Leaching of nitrate and phosphorus after autumn and spring application of separated solid animal manures to winter wheat

Animal slurry can be separated into solid and liquid manure fractions to facilitate the transport of nutrients from livestock farms. In Denmark, untreated slurry is normally applied in spring whereas the solid fraction may be applied in autumn, causing increased risk of nitrate and phosphorus (P) leaching. We studied the leaching of nitrate and P in lysimeters with winter wheat crops (Triticum aestivum L.) after autumn incorporation versus spring surface application of solid manure fractions, and we compared also spring applications of mineral N fertilizer and pig slurry. Leaching was compared on a loamy sand and a sandy loam soil. The leaching experiment lasted for 2 yr, and the whole experiment was replicated twice. Nitrate leaching was generally low (19–34 kg N/ha) after spring applications of mineral fertilizer and manures. Nitrate leaching increased significantly after autumn application of the solid manures, and the extra nitrate leached was equivalent to 23–35% of total manure N and corresponded to the ammonium content of the manures. After spring application of solid manures and pig slurry, only a slight rise in N leaching was observed during the following autumn/winter (<5% of total manure N). Total P leaching was 40–165 g P/ha/yr, and the application of solid manure in autumn did not increase P leaching. The nitrogen fertilizer replacement value of solid manure N was similar after autumn and spring application (17–32% of total N). We conclude that from an environmental perspective, solid manure fractions should not be applied to winter wheat on sandy and sandy loam soils under humid North European conditions.     

Nitrate leaching following autumn and winter application of animal manures to grassland

Abstract. Under a UK Government consultation procedure announced in 2001, it was proposed that measures agreed within already designated Nitrate Vulnerable Zones (NVZ 's) would be extended to include a considerably increased area of England, Wales and Scotland. Since existing NVZ 's in the UK have included relatively little grassland, it is important to examine how nitrate losses from grassland areas, especially from animal manures, one of the major potential sources of nitrate loss, can be minimized. Experiments were carried out on freely draining grassland soils at four sites (Devon, Hampshire, Shropshire and N Yorkshire) representative of a wide range of climatic and farming conditions across lowland England, over a four year period, 1990/91 to 1993/94. Slurry was applied to experimental plots over a range of times (including June and then monthly, from September to January) at a target rate of 200 kg N ha^–1. Nitrogen leaching over the four years ranged from 0 to >50% of applied slurry N, with the largest losses occurring following applications in the September to November period. The use of a nitrification inhibitor with slurry applied in November failed to provide consistent reduction in nitrate leaching.
A strategy to reduce the risk of N leaching from manures applied to freely draining grassland soils must take account of the characteristics of the manure, in particular its N content, the application rate and the amount of excess rainfall following application. The experimental results suggest that slurry applications to freely draining grassland, in September, October and November should generally be avoided, the rationale for this being dependent on the amount of excess rainfall subsequent to application. Farmyard manure represents a lower risk and does not justify the restrictions on application timing that appear to be necessary with slurry.     

Nitrate leaching from organic arable crop rotations: effects of location, manure and catch crop

Abstract. Nitrate leaching from crop rotations supporting organic grain production was investigated from 1997 to 2000 in a field experiment at three locations in Denmark on different soil types. Three experimental factors were included in the experiment in a factorial design: (1) proportion of N₂-fixing crops in the rotation (crop rotation), (2) catch crop (with and without), and (3) manure (with and without). Three, four-course rotations were compared, two at each location. The nitrate leaching was measured using ceramic suction cells. Leaching losses from the crop rotation with grass–clover green manure and without catch crops were 104, 54 and 35 kg N ha⁻¹ yr⁻¹ on the coarse sand, the loamy sand, and the sandy loam, respectively. There was no effect of manure application or time of ploughing-in the grass–clover green manure crop on the accumulated nitrate leaching from the entire rotation. Catch crops reduced nitrate leaching significantly, by 30–38%, on the sandy soils. At all locations catch crops reduced the annual averaged nitrate concentration to meet drinking water quality standards in the crop rotation with green manure. On the coarse sand there was a time lag between the onset of drainage and the start of N-uptake by the catch crop.     

Nitrate leaching loss following application of organic manures to sandy soils in arable cropping.

