, L33, L34could be considered as the primary focus for further breeding programs, due to the fact that they don?t have only improved NUE, but also high grain yield (even in unfavourable years), which indicates improved tolerance to various abiotic stressful factors.

Fertilizing potential and CO2 emissions following the utilization of fresh and composted food-waste anaerobic digestates

Wet and dry-batch anaerobic digestion, and composting are common technologies in food waste (FW) management, resulting in different outputs. However, the effects of composting on carbon dioxide (CO2) emissions, nitrogen (N) and phosphorus (P) fertilizing capacity in view of closing nutrient cycle are still poorly investigated. In this work, two FW anaerobic digestates from the wet (D1) and dry-batch process (D2), and their respective composts (C1 and C2) were tested in a soil incubation (84 days at 25 °C) to assess CO2 emissions in comparison with a mixed (animal slurry/energy crop) digestate (BD) and a reference municipal solid waste compost (MSWC). The same products were also tested for the relative P efficiency (RPE) in soil, in comparison with a chemical-P source (30 mg P kg−1). Lastly, the apparent recovery fraction of N (N-ARF) from the five organic products was determined in a pot test with ryegrass (84 days; 300 kg available N ha−1), compared to a chemical fertilizer (NPK). Composting strongly reduced net-CO2 emissions compared to the two digestates (625 vs. 2850 mg CO2 kg−1 soil). Oppositely, composting very modestly influenced RPE that ranged around 100–90% in D1 and C1, and ≈30% in D2 and C2. Moreover, composting did not significantly reduce N-ARF that ranked in descending order as follows: NPK (77.5%) > D1 = BD (17.7%) ≥ C1 (14.7%) > MSWC (3.6%) > D2 (1.2%) > C2 (−3.1%). Composting was shown a reliable strategy for FW digestate management, as it reduces potential CO2 emission without affecting these products' N- and P-fertilizing capacity.

Effects of continuous nitrogen application on seed yield, yield components and nitrogen-use efficiency of Leymus chinensis in two different saline-sodic soils of Northeast China

The effect of nitrogen (N) application on seed yields and yield components in Leymus chinensis (Trin.) Tzvel., a perennial rhizomatous grass, was measured in a field experiment with two saline-sodic soils at Da’an Sodic Land Experiment Station during 2010–11. Two grassland field sites were classified as moderately saline–sodic (MSSL) and severely saline–sodic (SSSL). Application rates of N at each site were 0, 30, 60, 90, 120, 150, 180 and 210 kg ha–1. Application of N significantly improved seed yield mainly through increased spike number (R2 = 0.96, P ≤ 0.001). Compared with nil N, seed yield increased 7.4–10.9 times with N application of 150 kg ha–1 at MSSL, and 5.3–7.5 times with N application of 120 kg ha–1 at SSSL. However, absolute increases at SSSL were relatively small. Some significant differences (P ≤ 0.01) in seed yield occurred between 2010 and 2011 with different N application rates in the same soil, and between MSSL and SSSL in the same year. Increasing N application rate significantly decreased N physiological efficiency (NPE) but increased N apparent-recovery fraction (NRF) and N partial-factor productivity (NPP) at both sites. Seed yield and NPP indicated that the optimal N application rates to increase yield were 150 kg ha–1 at MSSL and 120 kg ha–1 at SSSL. High soil pH was the major factor adversely impacting seed yield, and pH and soil salinity were major factors negative affecting NPE, NRF and NPP as well as decreasing the positive effect of N application. Nitrogen application is a practical and effective method to increase seed yield of L. chinensis in saline-sodic grasslands of Northeast China, particularly when soil pH and salinity are not limiting.

