Long-term nitrogen supply from cattle slurry

Abstract. Manures can supply nitrogen (N) beyond the year of application, producing residual effects that are are not fully expressed in short-term experiments. From 1997 to 2003 we conducted a field experiment on a sandy soil in the Netherlands to quantify the residual N effect. Treatments comprised different time series of cattle slurry applied at rates ranging from 0 to 220 kg total-N ha⁻¹ yr⁻¹, while compensating for differences in available potassium and phosphorus. Dry matter and N yields of silage maize responded positively ( P <0.05) to both current cattle slurry applications and applications in previous years. N yields could be satisfactorily predicted with a simple N model by adopting an annual relative decomposition rate (RDR) of the organic N in cattle slurry of 25–33%. Subsequent model calculations indicated that the relative N fertilizer value (RNFV) of cattle slurry rises from approximately 55–60% when manure is first applied to approximately 80% after 6 and 8 years for RDRs of 33% and 25%, respectively. Given the long manuring history of most agricultural systems, rethinking the fertilizer value of manure seems justified.     

Nitrogen recovery by timothy from surface application of dairy cattle slurry

Abstract

Field experiments were conducted on a Buxton silt loam (fine, illitic, frigid Aquic Dystric Eutrochrepts) to determine the effect of surface application of dairy cattle slurry on nitrogen (N) recovery by timothy (Phleum pratense L.). Two experiments were conducted over two years. The experiments differed in the timing of both treatment application and forage harvest. This research indicated that the higher rates (supplying 186 and 267 kg N/ha) of slurry did not consistently increase total yearly yield or percent N recovery by timothy in Maine. The lighter rates (supplying 132 and 134 kg N/ha) had the advantage of less physical suppression of growth during the first cut following application and is, therefore, recommended. Spring application of slurry provided the greatest N recovery due to greater uptake by the cool‐season grass than later in the growing season in the spring and is, therefore, recommended over summer application. If spring application is not feasible, summer application of a moderate rate of slurry would allow more slurry disposal without a reduction of yield. Although N recovery from the slurry was relatively low, the potassium (K) concentrations in the forage indicate that the slurry supplied K to the crop at a relatively high level. The ability of the slurry to recycle K may be the major benefit to surface‐applied slurry in crop production.     

Losses of nitrogen by denitrification from a grassland soil fertilized with cattle slurry and calcium nitrate

Losses of N by denitrification from an imperfectly drained grassland soil were measured by the acetylene-inhibition technique over a 1-yr period, during which applications of up to 200 kg ha ^?1 of N as cattle slurry or calcium nitrate were made. The quantities of N lost from nitrate-treated soil were much greater than from slurry-treated areas, and ranged up to 21% of the N applied. The losses occurred predominantly over brief periods following fertilizer application in the spring. Ratios of N released as N₂ to that released as N₂O increased as denitrification rates increased. The highest ratio recorded, 24, may have been a conservative estimate because inhibition of N₂O reduction may not have been complete on all occasions. Increased respiration was observed in the soil profile as a result of adding C₂H₂. This effect should be taken into account in interpreting experiments using the C₂H₂-inhibition technique.     

Fate of Escherichia coli and Escherichia coli O157 in soils and drainage water following cattle slurry application at 3 sites in southern Scotland

Abstract. Slurry from farm animals may contaminate water supplies, rivers and bathing waters with faecal coliforms, such as Escherichia coli . Where animals harbour the O157 strain the hazard to human health is particularly high, but both the hazard level, and the low incidence and sporadic nature of the excretion of E. coli O157 make it difficult to study this strain under field conditions. The survival of total E. coli and of E. coli O157 were compared in the laboratory for two soils under controlled temperature and moisture. E. coli O157 die-off rate was the same as or quicker than for total E. coli . This result meant that field experiments studying the fate of total E. coli should give a satisfactory evaluation of the risk of water contamination by the O157 strain. In four field experiments at three sites, slurry containing total E. coli numbers of 2.2 × 10⁴ to 5.7 × 10⁵ colony forming units per mL (c.f.u. mL^–1) was applied to drained field plots. Field die-off was faster than expected from laboratory experiments, especially in one experiment where two weeks dry weather followed application. In all but this experiment, the first drain flow events after slurry application led to very high E. coli concentrations in the drains (10³ to 10⁴ c.f.u. mL^–1). E. coli O157 was present in the slurry used for two of the experiments (33 c.f.u. per 100 mL in each case). However the proportion of E.coli O157 was very low (about 1 in 10⁵) and it was not detected in the drainage water. After the first week E. coli drainage water numbers decreased rapidly but they were 1–10 c.f.u. mL^–1 for much of the sampling period after slurry application (1–3 months).     

