Nitrogen Fertilizer Rates Research Articles

Determining optimal range of reduction rates for nitrogen fertilization based on responses of vegetable yield and nitrogen losses to reduced nitrogen fertilizer application

Vegetable production is commonly accompanied by high nitrogen fertilizer rates but low nitrogen use efficiency in China. Reduced fertilization has been frequently recommended in existing studies as an efficient measurement to avoid large amount of nutrient loss and subsequent nonpoint source pollution. However, the reported responses of vegetable yield and nitrogen losses to reduced fertilization rates varied in a large range, which has resulted into large uncertainties in the potential benefits of those recommended reduction rates. Thus, we constructed the relationship between responses of nitrogen losses and vegetable yield to reduced nitrogen fertilization rates to determine the optimal range of reduction rates for nitrogen fertilization in a proportional form based on data reported in literatures across China's mainland, and evaluated the roles of greenhouse, managing options, and vegetable species on the responses. The relationships were constructed separately for 4 subregions: Northern arid and semiarid, loess plateau regions (NSL), Temperate monsoon zone (TMZ), Southeast monsoon zone (SMZ), Southwest zone (SWZ). The optimal nitrogen fertilizer reduction range for the TMZ, SMZ and SWZ were 51 % to 67 %, 40 % to 66 % and 54 % to 80 %, respectively and no reduction for NSL. Vegetable yields were not be sacrificed when fertilizations were reduced within the optimal ranges. Greenhouse and managing options showed no significant effect on the responses of both vegetable yield and nitrogen losses by the optimal reduction range but vegetable species played a relatively important role on the responses of vegetable yield. This indicated that the optimal reduction rates can be effective on reducing nitrogen loss in both open-field and greenhouse conditions across China's mainland without extra managing options. Therefore, the optimal reduction rates can still serve as a good starting point for making regional plans of nitrogen reduction that help balancing the chasing of high vegetable yield and low nitrogen loss.

Management of Seeding Rate and Nitrogen Fertilization for Lodging Risk Reduction and High Grain Yield of Mechanically Direct-Seeded Rice under a Double-Cropping Regime in South China

Precision hill-drop direct seeding using mechanical drilling is a unique direct seeding technique employed in south China that offers advantages such as excellent grain yield and high lodging resistance. Improving yield and lodging-related traits is essential for efforts to improve mechanically direct-seeded rice (MDSR) production. Seeding rates (SR) and nitrogen (N) fertilization rate are two of the main factors affecting grain yield and lodging resistance under MDSR production. However, little information about double-season MDSR production in south China is available. Here, we evaluated yield and lodging risk for two rice cultivars Huanghuazhan, HHZ, lodging-resistant; Xiangyaxiangzhan, XYXZ, lodging-susceptible across two consecutive growing seasons under two under two seeding rates (LSR, 30 cm × 18 cm; HSR, 30 cm × 12 cm) and three N fertilization rates (N1 = 100 kg ha−1, reduced N; N2 = 150 kg ha−1, normal N; and N3 = 200 kg ha−1, enhanced N). We found that increased SR and N fertilization rate improved grain yield and increased lodging risk. SR and N were consistently and positively related to plant height (PH), gravity center height (GCH), the length from the broken basal internode to the panicle tip (SL), the fresh plant weight of the plant part above the broken point (FW), and the length of the two basal internodes. SR and N decreased breaking force (F) and breaking strength (BM), driving increased lodging risk as reflected by increases in lodging index (LI) values. Culm diameter (CD) and culm wall thickness (CWT) did not respond consistently to SR and N treatments. Correlation analysis revealed that PH, GCH, the length of first and second basal internodes, FW, and bending moment for the whole plant (WP) were positively correlated with LI, while F and BM were negatively associated with LI. These findings suggest that the increased lodging risk resulting from high SR could be mitigated by applying appropriate rates of N; that is, this work suggests that grain yield can be maximized and lodging risk minimized by increasing SR while decreasing N fertilization rate. Seasonal differences in the effects of SR and N fertilization should be considered to achieve a high grain yield and maintain high lodging resistance. Our study suggests that increasing SR and decreasing N fertilization can enhance rice grain yield while improving lodging resistance for both varieties. Optimizing grain yield by increasing SR while reducing lodging risk by lowering N application rates may maintain lodging resistance and improve grain yield.