Alternate partial root-zone drip irrigation improves water\u2013 and nitrogen\u2013 use efficiencies of sweet-waxy maize with nitrogen fertigation

Alternate partial root–zone drip irrigation (ADI) or fertigation has favorable effect on crop water- and nitrogen- use efficiencies (WUE and NUE). However, the advantage of combined application of ADI and nitrogen fertigation on crop WUE and NUE remains unclear. A pot experiment was conducted to investigate the impact of three irrigation methods (CDI conventional drip irrigation (both halves of pot irrigated), ADI (both halves of pot alternatively irrigated) and FDI fixed partial root–zone drip irrigation (fixed half of pot irrigated)) and five nitrogen treatments (F0 no N supplied, F1-F4 0.2, 0.18, 0.16 and 0.14 g N per kg soil via fertigation) on sweet-waxy maize. Compared with CDI, ADI reduced water consumption by 19.9%, but increased water use efficiency based on dry seed yield (WUEs) by 32.3%, and also enhanced nitrogen apparent recovery fraction (Nrf) and nitrogen agronomic efficiency (NAE). F1-F4 augmented dry mass accumulation, dry seed yield and total nitrogen uptake if compared to F0. Moreover, F2-ADI had higher shoot and total dry masses, WUEs, total nitrogen uptake, Nrf and NAE. Thus ADI increased nitrogen uptake, WUE and NUE of sweet-waxy maize with nitrogen fertigation of 0.18 g N per kg soil in this study.

Investigating the Combined Effect of Tillage, Nitrogen Fertilization and Cover Crops on Nitrogen Use Efficiency in Winter Wheat

A field study was conducted in northern France over two consecutive years to evaluate the combined effect of conventional tillage (CT) vs no till (NT) with or without cover crops (cc) and nitrogen (N) fertilization on various agronomic traits related to N use efficiency in winter wheat. Five years after conversion of CT to NT, significant increases in N use efficiency, N utilization efficiency, N agronomic efficiency, N partial factor productivity, N apparent recovery fraction and N remobilization were observed under three N fertilization regimes (0, 161, 215 kg ha−1). It was also observed that grain yield and grain N content were similar under CT and NT. The N nutrition index was higher under NT at the three rates of N fertilization. Moreover, N use efficiency related traits were increased in the presence of cc both under NT and CT. Thus, agronomic practices based on continuous NT in the presence of cc, appear to be promising strategies to increase N use efficiency in wheat, while reducing both the use and the loss of N-based fertilizers.

Phosphorous extractability and ryegrass availability from bio-waste composts in a calcareous soil

In this work four stable bio-waste composts (C1, C2, C3, C4) were selected on the basis of their increasing water soluble P (H2O-P). The P speciation was assessed via sequential chemical extraction (SCE) on the same products. Moreover, the plant-available P was assessed via apparent recovery fraction approach (ARF) in a pot test on ryegrass over 21 weeks at 15 mg P kg−1 of soil. An inorganic P source (P-chem) was added as a reference at the same P rate in addition to a non-fertilized control (Control). SCE showed that the sparingly soluble P (HCl-P) was the most important fraction in all composts: C1 (HCl 65% > NaHCO3 17% = NaOH 17% > H2O 1%); C2: (HCl 51% > NaOH 23% > NaHCO3 18% > H2O 7%); C3: (HCl 58% > NaOH 21% > NaHCO3 12% > H2O 9%); C4: (HCl 39% > NaOH 23% > NaHCO3 22% > H2O 16%). The plant test showed that the different treatments had a different ARF (%) at the first harvest: P-chem (14.7)> C4 (14.4)> C3 (14.1)> C2 (3.4)>C1 (3.1), compared to the cumulated ARF (%) of the six harvests: C4 (50.1)> C3 (35.0)> C1 (21.1)> C2 (18.3)> P-chem (17.4). Data showed a good correlation of H2O-P vs. plant ARF at the first harvest and a good correlation of labile P (H2O-P + NaHCO3-P) vs. total plant ARF over 21 weeks. The free and labile P forms from SCE can be a valuable tool in the assessment of fast and middle term plant-available P from stable bio-waste composts in calcareous soils.

