Surface Application Of Slurry Research Articles

Impact of rainfall to the effectiveness of pig slurry shallow injection method for NH3 mitigation in a Mediterranean soil

Ammonia emission from fertilized cropping systems is an important concern for stakeholders, particularly in regions with high livestock densities producing large amounts of manure. Application of pig slurries can result in very large losses of N through NH3 volatilization, thus decreasing the N use efficiency (NUE) of the applied manure. Shallow incorporation has been shown to significantly abate these losses. In this field study, we assessed the impact of contrasting weather conditions on the effectiveness of shallow injection to abate NH3 emissions from pig slurry application to a Mediterranean soil. As potential trade-offs of NH3 abatement, greenhouse gas emissions were also measured under conditions of high soil moisture. Compared with surface application of slurry, shallow injection effectively and significantly decreased NH3 losses independently of weather conditions, but reductions of NH3 emission were greater after heavy rainfall. In contrast, under these conditions, shallow injection triggered higher emissions of N2O and CH4. Our findings reinforce the idea that any single-pollutant abatement strategy needs to be designed and assessed in a regional context and considering potential trade-offs in the form of other pollutants.

Effects of slurry pre-treatment and application technique on short-term N 2O emissions as determined by a new non-linear approach

Direct injection of slurry is increasingly used to mitigate odour and ammonia emissions, but this may be at the expense of higher denitrification and N 2O emission rates. This study investigated how injection technique and slurry pre-treatment influence distribution and turnover of slurry nitrogen, and losses via N 2O. Two field experiments were carried out on a loamy sand. Pig slurry was applied to established crops, i.e., to spring barley ( Hordeum vulgare L.) in May 2007, and to winter wheat ( Triticum aestivum L.) in April 2008. In 2007 the slurry was applied by direct injection using either winged or straight tines. In 2008, three slurry types (digested, separated or untreated) were applied by straight tine injection. In both years band spreading of the slurries by trail-hose application was included as reference. Nitrous oxide emissions were quantified using static chambers for up to 44 days after slurry application. A new flux calculation method (HMR) was applied. With HMR, flux estimation is based on non-linear regression using a single-parameter criterion. In connection with gas samplings, soil cores were collected to 20-cm depth within and between bands for analysis of mineral N. Short-term emissions of N 2O corresponded to 0.3–1.5% of the N applied in 2007, and to 0.3–0.7% in 2008. In 2007 N 2O emissions were higher with injection than with surface application of slurry, while there was no consistent difference between the two injection techniques. In 2008 there was no effect of application method, and N 2O emissions from untreated, digested and separated slurry were similar, although higher N 2O emissions from treated slurry were indicated. A conceptual model to explain the observed patterns of N 2O is discussed. Accounting for the indirect emissions of N 2O associated with NH 3 volatilization, production of synthetic fertilizer N and energy used for slurry injection, the overall greenhouse gas emissions associated with trail-hose application, winged tine injection and straight tine injection of slurry corresponded to 830, 997 and 1482 kg CO 2 eq ha −1, respectively. Provided plant damage can be minimized, this moderate increase in greenhouse gas emissions compared to surface application appears to be an acceptable trade-off for the reduction in NH 3 losses achievable with direct injection of slurry to established crops.

Effect of lowering dietary crude protein on nitrogen excretion, manure composition and ammonia emission from fattening pigs

