Slurry Application Method Research Articles

Transport of Cryptosporidium parvum Oocysts in Soil Columns following Applications of Raw and Separated Liquid Slurries

The potential for the transport of viable Cryptosporidium parvum oocysts through soil to land drains and groundwater was studied using simulated rainfall and intact soil columns which were applied raw slurry or separated liquid slurry. Following irrigation and weekly samplings over a 4-week period, C. parvum oocysts were detected from all soil columns regardless of slurry type and application method, although recovery rates were low (<1%). Soil columns with injected liquid slurry leached 73 and 90% more oocysts compared to columns with injected and surface-applied raw slurries, respectively. Among leachate samples containing oocysts, 44/72 samples yielded viable oocysts as determined by a dye permeability assay (DAPI [4',6'-diamidino-2-phenylindole]/propidium iodide) with the majority (41%) of viable oocysts found in leachate from soil columns with added liquid slurry. The number of viable oocysts was positively correlated (r = 0.63) with the total number of oocysts found. Destructively sampling of the soil columns showed that type of slurry and irrigation played a role in the vertical distribution of oocysts, with more oocysts recovered from soil columns added liquid slurry irrespective of the irrigation status. Further studies are needed to determine the effectiveness of different slurry separation technologies to remove oocysts and other pathogens, as well as whether the application of separated liquid slurry to agricultural land may represent higher risks for groundwater contamination compared to application of raw slurry.

Comparison of Raw Dairy Manure Slurry and Anaerobically Digested Slurry as N Sources for Grass Forage Production

We conducted a 3-year field study to determine how raw dairy slurry and anaerobically digested slurry (dairy slurry and food waste) applied via broadcast and subsurface deposition to reed canarygrass (Phalaris arundinacea) affected forage biomass, N uptake, apparent nitrogen recovery (ANR), and soil nitrate concentrations relative to urea. Annual N applications ranged from 600 kg N ha−1in 2009 to 300 g N ha−1in 2011. Forage yield and N uptake were similar across slurry treatments. Soil nitrate concentrations were greatest at the beginning of the fall leaching season, and did not differ among slurry treatments or application methods. Urea-fertilized plots had the highest soil nitrate concentrations but did not consistently have greatest forage biomass. ANR for the slurry treatments ranged from 35 to 70% when calculations were based on ammonium-N concentration, compared with 31 to 65% for urea. Slurry ANR calculated on a total N basis was lower (15 to 40%) due to lower availability of the organic N in the slurries. No consistent differences in soil microbial biomass or other biological indicators were observed. Anaerobically digested slurry supported equal forage production and similar N use efficiency when compared to raw dairy slurry.

Analysis of A Novel Slurry Injection System in Chemical Mechanical Planarization

Slurry mean residence time (MRT), removal rate, and polishing defects were analyzed for a novel slurry injection system used in chemical mechanical planarization. The novel slurry injection system was placed adjacent to the wafer on the pad surface and slurry was injected towards the wafer through multiple holes in the trailing edge of the injector bottom. Results showed the novel slurry injection system provided more efficient slurry delivery to the pad–wafer interface and generated lower slurry MRT, higher removal rate, and lower polishing defects than the standard pad center area slurry application method currently used in the IC manufacturing industry.

Effect of Slurry Application/Injection Methods and Polishing Conditions on Bow Wave Characteristics

In this study, the effect of slurry application/injection methods and polishing conditions on slurry flow dynamics at the retaining ring bow wave was investigated. Two slurry application/injection methods (standard slurry application method and novel slurry injection method) were used. For each method, an ultraviolet enhanced fluorescence system was implemented to measure the slurry film thickness at bow wave for a polyetheretherketone (PEEK) retaining ring at different sliding velocities, slurry flow rates and ring pressures. Results indicated that the novel slurry injection method generated significantly thicker slurry film at the bow wave than that of the standard slurry application method. For both methods, slurry film thickness at the bow wave increased with increasing flow rate and ring pressure while it decreased with increasing sliding velocity.