Response of Different Wheat (Triticum Aestivum L.) Varieties to Graded Levels of Nitrogen

The present study entitled, “Response of different wheat (Triticum aestivum L.) varieties to graded levels of nitrogen” was conducted during winter season, 2009-10 on sandy clay loam soils of Students’ farm, College of Agriculture, Acharya N. G. Ranga Agricultural University, Rajendranagar, Hyderabad. The treatments consisted of three varieties (HP 4080, RAJ 4037 and HI 8682) and four nitrogen levels (0, 60, 120 and 180 kg N ha). The experiment was laid out in randomized block design with varieties as first factor and nitrogen levels as second factor with three replications. Plant height, tillers m, leaf area index and dry matter at 10, 30, 60, 90 days after sowing and at harvest were recorded maximum with variety RAJ 4037. Similarly, at 180 kg N ha plant height, tiller m, leaf area index and dry matter were found markedly higher compared to the rest of the doses. The physiological studies have indicated that crop growth rate was maximum between 60-90 DAS and maximum for variety RAJ 4037 and at 180 kg N ha among all the levels of nitrogen. Relative growth rate and net assimilation rates were found maximum between 10-30 days after sowing. Yield attributing characters i.e., number of ears m, spike length and 1000-grain weight were maximum with variety RAJ 4037. All the above yield attributing parameters were found maximum with 180 kg N ha. Grain and straw yield recorded maximum with variety RAJ 4037 over the other two varieties and among the nitrogen levels application of 180 kg N ha` recorded maximum grain and straw yields. Among the post harvest observations apparent recovery fraction, protein content were maximum with the variety RAJ 4037. Physiological efficiency was more with variety HP 4080. Agronomic efficiency was found to be on par with all the three varieties and all the nitrogen levels. Protein content was maximum with 180 kg N ha. Apparent recovery fraction was maximum with 60 kg N ha and physiological efficiency with 120 kg N ha. The nitrogen uptake in grain and straw was maximum with variety RAJ 4037. Among the nitrogen levels, 180 kg N ha recorded significantly maximum uptake of nitrogen in grain and straw. Net returns and benefit-cost ratio were maximum with variety RAJ 4037 and among the nitrogen levels application of 180 kg N ha recorded maximum values. It can be concluded that among the three varieties, variety RAJ 4037 with 180 kg N ha is the best combination for obtaining higher yields and returns on sandy clay loam soils of Southern Telangana region of Andhra Pradesh CHAPTER-

The effects of dairy cattle manure and mineral N fertilizer on irrigated maize and soil N and organic C

This work was aimed at providing a sustainable approach in the use of manure in irrigated maize crop under Mediterranean climatic conditions. To this end, the effect of continuous annual applications of dairy cattle manure, combined or not with mineral N fertilizer, on the following parameters was studied: grain yield, grain and plant N concentration, N uptake by plant, N use efficiency, and soil N and organic carbon. The experiment was conducted in a furrow-irrigated sandy soil under dry Mediterranean conditions during seven years. Three different rates of cattle manure (CM): 0, 30 and 60 Mg ha−1, were applied each year before sowing. These CM rates were combined with four mineral N rates (0, 100, 200 and 300 kg N ha−1) applied at sidedress. On average, the highest grain yields during the 7 years were obtained with the combination of CM at 30 Mg ha−1 and mineral fertilizer and with CM at 60 Mg ha−1 without mineral fertilizer. With CM at 30 Mg ha−1, mineral fertilizer increased yields during most of the growing seasons, meanwhile with CM at 60 Mg ha−1, there was not any significant effect of the joint application of mineral fertilizer on yields. Overall, best results were obtained exceeding maximum rates according to present legislation. The mean apparent nitrogen recovery (ANR) fraction during the 7 seasons was 29% for N exclusively applied as CM. Overall, increased N rates applied as CM resulted in decreased ANRs. However, ANR with CM at 30 and 60 Mg ha−1 increased during the first two seasons. This increased ANR ascribed to mineralization of residual organic N applied in previous seasons explained the increasing yields observed in the treatments along the study. The application of CM during 7 years increased the soil organic carbon in the first 30 cm by 5.7 and 9.9 Mg ha−1 with CM at 30 and 60 Mg ha−1, respectively, when compared to the initial stock. Thus, manure-based fertilization could be an alternative to mineral fertilizer in order to achieve high maize yields while improving soil quality under dry Mediterranean conditions.