Fate of fertilizer nitrogen applied to grassland. I. Field leaching results

Results are presented from a 3 year investigation into nitrate leaching from isolated 0.4 ha grassland plots fertilized with 250, 500 and 900 kg N ha^?1 a^?1. Cumulative nitrate leaching over the 3 years was equivalent to 1.5%, 5.4% and 16.7% of the fertilizer applied at 250, 500 and 900 kg N ha^?1 rates respectively. Over a whole drainage season, mean nitrate leachate concentrations at 250 kg N ha^?1 did not exceed 4 mgl^?1, although maximum values of 13.3 mgl^?1 were observed. In contrast, at 900 kg N ha^?1, the mean nitrate leachate concentration in two of the years exceeded 90 mgl^?1. Mineral nitrogen balances constructed for the 1979 growing season indicated that leaching at 250 kg N ha^?1 was low because net mineralization of soil organic nitrogen was small, and crop nitrogen uptake almost balanced fertilizer application. Although the pattern of nitrate leaching suggested that by-passing occurred in the movement of water down the soil profile, it was not possible to confirm this using simulation models of leaching. Possible reasons for this, including the occurrence of rapid water flow down gravitationally drained macropores, are discussed.     

Gaseous and leaching nitrogen losses from no-tillage and conventional tillage systems following surface application of cattle manure

Previous studies have demonstrated inconsistent results on the impact of tillage systems on nitrogen (N) losses from field-applied manure. This study assessed the impact of no-tillage (NT) and conventional tillage (CT) systems on gaseous N losses, N₂O:N₂O + N₂ ratios and NO₃⁻-N leaching following surface application of cattle manure. The study was undertaken during the 2003/2004 and 2004/2005 seasons at two field sites in Nova Scotia namely, Streets Ridge (SR) in Cumberland County and the Bio-environmental Engineering Centre (BEEC) in Truro. Results showed that the NT system had higher (p < 0.05) NH₃ losses than CT. Over the two seasons, manure incorporation in CT reduced NH₃ losses on average by 86% at SR and 78% at BEEC relative to NT. At both sites and during both seasons, denitrification rates and N₂O fluxes in NT were generally higher than in CT plots, presumably due to higher soil water and organic matter content in NT. Over the two seasons, mean denitrification rates at SR were 239 and 119 g N ha⁻¹ d⁻¹, while N₂O fluxes were 120 and 64 g N ha⁻¹ d⁻¹ under NT and CT, respectively. At BEEC mean denitrification rates were 114 and 71 g N ha⁻¹ d⁻¹, while N₂O fluxes were 52 and 27 g N ha⁻¹ d⁻¹ under NT and CT, respectively. Conversely, N₂O:N₂O + N₂ ratios were lower in NT than CT suggesting more complete reduction of N₂O to N₂ under NT. When averaged across all soil depths, NO₃⁻-N was higher (p < 0.05) in CT than NT. Nitrate-N decreased with depth at both sites regardless of tillage. In most cases, NO₃⁻-N was higher under CT than NT at all soil depths. Similarly, flow-weighted average NO₃⁻-N concentrations in drainage water were generally higher under CT. This may be partly attributed to higher denitrification rates under NT. Therefore, NT may be a viable strategy to remove NO₃⁻-N from the soil, and thus, reduce NO₃⁻-N contamination of groundwater. However, it should be noted that while the use of NT reduces NO₃⁻-N leaching it may come with unintended environmental tradeoffs, including increased NH₃ and N₂O emissions.     

