Simulation of mitigation strategies to reduce nitrogen leaching from grazed pasture

Strategies to reduce nitrogen leaching losses from pastoral farming in the Lake Taupo catchment are required to address declining water quality in the lake. This study used a biophysical whole farm simulation model, EcoMod, to explore the potential for four mitigation strategies to reduce N leaching in a soil and climate typical of the region. The strategies were use of: a nitrification inhibitor (DCD); steers instead of heifers (STEER); salt as a diuretic (SALT) and; high sugar ryegrass (HSG). These were compared to a BASE scenario of grazed heifers. Each of the simulated mitigation strategies showed the potential to significantly reduce nitrogen leaching compared to BASE by 25 to 45%. All mitigation strategies reduced nitrogen fixation due to more efficient plant use of nitrogen from urinary and faecal sources. This also contributed to an increase in pasture intake for SALT, STEER and DCD, but not for HSG. These mitigation strategies were explored at a single-paddock level and planned experimental studies will further examine the effectiveness of the strategies. Keywords: nitrogen leaching, mitigation, Lake Taupo, simulation, EcoMod

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Response of Vertical Migration and Leaching of Nitrogen in Percolation Water of Paddy Fields under Water-Saving Irrigation and Straw Return Conditions

Water ◽

10.3390/w11040868 ◽

2019 ◽

Vol 11 (4) ◽

pp. 868 ◽

Cited By ~ 4

Author(s):

Chengxin Zheng ◽

Zhanyu Zhang ◽

Yunyu Wu ◽

Richwell Mwiya

Keyword(s):

Vertical Migration ◽

Growth Stage ◽

Nitrogen Leaching ◽

Water Saving ◽

Paddy Fields ◽

N Leaching ◽

Leaching Losses ◽

Leaching Loss ◽

Straw Return ◽

Percolation Water

The use of water-saving irrigation techniques has been encouraged in rice fields in response to irrigation water scarcity. Straw return is an important means of straw reuse. However, the environmental impact of this technology, e.g., nitrogen leaching loss, must be further explored. A two-year (2017–2018) experiment was conducted to investigate the vertical migration and leaching of nitrogen in paddy fields under water-saving and straw return conditions. Treatments included traditional flood irrigation (FI) and two water-saving irrigation regimes: rain-catching and controlled irrigation (RC-CI) and drought planting with straw mulching (DP-SM). RC-CI and DP-SM both significantly decreased the irrigation input compared with FI. RC-CI increased the rice yield by 8.23%~12.26%, while DP-SM decreased it by 8.98%~15.24% compared with FI. NH4+-N was the main form of the nitrogen leaching loss in percolation water, occupying 49.06%~50.97% of TN leaching losses. The NH4+-N and TN concentration showed a decreasing trend from top to bottom in soil water of 0~54 cm depth, while the concentration of NO3−-N presented the opposite behavior. The TN and NH4+-N concentrations in percolation water of RC-CI during most of the rice growth stage were the highest among treatments in both years, and DP-SM showed a trend of decreasing TN and NH4+-N concentrations. The NO3−-N concentrations in percolation water showed a regular pattern of DP-SM > RC-CI > FI during most of the rice growth stage. RC-CI and DP-SM remarkably reduced the amount of N leaching losses compared to FI as a result of the significant decrease of percolation water volumes. The tillering and jointing-booting stages were the two critical periods of N leaching (accounted for 74.85%~86.26% of N leaching losses). Great promotion potential of RC-CI and DP-SM exists in the lower reaches of the Yangtze River, China, and DP-SM needs to be further optimized.

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NITROGEN LEACHING LOSSES FROM CONTAINER-GROWN ROSES.

HortScience ◽

10.21273/hortsci.27.6.583a ◽

1992 ◽

Vol 27 (6) ◽

pp. 583a-583 ◽

Cited By ~ 2

Author(s):

Raul I. Cabrera ◽

Richard Y. Evans ◽

J. L. Paul

Keyword(s):

Nitrogen Leaching ◽

N Leaching ◽

Leaching Losses ◽

Yield And Quality ◽

Flower Yield ◽

Use Efficiency ◽

Leaching Fraction ◽

Cut Flower Yield ◽

One Year ◽

Nutrient Solutions

Nitrogen leaching losses of 21, 40 and 49% were measured from container-grown `Royalty' roses irrigated for one year with nutrient solutions containing 77, 154 and 231 mg N/l. There were no significant differences in number of flowers per plant or dry matter per plant. The N present in the harvested flowers accounted for 43, 27 and 17% of the N applied for the 77, 154 and 231 mg N/l treatments, respectively. Plants receiving 154 mg N/l at leaching fractions of 0.1, 0.25 and 0.5 had corresponding N leaching losses of 22, 38 and 56%. In this experiment, however, the 0.5 leaching fraction produced yields significantly higher than those of the 0.1 and 0.25 treatments. The N recovered in the harvested flowers accounted for 28, 25 and 19% of that applied to the 0.1, 0.25 and 0.5 treatments, respectively. The results of these studies suggest that modifications in current irrigation and fertilization practices of greenhouse roses would result in a considerable reduction of N leaching losses and enhance N fertilizer use efficiency, without loss of cut flower yield and quality.