Efficiency of nitrogen fertilization in spring wheat

An assessment of the nitrogen fertilization efficiency should not only include quantitativeand qualitative yield changes, but also an analysis of formation some indicators such as: Nharvest index (NHI), N use efficiency (NUE), N utilization efficiency (NUtE), N agronomicefficiency (NAE), N physiological efficiency (NPE) and N apparent recovery fraction (NRF).The objective of the study was the evaluation of spring wheat N fertilization efficiency undersoil conditions of Luvic Chernozem. Factors of the experiment were: cultivar (Bombona andTybalt) and level of N fertilization (0, 60, 90, 120 and 150 kg N ha-1). The application ofincreasing N rates in the wheat crop raised the grain N from 56 to 92 kg N ha-1 and theaboveground biomass N from 70 to 123 kg N ha-1 and it decreased most of the efficiencyindicators. The highest NHI value of 84%, PFNUE of 139.5 kg kg-1, NAE of 32.7 kg kg-1, NPEof 72.2 kg kg-1 and an NRF of 47% were observed for the lowest N rate of 60 kg N ha-1. TheNUtE of 92.8 kg kg-1, was at the highest level on the control plot. Every increase on N rateresulted in a significant decrease in the efficiency indicators. The cultivar factor significantlyaffected the grain and aboveground biomass N and the NAE, NPE and NRF values. Lowrainfall depths during the vegetative period favorably affected the NHI, NUtE, NAE and NPEindicators. On the other hand, excessive rainfall depths limited PFNUE, NAE, NPE and NRF.

Recycling of Dry-Batch Digestate as Amendment: Soil C and N Dynamics and Ryegrass Nitrogen Utilization Efficiency

In this work a residue of dry-batch anaerobic digestion (DB) from the organic fraction of municipal solid waste, its composted homologous (CDB), and a municipal solid waste compost (MSWC) were characterized for their main physico-chemical traits and biological stability [oxygen uptake rate (OUR)]. These were then compared in soil incubations at 200 mg N kg−1, to assess carbon (C) and nitrogen (N) mineralization. The products’ nitrogen apparent recovery fraction (ARF) was assessed in a pot trial on Italian ryegrass. DB showed the highest OUR, followed by CDB and the more stable MSWC: 161.7; 20.7 and 5.7 mmol O2 kg−1 VS h−1, partially in agreement with the potentially mineralizable C pools in soil: 58.4; 16.6 and 19.5 % and their kinetics (k, 0.1906; 0.1405 and 0.1377 day−1). Composting greatly reduced the total carbon dioxide (CO2) emissions from 7,950 to 3,449 mg kg−1 in DB and CDB, even higher than MSWC (1,936 mg kg−1). After intense N-immobilization in soil (−22.3 %), DB finally reduced the gap (−6.9 %), also having a positive ARF (5.0 %), while CDB had greater N-immobilization (−12.9 %) and a negative ARF (−3.4 %). MSWC showed 3.8 % N-mineralization, and an intermediate ARF (2.7 %). The management of DB for plant nutrition therefore seems difficult since DB can furnish nitrogen not easily synchronizable with plant growth due to its release pattern characterized by initial immobilization. Composting increased stability but amplified N-immobilization due to the high C:N ratio of the bulking agent. A prolonged and more balanced composting process can reduce this restriction, aligning CDB with MSWC.