164 Effect of distillers grains supplementation and fertilization rate on performance of stocker cattle grazing wheat pasture and stand performance

Abstract Within this study, the objectives were to determine how varied Nitrogen (N) fertilization rates and inclusion of dried distiller’s grains plus solubles (DDGS) impacted stocker and wheat stand performance within a no-till (NT) production system. A total of twenty-four 1.62-ha pastures were split between 3 unsupplemented treatments with urea spread at fixed rates of 50.44, 67.25, 84.06 kg N/ha in autumn and again in spring along with an additional 6 pastures fertilized with 50.44 kg N/ha each growing season plus supplemented with DDGS. From fall of 2021 to Spring of 2023, 576 beef steers (286.62 ± 36.67 kg) were randomly allocated at fixed stocking rates of 2.47 steers/ha (4 steers/pasture) in the fall, and 4.94 steers/ha (8 steers/pasture) in the spring. Steers were weighed upon arrival, at turnout, every 28 d, and when pulled off pasture. Steers were pulled off pasture when forage mass (FM) became insufficient, temperatures became too cold to support regrowth, or forage entered reproductive phase. Sampling dates to determine forage mass and quality coincided with weigh dates, where 20 plate meter readings were taken in every field and were recorded with a 0.25m2 plate meter, and 0.25m2 grass clippings were obtained from 15 fields every sampling date to estimate FM. Pairwise comparisons using the Mixed Model procedure in JMP were used to analyze data, with N rates with and without supplementation as a single fixed categorical variable, and year modeled as a random effect. In the fall, supplemented pastures produced greater ADG than 67.25 and 84.06 kg N/ha pastures (P < 0.05), along with greater total costs of supplemented pastures compared with all unsupplemented treatments (P < 0.0001). In the spring, supplemented pastures produced greater end weights, gain per hectare, forage mass and ADG than all unsupplemented treatments (P < 0.0001), and supplementation provided more grazing days (P < 0.05). While total sale income for supplemented pastures were greater than all unsupplemented treatments (P < 0.05), total costs of supplemented pastures were all increased (P < 0.0001), resulting in less income after variable costs (P < 0.0002). Response changes to supplementation were more pronounced than responses to increased fertilization. In conclusion, these results indicate that DDGS supplementation provided greater performance benefits to stocker cattle grazing wheat pasture than increased N fertilization rate, but the added costs associated with feeding resulted in lower profitability. However, the addition of DDGS supplementation may provide an opportunity to increase stocking rates to potentially improve profitability.

167 Use of plant growth-promoting rhizobacteria in bermudagrass systems of the Southeast US

Abstract Since the discovery of plant growth-promoting rhizobacteria (PGPR) in the mid-20th century, efforts have focused on utilizing them to reduce synthetic fertilizer usage and to improve the sustainability of agricultural systems. However, research in forage systems is lacking. The objective of the current study was to determine the use of PGPR in bermudagrass (Cynodon dactylon) forage systems in Central Alabama. The study was designed as a split plot and conducted at the E.V. Smith Research and Extension Center (Shorter, AL) and compared four levels of PGPR and five levels of nitrogen fertility rates. The PGPR included a negative control, Paenibacillus riograndensis DH44, Bacillus subtilis DH267, and UrtrishaN (Corteva Agriscience, Indianapolis, IN) were allocated to main plots. The strains of DH44 and DH267 were sprayed during each application at a population of 1-5 × 108 cfu/mL while UtrishaN (Corteva) was sprayed at a population of 3×107 cfu/mL with an activator at the rate of 0.25% vol/vol according to the manufacturer’s recommendations. The nitrogen fertilizer treatments were the subplot and were 25 and 50% of the recommended nitrogen for bermudagrass. The N treatments were as follows: negative control, 25% urea, 25% ammonium sulfate, 50% urea (F4), and 50% ammonium sulfate. Plots were treated with PGPR and N fertilizer starting on 11 May 2023. The forage harvest operation was conducted with at least 4 wk intervals depending on precipitation. After one year of the study, PGPR did not have any significant effect on forage biomass (1,209 kg /ha; P = 0.58). There was also no effect of N fertilizer (1,596 kg/ha; P = 0.35) or PGPR × N fertilizer interaction on forage biomass (1,408 kg/ha; P = 0.56). The lack of differences between positive and negative control plots indicates that growing conditions (i.e., lack of timely rainfall) during the first year of the study limited forage production for all treatments. The results from future years of this study will provide a more accurate conclusion on the use of PGPR with and without N fertilizer for bermudagrass systems.