Dairy Slurry Application Method Impacts Ammonia Emission and Nitrate Leaching in No‐Till Corn Silage

Reducing ammonia (NH3) emissions through slurry incorporation or other soil management techniques may increase nitrate (NO3) leaching, so quantifying potential losses from these alternative pathways is essential to improving slurry N management. Slurry N losses, as NH3 or NO3 were evaluated over 4 yr in south-central Wisconsin. Slurry (i.e., dairy cow [Bos taurus] manure from a storage pit) was applied each spring at a single rate (-75 m3 ha(-1)) in one of three ways: surface broadcast (SURF), surface broadcast followed by partial incorporation using an aerator implement (AER-INC), and injection (INJ). Ammonia emissions were measured during the 120 h following slurry application using chambers, and NO3 leaching was monitored in drainage lysimeters. Yield and N3 uptake of oat (Avena sativa L.), corn (Zea mays L.), and winter rye (Secale cereale L.) were measured each year, and at trial's end soils were sampled in 15- to 30-cm increments to 90-cm depth. There were significant tradeoffs in slurry N loss among pathways: annual mean NH3-N emission across all treatments was 5.3, 38.3, 12.4, and 21.8 kg ha(-1) and annual mean NO3-N leaching across all treatments was 24.1, 0.9, 16.9, and 7.3 kg ha' during Years 1, 2, 3, and 4, respectively. Slurry N loss amounted to 27.1% of applied N from the SURF treatment (20.5% as NH3-N and 6.6% as NO,-N), 23.3% from AER-INC (12.0% as NH3-N and 11.3% as NO3-N), and 9.19% from INJ (4.4% as NH3-N and 4.7% as NO3-N). Although slurry incorporation decreased slurry N loss, the conserved slurry N did not significantly impact crop yield, crop N uptake or soil properties at trial's end.

Nitrogen Fertilizer Replacement Value of Cattle Slurry in Grassland as Affected by Method and Timing of Application

Slurry application with methods such as trailing shoe (TS) results in reduced emissions of ammonia (NH3) compared with broadcast application using splashplate (SP). Timing the application during cool and wet weather conditions also contributes to low NH3 emissions. From this perspective, we investigated whether reduced NH3 emissions due to improved slurry application method and timing results in an increase in the nitrogen (N) fertilizer replacement value (NFRV). The effects of application timing (June vs. April) and application method (TS vs. SP) on the apparent N recovery (ANR) and NFRV from cattle slurry applied to grassland were examined on three sites over 3 yr in randomized block experiments. The NFRV was calculated using two methods: (i) NFRV(N) based on the ANR of slurry N relative to mineral N fertilizer; and (ii) NFRV(DM) based on DM yield. The TS method increased the ANR, NFRV(N), and NFRV(DM) compared with SP in the 40- to 50-d period following slurry application by 0.09, 0.10, and 0.10 kg kg(-1), respectively. These values were reduced to 0.07, 0.06, and 0.05 kg kg(-1), respectively, when residual harvests during the rest of the year were included. The highest NFRV(DM) for the first harvest period was with application in April using STS (0.30 kg kg(-1)), while application in June with SP had the Slowest (0.12 kg kg(-1)). The highest NFRV(DM) for the cumulative harvest period was with application in April using TS (0.38 kg kg(-1)), while application in June with SP had the lowest (0.17 kg kg(-1)). Improved management of application method, by using TS instead of SP, and timing, by applying slurry in April rather than June, offer potential to increase the NFRV(DM) of cattle slurry applied to grassland.

Effect of dairy manure slurry application in a no-till system on phosphorus runoff

Incorporation of manure slurry under reduced tillage conditions remains a challenge in the northeastern US. New technologies to directly incorporate slurry are available but their agronomic and environmental benefits have generally not been quantified. This study evaluated the effects of five manure slurry application methods on phosphorus (P) loss in runoff (broadcasting with and without incorporation by tillage, shallow disk injection, banded application and aeration, and pressurized injection) and a control (no manure). Research was conducted over a 2 year period in central Pennsylvania on a well-drained Hagerstown silt loam (fine, mixed, semiactive, mesic Typic Hapludalf) under corn (Zea mays L.) production. Approximately 72 h after dairy (Bos Taurus) slurry application (56,000 l ha−1) to 10 × 13 m plots, a single rainfall simulation (68 mm h−1) was conducted in triplicate on 10 × 2 m areas within the plots. Trends in total P losses in runoff (kg ha−1) from plots varied between years and treatments. Aeration yielded lower losses than all other treatments in 2006 and was amongst the lowest in 2007 with losses statistically similar to shallow disk and pressure injection. Remarkably, few differences were apparent in losses of dissolved reactive P between treatments, reflecting high variability in runoff depths. Indeed, variability in runoff depths resulted in some unexpected trends, including high loads from the unamended control and modest loads from the tillage treatment. Results highlight tradeoffs in alternative manure slurry application practices but point to the potential to significantly lower runoff P losses from reduced tillage systems receiving manure slurry.