The effectiveness of N-fertilization and microbial preparation on spring wheat

The efficiency of the application of microbial preparations enhancing soil properties as well as the diversified fertilization of spring wheat nitrogen was evaluated in the field experiment. Factors of the experiment referred to the levels of nitrogen fertilization: 0, 40, 80, 120 and 160 kg/ha as well as the application of microbial preparations, namely, Proplantan (disaccharide, and polysaccharide, lactic acid, carotene, riboflavin, thiamine, amylase, sea salt, minerals), Effective microorganisms (milk bacteria, photosynthetic bacteria, yeast, actinomycetes, moulds) and UG<sub>max</sub> microorganisms (lactic acid bacteria, photosynthetic bacteria, nitrogen-fixing bacteria, actinomycetes, macro- and microelements). The quantity of N<sub>min</sub> in the soil layer of 0–0.9 m ranged in respective years from 72.8 to 98.5 kg/ha before the spring wheat seeding and from 58.6.8 to 68.2 kg/ha after the crop was harvested, whereas the amount of N mineralization ranged from 18.9 to 53.3 kg/ha. Grain yields of wheat developed at a high level from 3.26 to 8.31 t/ha. To create the biomass, spring wheat plants absorbed nitrogen ranging from 78 kg N/ha in objects not fertilized to 184 kg N/ha in objects fertilized with the dose of 160 kg N/ha, and the share of nitrogen accumulated in the seeds amounted on average to 82% of the total uptake of that element. The highest N use efficiency, N physiological efficiency, N agronomic efficiency and N apparent recovery fraction were detected in objects fertilized with the dose of 40 kg N/ha. Each increase in the level of nitrogen fertilization affected lowering of the values of evaluated fertilization efficiency ratios.

Excessive nitrogen application decreases grain yield and increases nitrogen loss in a wheat–soil system

Excessive use of nitrogen (N) fertilizers in wheat fields has led to elevated NO3-N concentrations in groundwater and reduced N use efficiency. Three-year field and 15N tracing experiments were conducted to investigate the effects of N application rates on N uptake from basal and topdressing 15N, N use efficiency, and grain yield in winter wheat plants; and determine the dynamics of N derived from both basal and topdressing 15N in soil in high-yielding fields. The results showed that 69.5–84.5% of N accumulated in wheat plants derived from soil, while 6.0–12.5%and 9.2–18.1% derived from basal 15N and top 15N fertilizer, respectively. The basal N fertilizer recovery averaged 33.9% in plants, residual averaged 59.2% in 0–200 cm depth soil; the topdressing N fertilizer recovery averaged 50.5% in plants, residual averaged 48.2% in 0–200 cm soil. More top 15N was accumulated in plants and more remained in 0–100 cm soil rather than in 100–200 cm soil at maturity, compared with the basal 15N. However, during the period from pre-sowing to pre-wintering, the soil nitrate moved down to deeper layers, and most accumulated in the layers below 140 cm. With an increase of N fertilizer rate, the proportion of the N derived from soil in plants decreased, but that derived from basal and topdressing fertilizer increased; the proportion of basal and top 15N recovery in plants decreased, and that of residual in soil increased. A moderate application rate of 96–168 kg N ha−1 led to increases in nitrate content in 0–60 cm soil layer, N uptake amount, grain yield and apparent recovery fraction of applied fertilizer N in wheat. Applying above 240 kg N ha−1 promoted the downward movement of basal and top 15N and soil nitrate, but had no significant effect on N uptake amount; the excessive N application also obviously decreased the grain yield, N uptake efficiency, apparent recovery fraction of applied fertilizer N, physiological efficiency and internal N use efficiency. It is suggested that the appropriate application rate of nitrogen on a high-yielding wheat field was 96–168 kg N ha−1.

Potential nitrogen mineralization, plant utilization efficiency and soil CO2 emissions following the addition of anaerobic digested slurries

Abstract The liquid (LS) and solid fraction (SS) of a biogas slurry from dedicated crops, the composted solid fraction (CSS) and a municipal solid waste compost (MSWC) were compared in a soil incubation at 200 mg N kg −1 , to assess CO 2 emissions and potential C and N mineralization. Products were also compared for nitrogen apparent recovery fraction (ARF) in a pot trial with Italian ryegrass. LS showed the highest C mineralization (63.6%), soil mineral N (>100 mg kg −1 ), and ARF (50.3%). SS showed 21.6% C mineralization, slight N immobilization (23.6 mg kg −1 ) and 7.3% ARF. In CSS, a 5.1% C mineralization in soil added to 26.3% C loss during composting, resulting in 31.4% overall C loss. Moreover, composting SS to CSS curbed the emission from 4210 to 1100 mg CO 2 kg −1 soil, still double than the reference MSWC (507 mg CO 2 kg −1 soil). Despite high mineralization of supplied carbon, LS emitted less CO 2 than SS: 936 mg CO 2 kg −1 soil. It appears, therefore, that LS acts as a source of easily available nitrogen, while SS plays the role of an amendment with some limitations due to soil N immobilization. CSS mitigates N immobilization, but the composting process determines relevant CO 2 losses to the atmosphere.

