scholarly journals Integration of measures to mitigate reactive nitrogen losses to the environment from grazed pastoral dairy systems

2014 ◽  
Vol 152 (S1) ◽  
pp. 45-56 ◽  
Author(s):  
R. M. MONAGHAN ◽  
C. A. M. DE KLEIN

SUMMARYThe need for nitrogen (N) efficiency measures for dairy systems is as great as ever if we are to meet the challenge of increasing global production of animal-based protein while reducing N losses to the environment. The present paper provides an overview of current N efficiency and mitigation options for pastoral dairy farm systems and assesses the impact of integrating a range of these options on reactive N loss to the environment from dairy farms located in five regions of New Zealand with contrasting soil, climate and farm management attributes. Specific options evaluated were: (i) eliminating winter applications of fertilizer N, (ii) optimal reuse of farm dairy effluent, (iii) improving animal performance through better feeding and using cows with higher genetic merit, (iv) lowering dietary N concentration, (v) applying the nitrification inhibitor dicyandiamide (DCD) and (vi) restricting the duration of pasture grazing during autumn and winter. The Overseer®Nutrient Budgeting model was used to estimate N losses from representative farms that were characterized based on information obtained from detailed farmer surveys conducted in 2001 and 2009. The analysis suggests that (i) milk production increases of 7–30% were associated with increased N leaching and nitrous oxide (N2O) emission losses of 3–30 and 0–25%, respectively; and (ii) integrating a range of strategic and tactical management and mitigation options could offset these increased N losses. The modelling analysis also suggested that the restricted autumn and winter grazing strategy resulted in some degree of pollution swapping, with reductions in N leaching loss being associated with increases in N loss via ammonia volatilization and N2O emissions from effluents captured and stored in the confinement systems. Future research efforts need to include farm systems level experimentation to validate and assess the impacts of region-specific dairy systems redesign on productivity, profit, environmental losses, practical feasibility and un-intended consequences.

Soil Research ◽  
2016 ◽  
Vol 54 (5) ◽  
pp. 604 ◽  
Author(s):  
G. D. Schwenke ◽  
B. M. Haigh

Summer crop production on slow-draining Vertosols in a sub-tropical climate has the potential for large emissions of soil nitrous oxide (N2O) from denitrification of applied nitrogen (N) fertiliser. While it is well established that applying N fertiliser will increase N2O emissions above background levels, previous research in temperate climates has shown that increasing N fertiliser rates can increase N2O emissions linearly, exponentially or not at all. Little such data exists for summer cropping in sub-tropical regions. In four field experiments at two locations across two summers, we assessed the impact of increasing N fertiliser rate on both soil N2O emissions and crop yield of grain sorghum (Sorghum bicolor L.) or sunflower (Helianthus annuus L.) in Vertosols of sub-tropical Australia. Rates of N fertiliser, applied as urea at sowing, included a nil application, an optimum N rate and a double-optimum rate. Daily N2O fluxes ranged from –3.8 to 2734g N2O-Nha–1day–1 and cumulative N2O emissions ranged from 96 to 6659g N2O-Nha–1 during crop growth. Emissions of N2O increased with increased N fertiliser rates at all experimental sites, but the rate of N loss was five times greater in wetter-than-average seasons than in drier conditions. For two of the four experiments, periods of intense rainfall resulted in N2O emission factors (EF, percent of applied N emitted) in the range of 1.2–3.2%. In contrast, the EFs for the two drier experiments were 0.41–0.56% with no effect of N fertiliser rate. Additional 15N mini-plots aimed to determine whether N fertiliser rate affected total N lost from the soil–plant system between sowing and harvest. Total 15N unaccounted was in the range of 28–45% of applied N and was presumed to be emitted as N2O+N2. At the drier site, the ratio of N2 (estimated by difference)to N2O (measured) lost was a constant 43%, whereas the ratio declined from 29% to 12% with increased N fertiliser rate for the wetter experiment. Choosing an N fertiliser rate aimed at optimum crop production mitigates potentially high environmental (N2O) and agronomic (N2+N2O) gaseous N losses from over-application, particularly in seasons with high intensity rainfall occurring soon after fertiliser application.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Fengliang Zhao ◽  
Ganghua Zou ◽  
Ying Shan ◽  
Zheli Ding ◽  
Minjie Dai ◽  
...  

