Academic literature on the topic 'Dairy farm effluents'

Field sampling and laboratory experimentation were conducted on wastewater effluent generated at a dairy farm in order to characterise the wastewater, evaluate existing primary treatment facilities, and examine an appropriate wastewater treatment system to produce good quality effluents. It has been found that the farm contributes effluents containing considerable loads of organics, solids and nutrient pollutants. Existing treatment facilities which are limited to batch-operated primary settling tanks, are not capable of producing good quality effluent. Experimentation on an aerobic, suspended growth, biological system using sequencing batch reactors (SBR) indicated that the pollutant loads in the primary-treated effluent could be substantially reduced. The study showed that a wastewater treatment system involving primary settling tanks combined with additional aerobic biological treatment is capable of removing about 94% COD and 96% SS from the farm effluents. This system could be easily integrated and coordinated with existing facilities. A wastewater management scheme has been proposed to include waste minimisation, waste treatment and effluent reuse in irrigation.

Water used for irrigation is a leading source of induced salinity in semiarid areas. Within the Irrigation District 005 in northern Mexico, there are more than 100 dairy farms housing over 72,000 dairy cows, 74% of which are concentrated in approximately 30 intensive-operation farms. Dairy farm effluents (DFE) and manure are collected and stored temporarily until they are applied to the land to fertilize pasture and other crops. DFE vary in salt content, depending on specific farm operations. The risk of soil salinization by DFE was estimated by measuring electrical conductivity (EC) of both well water and DFE, and comparing these values with 2.0 mS cm−1, a Mexican guideline for wastewater used in agriculture. Half of the effluents exceeded the EC limit, with values as high as 12.4 mS cm−1, whereas a few exceeded the EC limit in both well and effluent water. The generation of salt and its passing into soils expose a potential for soil salinization, if preventive measures are not taken. A salt load map was created that depicted the areas at higher risk of salinization. The simple technique utilized here can be applied in estimating salinization potential in areas where monitoring of soils, irrigation drains, and shallow groundwater is infrequent.

A more sustainable water management on dairy farms is necessary because of rising tap water production costs and exhaustion of groundwater resources in an increasing number of areas. Alternative water sources like rain water collected from roofs and yards and effluents from on-site wastewater treatment should be considered. The objective of this paper is to discuss options for closed water systems on dairy farms. Animal drinking and cleaning of milking equipment are major water demands on dairy farms. In some regions large volumes are needed for grassland irrigation or manure flushing. Treatment of dairy farm wastewater in constructed wetland systems seems to produce good quality effluents. The most plausible options for closed water systems on dairy farms are the collection and use of rain water and treatment and reuse of wastewater for irrigation, manure flushing and animal drinking water. Whether effluents are safe to be used as animal drinking water should be subject to further research.

Constructed wetlands (CWs) have been used to treat agricultural effluents with varying success especially with respect to their operational efficiency in winter and ability to retain phosphorus. Dirty water (DW) from dairy farms is a mixture of manure contaminated runoff and milk parlour washings with a highly polluting biochemical oxygen demand (BOD) ≤3,000 mg/L. The initial performance a CW of a 1.2 ha horizontal flow CW consisting of five ponds in series designed to treat DW from a dairy unit was assessed over four years. Ponds were earth-lined and shallow (0.3 m) with a water residence time of 100 days and planted with five species of emergent macrophytes. In comparison to CW inflow, annual reductions were as follows: BOD 99%, P 95% and N 92.8%. Coliforms were reduced by a 10−5 factor to natural levels. From May to October there was little CW discharge due to evaporative losses. Final effluent quality was poorest in February but remained within a regulatory effluent standard for BOD of 40 mg/L. If the CW had only four ponds (25% less surface area) effluent would have failed the BOD standard in three years.