Slurry 15NH4-N recovery in herbage and soil: effects of application method and timing

The effects of slurry application method and weather conditions after application on ammonia volatilisation are well documented, however, the effect on slurry N recovery in herbage is less evident due to large variability of results. The objective of this field experiment was to determine the recovery of cattle slurry NH4-N in herbage and soil in the year of application as affected by application method (trailing shoe versus broadcast) and season of application (spring versus summer), using 15N as a tracer. In 2007 and 2008, 15N enriched slurry was applied on grassland plots. N recovery in herbage and soil during the year of application was determined. Both spring and trailing shoe application resulted in significantly higher herbage DM yields, N uptake and an increased recovery of 15NH4-N in herbage. Additionally, the recovery of slurry 15NH4-N in the soil at the end of the growing season was increased. Spring and trailing shoe application reduced the losses of slurry 15NH4-N by on average 14 and 18 percentage points, respectively, which corresponded closely to ammonia volatilisation as predicted by the ALFAM model. It was concluded that slurry N recovery in temperate pasture systems can be increased by adjusting the slurry application method or timing.

Direct and residual response of wheat to swine slurry application method

Swine production represents more than 25% of net agricultural incomes in some Spanish regions. Most of the 25 million t of swine slurry produced yearly in Spain is applied to agricultural fields by surface broadcasting (splash-plate) with important atmospheric N losses that reduce the fertilizer value of the slurry. Surface banding, incorporation, and injection into the soil are recommended methods to reduce N losses. We examined during two consecutive years the response of a wheat crop to swine slurry (SS) applied in the first year at two rates (30 and 60 Mg ha−1) using two application methods: splash-plate (SP) and soil incorporation (SI). After SS application, the soil was sampled intensively to establish the actual amount of SS in the soil (N recovery) and its spatial variability (distribution uniformity) in the two methods. Wheat yield, above ground dry matter and N uptake were measured along the 2 years. Swine slurry distribution uniformity and soil N-recovery were higher in SI than in SP, but grain yield and N uptake were independent of the application method in the 2 years. Reliable management practices compatible with the protection of the environment require further studies on the pathways and the availability of N to crops subject to SS incorporation in the soil at the moment of application.

Low‐ammonia‐emission application methods can increase the opportunity for application of cattle slurry to grassland in spring in Ireland

AbstractApplication of slurry in spring to grassland in north‐west Europe increases the efficiency of nitrogen recovery compared with the application in summer. In Ireland, however, more than 0·50 of slurry is applied in the summer. The splash‐plate method of application, most commonly used in Ireland, can make application in spring difficult because of the risk of contamination of grass with slurry, affecting subsequent silage quality and grazing preferences. This study evaluated the potential of low‐emission spreading methods to increase the opportunity for spring application of slurry using an agro‐meteorological modelling approach. Weather data from two weather stations were combined with data on grass growth from two nearby sites. Using three soil‐drainage classes (well, moderate and poor), each with a typical regime of grassland management, a database of soil moisture deficits, drainage, patterns of grazing and cover of grass herbage was developed for three hypothetical management systems, one for each soil drainage class, at each site. Simulations of four slurry application methods [splash‐plate (SP), band‐spreader (BS), trailing‐shoe (TS) and shallow‐injection (SI)], subject to a series of constraints, were compared over an 8‐year period (1998–2005) in order to determine the number of days during the period from 1 January to approximately 10 May of each year, when it was considered that grassland was suitable for application of slurry. These constraints were: (i) restrictions on spreading imposed by current legislation in Ireland; (ii) the period before occurrence of drainage or overland flow; (iii) soil trafficability; (iv) the time‐lag before a subsequent grazing or harvest event; and (v) herbage mass of the pasture. On well and moderately drained soils, the model predicted that the highest number of days available for slurry spreading was found for the TS method followed by the BS, SI and SP methods. There was no difference between application methods in the number of available days on poorly drained soils.