Abstract. Experiments were set up at two sites to measure nitrogen (N) leaching loss from applications of separated pig/cattle slurry and cattle farmyard manure(FYM), during winters 1990/91–1993/94 (site A) and from broiler litter and FYM, during winters 1990/91–1992/93 (site B). The manures were applied at a target rate of 200 kg ha^-1 total N during the autumn and winter to overwinter fallow or top dressed onto winter rye. The total N in leachate was calculated from leachate N concentrations, in samples collected using ceramic cups buried at 90 cm, and an estimate of drainage volume. Nitrogen losses were greatest following manure applications in September, October and November but losses following applications in December or January were not significantly elevated above those from untreated controls. Losses were consistently lower from FYM than from broiler litter or separated slurry. The presence of a cover crop (winter rye) significantly reduced overall N leaching compared with the fallow, but only reduced the manure N leaching losses at one site during one winter when a high proportion of drainage occurred late. The incorporation of a nitrification inhibitor (DCD) with manures applied in October did not significantly reduce the manure N leaching.     

The effect of crop, N-level, soil type and drainage on nitrate leaching from Danish soil

Abstract. Nitrate leaching measurements in Denmark were analysed to examine the effects of husbandry factors. The data comprised weekly measurements of drainage and nitrate concentration from pipe drains in six fields from 1971 to 1991, and weekly measurements of nitrate concentration in soil water, extracted by suction cups at a depth of 1 m, from 16 fields in 1988 to 1993. The soils varied from coarse sand to sandy clay loam.
The model used for analysing the data was: Y = exp (1.136–0.0628 clay + 0.00565N + crop ) D^0.416, with R²= 0.54, where Y is the nitrate leaching (kg N/ha per y), clay is the % clay in 0-25 cm depth (%), N is the average N-application in the rotation (kg/ha/y) and D is drainage (mm/y). The most important factor influencing leaching was the crop type. Grass and barley undersown with grass showed low rates of leaching (17-24 kg/ha/y). Winter cereal following a grass crop, beets, winter cereals following cereals and an autumn sown catch crop following cereals showed medium rates of leaching (36-46 kg/ha/y). High rates of leaching were estimated from winter cereals following rape/peas, bare soil following cereals and from autumn applications of animal manure on bare soil (71-78 kg/ha/y). Estimates of leaching from soil of 5, 12 and 20% clay were 68, 44 and 26 kg/ha/y, respectively. Leaching was estimated to rise significantly with increasing amounts of applied N.
The model is suitable for general calculations of the effects of crop rotation, soil type and N-application on nitrate leaching from sandy soil to sandy clay loarns in a temperate coastal climate.     

Empirical analysis and prediction of nitrate loading and crop yield for corn-soybean rotations

Nitrate nitrogen losses through subsurface drainage and crop yield are determined by multiple climatic and management variables. The combined and interactive effects of these variables, however, are poorly understood. Our objective is to predict crop yield, nitrate concentration, drainage volume, and nitrate loss in subsurface drainage from a corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) rotation as a function of rainfall amount, soybean yield for the year before the corn-soybean sequence being evaluated, N source, N rate, and timing of N application in northeastern Iowa, U.S.A. Ten years of data (1994-2003) from a long-term study near Nashua, Iowa were used to develop multivariate polynomial regression equations describing these variables. The regression equations described over 87, 85, 94, 76, and 95% of variation in soybean yield, corn yield, subsurface drainage, nitrate concentration, and nitrate loss in subsurface drainage, respectively. A two-year rotation under average soil, average climatic conditions, and 125 kg N/ha application was predicted to loose 29, 37, 36, and 30 kg N/ha in subsurface drainage for early-spring swine manure, fall-applied swine manure, early-spring UAN fertilizer, and late-spring split UAN fertilizer (urea ammonium nitrate), respectively. Predicted corn yields were 10.0 and 9.7 Mg/ha for the swine manure and UAN sources applied at 125 kg N/ha. Timing of application (i.e., fall or spring) did not significantly affect corn yield. These results confirm other research suggesting that manure application can result in less nitrate leaching than UAN (e.g., 29 vs. 36 kg N/ha), and that spring application reduces nitrate leaching compared to fall application (e.g., 29 vs. 37 kg N/ha). The regression equations improve our understanding of nitrate leaching; offer a simple method to quantify potential N losses from Midwestern corn-soybean rotations under the climate, soil, and management conditions of the Nashua field experiment; and are a step toward development of easy to use N management tools.     