AbstractFarms usually apply excessive nitrogen (N) fertilizers, especially in a vegetable production system, resulting in severe N leaching loss. Although there have been some reports on the impact of biochar on the N leaching in farmlands, most of them focused on field crops in temperate or subtropical religions. Limited information about N leaching in the tropical vegetable system is available regarding the quantitative data and effective countermeasures. A field experiment was conducted to quantify N leaching in a tropical leafy production system (Ipomoea aquatica Forsk) and to evaluate the effects of coconut shell biochar on N loss and crop growth. The results showed that compared to conventional fertilization with the 240 kg N ha−1 application rate (NPK), biomass yield of water spinach increased by 40.1% under the high biochar application rate of 48 t ha−1 (HBC), which was significantly higher than that of NPK treatment. Moreover, The HBC treatment decreased N leaching by 34.0%, which can be attributed to enhanced crop uptake which increased by 40.3% as compared to NPK treatment. The NH4+/NO3− ratio in leachates was between 0.01 and 0.05. It was concluded that coconut shell derived biochar improved the biomass yields of water spinach and reduced the leaching N loss, which provides a promising amendment in tropical regions.


2016 ◽  
Vol 83 (1) ◽  
Author(s):  
Yun-Feng Duan ◽  
Xian-Wang Kong ◽  
Andreas Schramm ◽  
Rodrigo Labouriau ◽  
Jørgen Eriksen ◽  
...  

ABSTRACT Grassland cultivation can mobilize large pools of N in the soil, with the potential for N leaching and N2O emissions. Spraying with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) before cultivation was simulated by use of soil columns in which the residue distribution corresponded to plowing or rotovation to study the effects of soil-residue contact on N transformations. DMPP was sprayed on aboveground parts of ryegrass and white clover plants before incorporation. During a 42-day incubation, soil mineral N dynamics, potential ammonia oxidation (PAO), denitrifying enzyme activity (DEA), nitrifier and denitrifier populations, and N2O emissions were investigated. The soil NO3 − pool was enriched with 15N to trace sources of N2O. Ammonium was rapidly released from decomposing residues, and PAO was stimulated in soil near residues. DMPP effectively reduced NH4 + transformation irrespective of residue distribution. Ammonia-oxidizing archaea (AOA) and bacteria (AOB) were both present, but only the AOB amoA transcript abundance correlated with PAO. DMPP inhibited the transcription of AOB amoA genes. Denitrifier genes and transcripts (nirK, nirS, and clades I and II of nosZ) were recovered, and a correlation was found between nirS mRNA and DEA. DMPP showed no adverse effects on the abundance or activity of denitrifiers. The 15N enrichment of N2O showed that denitrification was responsible for 80 to 90% of emissions. With support from a control experiment without NO3 − amendment, it was concluded that DMPP will generally reduce the potential for leaching of residue-derived N, whereas the effect of DMPP on N2O emissions will be significant only when soil NO3 − availability is limiting. IMPORTANCE Residue incorporation following grassland cultivation can lead to mobilization of large pools of N and potentially to significant N losses via leaching and N2O emissions. This study proposed a mitigation strategy of applying 3,4-dimethylpyrazole phosphate (DMPP) prior to grassland cultivation and investigated its efficacy in a laboratory incubation study. DMPP inhibited the growth and activity of ammonia-oxidizing bacteria but had no adverse effects on ammonia-oxidizing archaea and denitrifiers. DMPP can effectively reduce the potential for leaching of NO3 − derived from residue decomposition, while the effect on reducing N2O emissions will be significant only when soil NO3 − availability is limiting. Our findings provide insight into how DMPP affects soil nitrifier and denitrifier populations and have direct implications for improving N use efficiency and reducing environmental impacts during grassland cultivation.


2001 ◽  
Vol 1 ◽  
pp. 440-448 ◽  
Author(s):  
Maria Herrmann ◽  
William E. Sharpe ◽  
David R. DeWalle ◽  
Bryan R. Swistock

Logging has been shown to induce nitrogen (N) leaching. We hypothesized that logging a watershed that previously exhibited forest decline symptoms would place additional stress on the ecosystem and result in greater N loss, compared to harvesting vigorous forests. We conducted a 10-year (1988 to 1998) assessment of N export from the Baldwin Creek watershed in southwestern Pennsylvania that was partially clearcut to salvage dead and dying northern red oak. N export from the watershed increased significantly following salvage logging operations and did not completely return to prelogging levels by the end of the study period. The largest annual NO3-N export of 13 kg/ha was observed during the first year after harvesting, an increase of approximately 10 kg/ha. Compared to data from other Appalachian Mountain watersheds in North Carolina, West Virginia, and Pennsylvania, calculated N loss for Baldwin Creek was considerably greater. Longer periods of reduced N uptake due to slow revegetation of salvage logged areas, coupled with increased amounts of N available to leaching, could have accounted for the large N losses observed for Baldwin Creek. Salvage logging of dead and dying trees from forested watersheds in this region appears to have the potential to result in much larger N losses than previously reported for harvest of healthy stands.