Manganese Deficiency in Winter Barley affected by Slurry Application Method and Slurry Alkalinity

: Ammonium fertilizer has an acidifying effect in soil that improves the plant availability of manganese (Mn), and the effect is most pronounced for band‐applied fertilizer. About 60% of the nitrogen (N) in animal slurries is ammonium‐N, and in livestock intensive areas the crop N requirement is fulfilled by animal slurry. To avoid N loss from surface‐applied slurry, direct injection in bands is desired but this application method is not common practice. However, slurry also contains alkaline reacting agents that may counteract the acidifying effect of ammonium. The aim of this study was to determine the Mn availability as affected by slurry type and application method.Two slurries, low and high in carbonate, were applied in spring by trailing hoses and direct injection in a winter barley crop, which is the crop most susceptible to Mn deficiency under Danish conditions. Mineral reference plots receiving nitrate and ammonium fertilizers were included. The differing quality of the two slurries did not affect the Mn off‐take and crop growth significantly. Only the ammonium treatment had a positive effect, but the treatment was not able to remedy the Mn deficiency. The possibility of remedying Mn deficiency in winter barley through the choice of N source for spring application seems to be limited.

Evaluating the use of gel-based sub-sampling for assessing responses of terrestrial microarthropods (Collembola and Acari) to different slurry applications and organic matter contents

Microarthropods show considerable small-scale spatial variation, which on statistical grounds demands the use of numerous samples per experimental unit to obtain a representative density estimate. To avoid the identification of all individuals in these samples a sub-sampling technique is desirable. Due to various factors, existing sub-sampling methods perform sub-optimally when working with soil microarthropods. As an alternative, this study evaluated a gel-based sub-sampling method. The method was applied in a practical situation comparing effects of two existing methods of slurry manure application (injection of control slurry and the superficial application of slurry to which an additive was added) on soil inhabiting springtails and mites. In the experiment, special attention was paid to the mediating influence of soil organic matter content. The gel-based sub-sampling data showed a Poisson distribution, supporting randomness. Furthermore, none of the identified specimens showed morphological damage, strongly suggesting that neither gel-suspension nor amylase treatment had damaged the integuments of the specimens. Therefore, gel-based sub-sampling seems to offer an efficient and safe tool for sub-sampling microarthropods. Of the two slurry applications studied, the surface application of the slurry manure with the additive resulted in the highest abundances of microarthropods, with an average of 17,890 individuals m −2 in broadcasted fields, compared to 11,486 individuals m −2 in the slit injected fields. A positive correlation between microarthropod abundance and the organic matter content of the soil was found for the fields that were slit injected with unamended slurry. The specially prepared slurry treatment did not show the latter correlation, probably because of the a priori relatively high organic matter content of most fields receiving this treatment. The relative dominance of surface dwelling species in the superficially applied slurry with additive suggests that the microarthropods responded in particular to the method of slurry manure application rather than to slurry manure type.

Effects of slurry application methods on soil faunal communities in permanent grassland

We studied the effects of two slurry manure application methods, broadcasting manure slurry (MB) and manure slit injection (SMI), on soil faunal communities 1 week and 4 or 5 weeks after application in the spring of 2002 and the summer of 2003. No effect on total numbers of Enchytraeidae and nematodes was found. Enrichment opportunistic nematodes (CP1) significantly decreased in the MB treatment, resulting in a significantly higher Maturity Index. In the SMI treatment the Maturity Index was unchanged. Effects of manure application methods on earthworms depended on soil moisture and season. Under wet conditions abundance of earthworms, especially epigeic earthworms, decreased significantly in the MB treatment. In the summer of 2003 total earthworm numbers, and the fraction of epigeics, decreased after SMI. Due to the drought in this period, abundances of epigeic earthworms were already low and possible significant effects of the different manure application methods were therefore hard to interpret.