Nitrate leaching in an organic dairy/crop rotationas affected by organic manure type, livestock densityand crop

Abstract. In dairy farming systems the risk of nitrate leaching is increased by mixed rotations (pasture/arable) and the use of organic manure. We investigated the effect of four organic farming systems with different livestock densities and different types of organic manure on crop yields, nitrate leaching and N balance in an organic dairy/crop rotation (barley–grass-clover–grass-clover–barley/pea–winter wheat–fodder beet) from 1994 to 1998. Nitrate concentrations in soil water extracted by ceramic suction cups ranged from below 1 mg NO₃-N l^?1 in 1^st year grass-clover to 20–50 mg NO₃-N l^?1 in the winter following barley/pea and winter wheat. Peaks of high nitrate concentrations were observed in 2^nd year grass-clover, probably due to urination by grazing cattle. Nitrate leaching was affected by climatic conditions (drainage volume), livestock density and time since ploughing in of grass-clover. No difference in nitrate leaching was observed between the use of slurry alone and farmyard manure from deep litter housing in combination with slurry. Increasing the total-N input to the rotation by 40 kg N ha^?1 year^?1 (from 0.9 to 1.4 livestock units ha^?1) only increased leaching by 6 kg NO₃-N ha^?1. Nitrate leaching was highest in the second winter (after winter wheat) following ploughing in of the grass-clover (61 kg NO₃-N ha^?1). Leaching losses were lowest in 1^st year grass-clover (20 kg NO₃-N ha^?1). Averaged over the four years, nitrate concentration in drainage water was 57 mg l^?1. Minimizing leaching losses requires improved utilization of organic N accumulated in grazed grass-clover pastures. The N balance for the crop rotation as a whole indicated that accumulation of N in soil organic matter in the fields of these systems was small.     

An empirical model for estimating nitrate leaching as affected by crop type and the long-term N fertilizer rate

Abstract. An empirical model was developed for prediction of annual average nitrate leaching as affected by the long-term rate of N fertilization and crop type. The effect of N fertilization was estimated from annual values of nitrate leaching obtained from two Danish investigations of drainage from pipe drains with four rates of N fertilization on a loamy sand and sandy clay loam from 1973-89. The effect of crop at normal N fertilization was estimated from 147 observations of annual nitrate leaching obtained from field measurements. The nitrate leaching model consists of a relative N fertilization submodel and an absolute submodel for specific combinations of crop, soil and drainage at the normal rate of N fertilization. The relative submodel is Y/Y _lN= exp[0.7l(N/ N₁– I)], where Y is the nitrate leaching (kg N/ha per year) at fertilization rate N , and Y _IN and N₁ are the corresponding values at the normal rate of N fertilization. The relative submodel is valid for cereals, root crops and grass leys fertilized with mineral fertilizer at N/N ₁ < 1.5, and on the prerequisite that the fertilization rate N has been constant for some years. To illustrate the use of the relative leaching submodel, estimated values of Y _IN corrected to mean annual drainage for 1970 to 1990 in Denmark for spring cereals and grass on sandy and loamy soils are given as input to the relative leaching submodel. The model can be used for sandy to loamy soils to estimate the mean nitrate leaching over a number of years.     

Nitrate leaching from an organic dairy crop rotation: the effects of manure type, nitrogen input and improved crop rotation

Abstract. Four management systems combining high and low livestock densities (0.7 and 1.4 livestock units ha⁻¹) and different types of organic manure (slurry and straw based FYM) were applied to an organic dairy crop rotation (undersown barley – grass–clover – grass–clover – barley/pea – oats – fodder beet) between 1998 and 2001. The effects of the management systems on crop yields and nitrate leaching were measured. In all four years, nitrate leaching, as determined using ceramic suction cups, was higher in the three crops following ploughing of grass–clover than under the barley or grass–clover. Overall, no significant differences in nitrate leaching were observed between the management systems. However, the replacement of the winter wheat crop used in the earlier experimental period (1994–97) by spring oats with catch crops in both the preceding and succeeding winters reduced nitrate leaching compared with the earlier rotation. Increasing the livestock density, which increased manure application by c. 60 kg total N ha⁻¹, increased crop yields by 7 and 9% on average for FYM and slurry, respectively. Yields were 3–5% lower where FYM was used instead of slurry. The experiment confirmed the overriding importance of grassland N management, particularly the cultivation of the ley, in organic dairy crop rotations.     