Nitrogen fertilization rates in a subtropical peach orchard: Effect on fruit nutritional value and flavor

AbstractBackgroundThe necessity to help farmers improve yields has resulted in many years of agricultural research focused on productivity and disease resistance, neglecting other areas of fruit quality such as flavor, health benefits, and external appearance. Nitrogen is required for several biochemical processes. However, reducing N fertilization can increase the synthesis of antioxidants and volatile aroma compounds. Four‐N rates (0 (N0), 45 (N1), 90 (N2), 179 (N3), and 269 (N4) kg ha−1) were tested each year from 2011 to 2017 in two peach varieties melting flesh (MF) ‘TropicBeauty’ (TB), a soft texture peach, and non‐melting flesh (NMF) ‘UFSharp’ (UFS), a crispy texture peach, to determine the effect of N on nutritional value and flavor.ResultsThe phytochemical composition of the NMF ‘UFSharp’ (UFS) and MF variety ‘TropicBeauty’ (TB) were not cleared affected by N rates. Volatile synthesis was little affected by N. The sensory evaluation showed that consumers preferred MF peaches compared with NMF, because of its juiciness.ConclusionsNitrogen fertilization had minor effects on peach fruit phytochemical composition, volatile aroma compounds, and consumer acceptability. The N effect could had been influence by pruning practices, training of the orchard, and the delay of fruit developmental period.

Policy measures effectively reduce soil nitrous oxide emissions with minor trade‐offs in crop yield

AbstractNitrous oxide (N2O) emissions are closely linked to agricultural fertilisation. European and national policy incentives have been set to reduce greenhouse gas (GHG) emissions; however, only a few evaluations have been conducted. Avoiding such emissions is an important climate change mitigation measure, but it is still uncertain which management measures over a long‐term, best out‐balance crop yield and GHG balances in agricultural systems. We here used the process‐based LandscapeDNDC model to simulate N2O emissions and trade‐offs in yield and soil nitrogen budget for four alternative arable cropping systems in three Austrian agricultural production zones belonging to different climatic regions. We evaluated statistical data on crop rotations and management practices, predominant soil types, and 10‐year daily weather conditions for four cropping systems: (1) conventional farming receiving the maximum allowed nitrogen fertilisation rate (Nmax), (2) conventional farming receiving 15% less fertiliser, (3) conventional farming receiving 25% less fertiliser, and (4) organic farming. Our results showed that soil N2O emissions could be best reduced in wet, high‐yield regions. Reducing nitrogen fertilisation by 15% and 25% mitigated N2O emissions by, on average, 22% and 39%, respectively, while the yield was reduced by 5% and 9%, respectively. In comparison, the same crops grown in the organic cropping system released 60% less N2O, but yield declined on average by 23%. Corn, winter barley, and vegetables showed the highest N2O reduction potential under reduced fertiliser input in conventional farming. In addition to N2O emissions, reduced fertilisation substantially decreased other nitrogen losses into the water and atmosphere. Generally, the soils under all cropping systems maintained a positive mean nitrogen budget. Our results suggest a significant emission reduction potential in certain production zones which, however, were accompanied by yield reductions. Knowledge of the emission patterns from cropping systems under different environmental conditions is essential to set the appropriate measures. In addition, region‐specific measures to reduce soil N2O emissions have to be in line with farmers' interests in order to facilitate the successful implementation of targeted nitrogen management.

Relationship between mineral fertilization, plant macro- and microelement contents and yield of wheat (Triticum aestivum L.)

Abstract. The effectiveness of mineral fertilization on wheat productivity was determined in a field experiment on Alluvial-meadow soil (Fluvisol, FAO 2015) at the experimental field of Tsalapitsa village, Plovdiv region, during 2019-2020. Four increasing rates of nitrogen fertilization along with a constant background of phosphorus fertilization were tested in the following variants: N40P100; N80P100; N120P100; N160P100, and N0P0 (control) – without any fertilization. The influence of these variants on yield and the content of basic macro- and microelements in wheat’s dry biomass were assessed. Plant samples were collected at the full maturity phase of wheat, with each variant sampled in triplicate, to determine the concentrations of N, P, K, Ca, Mg, Cu, Zn, Mn, and Fe. Correlation analysis and analysis of variance (ANOVA) were employed to identify dependencies between observed variables. Significant differences between the variants for N% content in grain, chaff and straw of wheat were established. The highest nitrogen values were observed in the grain of the N160P100 and N120P100 variants, at 2.10% and 2.02%, respectively. The applied fertilization had a significant positive effect on the accumulation of potassium, calcium, copper, manganese and iron in wheat biomass. This finding was supported by the correlation coefficients between fertilizer rates and N (R = 0.948), Ca (R = 0.854), Cu (R = 0.681), Mn (R = 0.735), and Fe (R = 0.769) in the wheat grain. Significant yield differences were observed among the variants, with the highest yield recorded for N120P100 (7123.0 kg/ha), more than tripling that of the control variant. The uptake of nitrogen, phosphorus and potassium by the total biomass of wheat increased depending on the fertilization rates and it was the highest in the N120P100 variant.