2021 ◽  
Vol 13 (2) ◽  
pp. 994
Author(s):  
Chunlian Qiao ◽  
Shamim Mia ◽  
Yeqin Wang ◽  
Jiajia Hou ◽  
Burenbayin Xu

The effects of nitrification inhibitor in tea gardens with different urea–N rates have rarely been assessed. For eight months, a glasshouse experiment was conducted to investigate the effects of a nitrification inhibitor (3, 4–dimethylpyrazole phosphate, DMPP) on the changes of soil pH and inorganic N loss. Urea (0, 300, 500, and 800 kg N ha−1) with or without DMPP (1% of urea–N applied) were added to pots that hosted six plants that were three years old. Next, three leaching events were conducted with 600 mL of water after 7, 35, and 71 days of intervention while soil samples were collected to determine pH and inorganic N. Averaged across sampling dates, urea–N application at an increasing rate reduced soil pH with the lowest values at 800 kg urea–N ha−1. Adding DMPP increased soil pH up to a rate of 500 kg ha−1. Irrespective of the addition of DMPP, gradient urea–N application increased the leaching loss of inorganic N. On overage, DMPP increased soil pH and decreased leaching losses of total inorganic N, suggesting a higher soil N retention. Therefore, we believe that this increase in soil pH is associated with a relatively lower proton release from the reduced nitrification in the DMPP–receiving pots. This nitrification reduction also contributed to the N loss reduction (NO3−–N). Altogether, our results suggest that DMPP can reduce N leaching loss while maintaining the pH of tea–cultivated soils. Therefore, DMPP application has a significant potential for the sustainable N management of tea gardens.


Author(s):  
K.C. Cameron ◽  
H.J. Di ◽  
J.L. Moir ◽  
A.H.C. Roberts

The decline in water quality in Lake Taupo has been attributed to nitrogen (N) leaching from surrounding land areas. Pastoral agriculture has been identified as a significant contributor to this N transfer to the lake through animal urine deposition. There is therefore an immediate need for new management options to reduce N losses. The objective of this study was to measure the effectiveness of using a nitrification inhibitor (eco-n) to reduce nitrate leaching losses from a pasture soil of the Taupo region. A 3-year study was conducted using 20 lysimeters on Landcorp's 'Waihora' sheep and beef farm, within 10 km of Lake Taupo. The results show that animal urine patches were the main source of nitrate leaching (>95% of the total annual loss) and that eco-n significantly (P


Author(s):  
C.L. Christensen ◽  
M.J. Hedley ◽  
J.A. Hanly ◽  
D.J. Horne

Dairy farmers in New Zealand are encouraged to adopt a range of management strategies, both well established and emerging, to reduce nitrogen (N) losses to waterways. In most regions the OVERSEER® nutrient budgeting software (Version 6) (hereafter referred to as Overseer) is the tool of choice in the assessment of N losses for both regulatory and monitoring purposes. As part of these processes, Overseer is used to assess the impact of improved farm practices on N leaching and runoff from individual farms. In a 3-year dairy system field trial at Massey University, N losses in leaching and runoff under duration-controlled grazing (DC; 4 hours per grazing) were compared with those under standard grazing (SG; 7 hours per day-grazing, 13 hours per night-grazing). A 36% reduction in total nitrogen (TN) losses under DC grazing was measured (14 kg TN/ha) relative to standard grazing (22 kg TN/ha). Farmers adopting DC grazing as a mitigation strategy will only be able to claim the reduction in TN losses estimated by Overseer, and thus observations from the field trial were compared with outputs from Overseer. There was good agreement between the Overseer predictions of N leaching and values measured at the trial site for both the SG and DC grazing treatments. A second Overseer simulation of a DC system suggests that while Overseer is able to predict the reductions in N leaching under DC grazing reasonably well, some issues such as runoff losses and storage of effluent need further consideration. Keywords: Duration-controlled grazing; OVERSEER®; N leaching


2020 ◽  
Vol 60 (1) ◽  
pp. 78 ◽  
Author(s):  
David Chapman ◽  
Ina Pinxterhuis ◽  
Stewart Ledgard ◽  
Tony Parsons

