•N2O emissions were measured at six site-years in Irish grassland.•90 N2O-EF were observed from three N fertilisers and five rates.•Average direct N2O-EF for CAN (1.62 %)>urea + NBPT (0.6 %)>urea ...(0.46 %).•The urea EF was most sensitive to increasing N rate.•The EF increased significantly with increasing rate in 3 (CAN), 5 (urea) and 2 (urea + NBPT) site-years.
The present study evaluated the impact of three nitrogen (N) fertiliser formulations, applied at five N rates, on nitrous oxide (N2O) fluxes and annual direct N2O-N emission factors (EF) in temperate grassland. Closed static chambers were used to measure direct N2O fluxes at three geographically dispersed locations in Ireland over a two-year period, generating a total of 90 EFs across the six site-years and treatments. The three fertiliser formulations tested were calcium ammonium nitrate (CAN), urea, and urea amended with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) at 100, 200, 300, 400 and 500 kg N ha−1 yr−1. All treatments were applied in five equal split applications ranging from 20 to 100 kg N ha−1 split-1 over the growing season. The N2O-N EFs for CAN ranged from 0.39 − 4.68 with a mean of 1.62 (cv. 81 %), for urea from 0.04 – 1.7 with a mean of 0.46 (cv. 77 %) and for urea + NBPT from 0.18 – 1.7 with a mean of 0.60 (cv. 59 %). A significant positive relationship was found between the N rate and the annual N2O-N EFs in three (CAN), five (urea) and two (urea + NBPT) of six the site-years. For the remainder of the site-years EF was unaffected by N rate. These results indicate that fertiliser N choice and rate can be management factors that enable farmers to alter N2O losses in temperate grassland. Notably, the response of EF to increasing N rate was not consistent across the fertilisers, with the EF from urea being the most sensitive to the increasing N rate, urea + NBPT the least sensitive and CAN being intermediate. The accuracy of national greenhouse gas accounting could be improved by including N fertiliser formulation and its rate of application. Further research is also needed to understand the inconsistency in EF response to N rate across sites.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Emissions of nitrous oxide (N2O), a potent greenhouse gas, are a challenge associated with application of nitrogen (N) fertilizers to soil. However, N source selection can play a role in reducing ...these emissions. Nitrous oxide emissions were measured from ammonium (ammonium sulfate) and nitrate (calcium nitrate) fertilizers over one year in temperate grassland using the closed static chamber method. Nitrogen was applied at a system representative rate of 220 kg ha−1 y−1 in six split applications. Cumulative annual N2O-N emissions were 0.29 kg ha−1 for the control, 1.07 kg ha−1 for the ammonium fertilizer and significantly higher at 2.54 kg ha−1 for the nitrate fertilizer. The annual emission factor (EF) for the ammonium fertilizer was 0.35% vs 1.02% for the nitrate fertilizer, a 66% reduction in the EF for ammonium vs nitrate and a 2.9 times higher EF for nitrate compared with ammonium. No difference in grass yield or N uptake was detected between fertilizers. This study shows that an ammonium fertilizer produces the same yield and N efficiency as a nitrate fertilizer with lower N2O emissions. The results also demonstrate that the nitrate portion of fertilizers is a key factor in N2O emissions in temperate grassland. This work is the first of its kind detailing the annual EF of both a solely ammonium-N and a solely nitrate-N fertilizer we could find.
Grass uptake and phytoaccumulation factors of N-(n-butyl) thiophosphoric triamide (NBPT) and dicyandiamide (DCD) were quantified. Following the application of urea fertilizer treated with the ...inhibitors in Irish grassland, grass samples were collected at 5, 10, 15, 20, and 30 day time intervals following five application cycles. Uptake of NBPT by grass was below the limit of quantitation of the analytical method (0.010 mg NBPT kg
-1
). Dicyandiamide concentrations in grass ranged from 0.004 to 28 mg kg
-1
with the highest concentrations measured on days 5 and 10. A reducing trend in concentration was found after day 15. The DCD phytoaccumulation factor was ranged from 0.004% to 1.1% showing that DCD can be taken up by grass at low levels when co-applied with granular urea. In contrast, NBPT was not detected indicating that grass uptake is unlikely when co-applied with granular urea fertilizer. The contrasting results are likely due to very different longevity of DCD and NBPT along with the much lower rate of NBPT, which is used compared with DCD.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
N-(n-butyl) thiophosphoric triamide (NBPT) is a urease inhibitor utilised in urea-based fertilizers. In Ireland, fertilizer treated with NBPT is applied to pasture to mitigate both ammonia and ...nitrous oxide emissions, but concerns arise as to the potential for residues in milk products. A quick ultrafiltration extraction and ultra-high performance liquid chromatography coupled with mass spectrometry triple quadrupole (UHPLC-MS/MS) quantitation method was developed and validated in this study. The method was applied in the analysis of samples collected from a field study investigating potential transfer of NBPT residues into milk. NBPT and NBPTo residues, were extracted from fortified milk samples and analysed on a UHPLC-MS/MS with recoveries ranging from 74 to 114%. Validation of the UHPLC-MS/MS method at low (0.0020 mg kg−1) and high (0.0250 mg kg−1) concentration levels in line with SANTE/12682/2019 showed overall trueness in the range of 99 to 104% and precision between 1 and 10%, RSD for both compounds. The limit of quantitation (LOQ) was 0.0020 mg kg−1 and other tested parameters (linearity, sensitivity, specificity, matrix effect, robustness, etc.) satisfied acceptance criteria. Stability assessment using spiked samples revealed the compounds were stable in raw and pasteurised milk for 4 weeks at –80 °C storage temperature. Maintaining samples at pH 8.5–9.0 further improved stability. Analysis of 516 milk samples from the field study found that NBPT and NBPTo concentrations were below the LOQ of 0.0020 mg kg−1, thus suggesting very low risk of residues occurring in the milk. The method developed is quick, robust, and sensitive. The method is deemed fit-for-purpose for the simultaneous determination of NBPT and NBPTo in milk.