SUMMARYThe need for nitrogen (N) efficiency measures for dairy systems is as great as ever if we are to meet the challenge of increasing global production of animal-based protein while reducing N losses to the environment. The present paper provides an overview of current N efficiency and mitigation options for pastoral dairy farm systems and assesses the impact of integrating a range of these options on reactive N loss to the environment from dairy farms located in five regions of New Zealand with contrasting soil, climate and farm management attributes. Specific options evaluated were: (i) eliminating winter applications of fertilizer N, (ii) optimal reuse of farm dairy effluent, (iii) improving animal performance through better feeding and using cows with higher genetic merit, (iv) lowering dietary N concentration, (v) applying the nitrification inhibitor dicyandiamide (DCD) and (vi) restricting the duration of pasture grazing during autumn and winter. The Overseer®Nutrient Budgeting model was used to estimate N losses from representative farms that were characterized based on information obtained from detailed farmer surveys conducted in 2001 and 2009. The analysis suggests that (i) milk production increases of 7–30% were associated with increased N leaching and nitrous oxide (N2O) emission losses of 3–30 and 0–25%, respectively; and (ii) integrating a range of strategic and tactical management and mitigation options could offset these increased N losses. The modelling analysis also suggested that the restricted autumn and winter grazing strategy resulted in some degree of pollution swapping, with reductions in N leaching loss being associated with increases in N loss via ammonia volatilization and N2O emissions from effluents captured and stored in the confinement systems. Future research efforts need to include farm systems level experimentation to validate and assess the impacts of region-specific dairy systems redesign on productivity, profit, environmental losses, practical feasibility and un-intended consequences.

Estrogenic contamination of waterways is of world-wide concern due to the adverse effects observed in aquatic biota. Recently, wastes from agricultural activities have been identified as likely sources of steroid estrogens released into the environment. Wastes from dairying activities are of particular concern in New Zealand. This project included development of analytical methods to measure free and conjugated estrogens, measurement of estrogens from the source to receiving environments and an investigation of effluent treatment technologies. The analytical method developed in this study was based on GC-MS measurement of free estrogens (17α-estradiol (17α-E2), 17β-estradiol (17β-E2) and estrone (E1)) and LC-IT-MS measurement of their sulfate-conjugates (17α-E2-3S, 17β-3S, E1-3S) in raw and treated farm dairy shed effluents (DSE). Effluents from farms in the Canterbury and Waikato Regions, two regions where dairy farming is the dominant land-use, were collected and analysed. All effluents demonstrated high concentrations of steroid estrogens, particularly 17α-E2 (median 760 ng/L). Estrogenic activity was also elevated, at up to 500 ng/L 17β-E2 equivalents using the E-Screen, an in vitro cell proliferation bioassay. Comparison to the chemical data indicated that for most samples, the highest proportion of estrogenic activity was derived from steroid estrogens naturally excreted by dairy cows. Conjugated estrogens were measured in several raw effluent samples, at similar concentrations to those of free estrogens, particularly E1. Dairy effluent treatment systems reduced free estrogen concentrations by 63-99% and reduced estrogenic activity by up to 89%. In spite of high removal efficiencies, estrogens remained elevated in the treated effluents that are discharged into waterways. Steroid estrogens and estrogenic activity were detected in streams and groundwater in areas impacted by dairy farming. Although concentrations were generally low, in two streams the concentrations were above levels regarded as safe for aquatic biota (<1 ng/L). The results demonstrate that dairy effluents are indeed a major source of estrogens to the environment and to waterways.