As the pressure intensifies to reduce nitrogen (N) losses to the environment from pasture-based dairy systems, interest in reducing N-fertiliser inputs and returning to grass–clover mixtures, where more N for pasture growth is supplied by biological N fixation (BNF), have been revived. However, the following question then arises: is BNF fundamentally different from fertiliser N with respect to N losses, especially nitrate-N leaching risk? The present paper addresses this question by reviewing empirical evidence in the context of N-cycling processes and the efficiency of N use for herbage production. Nitrate leaching data from studies comparing different sward treatments at the same level of total N inputs (fertiliser plus BNF) provide no evidence to suggest that leaching differs when N is supplied solely by fixation in mixtures, by fixation plus fertiliser in mixtures, or solely as a fertiliser to grass monoculture. Increasing clover content in mixed grass–clover pastures is likely to increase N leaching due to a lower ratio of soluble sugar and starch to N in herbage than the common companion grass species perennial ryegrass, and, therefore, a higher partitioning of N eaten to urine. Counteracting this effect, mixed grass–clover pastures may offer some potential for increasing N-use efficiency and reducing the whole-farm N surplus compared with grass-dominant pasture receiving high rates of N fertiliser. While there are undeniable benefits for the productivity of dairy systems from maintaining strong grass–clover mixtures, it is the total amount of N entering the system, rather than the form of N (BNF or fertiliser), that influences nitrate leaching rates.


2016 ◽  
Vol 9 (1) ◽  
pp. 28 ◽  
Author(s):  
Frank E. Johnson II ◽  
Kelly A. Nelson ◽  
Peter P. Motavalli

<p>Practices to increase nitrogen (N) use efficiency (NUE) include selecting appropriate N fertilizer sources and application methods, but minimal research has focused on these practices in poorly-drained claypan soils which are prone to N loss. This research assessed the impact of different urea fertilizer placement practices on corn (<em>Zea mays</em> L.) production and N utilization in a poorly-drained claypan soil. Field trials were conducted in 2014 and 2015 in Missouri. Treatments consisted of pre-plant deep banding (20 cm) urea at 202 kg N ha<sup>-1</sup> or urea plus a nitrification inhibitor (NI) (nitrapyrin) compared to pre-plant urea broadcast surface-applied or incorporated to a depth of 8 cm. In 2014, incorporating urea, deep banding urea, and deep banding urea plus NI had higher yields (&gt; 10%) of corn compared to the control with grain yields ranging from 13.73 to 14.05 Mg ha<sup>-1</sup>. In 2015, grain yields were lower than in 2014, ranging from 4.1 to 7.9 Mg ha<sup>-1</sup>. Deep placing banded urea with a NI yielded an increase in grain yield up to 48% compared to the other treatments. Rainfall amounts were higher in 2015, which could have resulted in poorer root growth and greater N loss in deep banded treatments. In 2014, deep banding urea with a NI produced the highest NUE. Similar to NUE, silage tissue N concentrations in 2014 were greater with deep banded urea plus NI, while in 2015 silage tissue N concentrations were higher with surface applied urea. The results suggest that urea fertilizer incorporation including deep banding may improve corn grain production, N uptake, and NUE, but response was affected by climatic conditions. The addition of an NI may be an important safeguard when deep banding urea in years with excessive precipitation.</p>


Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1921
Author(s):  
Ayaz Ahmad ◽  
Shahzada Sohail Ijaz ◽  
Zhenli He

Global use of urea nitrogen (N) fertilizer is increasing, but N losses are still very high (40–70%). Zeolites have the capability of holding NH4+, thus reducing N losses when applied as a soil amendment. However, application of a large quantity of zeolite is costly and inconvenient. In this study, zeolitic fertilizers were evaluated to select the best formulation with reduced leaching of NH4-N and NO3-N and NH3 volatilization in agricultural soils (Alfisol and Spodosol). The treatments included the following: T0 = control, T1 = urea fertilizer, T2 = zeo-urea (1:1), T3 = zeo-urea (2:1), T4 = zeo-urea (3:1), T5 = zeo-urea (1:2), and T6 = zeo-urea (1:3). Leaching was performed at 4, 8, 12, 19, 25, 32, 39 and 45 days after the soils were treated with the designated fertilizers, including control, and packed into columns. Leachate samples were collected after each leaching event and analyzed for the concentrations of NH4-N and NO3-N and the quantity of leachate. Ammonia volatilization was recorded at days 1, 5, 9, 13 and 20 of soil treatments. Results indicate that zeolitic fertilizer formulations effectively reduced N losses. NH4-N loss was reduced by 13% and 28% by zeo-urea (1:1) in Alfisol and Spodosol soils, respectively, whereas zeo-urea (2:1) and zeo-urea (3:1) effectively decreased NO3-N leaching in Alfisol. Volatilization loss of NH3 was reduced by 47% in Spodosol and 32% in Alfisol soil with zeo-urea (1:1) as compared with that of urea fertilizer. The results suggest that zeo-urea (1:1) is an effective fertilizer formulation for reducing N losses, especially in Alfisol, as compared with conventional urea fertilizer.


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