Precipitation but not soil texture alters effectiveness of dicyandiamide to decrease nitrate leaching from dairy cow urine

This experiment compared the effectiveness of the nitrification inhibitor dicyandiamide (DCD) in decreasing NO₃‐N leaching from dairy cow urine (1000 kg N/ha equivalent). DCD was applied to perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) on three soil types (silt loam, sandy loam and clay) and under two precipitation regimes using intact soil monolith zero tension lysimeters (50 cm diameter by 65 cm deep). Over the two experiment years, annual precipitation (rainfall plus supplemented irrigation) covered the range 1103 to 2351 mm. Soil type affected the forms of N that leached after urine application. Most urea was lost from the clay soil in the first drainage collections after application. Ammonium‐N leached from the sandy soil. Apart from one soil type (sandy loam) giving a nil response to DCD in 1 yr, there was no strong evidence that soil type changed DCD effectiveness (the amount of NO₃‐N retained, expressed as a percentage of the NO₃‐N leached from untreated urine). Where DCD decreased leaching, effectiveness ranged between 6 and 57% with a mean value of 34 ± 5%. Drainage depth explained 50% of the variation in DCD effectiveness (P < 0.05) and indicated a 7% decrease per 100 mm extra drainage. Extra pasture growth and N uptake were strongly related to the amount of N saved by DCD application. We conclude that there may be scope to use rainfall/drainage as an estimate of likely DCD effectiveness at a site, but further work is required to test this across a wider range of circumstances.     

Modeling of Nitrate Leaching from a Potato Field using HYDRUS-2D

Excessive use of nitrogen (N) fertilizers is likely to be responsible for the increasing nitrate in groundwater. Thus, appropriate water and nutrient management is required to minimize groundwater pollution and to maximize the nutrient-use efficiency. In this study HYDRUS-2D software package was applied to simulate nitrate leaching from a drip-irrigated sandy agricultural soil for varying emitter discharges and various amounts of fertilizer. It was found that for small emitter discharge values free drainage increased significantly with increase in discharge, whereas the increase was leveled out at greater discharge values. Nitrate leaching increased with an increase in emitter discharge and amount of fertilizer, but the rate of increase was most significant for low emitter discharges. Based on the results, with regard to the selection of emitter discharge and the amount of appropriate fertilizer amount, nitrate leaching from a potato field can be minimized even in a sandy soil.     

Nitrate leaching from grazed grassland lysimeters: effects of fertilizer input, field drainage, age of sward and patterns of weather

Drained and undrained grassland lysimeter plots were established in 1982 on a clay loam of the Hallsworth series at a long-term experimental site in south-west England. The plots were continuously grazed by beef cattle, and received fertilizer at either 200 or 400 kg N ha^-1 per annum to the existing permanent sward, or at 400 kg N ha^-1 to a new sward, reseeded to perennial ryegrass following cultivation. Drainage water was monitored at V-notch weirs and sampled daily for the analysis of nitrate-N. Seven years of data are presented (five years for the reseeded swards). On the drained plots a large proportion of the rainfall was routed preferentially down large pores to the mole drains, whilst on the undrained plots, drainage was mainly by surface runoff. The average quantities of nitrate N leached per year were 38.5, 133.8 and 55.7 kg ha^-1 from the old sward that received 200 and 400 kg N ha^-1, and from the reseed that received 400 kg N ha^-1 fertilizer, respectively. Ploughing and reseeding resulted in a two-fold reduction in leaching, except during the first winter after ploughing, and twice as much leaching occurred after a hot, dry summer as after a cool, wet one. Nitrate concentrations in drainage from either drained or undrained plots were rather insensitive to rainfall intensity, such that concentration was a good predictor of nitrate load for a given drainage volume. The drainage volume determined the proportion of the leachable N that remained in the soil after the winter drainage period. Initial (peak) concentrations of nitrate N ranged, on average, from 55 mg dm^-3 for the drained old sward that received 400 kg N ha^-1 fertilizer, to 12 mg dm^-3 for the undrained sward at 200 kg N ha^-1 fertilizer input. Concentrations of nitrate N in drainage from similar, unfertilized plots rarely exceeded 1 mg dm^-3. The results suggest that manipulating the nitrate supply can lessen leaching and that the route of water through soil to the watercourse determines the maximum nitrate concentration for a given load.     