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Effect of nitrogen fertiliser rate on production and nitrogen leaching from Italian ryegrass following a maize silage crop

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.2003.65.2508 ◽

2003 ◽

pp. 133-137

Author(s):

A.A. Judge ◽

R.N. Jensen ◽

M.S. Sprosen ◽

S.F. Ledgard ◽

E.R. Thom ◽

...

Keyword(s):

Dry Matter ◽

Lolium Multiflorum ◽

Nitrogen Leaching ◽

Italian Ryegrass ◽

Yield Response ◽

N Leaching ◽

Silt Loam ◽

Significant Treatment ◽

Leaching Losses ◽

Yield Responses

Dry matter (DM) yield responses and field nitrogen (N) leaching losses were assessed following the application of 4 rates of N fertiliser to an Italian ryegrass (Lolium multiflorum) crop grown after maize. The trial was conducted on a free-draining Horotiu silt loam (typic orthic allophanic soil) at Dexcel's Scott Farm near Hamilton, New Zealand. The grass was direct dr illed into maize stubble on 13 April 2002. Small plots received a total of 0, 40, 100 or 160 kg N/ha as urea, split into 4 equal applications from May to July. Total DM production over 24 weeks for the 0, 40, 100 or 160 kg N/ha treatments was 2730, 3487, 4238 and 4840 kg DM/ha, respectively. Additional kg DM produced/kg N applied was 19, 15 and 13, respectively. The 'apparent' proportion of applied N removed in the herbage from all plots was 55- 60%. Herbage nitrate-N concentrations exceeded the commonly accepted critical level of 0.21% on the 160 kg N/ha treatment at the first harvest on 3 July 2002, when only half of each N rate had been applied. There were no significant treatment differences in leaching losses (range 17-34 kg N/ha). Italian ryegrass grown on a silt loam soil after maize showed an almost linear yield response to N fertiliser over the range 40-160 kg N/ha, without increased inorganic N leaching. Further work is necessary to confirm these results and to establish whether or not higher rates of N fertiliser can be used to increase winter dry matter yields from Italian ryegrass, without increasing N leaching losses. Keywords: annual ryegrass, dairy systems, double cropping, nitrogen leaching

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Nitrogen leaching losses from fodder beet and kale crops grazed by dairy cows in southern SouthlandNitrogen leaching losses from fodder beet and kale crops grazed by dairy cows in southern Southland

Journal of New Zealand Grasslands ◽

10.33584/jnzg.2020.82.444 ◽

2020 ◽

Vol 82 ◽

pp. 61-71

Author(s):

L. Chris Smith ◽

Ross M. Monaghan

Keyword(s):

Dairy Cows ◽

Nitrogen Leaching ◽

N Leaching ◽

First Year ◽

Leaching Losses ◽

Fodder Beet ◽

Previous Season ◽

Crop Type ◽

Dairy Animals ◽

Urinary Nitrogen

Fodder beet has become increasingly common as both a winter forage and as a supplement at the shoulders of the dairy season in southern New Zealand. One advantage over the more traditional kale crop option is that fodder beet results in less urinary nitrogen (N) excretion in dairy animals, potentially reducing N leaching. Two trials were undertaken to measure nitrogen leaching losses under both autumn-grazed or autumn-lifted fodder beet crops. Leaching losses were also measured from winter-grazed fodder beet and winter-grazed kale treatments. Results from Trial 1 show that leaching losses from autumn-lifted or autumn-grazed fodder beet treatments were large (108–131 kg N ha-1) relative to losses measured in the winter-grazed fodder beet treatment (82 kg N ha-1). This indicates that autumn-grazed fodder beet crops have a greater potential for N leaching than winter-grazed fodder beet. The practice of lifting and removing fodder beet during autumn appeared to reduce N leaching somewhat, but losses were still relatively large, perhaps due to carryover of N from the previous season as a result of the dry summer conditions that preceded the drainage season in in the first year of Trial 1. The amount of N leached from the winter-grazed fodder beet treatment from Trial 1 at 82 kg N ha-1 was 50% less than the 176 kg N ha-1 observed for the kale crop. Results from Trial 2 using larger plots showed a similar trend, with winter-grazed fodder beet leaching 42% less N than winter-grazed kale (41 vs 70 kg N ha-1; P<0.001), despite not all the urine N being collected by the end of the drainage season. These losses are relatively large compared to the annual N leaching losses measured from pasture paddocks on the same farm, which ranged from 13–23 kg N ha-1. Considerations of grazing and/or harvest timing (autumn vs winter) as well as crop type appear to be important factors that determine N leaching losses from Southland dairy systems.