The aim of this study was to evaluate the effects of three strategies of protein feeding (12%, 16% and 20%), supplying adequate levels of all essential amino acids, on finishing pig performance, nitrogen excretion and ammonia emission in the laboratory and in the field. The animals (15 castrated males) were housed individually in metabolism cages and were fed one of the three diets. The experiment lasted 21 days and urine and faeces were collected separately. Samples of each type of manure (urine alone, fresh slurry and 18-day slurry) were placed for 6 days in a laboratory pilot scale system designed to measure ammonia emission. In the field, measurements of ammonia volatilization were made during storage and surface application of slurry. Lowering dietary crude protein, while maintaining similar levels of essential amino acids, reduced total amount of manure, because of a lower water consumption, without any negative effect on animal performance. Total ammoniacal nitrogen content in the slurry was reduced from 4.32 g N kg −1 to 3.13 and 1.92 g N kg −1 when dietary CP decreased from 20% to 16% and 12%, respectively (the corresponding figures for total nitrogen content were 5.48, 4.30 and 3.05 g N kg −1, respectively). The pH of slurry decreased by 1.3 units when dietary crude protein decreased from 20% to 12%. These changes in slurry composition and pH resulted in a reduction of ammonia emissions at each stage of manure management. Over the whole process of the slurry, ammonia emission was decreased by 63% when dietary protein decreased from 20% to 12%.

Groundwater contamination due to cattle slurry: modelling infiltration on the basis of soil column experiments

Infiltration into soil of contaminants present in cattle slurry was studied. Column experiments were performed in order to characterize the release of contaminants at the slurry-soil interface after surface application of slurry, with subsequent rainfall or irrigation. A gradual decrease of contaminant concentrations was observed at this interface. The shape of the release curves suggests that the release of substances from slurry can be modelled by a single-parameter release function derived from the Lapidus and Amundson solution of the convection–dispersion equation (CDE). The release process is mainly controlled by physical properties of the slurry, the soil, and their interface, on which water flow during infiltration depends. The spatial and temporal heterogeneity of water flow across the slurry-soil interface are the major causes of the observed variations in the release process between column replicates. However, good predictions of breakthrough curves (BTCs) were obtained using the release data as input for simulation of solute transport through the column. The shape of the release curve was best fitted by the release function. We compared prediction of solute transport (a) with input defined by the release function and (b) assuming rectangular-pulse input. The results show that the parameter space (soil Peclet number, release number) can be divided into two regions, one in which the assumption of rectangular pulse gives acceptable prediction of the transport through the column, and another in which this assumption is invalid.

Fate of phosphorus applied in slurry and mineral fertilizer: accumulation in soil and release into surface runoff water

Phosphorus (P) accumulation on the soil surface and its effect on the concentration of dissolved orthophosphate P (PO4-P) in surface runoff water were studied after three years of surface application of slurry and mineral fertilizer to grass ley on a sandy soil, poor in P. The total amount of P applied was 107–143 kg ha−1>, of which 72–119 kg ha−1> was applied on the soil surface during two or three years without incorporation or mixing. The addition of slurry and mineral fertilizer resulted in an increase in inorganic P in the 0–5 cm but not the 5–25 cm soil layer, but organic P was not affected. The measured changes in inorganic P deviated only by 4–6 kg ha−1> from the values derived from inputs and outputs of P (crop uptake + losses in surface runoff and drainage water). The increase in inorganic-P was accompanied by increases in the degree of P saturation (DPS) and in P extracted with acid am monium acetate (PAc ), sodium bicarbonate (POlsen) and anion-exchange resin (PResin). In surface runoff, 10–18 months after the last surface application of P, the mean flow-weighted concentration of PO4-P was linearly increased with the values of DPS, PAc, POlson and PResin in the 0–5 cm soil layer. PO4-P was lowest (0.033 mg l−1> ) in the control plots and highest (0.62 mg l−1>) in the plot where 143 kg ha−1> P had been applied in slurry and fertilizer. On that plot, the corresponding values of DPS, PAc, POlson and PResin were 16%, 13 mg kg−1>, 85 mg kg−1> and 71 mg kg−1 , even within a few years, and multiply the P loading to surface runoff from the site. A very shallow soil sampling (< 5 cm) is needed to assess P loading potential in a soil where P has been surface-applied.