Effect of some Nitrogen Fertilization Rates on the Yield and Its Components for some New Egyptian Bread Wheat Cultivars

Effect of some Nitrogen Fertilization Rates on the Yield and Its Components for some New Egyptian Bread Wheat Cultivars

Interactive effects of number of plants and nitrogen fertilization on quality parameters of Salvia officinalis L. cultivated in semi-arid environments

This research aimed to elucidate the interplay between number of plants and nitrogen dose on the agronomic attributes, as well as the essential oil yield and composition of Salvia officinalis L. (sage) in the challenging ecological conditions of Mardin, situated in South Eastern Anatolia. A split-plot experimental design was employed during 2018-2019, manipulating the variables of number of plants and nitrogen application rates. The experiment identified camphor, 1,8-cineole, α-thujone, and β-thujone as the major components. The PCA analysis unveiled statistically significant inverse correlations between the concentration of camphor and 1,8-cineole, as well as α- and β-thujone. The results demonstrated that the combination of lower plant number with elevated nitrogen levels yielded higher fresh herb dry herb and dry leaf. While lower plant number and higher nitrogen application independently exerted positive influences on essential oil production and yield, the interactive impact of these treatments yielded inconclusive results. Specifically, nitrogen treatments led to an increase in camphor content while reducing α- and β-thujone contents in the essential oil. Conversely, lower plant numbers resulted in decreased camphor content and an increase in thujone content within the oil. In light of these findings, it is recommended that, under semi-arid conditions, optimal yields can be achieved by employing plant number of 50000 plants ha−1 and a nitrogen fertilizer rate of 120 kg ha−1. This research sheds light on the intricate relationship between agronomic factors and the quality of sage cultivation, offering valuable insights into sustainable agricultural practices in semi-arid regions.

Irrigation as an Effective Way to Increase Potato Yields in Northern China: A Meta-Analysis

A meta-analysis was conducted with the aim of exploring the influence of irrigation on potato yield, evapotranspiration (ET), and water-use efficiency (WUE) in northern China, considering factors such as irrigation methods, growing region, irrigation water-use efficiency (IWUE), irrigation frequency, soil types, and nitrogen (N) fertilizer rate. Overall, irrigation significantly increased potato yield and ET by an average of 45 and 54% compared to non-irrigation, respectively, but did not significantly increase the WUE. The increase in potato yield under irrigation is the most evident in aeolian sandy soil in northeast China and northwest China. Drip irrigation demonstrated the highest positive impact on both yield and WUE. Optimal yields were achieved with an irrigation amount ranging from 100 to 200 mm, while the highest WUE was observed with an irrigation amount of 30–50 mm. When the amount of irrigation exceeded 100 mm, the irrigation significantly resulted in decreased WUE compared to non-irrigation. The relative increase in yield per unit of irrigation amount and IWUE gradually decreased and eventually stabilized when the irrigation amount exceeded 100 mm. Therefore, the yield and WUE perform best when the irrigation amount is below 100 mm and the irrigation frequency is less than three times for sprinkling and flood irrigation methods. The greatest increases in yield and WUE under irrigation were found under a moderate N rate (150–250 kg N ha−1). Additionally, the relative increase in yield per unit of irrigation amount decreases gradually as the organic matter content increases. These findings suggest that the optimal benefits from irrigation might be realized when the irrigation amount is below 100 mm, with a moderate nitrogen fertilizer application and an irrigation frequency of three times. However, it is essential to consider local environmental factors such as the growing region, soil types, and organic carbon content.

The Effects of Tillage Systems on the Management of Agronomic Factors in Winter Oilseed Rape Cultivation: A Case Study in North-Eastern Poland

The aim of this study was to analyze agronomic management in the production of winter oilseed rape (WOR) in different tillage systems. The field experiment (Poland, 2016–2019) had a 35–1 fractional factorial design with two replications, where five fixed factors were tested at three levels. The experimental factors were as follows. A—tillage: (A0) strip-till, (A1) low-till, (A2) conventional tillage; B—weed control: (B0) pre-emergent, (B1) foliar, (B2) sequential; C—growth regulation: (C0) none, (C1) in fall, (C2)—in fall and spring; D—rate of spring nitrogen (N) fertilizer: (D0) 160, (D1) 200, (D2) 240 kg ha−1; E—rate of spring sulfur (S) fertilizer: (E0) 0, (E1) 40, (E2) 80 kg ha−1. Seed yields were the highest in the strip-till system (5.95 Mg ha−1). The effectiveness of weed control methods varied across different tillage systems. Foliar herbicides exerted the highest yield-forming effect in the strip-till system, pre-emergent and sequential herbicides were most effective in the low-till system, and pre-emergent herbicides were most effective in the conventional tillage system. Seed yields increased up to the N rate of 200 kg ha−1. The highest N rate of 240 kg ha−1 was justified only when S was applied in spring. Sulfur significantly increased seed yields (by 17%). The results of the study indicate that low-till and strip-till systems can be viable alternatives to the conventional tillage system in WOR production.