Effects of cropping system and rates of nitrogen in animal slurry and mineral fertilizer on nitrate leaching from a sandy loam

Abstract. Leaching of nitrate from a sandy loam cropped with spring barley, winter wheat and grass was compared in a 4-year lysimeter study. Crops were grown continuously or in a sequence including sugarbeet. Lysimeters were unfertilized or supplied with equivalent amounts of inorganic nitrogen in calcium ammonium nitrate (CAN) or animal slurry according to recommended rates (1N) or 50% above recommended rates (1.5N).
Compared with unfertilized crops, leaching of nitrate increased only slightly when 1N (CAN) was added. Successive annual additions of 1.5N (CAN) or 1N and 1.5N (animal slurry) caused the cumulative loss of nitrate to increase significantly. More nitrate was leached after application of slurry because organic nitrogen in the slurry-was mineralized.
With 1N (CAN) the leaching losses of nitrate were in the following order: continuous spring barley undersown with Italian ryegrass < continuous ley of perennial ryegrass < spring barley in rotation and undersown with grass < perennial ryegrass grown in rotation = winter wheat grown in rotation < sugarbeet in rotation < continuous winter wheat < continuous barley < bare fallow.
At recommended levels of CAN (1N), cumulative nitrate losses over the four years were similar for the crops when grown in rotation or continuously. When crops received 1.5N (CAN) or animal slurry, nitrate losses from the crops grown continuously exceeded those from crops in rotation. Including a catch crop in the continuous cropping system eliminated the differences in nitrate leaching between the two cropping systems.     

The impact of nitrogen deposition on upland surface waters in Great Britain: A regional assessment of nitrate leaching

A national dataset of water chemistry collected for critical loads mapping is used to make a regional assessment of surface water nitrate concentrations in Great Britain. The primary data are dominated by high concentrations in lowland regions Where N inputs are dominated by non-atmospheric sources. Land cover data are used to screen out sites with potential catchment sources of N, allowing the evaluation of nitrate leaching due to atmospheric deposition alone. In the screened dataset several upland regions show elevated nitrate concentrations, notably Wales, the Pennines, Cumbria, Galloway and the Cairngorms, and there is a clear relationship between surface water nitrate and total N deposition.     

Nitrogen Fertilizer Replacement Value of Concentrated Liquid Fraction of Separated Pig Slurry Applied to Grassland

Seven grassland experiments on sandy and clay soils were performed during a period of 4 years to estimate the nitrogen (N) fertilizer replacement value (NFRV) of concentrated liquid fractions of separated pig slurry (mineral concentrate: MC). The risk of nitrate leaching when applying MC was compared to when applying mineral fertilizers. Grassland yields in 2009–2012 fertilized with MC were compared with grassland fertilized with two mineral fertilizers: granulated calcium ammonium nitrate and liquid ammonium nitrate (LAN). The mineral fertilizers comprised 50% nitrate-N and 50% ammonium-N, and MC comprised 95–100% ammonium-N. Treatment application rates included zero N and three incremental rates of N fertilization. The liquid fertilizers were shallow injected (0–5 cm). The NFRV of MCs was 75% on sandy and 58% on clay soil with granulated ammonium nitrate as reference, and 89% on sandy and 92% on clay soil with LAN as reference. Risk of nitrate leaching after application of MC, measured in residual soil mineral N post-growing season and N in the upper groundwater in the following spring, was equal to that for mineral fertilizers.     

N-Wirkung von Rindergülle unter Zusatz von Dicyandiamid bzw. Stroh in Gefäß- und Lysimeterversuchen

Utilization of N in cattle slurry after addition of Dicyandiamide resp. straw in pot and lysimeter trials In a pot and lysimeter trial, leaching of nitrate of cattle slurry applied at different times (August, September, October, March) was tested with and without addition of DCD, and utilization of N by the following crop was determined. In a pot trial (sandy silt loam), the effect of additional straw manuring was also investigated. Pots were exposed to natural weather conditions from start of experiment (August) until sowing of rye grass (April). Application of straw as well as addition of DCD to slurry reduced leaching of N considerably. DCD addition with and without straw resulted in significantly higher N removals by rye grass. Unlike ammonium nitrogen “preserved” by DCD, slurry nitrogen biologically fixed by the rotting straw, however, was not yet available to the following rye grass crop (May to July). Slurry + straw + DCD generally led to higher amounts of residue N in the soil as a result of N balance. Also in the lysimeter trial, DCD reduced leaching of nitrate especially in vegetationless periods and thus improved the effect of cattle slurry applied in August resp. November (higher yields and N removals by silage maize).     