Diet selection by cattle offered a choice between swards treated or untreated with slurry: effects of application method and time since application

Reduced contamination of herbage following shallow injection rather than surface spreading of slurry may affect the acceptability to cattle of swards that recently received slurry. A short-term, indoor test was used to assess selection by cattle between untreated swards, and swards treated with slurry. Grass turves (0.25 m 2) were placed on a 20 cm deep soil base in a sward box. Dairy cow slurry, applied at a rate of 36 m 3 ha −1, was either spread evenly on the surface (S), or poured into two slots cut into the sward 10 cm apart and 5 cm deep, to simulate shallow injection (I). Control swards (C) received no slurry. Individual Limousin × Friesian steers were offered paired combinations S vs C or I vs C at 10 min, 2 h, 24 h, 4 days, 7 days, 14 days or 21 days after slurry application (six steers per treatment on each occasion), and allowed to take 50 bites (Phase 1) after which grazing was terminated. Three animals per treatment were then allowed to resume grazing until no further grazing occurred (Phase 2). A greater time was spent examining and eating C, a greater proportion of bites was taken on C and sward surface height (SSH) was reduced more on C compared with the treated sward S or I in both S vs C and I vs C, in both Phase 1 and Phase 2. More time was spent eating on I, a greater proportion of bites was taken on I and SSH was reduced more on I in I vs C than on S in S vs C, in both Phase 1 and Phase 2. The effect of method of slurry application to the treated sward was to modify grazing on the adjacent control sward. Thus, SSH reduction was greater on C for I vs C than for S vs C in Phase 1, although fewer bites were taken. The addition of water immediately after surface application of slurry (SW) gave a significant increase in the time spent grazing and the proportion of bites taken on SW when offered with a control sward with water applied (CW) compared with S for S vs C.

Studies on the relationship between slurry pH, volatilization processes and the influence of acidifying additives

The mutual influence of slurry pH and volatilization processes on one hand, and the possibility of N conservation by the use of acidifying additives on the other, were investigated in static incubation experiments. The influence of the NH3 and CO2 volatilizations on slurry pH was studied by selectively supporting one or both processes. The addition of Ca2+ to slurry was compared to that of K+ and H+. The effects of Cl−, SO 4 2− and NO 3 − as corresponding anions of Ca2+ on slurry pH as well as NH3 and N2O emissions were tested. The slurry pH (7.4) increased during incubation. When CO2 volatilization was suppressed, the pH increase was reduced, and NH3 volatilization was cut down by 50%. Ca2+ additions hardly influenced the initial slurry pH, but reduced the pH increases and NH3 losses. Proton addition, in contrast, decreased slurry pH but did not decrease the subsequent pH rise. K+ had no effect on slurry pH and N losses. As compared to CaCl2, CaSO4 showed less effect on slurry pH and N losses. Ca(NO3)2 was nearly as effective as CaCl2 in preventing NH3 volatilization, but caused denitrification losses and elevated N2O production. Titration curves of the different slurry treatments were used to interpret the results of the incubation experiments. In a microplot field experiment the NH3 volatilization and slurry pH after surface application of slurry was measured. The acidifying and N conserving effects of Ca2+ and H+ additions were confirmed.

Computer-captured expert knowledge to evaluate possibilities for injection of slurry from animal manure in the Netherlands

Surface application of slurry from animal manure substantially contributes to acid deposition in the Netherlands because of volatilization of ammonia. A qualitative physical land evaluation procedure was used to explore the possibilities for slurry injection. Expert knowledge, characteristic for qualitative land evaluation methods, was captured into the Automated Land Evaluation System (ALES) and successfully linked to a geographical information system (GIS) in which a small-scale soil map was stored. Decision trees to assess the physical suitability for slurry injection were developed within ALES. Maps are presented showing the physical suitability of the individual soil units and of agro-statistical regions. The latter were obtained by aggregation. A table is provided with the relative area for each suitability class of the agro-statistical regions. In a number of major Dutch grassland regions less than 40% of the area turned out to be suited for slurry injection, which was judged by the Dutch government to be insufficient for successful incorporation of injection in environmental legislation. A combined use of small-scale soil maps, computer-captured expert knowledge and GIS proved to be very useful in exploring land use options in a reconnaissance stage. Quick results are obtained which reduce the number of possible land use options within a short time. Thus, efforts can be concentrated on promising land use options, probably requiring application of quantitative evaluation methods.