Dans ce travail de thèse, il a constaté que l’étude des technologies numériques dans l’agriculture est récente dans le domaine de l’économie et par un scoping review, il a été identifié certains gaps dont le manque des études empiriques. Ainsi, quatre technologies ont été étudiées : connexion internet, robot de traite, outils d’aide à la décision (OAD) et outils de surveillances électroniques. Dans le secteur du lait, elles augmentent la production mais les effets sont plus importants pour les petites et moyennes exploitations. Plus important encore, les technologies connexion internet et OAD sont bénéfiques à tous les agriculteurs, utilisateurs ou non, puisque grâce à la proximité physique, ils arrivent à capter les effets d’agglomération techniques.Aussi, il a été trouvé qu’il existe un certain effet de rebond dans l’impact des technologies sur la production d’effluent. La contribution de la thèse est tout d’abord,nous avions été le premier, à notre connaissance, à avoir pu estimer ces effets à l’échelle nationale, effectivement les données étant encore très récentes l’appariement de plusieurs sources a été notre premier défi. Ensuite, nous avions appliqué deux nouvelles approches pour estimer les effets d’une utilisation de technologie, le Two-Stage least square (Geraci et al., 2014) et le Coarsening Exact Matching (Iacus et al, 2008) qui promettent des résultats plus pertinents pour notre contexte de donnée en coupe transversale et présentant une endogénéité. Enfin, la dernière contribution de la thèse est d’apporter des recommandations afin de permettre aux politiques publiques de comprendre les effets des nouvelles technologies et promouvoir les meilleures d'entre elles
In this thesis, it was found that the subject of study of digital technologies is still recent in the field of agricultural economics. Thus, through a scoping review, gaps were identified whose lack of empirical studies, as well as today's digital technologies, can be categorized into four groups: connection, recording, decision and execution. In the milk sector, these innovations increase production, but these advantages are inversely proportional to the intensity of production. In addition, internet connection technologies and decision support tools are beneficial to all farmers whether they are users or not. Since, thanks to their proximity, they manage to capture more agglomeration advantage. Also, it was found that there is a rebound effect as to the impact of these technologies on the manure production. The contributions of the thesis are that, first of all, it represents the first estimations, to our knowledge, of impacts of digital technologies on a farm on a national scale. Indeed, the data still very recent, matching multiple sources was our first challenge. As well, our estimation methods, namely the Two-Stage least square (2SRI) and the Coarsening Exact Matching (CEM), are new approaches and have more relevant results especially in our context of cross-sectional data with endogeneity. Finally, the last contribution is to make recommendations to enable public policies to understand the effects of new technologies and promote the best of them

An important number of Canadian dairy farms manage their manure as solids and in doing so, must handle large volumes of manure seepages and milk house wastewater (dairy farm effluent-DFE). The present project adapted surface irrigation as a more economical and sustainable method of disposing of this large volume of DFE on cropped land near their storage facility. The experimental surface irrigation system consisted of a gated pipe installed perpendicular to the slope of the field allowing the discharged DFE to run down the slope.
The adaptation of the system and the measurement of its environmental impact were conducted on two dairy farms, A and B, in the region South West of Montreal where their DFE were characterized. In 2003 and 2004, DFE was applied on one of two 0.5 and 0.3ha plots, on each farm, to observe losses through the subsurface drainage system, by means of sampling wells, and effects on soil nutrient levels.
The DFE collected in 2002 and 2003 had a lower nutrient content than that collected in 2004 because of higher precipitations. The DFE generally contained between 150-500 mg/L of TKN, 15 to 40 mg/L of TP and 500 to 700 mg/L of TK.
DFE losses through the subsurface drainage system were observed on both farms during each irrigation test. Nevertheless, outlet losses were observed only when irrigating under wet soil conditions or when applying more than 50mm of DFE. Outlet losses represented at the most 1.2% of the total DFE volume applied and 0.32% of the nutrient and bacterial loads.
Although only 65 to 75% of the soil surface was covered by the applied DFE, the irrigation sessions did provide some additional soil moisture for crops, increasing yield by 31% in 2004. Once absorbed by the soil, the applied DFE did not increase the soil nutrient level and variability in the presence of crop. Thus, the DFE contributed to the irrigation and fertilization of the plots.
Surface irrigation to spread low nutrient DFE, as compared to the conventional tanker system reduced the application costs from $3.05/m3, to $0.95/m3.