Nitrogen fertilizer source, rate, placement, and application timing effect on sorghum (grain and forage) and corn grain yields

AbstractIdentifying the limiting nutrient, fertilizer source, rate, placement, additives, and timing of application are critical components of fertilizer management. The objective of this study was to quantify the impact of nitrogen (N) fertilizer source, rate, placement method, additives, application timing, and environment on yields of grain sorghum, forage sorghum [Sorghum bicolor (L.) Moench], and corn (for grain, Zea mays L.). Independent field experiments were conducted at 13 different environments in Kansas from 2008 through 2013 on grain sorghum, forage sorghum, and corn. Treatments were an incomplete factorial combination of four fertilizer placement methods, three fertilizer types, five fertilizer additives, three fertilizer application times, and six fertilizer rates that varied by location and across years. Results showed grain and forage sorghum yields responded to N fertilizer in environments that were not extremely dry (<136 mm) or wet (>651 mm). Corn responded to N fertilizer application only in high‐precipitation environments. For grain sorghum, where rate × placement × source × additive interaction was significant, broadcast application of urea (source) at high rates (67–134 kg N ha−1), with summer application timing, or with additive in winter (with environmentally smart nitrogen [ESN]) resulted in up to 43% greater yield compared with application of urea‐ammonium nitrate (UAN; source) and surface band (placement) at 67 kg ha−1 without additives. In the one site‐year where forage sorghum responded to fertilizer application, forage yields with preplant application of UAN at 56–140 kg ha−1 were 164% greater than the control. For corn, application of either urea or UAN fertilizer, UAN in coulter or surface band, with ESN blend, applied at planting, and at highest rates (160 kg ha−1) resulted in best yields compared with the alternatives and 110% greater yield compared with the unfertilized control. We concluded that fertilizer rate is an important management component as it consistently affected yield regardless of crop considered. Fertilizer placement and timing have crop‐specific importance as they were significant for only corn, but the main effect of additives (N stabilizers) was not significant for any of the crops. Environment and crop type influenced crop response to N fertilizer rate, timing, placement, and additives.

Identifying synergistic solutions for the food-energy-water nexus via plastic film mulching cultivation

Food security, water scarcity, and excessive fossil energy use pose considerable challenges to sustainable agriculture. To understand how rain-fed farming systems on the Loess Plateau, China, reconcile yield increases with ecological conservation, we conducted an integrated evaluation based on the denitrification-decomposition (DNDC) model, agricultural statistics data using the Food-Energy-Water (FEW) nexus indicator. The results showed that maize yields with ridge-furrow plastic film mulching (PFM) were 3479, 8942, and 11,124 kg ha−1 under low (50 kg N ha−1), medium (200 kg N ha−1), and high (350 kg N ha−1) nitrogen (N) fertilizer rates, respectively, and that PFM increased yield and water use efficiency (WUE) by 110–253 % and 166–205 % compared to using no mulching (control, CK), respectively. Plastic film mulching also increased net energy (126–436 %), energy use efficiency (81–578 %), energy productivity (100–670 %), and energy profitability (126–994 %), and nitrogen fertilizer, compound fertilizer, and diesel fuel consumption by agricultural machinery were the main energy inputs. The PFM system reduced water consumption during the maize growing season and the green water footprint and gray water footprint decreased by 66–74 % and 44–68 %, respectively. The FEW nexus indicator, based on a high production at low environmental cost scenario, was greater under the PFM system and had the widest spatial distribution area at the medium-N application rate. Among the environmental factors, the nexus indicator was negatively correlated with precipitation (−0.37), air temperature (−0.36), and the aridity index (−0.36), but positively correlated with elevation (0.17). Our results suggest that the PFM system promotes resource-saving while increasing yields and moves dryland agriculture in an environmentally friendly direction, thus promoting the sustainable development of agroecosystems.