Comparison of N losses (NO −3, N 2O, NO) from surface applied, injected or amended (DCD) pig slurry of an irrigated soil in a Mediterranean climate

Nitrous oxide (N 2O), nitric oxide (NO), denitrification losses and NO−3 leaching from an irrigated sward were quantified under Mediterranean conditions. The effect of injected pig slurry (IPS) with and without the nitrification inhibitor dicyandiamide (DCD) was evaluated and also compared with that of a surface pig slurry application (SPS) and a control treatment (Control) without fertiliser. After application, fluxes of NO and N 2O peaked from SPS (3.06 mg NO-N m −2 d −1 and 108 mg N 2O-N m −2 d −1) and IPS (3.50 mg NO-N m −2 d −1 and 105 mg N 2O-N m −2 d −1). However, when irrigation was applied, N 2O and NO emissions declined. The total N 2O and denitrification losses were slightly large from IPS than from SPS, although the differences were not significant (P < 0.05). Emission of NO was not affected by the method of pig slurry application. DCD inhibited nitrification during the first 20–30 days and reduced N 2O and NO emissions from pig slurry by at least 46% and 37%, respectively. Considering the 215 days following pig slurry application, the emission factor of N 2O based on N fertiliser was 1.60% (SPS), 2.95% (IPS), and 0.50% (IPS + DCD). The emission factor for NO was 0.14% (SPS), 0.12% (IPS), and 0.02% (IPS + DCD). Environmental conditions of the crop favoured the denitrification process as the most important source of N 2O during the experimental period. The differences in the denitrification rate between treatments could be explained by the pattern of water soluble carbon (WSC), that was the highest value in injected pig slurry (with and without DCD). Due to low drainage (5% of water applied), leaching losses of NO 3 − were lower than those of denitrification from the upper soil layer (0–10 cm) in all treatments and especially with IPS + DCD, where the nitrification inhibitor was very efficient in reducing leaching losses.

Short-term sequestration of slurry-derived carbon into particle size fractions of a temperate grassland soil

Surface application of animal wastes in intensive grassland systems has caused growing environmental problems during the last decade and, therefore, increasing public and scientific concern. In the present study we examined if the natural abundance 13C stable isotope tracer techniques could be used to investigate a poorly defined aspect of waste application, i.e. incorporation of slurry-derived C and its distribution in soil organic matter (SOM) fractions with different turnover times of a pasture soil. C3 and C4 slurries (δ13CV-PDB = −30.7‰ and −21.3‰, respectively) from cows fed either on a maize (C4) or perennial ryegrass (C3) diet were applied to a C3 soil with a δ13C value of −30.0 ± 0.2‰. The cattle slurry was applied at 50 m3 ha−1. Coarse sand, fine sand, silt, clay and fine clay were isolated from bulk soil samples (0–2 cm depth), freeze-dried and ground prior to total organic C (TOC) using elemental analysis and 13C natural abundance analysis by isotope-ratio mass spectrometry. The stable isotope tracer technique did allow to quantify the short-term sequestration of slurry-derived C in particle-size fractions of the grassland soil. Slurry-derived carbon was sequestered in various amounts in the five particle-size fractions, but most of it was sequestered in the coarse sand fraction during the two week experiment. The preferential input into the coarse sand fraction suggests that only the larger particulate slurry-derived materials were trapped into the soil during the experimental period. Less than 40% of the applied slurry-derived C was sequestered into the soil, suggesting a potential for large losses into the wider environment. The practice of surface spreading of slurry to temperate grassland soils is clearly not efficient, and improvements in slurry application methods, such as incorporation directly into the soil, should therefore be encouraged.

DEVELOPMENT AND EVALUATION OF A MULTI-HOSE SLURRY APPLICATOR FOR RICE PADDY FIELDS

Effective application of livestock manures on rice paddy fields provides nutrient recycling and can improve theenvironmental sustainability of animal operations. However, current manure slurry application methods have two majordisadvantages: poor application uniformity and nuisance odor emissions. The objective of this study was to develop andevaluate a multi-hose manure spreader for use in rice paddies with reduced odor emissions and increased applicationuniformity when compared to currently used systems. Both swine and dairy slurries were applied to a 0.5-ha field. Themulti -hose spreader showed improved application uniformity and reduced odor intensity compared to the conventionalsplash-plate applicator. Splash-plate spreaders are generally reported to have a coefficient of variation of approximately25% to 27% (not tested in this study), while coefficients of variation for the multi-hose spreader ranged from 7% to 14%.Odor indices measured using three different methods all indicated that the multi-hose spreader notably reduced odoremissions. Additionally, it was determined that the highest application uniformity was achieved with a high rotor speed(250 to 330 rpm) for both dairy and swine slurries. Higher rotor speeds provided more pressure in the distributor resultingin more uniform distribution.