Effects of tillage and application of cattle slurry on carbon pools and aggregate distribution in temperate grassland soils

The objective was to study the effects of tillage and cattle slurry application on organic C dynamics in grassland soils. Treatments included long‐term grassland and reinstalled grassland (after tillage and winter wheat cropping) with and without cattle slurry application (240 kg N ha^–1 y^–1). A period of 4 y slurry application sufficed to increase microbial activity 1.6‐fold in surface soil (0–10 cm). Tillage affected aggregate distribution and basal respiration in the surface soil.     

Dissolved phosphorus composition of grassland leachates following application of dairy‐slurry size fractions

Appropriate management of P from slurry can increase crop production and decrease nutrient loss to water bodies. The present study examined how the application of different size fractions of dairy slurry influenced the quantity and composition of P leached from grassland in a temperate climate. Soil blocks were amended (day 0 = start of the experiment) with either whole slurry (WS), the > 425 μm fraction (coarse slurry fraction, CSF), the < 45 μm slurry fraction (fine liquid slurry fraction, FLF), or not amended, i.e., the control soil (CON). Deionized water was added to the soil blocks to simulate six sequential rainfall events, equivalent to 250 mm (day 0.2, 1.2, 4.2, 11.2) or 500 mm of rainfall (day 18.2 and 25.2), with leachates collected the following day. The results showed that total dissolved P (TDP), dissolved reactive P (DRP), dissolved unreactive P (DUP), orthophosphate, phosphomonoester, and pyrophosphate concentrations generally decreased with the increasing number of simulated rain events. Total dissolved P was leached in the following order WS > FLF ≈ CSF > CON. Dissolved organic C was correlated with TDP, DRP, and DUP in leachates of all treatments. The highest concentrations of dissolved phosphomonoesters and pyrophosphate (147 μg P L^–1 and 57 μg P L^–1, respectively) were detected using solution ³¹P‐NMR spectroscopy in the WS leachates. Overall, there were significant differences observed between slurry treatments (e.g., relative contributions of inorganic P vs. organic P of dissolved P in leachates). Differences were independent from the rate at which slurry P was applied, because the highest dissolved P losses per unit of slurry P applied were measured in the FLF, i.e., the treatment that received the smallest amount of P. We conclude that the specific particle‐size composition of applied slurry influences dissolved P losses from grassland systems. This information should be taken in account in farm‐management approaches which aim to minimizing dissolved slurry P losses from grassland systems.     

Fate of fertilizer nitrogen applied to grassland. II. Nitrogen-15 leaching results

Results are presented from a 3-year investigation into nitrate leaching from grassed monolith lysimeters treated with double (¹⁵NH₄¹⁵NO₃) or single (¹⁵NH₄NO₃) labelled ammonium nitrate at three rates, 250, 500 and 900 kg N ha^?1 a^?1. Over the 3 years of the experiment, 0.14%, 3.1% and 18.1% of the applied fertilizer was recovered in the leachate at 250, 500 and 900kg N ha^?1 respectively. This represented 9%, 39% and 75% of the overall nitrate leaching at the three application rates. A significant proportion of the fertilizer leached as nitrate at the three application rates was derived, via nitrification, from the fertilizer ammonium. Increasing fertilizer applications caused a rise in the leaching of both soil and fertilizer derived nitrogen, although whether the increase reflected a true priming effect was not clear.     

Fate of heavy metals and bacterial community composition following biogas slurry application in a single rice cropping system

Journal of Soils and Sediments - Biogas slurry (BS) is widely used as a valuable fertilizer for crop production. However, little is known about the effects of long-term BS application on potential...     

Short-term effects of single or combined application of mineral N fertilizer and cattle slurry on the fluxes of radiatively active trace gases from grassland soil