Nitrate Pollution Characteristics and Its Quantitative Source Identification of Major River Systems in China

Accurate source identification/apportionment is essential for optimizing water NO3--N pollution control strategies. This study conducted a meta-analysis based on data from 167 rivers across China from 2000 to 2022 to analyze the spatial and temporal variation patterns of nitrate pollution in seven major river systems and to quantitatively identify the source composition of riverine nitrate. The average ρ（NO3--N） in the seven major river systems was （4.54±3.99） mg·L-1， with 9.6% of river ρ（NO3--N） exceeding 10 mg·L-1. The riverine ρ（NO3--N） in eastern China were higher than that in western China， and the highest concentration was observed in the Haihe River system. Additionally， tributaries experienced more serious NO3--N pollution than that in the main stream. The ρ（NO3--N） in most river systems in the dry season was higher than that in the wet season， except in the Yellow River system. There was significant nitrification in the Pearl River system， the middle and lower reaches of the Yellow River system， the middle reaches of the Liaohe River system， the Songhua River system， and the Haihe River system， whereas there was significant denitrification in the Yangtze River system， the Huaihe River system， and the lower reaches of the Pearl River system. Based on the dual stable isotopes-based MixSIAR model， the major NO3--N source was sewage/manure （ > 50%） in the Yangtze River system， Haihe River system， Liaohe River system， and Southeast River system. Soil nitrogen was the main NO3--N source in the Songhua River system （56.4%）， and the contribution of fertilizer nitrogen， soil nitrogen， and sewage/manure to NO3--N pollution in the Pearl River system， Huai River system， and Yellow River system was 20%-40%. The contribution rate of sewage/manure to NO3--N in the tributaries was higher than that in the main stream， whereas the contribution rate of soil nitrogen to NO3--N in the main stream was higher than that in the tributaries. The contribution rate of soil nitrogen， fertilizer nitrogen， and atmospheric deposition nitrogen to nitrate nitrogen in the wet season was higher than that in the dry season， whereas the contribution rate of sewage/manure to NO3--N pollution in the dry season was higher than that in the wet season. Therefore， point source pollution such as domestic and production sewage discharge should be controlled in the Haihe River system， the Yangtze River system， the Liaohe River system， the tributaries and the downstream main stream areas of Yellow River system， and the downstream area of the Pearl River system， whereas non-point source pollution caused by the loss of fertilizer and soil nitrogen should be controlled in the Huaihe River system， the Songhua River system， the middle reaches of the main stream area of the Yellow River system， and the middle and upper reaches of the Pearl River system. The results can provide a scientific basis for the effective control of nitrate pollution in the river systems in China.

Impact of Nitrogen Fertilizer Rate and Timing on Short-day Onion Production

Onions (Allium cepa) are typically planted late fall and harvested in spring in the Vidalia, GA, USA, region. Onions grown here are renowned for their for sweetness and are marketed to consumers as Vidalia onions. High rainfall during the relatively long growing season (4 to 5 months) may result in nitrogen (N) leaching during production. Therefore, fertilizer applications are usually aligned with stages of crop development to ensure nutrient availability for the entire season. Although the impacts of N application rate have been previously investigated for Vidalia onion production, the optimal timing for the final N application of the season has not been determined. The objectives of this study were to determine the optimal timing of the last fertilizer N application (at bulb initiation, during bulb growth, or during bulb maturation) in conjunction with the impact of three N application rates (75, 105, and 135 lb/acre N) on yield and quality in Vidalia onion. Soil N levels were affected by N rate, year, and onion growth stage. In 2020, up to 135 lb/acre N was required to maximize onion yields, and in 2021, onion yields were unchanged among N fertilizer treatments. Final N applications at bulb initiation resulted in greater yields than applications made during bulb growth or bulb maturation. In addition, as the N rate increased and the time of final application occurred later in bulb development, pungency values increased. Incidence of sour skin (Burkholderia cepacia) and center rot (Pantoea sp.) diseases were greater in 2020 compared with 2021 and seemed to be affected by environmental conditions more than N fertilization.

Unveiling the potential of cellulose nanofibre based nitrogen fertilizer and its transformative effect on Vigna radiata (Mung Bean): nanofibre for sustainable agriculture.