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Reducing nitrate leaching losses from a Taupo pumice soil using a nitrification inhibitor eco-n

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.2007.69.2694 ◽

2007 ◽

pp. 131-135 ◽

Cited By ~ 4

Author(s):

K.C. Cameron ◽

H.J. Di ◽

J.L. Moir ◽

A.H.C. Roberts

Keyword(s):

Water Quality ◽

Nitrate Leaching ◽

Nitrification Inhibitor ◽

N Leaching ◽

N Transfer ◽

Management Options ◽

N Losses ◽

Leaching Losses ◽

Significant Contributor ◽

Annual Loss

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

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Administration of dicyandiamide to dairy cows via drinking water reduces nitrogen losses from grazed pastures

The Journal of Agricultural Science ◽

10.1017/s0021859613000634 ◽

2013 ◽

Vol 152 (S1) ◽

pp. 150-158 ◽

Cited By ~ 9

Author(s):

B. G. WELTEN ◽

S. F. LEDGARD ◽

J. LUO

Keyword(s):

Dairy Cows ◽

Soil Depth ◽

Nitrification Inhibitor ◽

Environmental Benefits ◽

Control Treatment ◽

N Leaching ◽

Gaseous Emissions ◽

N Losses ◽

Total N ◽

Leaching Losses

SUMMARYOral administration of the nitrification inhibitor dicyandiamide (DCD) to ruminants for excretion in urine represents a targeted mitigation strategy to reduce nitrogen (N) losses from grazed pasture. A farmlet grazing study was undertaken to examine the environmental benefits of administering DCD in trough water to non-lactating Friesian dairy cows that consecutively grazed 12 replicated plots (each 627 m2with a grazing intensity of up to 319 cows/ha/day) during two grazing rotations in the winter of 2007 in the Waikato region, New Zealand. Nitrate-N (NO3−-N) leaching losses were measured using ceramic cup samplers (600 mm soil depth) and gaseous emissions of nitrous oxide (N2O) were quantified using a static chamber technique in the DCD and control treatments. Administration of DCD in trough water had no effect on daily water intake by dairy cows, which averaged 15 and 18 l/cow/day for the June and August grazing rotations, respectively. This resulted in a mean daily DCD intake of 46 and 110 g/cow/day, respectively. The DCD farmlet had significantly lower NO3−-N concentrations in leachate at the last three samplings, which reduced total NO3−-N leaching losses by 40% (from 32·0 to 19·2 kg N/ha). The DCD treatment reduced N2O emission rates compared to the control treatment following the August grazing, resulting in a 45% reduction in total N2O emissions relative to the control treatment (from 0·49 to 0·27 kg N2O-N/ha). This preliminary study highlights the potential for administering ruminants with DCD as an effective mitigation option for reducing N losses from agricultural systems.

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The implications of lag times between nitrate leaching losses and riverine loads for water quality policy

Scientific Reports ◽

10.1038/s41598-021-95302-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

R. W. McDowell ◽

Z. P. Simpson ◽

A. G. Ausseil ◽

Z. Etheridge ◽

R. Law

Keyword(s):

Water Quality ◽

Mean Transit Time ◽

Lag Time ◽

Practice Change ◽

N Leaching ◽

N Losses ◽

Leaching Losses ◽

Nitrate N ◽

The Mean ◽

Lag Times

AbstractUnderstanding the lag time between land management and impacts on riverine nitrate–nitrogen (N) loads is critical to understand when action to mitigate nitrate–N leaching losses from the soil profile may start improving water quality. These lags occur due to leaching of nitrate–N through the subsurface (soil and groundwater). Actions to mitigate nitrate–N losses have been mandated in New Zealand policy to start showing improvements in water quality within five years. We estimated annual rates of nitrate–N leaching and annual nitrate–N loads for 77 river catchments from 1990 to 2018. Lag times between these losses and riverine loads were determined for 34 catchments but could not be determined in other catchments because they exhibited little change in nitrate–N leaching losses or loads. Lag times varied from 1 to 12 years according to factors like catchment size (Strahler stream order and altitude) and slope. For eight catchments where additional isotope and modelling data were available, the mean transit time for surface water at baseflow to pass through the catchment was on average 2.1 years less than, and never greater than, the mean lag time for nitrate–N, inferring our lag time estimates were robust. The median lag time for nitrate–N across the 34 catchments was 4.5 years, meaning that nearly half of these catchments wouldn’t exhibit decreases in nitrate–N because of practice change within the five years outlined in policy.

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