Nitrate leaching in field lysimeters at an agricultural site in Zimbabwe

Abstract. Nitrate leaching in lysimeters containing a tropical sandy agricultural soil was studied over two summers with maize ( Zea mays L.) and one winter season with wheat ( Triticum aestivum L.). The treatments included two moisture regimes and two nitrogen sources, cattle manure and inorganic fertilizer-N (either ammonium nitrate or ammonium sulphate) applied at 100 kg N/ha in the summers. Neither manure nor fertilizer-N was applied in the intervening winter. Leachate volume from the manured lysimeters was mostly larger than from fertilized ones because of poor growth and less evapotranspiration. The largest seasonal nitrate loads (17–39 kg N/ha) were obtained in the wet summer immediately after installation of the lysimeters. Nitrate loads in winter (3.7–18.6 kg N/ha) were larger than those obtained in fertilized (0.6 and 9.3 kg N/ha) and manured (0.3 and 3.0 kg N/ha) lysimeters for the two moisture regimes in the second summer. The drier conditions in the second summer decreased N-mineralization and leaching of manure.     

重庆市主要土壤类型硝态氮淋失及其影响因素

采用SRC(Soil-Resin-Core)装置,研究了重庆市主要土壤类型硝态氮淋失的差异以及硝态氮淋失与硝态氮含量、有效氮含量、降雨和气温等4个方面的关系。结果表明:酸性紫色土的硝态氮淋失量最大,而黄壤与碱性紫色土的硝态氮淋失量较小。酸性紫色土硝态氮含量、有效氮含量与硝态氮淋失量之间显著相关,而黄壤和碱性紫色土的硝态氮含量、有效氮含量与硝态氮淋失量之间没有显著的相关性。降雨量、气温也是引起硝态氮淋失的原因。农田施肥对地下水的污染受施肥量、施肥次数、降雨量和气温等综合作用的影响,可采取控制氮肥用量,减少施用人粪尿,避免在降雨量大的时期追肥的措施。     

Simulation of nitrogen dynamics in farmland areas of Denmark (1989–1993)

Abstract. Each year since 1986 information has been collected about the farming systems at intersections of a nationwide 7 km square grid in Denmark. These management data and corresponding soil analyses were used in the model DAISY to simulate water and nitrogen dynamics. The model was validated with respect to harvested dry matter yield and nitrogen content in the soil. Simulated nitrate leaching from farmland areas from 1 April 1989 to 31 March 1993 was related to precipitation zones, soil type, fertilizer strategies and cropping systems. The mean simulated nitrate leaching for the whole of Denmark was 74 kg N/ha/yr, with a large yearly variation in the period considered. The simulated nitrate leached from soils with a sandy subsoil corresponded to 51% of the applied fertilizer, twice that leached from soils with a loamy subsoil. The application of pig manure resulted in average leaching losses of 105 kg N/ha/yr. The simulated nitrate leaching losses at sites where only artificial fertilizer was applied were in the following order: cereal with undersown grass < crop followed by winter cereal or winter rape < cereal or rape without a catch crop < root crops without a catch crop. Where only artificial fertilizers were applied, the simulated mean annual leaching was 59 kg N/ha from spring barley and 40 kg N/ha from winter wheat. A map of simulated nitrate leaching in Denmark was produced using a Geographical Information System.     

Predicting nitrogen availability and losses following application of organic manures to arable land: MANNER

Abstract. A decision support system to predict the plant availability of nitrogen (N) following organic manure applications to land has been developed, drawing together the latest UK research information on factors affecting manure N availability and losses. The ADAS MAN ure N itrogen E valuation R outine (MANNER) accounts for manure N analysis, ammonia volatilization, nitrate leaching and mineralization of manure organic N. Only a few easily available inputs are required to predict the amount of N volatilized or leached, and the fertilizer N value for the next crop grown. Predictions from MANNER have been evaluated by comparison with independently collected data from a range of experimental studies where pig, cattle and poultry manures were applied to arable crops. Good agreement was found ( r ² 60–79%, P <0.001), confirming that MANNER can provide a reliable estimate of the fertilizer N value of farm manures spread to arable land under a range of conditions.