Fertilizer management is crucial to maintaining a balance between environmental health, plant health, and total crop yield. Farmers are overutilizing fertilizers with a mind set to enhance the productive capacity of the field, which adversely impacts soil fertility and causes serious environmental hazards. To mitigate the issues of over-utilization of fertilizers, controlled-release fertilizers were developed using nitrogen fertilizer (ammonium chloride) loaded on cellulose nanofibres (named CNF*N). In this study, the effects of CNF*N were compared with commercial nitrogen fertilizer (ammonium chloride) on Vigna radiata (Mung) under greenhouse conditions. The pot experiment was conducted using six treatments: first treatment was control, where the plant was cultivated (T1); second treatment was T2, where the plant was cultivated with CNF to determine the impact of CNF on the plant; third was T3 where commercial ammonium chloride (24 mg/ 2 kg soil) was added to the plant; fourth was T4, where the plant was loaded with CNF, viz. CNF*N contains 4.8 mg of nitrogen; fifth was T5 CNF*N pellet contains 12 mg of nitrogen, and the last sixth treatment (T6) where CNF*N pellet containing 24 mg of nitrogen. It indicated that the growth parameters were best achieved in T6 treatment. Plant height was at its maximum in the T6 treatment (44.4 ±0.1cm) after the second harvest, whereas the minimum plant height was observed in T1, which was 39.1 ±0.1 cm. Root-to-shoot weight ratio was also maximum in T6 (0.183± 0.02) and minimum in T1 (0.07± 0.01) after second harvesting. The significant difference among the treatments was determined with Tukey's honestly significant difference (HSD). The nitrogen content (available and total) was significantly higher in the T4, T5, and T6 treatments (0.22, 0.25, and 0.28%) as compared to the control treatments (T1 (0.12%), T2 (0.13%), and T3 (0.14%) during the second harvesting stage (90 days), as nitrogen plays a crucial role in the development of vegetative growth in Vigna radiata. The rate of controlled-release nitrogen-fertilizer was found to be optimal in terms of plant growth and soil nutrients; hence, it could potentially play a crucial role in improving soil health and the yield of the crop.

Disproportional oxidation rates of ammonia and nitrite deciphers the heterogeneity of fertilizer-induced N2O emissions in agricultural soils

Nitrous oxide (N2O) is a potent greenhouse gas and ozone-depleting chemical. Although nitrogen (N) fertilizer rate is the best single predictor of N2O emissions, the spatial heterogeneity of the emission factor is striking and poorly understood. Nitrite (NO2−) dynamics have been reported to be correlated with N2O production in many soils; however, NO2− is often overlooked owing to its rare accumulation, and the underlying mechanisms of NO2− accumulation and the relationship with spatiotemporal heterogeneity of N2O emissions in response to N addition remains unclear. Here, we collected upland agricultural soils that cover the main upland agricultural production regions of China and investigated the soil-specific effects on N2O emissions, changes in microbial abundances and community structures of nitrifiers, and co-occurrence networks for ammonium (NH4+)-based fertilizer addition. Our results showed that high NO2− accumulation and high N2O emissions were generally correlated with low nxrA/AOB gene ratios (R2 = 0.90 and 0.86, respectively, P < 0.01). Further network analyses revealed that NH4+ addition increased the network links of the nitrification functional communities by 23% and enhanced the interrelationship between AOB and nitrite oxidizers. By synthesizing our data with previous studies in the literature, we found that soil N2O emission rate and nxrA/AOB gene ratio exhibit a threshold behavior worldwide, suggesting that disproportionality of NH3 and NO2− oxidations rates are involved in the heterogeneity of fertilizer-induced N2O emissions in agricultural soils. These findings enhance our understanding of spatiotemporal heterogeneity in NO2− accumulation and N2O emissions within upland agricultural soils in view of nitrification functional communities.

Response of Some Soybean Genotypes to Insect Infestation under Three Mineral Nitrogen Fertilizer Rates

Background: A two-year study was conducted at Giza Agricultural Research Station, Agricultural Research Center (ARC), Egypt, to evaluate the productivity of six genotypes of soybeans under three mineral nitrogen (N) fertilizer rates, as well as their resistance to insects, in comparison to four check varieties. Methods: The study took place during the 2021 and 2022 summer seasons. The treatments included three mineral N fertilizer rates (N1=67% of N fertilizer rate “71.4 kg N/ha”, N2=33% of N fertilizer rate “35.7 kg N/ha” with seed inoculation by Bradyrhizobium japonicum and N3=100% of N fertilizer rate of the recommended rate “107.1 kg N/ha”) and ten soybean genotypes (H4L4, H6L198, H18L54, H29L115, H129, Misr 10, along with Dr101 and Giza 111 “resistant” and Giza 82 and Crawford “susceptible”). The experiment used a split plot design with three replications. The main plots were assigned the mineral N fertilizer rates, while the subplots, were assigned the soybean genotypes. Result: Fewer cotton leaf worms, whiteflies and leaf miners were found after applying N1 or N2. In the 6th week from sowing, Misr 10 and Dr 101 had fewer cotton leaf worms and whiteflies. In contrast, throughout the 7th, 8th and 9th weeks from sowing, Misr 10 and H6L198 had fewer cotton leaf worms. Misr 10 had fewer leaf miners in every week and fewer whiteflies in the 7th, 8th and 9th weeks from sowing. In the 6th week of the first season, Misr 10, Dr101, H18L54 and Giza 111 that received N1 or N2 had fewer cotton leaf worms; in the 7th and 9th weeks from sowing, Misr 10, Dr101 and H6L198 harbored fewer whiteflies. The lowest pod weight/plant, seed yield/plant, 100-seed weight, seed yield/ha and HI were obtained by using N3. Higher biological yield/ha, seed yield/plant, 100-seed weight, seed yield/ha and HI were attained by Misr 10. In the second season, seed yield per plant and seed yield per hectare were significantly affected by the interaction between soybean genotypes and mineral N fertilizer rates. Growing Misr 10 with 67 per cent N of the recommended rate increased seed yield/plant and seed yield/ha, along with fewer cotton leaf worm, whiteflies and leaf miners compared to the commercial cultivar Giza 111 receiving the recommended mineral N fertilizer rate.

