scholarly journals Field-scale monitoring of nitrate leaching in agriculture: assessment of three methods

2021 ◽  
Vol 194 (1) ◽  
Author(s):  
Hannah Wey ◽  
Daniel Hunkeler ◽  
Wolf-Anno Bischoff ◽  
Else K. Bünemann

AbstractDeterioration of groundwater quality due to nitrate loss from intensive agricultural systems can only be mitigated if methods for in-situ monitoring of nitrate leaching under active farmers’ fields are available. In this study, three methods were used in parallel to evaluate their spatial and temporal differences, namely ion-exchange resin-based Self-Integrating Accumulators (SIA), soil coring for extraction of mineral N (Nmin) from 0 to 90 cm in Mid-October (pre-winter) and Mid-February (post-winter), and Suction Cups (SCs) complemented by a HYDRUS 1D model. The monitoring, conducted from 2017 to 2020 in the Gäu Valley in the Swiss Central Plateau, covered four agricultural fields. The crop rotations included grass-clover leys, canola, silage maize and winter cereals. The monthly resolution of SC samples allowed identifying a seasonal pattern, with a nitrate concentration build-up during autumn and peaks in winter, caused by elevated water percolation to deeper soil layers in this period. Using simulated water percolation values, SC concentrations were converted into fluxes. SCs sampled 30% less N-losses on average compared to SIA, which collect also the wide macropore and preferential flows. The difference between Nmin content in autumn and spring was greater than nitrate leaching measured with either SIA or SCs. This observation indicates that autumn Nmin was depleted not only by leaching but also by plant and microbial N uptake and gaseous losses. The positive correlation between autumn Nmin content and leaching fluxes determined by either SCs or SIA suggests autumn Nmin as a useful relative but not absolute indicator for nitrate leaching. In conclusion, all three monitoring techniques are suited to indicate N leaching but represent different transport and cycling processes and vary in spatio-temporal resolution. The choice of monitoring method mainly depends (1) on the project’s goals and financial budget and (2) on the soil conditions. Long-term data, and especially the combination of methods, increase process understanding and generate knowledge beyond a pure methodological comparison.

2002 ◽  
Vol 12 (2) ◽  
pp. 250-256 ◽  
Author(s):  
Hudson Minshew ◽  
John Selker ◽  
Delbert Hemphill ◽  
Richard P. Dick

Predicting leaching of residual soil nitrate-nitrogen (NO3-N) in wet climates is important for reducing risks of groundwater contamination and conserving soil N. The goal of this research was to determine the potential to use easily measurable or readily available soilclimatic-plant data that could be put into simple computer models and used to predict NO3 leaching under various management systems. Two computer programs were compared for their potential to predict monthly NO3-N leaching losses in western Oregon vegetable systems with or without cover crops. The models were a statistical multiple linear regression (MLR) model and the commercially available Nitrate Leaching and Economical Analysis Package model (NLEAP 1.13). The best MLR model found using stepwise regression to predict annual leachate NO3-N had four independent variables (log transformed fall soil NO3-N, leachate volume, summer crop N uptake, and N fertilizer rate) (P < 0.001, R2 = 0.57). Comparisons were made between NLEAP and field data for mass of NO3-N leached between the months of September and May from 1992 to 1997. Predictions with NLEAP showed greater correlation to observed data during high-rainfall years compared to dry or averagerainfall years. The model was found to be sensitive to yield estimates, but vegetation management choices were limiting for vegetable crops and for systems that included a cover crop.


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.