On-farm impact of cattle slurry manure management on biological soil quality

The effects of dairy cattle slurry management on soil biota, soil respiration and nitrogen (N) mineralization were evaluated in a farm trial across 12 farms and a field experiment on 2 farms located in a dairy farming area in the north of the Netherlands. The slurry management consisted of slit injection or surface application of slurry; the use or no use of additives [Euromestmix® (MX) and Effective Microbes® (EM)] and the type and level of inorganic N fertilization. Slit injection negatively affected epigeic earthworms whereas its effect on anecic and endogeic earthworms was absent or even positive. Enchytraeids were not affected in a consistent way, whereas numbers of nematodes indicative of nutrient-enriched conditions increased. Inorganic N fertilizer had similar effects. Bacterial diversity was not different among the treatments. Nitrifier diversity, however, was high at one of the farms in the field experiment, and was negatively affected by inorganic N fertilizer. The use of MX was usually associated with higher numbers of earthworms. EM affected numbers of earthworms and numbers of bacterial and plant-feeding nematodes, but only in specific combinations of field history, slurry type and slurry application method. We found no effects of EM on the composition of the microbial community. Soil respiration was increased when slurry was surface-applied. The calculated N mineralization by earthworms was in the order of 70–200 kg N ha −1 year −1. It was highest under farm-characteristic surface application of slurry with MX and lowest under farm-characteristic slit injection of slurry without additives. Compared with the N mineralization by earthworms, that by enchytraeids and nematodes was quantitatively insignificant. Negative treatment effects on earthworms led to corresponding reductions in calculated N mineralization.

Effects of slurry application method and timing on grass silage quality

Small-scale silos (60-litre polyethylene barrels) were used to examine the chemical composition of grass silage after the application of slurry, at 40 m3/ha, at a range of timings, at two sites with contrasting rainfall; North Wyke, in Devon (high rainfall) and Reaseheath College, Cheshire (low rainfall). Grass plots (60 m2) received cattle slurry via surface broadcast (S), shallow injection (I) or surface placement by trailing shoe (T) techniques at 10, 6 or 2 weeks before an early silage (first) cut in May/June, and 6 or 2 weeks before a second cut in June/July. Control plots (C) received no slurry treatment. The harvested grass was compressed and sealed in the experimental silos and samples of the herbage at ensiling and of ensilage (after &gt;100-day fermentation) were analysed for various chemical components. Herbage yield was measured when the harvests were taken. Wetter than average weather conditions in both years resulted in silages with variable DM content (range 140–277 g/kg) being made at both sites. Generally, silages were poorly preserved with high pH and NH4+-N and low lactic acid contents. In particular, the silages from treatment S where slurry was applied 2 weeks prior to harvest exhibited characteristics indicative of clostridial growth, with high pH (range 4·0–5·2) and NH4+-N (106–213 g/kg total N) and low lactic acid (16–86 g/kg DM) contents. Damage to herbage caused by the injection tines on taller swards (treatments I at 6 and 2 weeks before cutting) was evident and the injection process was impeded by tall grass. This contributed to herbage contamination with soil and slurry on these treatments and, consequently, to poor silage fermentation. Silages made with slurry application method T at all timings showed improved fermentation characteristics compared with the other treatments, particularly at North Wyke. The results indicate that silage quality is unlikely to be compromised by slurry applications made in early spring, during February, March or even in April, where these are at agronomically sensible rates. Such practice will enable better utilization of slurry nitrogen (N), reducing risks of nutrient losses via leaching or surface runoff. Furthermore, shallow injection and, particularly, trailing shoe slurry application techniques may be used to increase flexibility of slurry management by allowing more immediate spreading before cutting than with conventional surface broadcasting, without detriment to silage quality.