After implementation of legislative measures for the reduction of environmental hazards from nitrate leaching and ammonia volatilisation when using organic manures and fertilizers in Europe, much attention is now paid to the specific effects of these fertilizers on the dynamics of global warming-relevant trace gases in soil. Particularly nitrogen fertilizers and slurry from animal husbandry are known to play a key role for the CH₄ and N₂O fluxes from soils. Here we report on a short-term evaluation of trace gas fluxes in grassland as affected by single or combined application of mineral fertilizer and organic manure in early spring. Methane fluxes were characterised by a short methane emission event immediately after application of cattle slurry. Within the same day methane fluxes returned to negative, and on average over the 4-day period after slurry application, only a small but insignificant trend to reduced methane oxidation was found. Nitrous oxide emissions showed a pronounced effect of combined slurry and mineral fertilizer application. In particular fresh cattle slurry combined with calcium ammonium nitrate (CAN) mineral fertilizer induced an increase in mean N₂O flux during the first 4 days after application from 10 to 300 μg N₂O-N m⁻² h⁻¹. ¹⁵N analysis of emitted N₂O from ¹⁵N-labelled fertilizer or manure indicated that easily decomposable slurry C compounds induced a pronounced promotion of N₂O-N emission derived from mineral CAN fertilizer. Fluxes after application of either mineral fertilizer or slurry alone showed an increase of less than 5-fold. The NO_x sink strength of the soil was in the range of −6 to −10 μg NO_x-N m⁻² h⁻¹ and after fertilization it showed a tendency to be reduced by no more than 2 μg NO_x-N m⁻² h⁻¹, which was a result of both, increased NO emission and slightly increased NO₂ deposition. Associated determination of the N₂O:N₂ emission ratio revealed that after mineral N application (CAN) a large proportion (c. 50%) was emitted as N₂O, while after application of slurry with easily decomposable C and predominantly -N serving as N-source, the N₂O:N₂ emission ratio was 1:14, i.e. was changed in favour of N₂. Our work provides evidence that particularly the combination of slurry and nitrate-containing N fertilizers gives rise to considerable N₂O emissions from mineral fertilizer N pool.     

Nitrogen losses following application of pig slurry to arable land

Abstract. Emissions of ammonia (NH₃) and nitrous oxide (N₂O), and nitrate (NO^-₃) leaching were measured in two field experiments following application of pig slurry at rates corresponding to 83–96 kg NH₄-N ha^-1 before sowing. In spring and in autumn 1994, slurry was applied by four methods: trenching (T), shallow injection (S), band spreading immediately followed by harrowing (B/H) and band spreading (B). NH₃ emission measurements were made during the first week after application in both experiments. In the spring experiment N₂O emissions and NO^-₃ leaching were measured during 6 and 52 weeks after spreading respectively, and during 11 and 33 weeks after spreading in the autumn experiment. In spring, the increased N₂O emissions (i.e. control subtracted) ranged from 0.27% (T) to 0.45% (B/H), and in the autumn study from 0.92% (T) to 1.14% (B/H), of applied NH₄-N, although showing no statistically significant differences. In order to validate the chamber measurements, a ‘megachamber’(21 m²) was used together with an infrared spectrometer. The emissions agreed well for (B/H), while (B) resulted in lower emissions compared with the smaller chambers. Emissions of NH₃ were about one order of magnitude higher. In spring, (B) gave the highest emission, reaching 19.5% of applied NH₄-N, whereas (S), and (B/H) gave the lowest emissions, reaching 1.2 and 3.5% of applied NH₄-N, respectively. NH₃ emissions in autumn were 15–20% lower compared with spring. In spring the increased nitrate leaching ranged from 10.1 (T) to 24.9 kg ha^-1 (B/H) and from 29.5 (B) to 37.8 kg ha^-1 (T) in the autumn experiment, showing no statistically significant differences. Estimations of indirect N₂O emissions due to ammonia deposition and nitrate leaching, suggested that the N₂O contribution from NH₃ deposition was relatively small, while the indirect N₂O emissions from NO^-₃ leaching were of the same order of magnitude or higher than the direct N₂O emissions.     

Efficiency parameters of nitrogen in hog and cattle manure in the second year following application