Long term response and adaptation of farmland water, carbon and nitrogen balances to climate change in arid to semi-arid regions

Climate change poses a challenge for resource utilization and environmental pollution issues caused by agricultural production, especially in arid to semi-arid regions. Farmland water, carbon and nitrogen balances are closely related to these resource and environmental issues. Thus, the Agro-Hydrological & chemical and Crop systems simulator was used to assess the response of water, carbon and nitrogen balances to climate change in a spring wheat farmland of arid to semi-arid Northwest China and to propose adaptation strategies. Five Global Climate Models from the Coupled Model Intercomparison Project 6 and two Shared Socioeconomic Pathways (SSP1–2.6 and SSP5–8.5) were used to establish scenarios with the Agro-Hydrological & chemical and Crop systems simulator to simulate farmland water, carbon and nitrogen balances for the 2025–2100 period. Various irrigation amounts and nitrogen fertilization rates were tested as compensation strategies. Results indicated that climate change could negatively affect farmland water, carbon and nitrogen balances, especially under the SSP5–8.5 scenario. Precipitation showed an increasing trend, thus percolation increased and soil water consumption decreased from 2025 to 2100. However, for the carbon budget, although the soil carbon dioxide emissions tend to decrease, the net primary production was also significantly reduced, which resulted in declining the net ecosystem carbon budget under future climatic conditions. In addition, higher temperature and increased precipitation enhanced soil inorganic nitrogen leaching and nitrous oxide emissions but reduced ammonia volatilization from 2025 to 2100. Overall, the soil total nitrogen loss was increased over time, whereas crop nitrogen uptake was significantly reduced. In relation to the SSP1–2.6 scenario, the SSP5–8.5 scenario accelerated the increase rates of soil water percolation and total nitrogen loss over time, as well as the decrease rates of crop nitrogen uptake and net primary production over time. The negative effects caused by climate change can be mitigated by reducing irrigation and increasing nitrogen fertilization. For the SSP1–2.6 scenario, 30% irrigation reduction and 30% nitrogen fertilization increase can effectively decrease soil water percolation and the related nitrogen losses while crop nitrogen uptake, net primary production and net ecosystem carbon budget increase in relation to the current management (irrigation = 240 mm and nitrogen fertilization = 200 kg ha–1). For SSP5–8.5 the strategy with 45% irrigation reduction and 45% nitrogen fertilization increase can also decrease nitrogen losses and increase crop nitrogen uptake, net primary production and net ecosystem carbon budget.

Perennializing marginal croplands: going back to the future to mitigate climate change with resilient biobased feedstocks

Managing annual row crops on marginally productive croplands can be environmentally unsustainable and result in variable economic returns. Incorporating perennial bioenergy feedstocks into marginally productive cropland can engender ecosystem services and enhance climate resiliency while also diversifying farm incomes. We use one of the oldest bioenergy-specific field experiments in North America to evaluate economically and environmentally sustainable management practices for growing perennial grasses on marginal cropland. This long-term field trial called 9804 was established in 1998 in eastern Nebraska and compared the productivity and sustainability of corn (Zea mays L.)—both corn grain and corn stover—and switchgrass (Panicum virgatum L.) bioenergy systems under different harvest strategies and nitrogen (N) fertilizer rates. This experiment demonstrated that switchgrass, compared to corn, is a reliable and sustainable bioenergy feedstock. This experiment has been a catalyst for other bioenergy projects which have also expanded our understanding of growing and managing bioenergy feedstocks on marginal cropland. We (1) synthesize research from this long-term experiment and (2) provide perspective concerning both the knowledge gained from this experiment and knowledge gaps and how to fill them as well as the role switchgrass will play in the future of bioenergy.