Nitrogen release from a 15N‐labeled compost in a sorghum growth experiment

AbstractIn the near future, composted bio‐solids are expected to play a major role in agriculture. In order to evaluate their contribution to plant growth and nutrition, a mixed sorghum–poultry manure compost was prepared using 15N‐labeled materials. Four treatments were compared in a pot trial: fertilized with compost vs. unfertilized, both of them combined with (cultivated) and without (bare) plants of fibre sorghum (Sorghum bicolor [L.] Moench.). Soil mineral nitrogen (N‐min), plant growth, and N uptake were monitored over a whole growing season (167 d after fertilizer treatment; DAT). Apparent soil mineralization (ASM) and apparent recovery fraction of nitrogen by the plant (ARF) were assessed, as well as the 15N recovery fraction by the plant (15NRF). Compost enhanced sorghum biomass at mid growth (+ 200% of dry weight compared to the unfertilized). However, the difference between the control and the fertilized plants progressively decreased towards the end of the season (+ 70%). Fertilized and unfertilized plants followed different growth patterns over time, although of the same sigmoid type. Conversely, N concentration in plant tissues followed a common dilution curve, indicating that fertilized sorghum efficiently used the supplied N, avoiding luxury consumption. Apparent soil mineralization approximately reached 45% of compost total N in pots without plants. Apparent recovery fraction attained 100% at about two third of the growing season (DAT 111), then declined to about 50% because of root and leaf decline. Compared to it, 15NRF only reached ≈ 20% at mid growth (DAT 83), then declined to 12%. Despite the large difference in absolute values, ARF and 15NRF exhibited a significant correlation, indicating a common trend in time. In contrast to 15NRF, the amount of nutrient derived from fertilizer (Ndff) taken up by the plant decreased over the growth season, proving that compost contributed more to plant nutrition in the early (Ndff ≈ 50%) than in the late growing season (Ndff ≈ 25%). The large difference between ARF and 15NRF suggests that sorghum exerted a strong nutrient demand on the soil and on the fertilizer. Both 15NRF and ARF are considered valuable traits: the former better describes fertilizer behavior and actual supply of N, while the latter outlines the overall effect of fertilizer application on crop nutrition.

Comparative response of bread and durum wheat cultivars to nitrogen fertilizer in a rainfed Mediterranean environment: soil nitrate and N uptake and efficiency

A 3-year multi-site study was carried out on rainfed Vertisols under Mediterranean conditions in southern Europe to determine the influence of the N fertilizer rate on soil nitrates, N uptake and N use efficiency in bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. var. Durum Desf.) in rotation with sunflower (Heliathus annuus L.). Nitrogen fertilizer rates were 0, 100, 150 and 200 kg N ha−1 applied in equal proportions at sowing, tillering and stem elongation. The experiment was designed as a randomized complete block with a split plot arrangement and four replications. Nitrogen harvest index (NHI), N uptake/grain yield (NUp/GY), N use efficiency (NUE), N utilization efficiency (NUtE), N uptake efficiency (NUpE) and N apparent recovery fraction (NRF) were calculated. Differences were observed in N use efficiency between the two modern bread wheat and durum wheat cultivars studied. In comparison to durum, bread wheat displayed greater N accumulation capacity and a more efficient use of N for grain production. While under N-limiting conditions, the behavior was similar for both wheat types. No difference was noted between wheat types with regard to changes in soil residual \( {\text{NO}}^{ - }_{{\text{3}}} - {\text{N}} \) levels over the study period at the various sites. The 100-kg ha−1 N fertilizer rate kept soil nitrates stable at a moderate level in plots where both wheat types were sown.