The efficiency of nitrogen (N) derived from different manures in the years following application must be determined to optimize use of N and reduce impact on the environment. Five N efficiency parameters that were originally developed for commercial inorganic N fertilizers were selected to measure the manure N efficiency in the second year following application of liquid hog and solid cattle manure in semiarid east‐central Saskatchewan, Canada. The manures were applied at two sites (Dixon and Burr) at four rates covering a range from zero to 912 kg N ha^–1 in 1997. A canola (Brassica napus L.) crop was grown in 1997 followed by a spring wheat (Triticum aestivum L.) in 1998 without fertilization. Tested by the wheat, N utilization efficiency (NUE) was similar between the two manures at either site, but it was higher at Dixon site, where the soil properties were better, than at the Burr site (P < 0.07) with cattle manure. Nitrogen physiological efficiency (NPE) was not affected by either manure source or soil. At the Burr site, N agronomic efficiency (NAE) and N recovery rate (NRR) were all higher with the hog than with the cattle manure (P < 0.08 and P < 0.07, respectively), but N harvest index (NHI) was lower with the hog than with the cattle manure (P < 0.04). The similar trends of the NAE, NRR, and NHI between the hog and cattle manure were also found at the Dixon site. However, the differences in NRR between the hog and cattle manure in the second year was rather small in contrast to the large differences in the year of application. Despite that the wheat crop utilized residual hog and cattle manure N equally efficient in producing grain yield, a higher grain N concentration and a higher NHI with the cattle than with the hog manure revealed different N supply dynamics between the two. Possibly due to the low proportion of ammonium (NH₃)‐N in the total N and the high C : N ratio in the cattle manure, mineralization of cattle manure N provided more available N in the later stage of wheat growth than did the hog manure. The N efficiency parameters were useful tools in understanding the impact of residual manure N on wheat production on the Canadian prairies.     

Effect of cattle slurry in grassland on microbial biomass and on activities of various enzymes

We examined the long-term effects of cattle slurry, applied at high rates, on microbial biomass, respiration, the microbial quotient (qCO₂) and various soil enzyme activities. In March, June, July, and October 1991, slurry-amended grassland soils (0–10 cm) contained significantly higher levels of microbial biomass, N mineralization and enzyme activities involved in N, P, and C cycling. With microbial biomass as the relative value, the results revealed that the slurry treatment influenced enzyme production by the microbial biomass. High levels of urease activity were the result not only of a larger microbial biomass, but also of higher levels of enzmye production by this microbial biomass. The ratio of alkaline phosphatase and xylanase to microbial biomass was nearly constant in the different treatments. The metabolic quotient (qCO₂) declined with increased levels of slurry application. Therefore it appears that microorganisms in slurry-amended soils require less C and energy if there is no competition for nutrients. The results of this study suggest that urease activity, nitrification, and respiration (metabolic quotient) can be used as indicators of environmental stress, produced by heavy applications of cattle slurry.     

Ammonia volatilization from five nitrogen compounds used as fertilizers following surface application to soils

Measurements were made of the volatilization of ammonia from mono-ammonium phosphate (MAP), di-ammonium phosphate (DAP), ammonium sulphate (AS), ammonium nitrate (AN) and urea, applied to the surface of five contrasting soils. The compounds were applied as solids, at a rate equivalent to 100 kg N ha^?1, to samples of moist soil packed into columns (48 mm diameter) and placed individually in jars through which a stream of air was passed for a period of 8 d. Volatilization ranged from nil to 53% of the N applied, with both the nature of the compound and soil type having large effects. Taking all combinations into account, there was a close relationship between the extent of volatilization, expressed as a percentage of the ammonium or urea N, and the pH attained after 24 h by the corresponding mixtures of soil and compound. Using the results of these and other experiments, the proportion of fertilizer N volatilized as ammonia is estimated to be about 3.4% over the UK as a whole.     

Evidence of carbon stimulated N transformations in grassland soil after slurry application