Effects of method, rate and timing of slurry application to grassland on the preference by cattle for treated and untreated areas of pasture

AbstractTwo experiments were conducted in the UK to investigate preference by cattle for areas of pasture treated or untreated with dairy cow slurry. Experiment 1 examined the effects of method and rate of slurry applied to a grass pasture in March (Spring); Experiment 2 examined the effects of method and timing of slurry application after cutting for silage in June (Summer). In both experiments, beef steers grazed grassland plots that had been treated with slurry on one half only of the plots for 4 weeks. Slurry was applied by shallow injection (I), trailing shoe (T) or conventional surface broadcasting (S) techniques. In Experiment 1, slurry was applied at 40 m3 ha−1 (HI) or 20 m3 ha−1 (LO) 21 d before grazing commenced; in Experiment 2, slurry was applied at 20 m3 ha−1 either 32 d (E) or 10 d (L) before grazing commenced. Sward height was measured and animal behaviour was recorded during 8 × 24 h measurement periods in each experiment. Preference for slurry‐treated or untreated swards was indicated by a comparison of post‐grazing sward height on each sward and the proportion of total grazing time spent on the slurry‐treated swards. In Experiment 1, a smaller proportion of grazing time was spent on slurry‐treated areas of swards compared with untreated areas of swards on all treatments, but the proportion of time spent grazing the slurry‐treated sward was greater on method T than on methods I or S (0·28, 0·31 and 0·39 for methods S, I and T, respectively, s.e.d. = 0·035, P &lt; 0·05). Steers showed no preference between slurry‐treated and untreated swards by 49, 45 and 44 d after slurry application for methods S, I and T respectively. Differences between HI and LO were not significant (P &gt; 0·05). In Experiment 2, aversion to slurry‐treated swards compared with untreated swards was less for treatment E than for L, with a greater proportion of both residence and grazing time spent on the slurry‐treated sward of treatment E than L (0·43 and 0·28, respectively, for residence time, s.e.d. = 0·025, P &lt; 0·001, and 0·47 and 0·30, respectively, for grazing time, s.e.d. = 0·021, P &lt; 0·001). Significant differences were shown between the methods of slurry application for treatment E, with a greater proportion of grazing time spent on the slurry‐treated swards of methods I and T than method S (0·40, 0·52 and 0·49 for S, I and T, respectively, s.e.d. = 0·032, P &lt; 0·001), and a greater difference between post‐grazing heights on slurry‐treated and untreated swards for method S than for I or T (30, 12 and 15 mm, respectively, s.e.d. = 4·8, P &lt; 0·001). For treatment L, differences in the proportion of time spent grazing on slurry‐treated swards compared with untreated swards were not significant between treatments (0·26, 0·34 and 0·31 for methods S, I and T, respectively, s.e.d. = 0·040, P &gt; 0·05) and indifference between slurry‐treated and untreated swards was achieved 77, 60 and 58 d after slurry spreading for methods S, I and T respectively. These results show that, when slurry is applied to pasture in a grazing rotation, the adverse effects on grazing behaviour associated with conventional surface broadcasting may be overcome by the use of novel slurry application techniques.

Time Domain Reflectometry Measurements of Nitrate Transport in Manure‐Amended Soil

AbstractTo obtain more detailed information about N processes in agricultural soils, nondestructive measurement techniques with high spatial and temporal resolution are needed. The ability of time domain reflectometry (TDR) in combination with small polysulfone hollow fiber (PHF) solution samplers to follow NO−3 production and transport in soil fertilized with cattle slurry and exposed to different rainfall events was investigated. The experiments were conducted in minilysimeters using a coarse sandy soil and two different slurry application methods: (i) surface application followed by harrowing (homogenous incorporation) or (ii) direct injection (incorporation as a manure string). Comparison between soil‐water electrical conductivity (ECw) obtained with TDR and the sum of NO−3 and Cl− concentrations in the soil water measured with solution samplers showed a good agreement both with respect to concentration levels and temporal and spatial development. Except for an initial leaching of the natural ion content in the soil water when water application was started, NO−3 released from the manure was the dominating anion in the soil water and changes in NO−3 corresponded well to changes in ECw. Both slurry and water application strategy had a large effect on the temporal development in nitrification and NO−3 leaching. In the case of homogeneously incorporated slurry and constant water application for 3 wk, NO−3 formation and leaching started after 4 to 5 d, while it started after 9 to 10 d in the case of directly injected slurry. If water was applied only in the last (third) week to the directly injected slurry system, a large amount of the NH+4 in the slurry was oxidized to NO−3 before water application and subsequently leached. The TDR measurements of ECw with high spatial and temporal resolution combined with a few measurements of ion concentrations by PHF solution samplers is a new, valuable method for analyzing turnover and transport of nonconservative ions in soil.