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The efficacy of the new nitrification inhibitor 3,4 dimethylpyrazol succinic acid (DMPSA) was tested with calcium ammonium nitrate (CAN) and ammonium sulphate (AS) fertilisers in an incubation ...experiment using a sandy loam soil and a sandy textured soil. The experiment was conducted over 80 days. For AS fertiliser, inclusion of DMPSA resulted in significantly less NO3−-N present after 19 days in both soils. In the case of CAN, inclusion of DMPSA resulted in significantly less NO3−-N present after 45 days in the sandy loam soil and after 30 days in the sandy soil. DMPSA is effective nitrification inhibitor when combined with CAN and AS, with a mean reduction of 61% and 58%, respectively, in the average daily nitrification rate over the study period. Over the 80-day incubation period in the sandy loam soil, only 35% NH4+-N was converted to NO3−-N for AS + DMPSA compared to 88% for AS. In the sandy soil, 92% NH4+-N was converted to NO3−-N for AS compared with only 9% for AS + DMPSA by day 80. The results demonstrate that DMPSA is an effective nitrification inhibitor when combined with CAN and AS.
The European dairy industry generates large volumes of wastewater from milk and dairy food processing. Removal of phosphorus (P) by complexing with metal (e.g., aluminium, calcium) cations in P rich ...sludge is a potential P source for agricultural reuse and P recycling. However, there is a significant knowledge gap concerning the plant availability of this complexed P in comparison to conventional mineral P fertiliser. The current absence of information on plant P bioavailability of dairy processing sludge (DPS) limits the ability of farmers and nutrient management advisors to incorporate it correctly into fertiliser programmes. The present study examined the most common types of dairy sludge—(1) aluminium-precipitated sludge (“Al-DPS”) and (2) calcium-precipitated lime-stabilised sludge (“Ca-DPS”) at field scale to assess P availability in grassland versus mineral P fertiliser over a growing season. The experimental design was a randomised complete block with five replications. Crop yield and P uptake were assessed for 4 harvests. The initial soil test P was at a low level and the experimental treatments were super phosphate at 15, 30, 40, 50 and 60 kg P ha−1, two dairy sludge applied at 40 kg P ha−1 (comparison was made with mineral P at same application rate) and a zero P control applied in a single application at the beginning of the growing season. Results showed a significant positive slope in the relationship between P uptake response and mineral P application rate indicating the suitability of the experimental site for P availability assessment. The P bioavailability of Al- and Ca-DPS varied greatly between treatments. The P fertiliser replacement value based on the 1st harvest was 50 and 16% increased to 109 and 31% cumulatively over the four harvests for Al- and Ca-DPS, respectively. The Al concentration in Al-DPS did not limit P bioavailability, but low P bioavailability from Ca-DPS can be associated with its high Ca content that can lead to formation of low soluble Ca-P compounds at alkaline pH conditions with a high Ca/P ratio. These findings show that P availability from dairy sludge can be quite different depending on treatment process. Consequently, it is critical to have P availability information as well as total P content available to ensure the application rate meets crop requirements without creating environmental risk by over application.
Currently, nitrogen fertilizers are utilized to meet 48% of the total global food demand. The demand for nitrogen fertilizers is expected to grow as global populations continue to rise. The use of ...nitrogen fertilizers is associated with many negative environmental impacts and is a key source of greenhouse and harmful gas emissions. In recent years, urease and nitrification inhibitors have emerged as mitigation tools that are presently utilized in agriculture to prevent nitrogen losses and reduce greenhouse and harmful gas emissions that are associated with the use of nitrogen-based fertilizers. Both classes of inhibitor work by different mechanisms and have different physiochemical properties. Consequently, each class must be evaluated on its own merits. Although there are many benefits associated with the use of these inhibitors, little is known about their potential to enter the food chain, an event that may pose challenges to food safety. This phenomenon was highlighted when the nitrification inhibitor dicyandiamide was found as a residual contaminant in milk products in 2013. This comprehensive review aims to discuss the uses of inhibitor technologies in agriculture and their possible impacts on dairy product safety and quality, highlighting areas of concern with regards to the introduction of these inhibitor technologies into the dairy supply chain. Furthermore, this review discusses the benefits and challenges of inhibitor usage with a focus on EU regulations, as well as associated health concerns, chemical behavior, and analytical detection methods for these compounds within milk and environmental matrices.