High nitrification rates which convert ammonium (NH₄⁺) to the mobile ions NO₂⁻ and NO₃⁻ are of high ecological significance because they increase the potential for N losses via leaching and denitrification. Nitrification can be performed by chemoautotrophic or heterotrophic organisms and heterotrophic nitrifiers can oxidise either mineral (NH₄⁺) or organic N. Selective nitrification inhibitors and ¹⁵N tracer studies have been used in an attempt to separate heterotrophic and autotrophic nitrification. In a laboratory study we determined the effect of cattle slurry on the oxidation of mineral NH₄⁺-N and organic-N by labelling the NH₄⁺ or NO₃⁻ pools separately or both together with ¹⁵N. The size and enrichment of the mineral N pools were determined at intervals. To calculate gross N transformation rates a ¹⁵N tracing model was developed. This model consists of the three N-pools NH₄⁺, NO₃⁻ and organic N. Sub-models for decomposition of degradable carbon in the soil and the slurry were added to the model and linked to the N transformation rates. The model was set up in the software ModelMaker which contains non-linear optimization routines to determine model parameters. The application of cattle slurry increased the rate of nitrifcation by a factor of 20 compared with the control. The size and enrichment of the mineral N pools provided evidence that nitrification was due to the conversion of NH₄⁺ to NO₃⁻ and not the conversion of organic N to NO₃⁻. There was evidence that slurry-enhanced oxidation of NH₄⁺ to NO₃⁻ was due to a combination of autotrophic and heterotrophic transformations. Slurry application increased the mineralisation rate by approximately a factor of two compared with the control and the rate of immobilisation of NH₄⁺ by approximately a factor of three.     

Nitrous oxide, methane and ammonia emissions following slurry spreading on grassland

In Sweden, 90% of ammonia (NH₃) emissions to the atmosphere originate from agriculture, predominantly from animal manure handling. It is well known that incorporation of manure into soil can reduce NH₃ emissions after spreading. However, there is a risk of increased nitrous oxide (N₂O) and methane (CH₄) emissions caused by bacterial activity and limited oxygen availability under these conditions. A full‐scale injector was developed and evaluated in a field experiment on grassland. Cattle slurry was either injected in closed slots 5 cm below ground or band spread on the soil surface above the crop canopy at a rate of 25 t ha^?1. In a control treatment, no slurry was applied. During a 5‐day period after application, NH₃ emissions were measured using an equilibrium concentration method. Gas samples for estimating CH₄ and N₂O emissions were also collected during 7 weeks following slurry application. Injection in closed slots resulted in no detectable NH₃ emissions. After band spreading, however, NH₃ emissions corresponded to nearly 40% of the total ammoniacal nitrogen in the applied slurry. The injection of slurry gave rise to a broad peak of N₂O emissions during the first 3 weeks after application. In total, for the measuring period, N₂O emissions corresponded to 0.75 kg N ha^?1. Band spreading resulted in only a very small N₂O release of about 0.2 kg N ha^?1 during the same period. Except for the first sampling occasion, the soil was predominantly a sink for CH₄ in all the treatments. The use of the injector without slurry application reduced grass yield during unfavourable growing conditions. In conclusion, shallow injection in closed slots seems to be a promising technique to reduce negative environmental impacts from NH₃ emissions with a limited release of N₂O and CH₄.     

Slope position regulates response of carbon and nitrogen stocks to cattle grazing on rough fescue grassland

Purpose

Grasslands play a crucial role in offsetting greenhouse gas emissions and mitigating climate change. A moderate change in grassland carbon (C) and nitrogen (N) stocks may substantially alter the global C and N cycle and thereby influence climate. But how grassland C and N stocks respond to grazing and slope position remains uncertain. This research investigates how C and N stocks respond to cattle grazing along a landscape slope.

Materials and methods

We studied a grassland that has been grazed by cattle at four cattle stocking rates (0, 1.2, 2.4, and 4.8 animal unit months (AUM) ha^?1) since 1949, representing control (CK), light (L), heavy (H), and very heavy (VH) grazing intensities, respectively. Samples were taken from the top and bottom slope positions within each paddock (only the top position in CK); C and N stocks in soil, roots, litter, and standing crop were estimated. Soil C and N stocks were estimated based on equivalent mass (1500 Mg ha^?1). Root C and N stocks were estimated to the depth of 15 cm.

Results and discussion

All parameters, except for litter N stock and standing crop C stock, significantly responded to the interaction of grazing intensity and slope position. In the bottom position, soil and standing crop C and N stocks as well as litter C stock were higher with the L treatment than with VH, while no significant differences were found among the three grazed treatments for root C and litter N stocks. In the top position, soil and root C and N stocks were higher with the VH treatment than with L, whereas litter C and N stocks and standing crop C stock were lower with VH than with L.

Conclusions

Our results provide evidence that slope position plays an important role in regulating the response of C and N stocks to grazing and may need to be considered when developing optimal grazing management strategies.