2007 ◽  
Vol 146 (1) ◽  
pp. 77-84 ◽  
Author(s):  
K. SIELING ◽  
H. KAGE

SUMMARYIn northwest (NW) Europe, oilseed rape (OSR) is often used as a preceding crop for winter wheat. Due to its low N harvest index (HI) and to favourable soil conditions after harvest, large amounts of mineral N remain in the soil, which cannot completely be taken up by the subsequent wheat crop. This increases the risk of N leaching into the groundwater during the following winter. Recently, semi-dwarf genotypes of OSR were developed and made commercially available that show similar yields but reduced height growth compared to conventional genotypes. The present authors hypothesized that the introduction of dwarfing genes leads to an increase in HI for dry matter (DM) and for N of OSR. As a consequence, semi-dwarf genotypes would accumulate less aerial biomass, return fewer plant residues to the soil and need less N to achieve yield maximum compared to conventional hybrids or open pollinating varieties. This may lead to a reduced risk of N leaching after growing OSR. In order to test this hypothesis, field trials conducted in 2003/04–2005/06 near Kiel in NW Germany combined four commercial varieties of OSR (Express, Talent, Trabant and Belcanto as semi-dwarf genotype), two seeding dates (mid-August and beginning of September) and eight mineral N fertilization rates (0–240 kg N/ha). On average in 2003/04–2004/05, the semi-dwarf genotype Belcanto achieved significantly less seed yield (4·44 t/ha) than the other varieties (4·65–4·88 t/ha). However, all varieties tested required similar N fertilization to achieve maximum yield. In addition, N offtake by the seeds did not differ. No interaction between genotype and N treatment was observed. Detailed analysis of DM accumulation and N uptake during the growth period revealed only small differences between the varieties in the averages of all N treatments and both years. At harvest, Belcanto produced more pods/m2 and a slightly higher 1000 seed weight. Nevertheless, HI and N HI were similar for all genotypes. It is concluded that, despite its lower plant height, the semi-dwarf genotype did not provide the opportunity to reduce the risk of N leaching after growing OSR.


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


1997 ◽  
Vol 128 (1) ◽  
pp. 79-86 ◽  
Author(s):  
K. SIELING ◽  
O. GÜNTHER-BORSTEL ◽  
H. HANUS

Nitrogen (N) fertilizer not used by the crop can increase the risk of nitrate leaching into the groundwater. In two growing seasons, 1990/91 and 1991/92, the relationships between N fertilization and yield, N uptake by the grain and the N leaching in the subsequent percolation period were investigated in a multifactorial field experiment at Hohenschulen Experimental Station near Kiel in NW Germany. The crop rotation was oilseed rape – winter wheat – winter barley, and effects of soil tillage (minimum tillage without ploughing, conventional tillage), application of pig slurry (none, application in autumn, application in autumn and in spring), mineral N fertilization (none, 80 or 200 kg N ha−1 to oilseed rape and 120 or 240 kg N ha−1 to cereals) and application of fungicides (none, intensive) were all tested. In each year, the rotation and the treatments were located on the same plots. Mineral N fertilization and fungicide application increased yield and N uptake by grain or seed in all crops. In contrast, the application of slurry, especially in autumn, had only small effects on yield and N uptake. Nitrogen losses by leaching (measured using porous ceramic cups) were affected mainly by the year and the crop. In 1992/93, averaged over all factors, 80 kg N ha−1 was leached compared with 28 kg N ha−1 the previous year. Oilseed rape reduced N losses, whereas under winter wheat up to 160 kg N ha−1 was leached. Due to a lower N-use efficiency, autumn applications of slurry increased N leaching, and mineral N fertilization of the preceding crop also led to higher N losses.Since the amount of leached N depends both on the nitrogen left by the preceding crop (unused fertilizer N as well as N in residues) and on N uptake by the subsequent crop, it is not possible to apportion the N losses to any particular crop in the rotation. The cropping sequence, together with its previous and subsequent crops, must also be considered.To minimize leaching, N fertilization must meet the needs of the growing crop. In order to improve the efficiency further, investigations must be conducted in order to understand the dynamics of N in the plant–soil system in conjunction with the weather and crop management practices.


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.


Author(s):  
M. Shepherd ◽  
A. Stafford ◽  
D. Smeaton

Grazing of brassica winter forage crops returns large amounts of excreted nitrogen (N) back to the paddock during winter when risk of leaching is high. This experiment measured nitrate-N leaching below 60 cm of 132 and 173 kg N/ha following June grazing by dairy cows of swede/kale crops in 2008 and 2009. Application of DCD immediately after grazing plus 6 weeks later decreased leaching by 20-27% (significant at P


HortScience ◽  
2004 ◽  
Vol 39 (2) ◽  
pp. 267-271 ◽  
Author(s):  
J.P. Syvertsen ◽  
J.M. Dunlop