Plant growth and food security depend heavily on phosphorus (P). Recovering and recycling P from animal, municipal, and food waste streams can significantly reduce dependency on traditional mineral ...P. This is particularly pertinent in the EU regions with limited native P supplies. The agronomic performance of including P-based recycling-derived fertilisers (two struvite and two ashes) or cattle slurry was compared to a conventional mineral P fertilisation programme along with no P and no fertiliser controls over three years. A field-scale experiment was set up to evaluate the perennial ryegrass dry matter yield (DMY), P uptake, and soil test P effects. Struvite, ash, and cattle slurry proved effective in replacing P mineral fertiliser and produced yields similar to those of the mineral fertiliser programme. Differences were observed in plant P recovery, with struvite-based programmes achieving a significantly higher P recovery than ash-based programmes, which had the lowest plant P recovery. Differences in Morgan’s soil test P were also noted, with potato waste struvite (PWS) and poultry litter ash (PLA) showing significantly higher soil test P values. The findings strongly indicate that a range of recycled bio-based fertilisers from the bioeconomy can be used to reduce reliance on conventional imported mineral P fertiliser, with some programmes based on recycled fertilisers even surpassing the performance of conventional linear economy mineral fertilisers.
Background
Globally and at the European Union level there are mounting concerns regarding nitrogen (N) losses from agricultural systems and pressure to reduce N losses to water and air. Suboptimal ...plant sulfur (S) availability can reduce plant N efficiency and thereby increase N loss potential. Climate change action demands lower sulfur dioxide emissions thus S deposition levels are at an all‐time low.
Aims
The objectives of the current study were to (1) determine the potential for adequate S nutrition to increase grassland yield and N efficiency, (2) determine if alleviating S deficiency reduces nitrate leaching, and (3) evaluate a number of strategies for applying S including the use of cattle slurry.
Methods
This work was completed using a free‐draining sandy loam grassland lysimeter facility. There were six treatments using calcium ammonium nitrate (CAN), CAN + calcium sulfate (CAN+S), ammonium sulfate + CAN (AS+CAN), and slurry (Slurry+CAN and Slurry+CAN+S, respectively) to deliver S strategies. The yield, plant N and S uptake, and nitrate and sulfate leachate were measured to compare treatments.
Results
Application of mineral S fertilizer increased yields significantly (up to 2,907 kg ha–1) and increased apparent fertilizer nitrogen recovery from 39% to 47–49%. Alleviating S deficiency also significantly decreased nitrate leaching to levels not differing significantly from the control. There was a reduction of 46% in nitrate leaching with the addition of mineral S (CAN+S and AS+CAN) compared to N only. The nitrate concentration standard for drinking water was not breached for treatments that included S (6.6–11 mg NO3–‐N L–1), whereas it was breached for those without S (23–40 mg NO3–‐N L–1). The S applied in the slurry treatment was not adequate (9 kg S ha–1) to meet plant requirements.
Conclusion
This study provides evidence that optimization of S nutrition has the potential to deliver large agronomic and environmental benefits along with potential as a nitrate leaching migration strategy on S‐deficient soils.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Nitrogen fertiliser application represents the largest anthropogenic source of nitrous oxide (N2O) emissions, and the magnitude of these emissions is dependent on the type of fertilisers applied in ...the agroecosystems. Despite N-P-K compound fertilisers being commonly used in agricultural soils, a lack of information exists regarding their effects on N2O emissions. This study aims at examining the effects of different commonly used N-P-K compound fertiliser formulations with contrasting nitrate to ammonium ratios (0.05 to 0.88) on N2O emissions, yield, and nitrogen use efficiency (NUE) in temperate grassland and to compare these variables with common straight N fertilisers. Compound fertilisers with varying NPK inclusion rates (18-6-12, 10-10-20, 24-2.2-4.5, and 27-2.5-5), and calcium ammonium nitrate (CAN) and urea + N-(n-butyl) thiophosphoric triamide (NBPT) were applied at 80 kg N ha−1 to experimental plots in managed grassland on two occasions in a growing season. Fluxes of N2O during the experiment period, yield and NUE following two harvests were measured. The cumulative N2O emission from urea + NBPT, 18-6-12, 10-10-20, and 24-2.2-4.5 treatments were significantly reduced by 44%, 43%, 37%, and 31% compared with CAN treatment under conducive soil moisture condition. Under the same soil condition, 18-6-12 and 10-10-20 treatments showed higher yield, N uptake, and NUE although did not significantly differ from the other fertiliser treatments. Our results suggest that ammonium-based compound fertilisers have a potential to reduce N2O emissions while maintaining yields. Further long-term study is needed to capture the full magnitude of variations in N2O emissions, including ammonia (NH3) volatilization from nitrate and ammonium-based compound fertiliser applications from multiple soil types and under different climatic conditions.
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