We tested the hypothesis that amendments of two hydrophilic gels to a sand soil would reduce N leaching losses and increase growth of citrus seedlings. Three-month-old seedlings of `Swingle' citrumelo [Citrus paradisi Macf. × Poncirus trifoliata (L.) Raf.] were transplanted into containers of steam-sterilized Candler sand, amended with a linear acrylamide/acrylate copolymer (PAM), and/or a cross-linked copolymer agronomic gel (AGRO). Two rates of each amendment were applied either alone or together and were either mixed into dry sand prior to seedling transplant, used as a root-dip slurry at transplant or applied to the soil surface in a solution after transplant. Seedlings were grown in the greenhouse for 5 months and irrigated to container capacity with a dilute nutrient solution without leaching. Pots were leached every 2 weeks and total N losses from the soil were measured in the leachate. PAM amendments increased N retention in soil slightly but PAM had no effect on plant growth, water use, N uptake, or N leaching relative to unamended control plants. The AGRO amendments increased seedling growth, plant water use and uptake of N from 11% to 45% above that of the unamended control plants depending on application method. AGRO decreased N concentrations in the leachate to as low as 1 to 6 mg·L-1. Only 6% of the total applied N was leached from the AGRO treatments, which was about half that from the untreated control plants. There was no additional benefit of using both amendments together or of an additional AGRO root dip treatment. The largest plants used the most water, required the most N and had the greatest N uptake efficiency. AGRO amendments clearly enhanced seedling growth, increased their N uptake efficiency, and reduced N losses from this sand soil.


1993 ◽  
Vol 73 (4) ◽  
pp. 387-397 ◽  
Author(s):  
C. A. Campbell ◽  
R. P. Zentner ◽  
F. Selles ◽  
O. O. Akinremi

The possibility of nitrates being leached into groundwater supplies from improper use of fertilizers is a concern to society. Two experiments were conducted on a loam soil in the Brown soil zone at Swift Current, Saskatchewan. In the first experiment, continuous wheat (Triticum aestivum L.), grown under various fertilizer-N management systems and with and without cereal trap strips (tall stubble, 0.4–0.6 m) to capture snow and enhance soil-moisture storage, was compared with short stubble cut at the standard height (0.15–0.2 m). Prior to seeding in spring 1991, tall stubble had stored 14.7 ha-cm of soil moisture at 0–1.2-m depth compared with 10.9 ha-cm under short-stubble treatment. Because growing-season precipitation in 1991 was much higher than normal (302 mm from 1 May to 31 My), considerable NO3-N was leached below the rooting zone of wheat (1.2 m), particularly in the tall-stubble treatment. Leaching patterns were as expected in short stubble, with major leaching occurring only at the highest N rate (125 kg ha−1), where yield and N-uptake response had levelled off. However, in tall stubble, the amount of NO3-N leached beyond the root zone under the 0 and 25 kg N ha−1 rates was similar to that under the 125 kg N ha−1 rate. This result was attributed to poor tillering obtained at low N rates, which contributed to lower evapotranspiration, thereby permitting more moisture to be leached and enhancing N mineralization. When we used a leaching model (NLEAP) to simulate our results, it gave lower estimates of NO3 leached and did not reveal the interaction of NO3-N leaching with N rates that was observed under tall stubble. The second experiment measured soil NO3-N distribution to 2.4 m under two fallow–wheat–wheat systems after a 24-yr period. One system received only N, the other, N + P fertilizer. The results corroborated those obtained under tall stubble in the first experiment: the poorly fertilized system had the most NO3-N below the root zone. The results of this study suggest that the key to reducing nitrate leaching is the adoption of proper fertilization practices, since too little fertilization may potentially be as detrimental to groundwater pollution as too much. Key words: Fertilizer N, N uptake, snow management, crop rotations, NO3 leaching


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
N. Villar ◽  
M. Aranguren ◽  
A. Castellón ◽  
G. Besga ◽  
A. Aizpurua

Abstract Nitrogen budgets help explain the supply pattern of N from the soil to the crop. Through budgeting, an improvement of the N fertilization strategy can be achieved. The objective of the present study, which was carried out under humid Mediterranean climate conditions, was to assess the influence of N fertilization, temperature and soil humidity on soil N dynamics during a whole oilseed rape growing cycle. A field experiment was conducted with two treatments: without N (0 N) and with application of 180 kg N ha−1(180 N). Mineralization was calculated from N balances made throughout the growing cycle, all while taking into account measured N uptake by oilseed rape and N losses by leaching and N2O emissions. Nitrogen net mineralization was negative after fertilization, reaching –6.73 kg N ha−1, day−1, but total net mineralization over the year was similar for the 0 N and 180 N treatments (21 and 8 kg N ha−1, respectively). Temperatures over 5 °C were sufficient for initiating the mineralization processes. In the summer, when the soil water content was below the wilting point, immobilization took place; however, there is a risk of N leaching if rainfall occurs thereafter, mainly in the 180 N treatment.


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