New Zealand dairy farmers have been accused in a national 'dirty dairying' campaign of 'selfishly destroying the community's natural water resources' (Fish & Game 2001, pg l) through a combination of point and diffuse source pollution and habitat modification. The dirty dairying debate in response to Fish & Game's campaign is about the conflicts that arise through differing values of rural water resources in New Zealand. That farming practices affect freshwater ecosystems is broadly recognised but poorly understood. The problems encountered in New Zealand's dairy sector, however, are exacerbated by the nature of relationships between dairy industry actors, gaps in information and provision of environmental advice to farmers. This thesis examines aspects of the debate through scientific and social frameworks using three strongly interrelated investigations situated in the laboratory, field and social environment. Each investigation adds further levels of complexity providing potential biophysical solutions as well as insights into the challenges facing those seeking to manage the effects of dairy farming practices. Investigations focused mainly on dairy effluent and stream ecology in the Waikato and Taranaki areas. The research showed that both dairy shed effluent (DSE) dilution in stream flow and stream management practices, particularly riparian shading, were important in reducing the effects of discharges to stony stream communities. In some situations, diffuse inputs from stream management practices had already degraded stream communities, making them less sensitive to discharges. However, significant adverse effects on stream benthic invertebrates were observed for oxidation pond discharges at 338-fold and below, but not at 1000-fold dilution. Significant improvements in rural water and habitat quality are unlikely to be achieved under the regulatory regime in place at the time of the interviews carried out in this research. DSE discharges are controlled through statutory regulation, but in many cases the permitted dilution rates are too low. Controls on diffuse pollution and habitat modification are voluntary, and undertaken by some farmers. Improvements in rural water and habitat quality are constrained by a lack of clear understanding by farmers on the importance of DSE treatment and stream management practices and a lack of impetus to act. Contributing to this is limited availability, transfer and often misalignment of information between dairy industry actors involved in environmental management. However, enhanced information provision alone is unlikely to lead to improved rural water and habitat quality and Fonterra's Clean Stream Accord (May 2003), while contentious, represents a potentially effective way forward for stream management in New Zealand. Success of this Accord depends on all dairy industry actors (including farmers) working together and combining their strengths in order to generate useful, practical information and solutions to achieve improvements in rural water and habitat quality.

Anaerobic ponds are an established technology for treating farm dairy effluent in New Zealand. These ponds produce a significant amount of methane but because of their large size, they are rarely covered for methane capture. The removal of solids prior to entering the ponds would allow for shorter retention times resulting in smaller ponds that could be covered. However, removal of solids entails loss of organic material and thus methane production. It was proposed that improved hydrolysis of solid content prior to solids separation could increase the organic content of the liquid fraction. No literature was found describing two-stage (acidogenic/hydrolytic and methanogenic) systems which achieve hydrolysis combined with solids separation of manure slurries. Hence, the aim of the present study is to examine the feasibility of such a system. Five parameters were examined to determine favourable conditions for hydrolysis of solids and acidogenesis in farm dairy effluent. These were: 1) mixing, 2) hydraulic retention time (HRT), 3) liquid to solid ratio (dilution), 4) addition of rumen contents, and 5) reactor configuration. Continuous mixing of cow manure sludge inhibited net volatile fatty acid (VFA) production, likely due to oxygenation. By comparison, a once-daily brief stirring regime resulted in production of 785 mgVFA/Lsludge compared with 185 mg/L from a continuously stirred reactor. Mixing had little effect on soluble COD yield. HRTs ranging between 1 and 10 days resulted in greater hydrolysis yields (0.25 to 0.33 gCOD/gVSadded) compared with 0.15 gCOD/gVSadded for a 15-day HRT. It was hypothesised that the attachment of hydrolytic bacteria to solids prevented washout at shorter HRTs. In contrast, longer HRTs favoured VFA production. This may have been due to the planktonic nature of acidogenic bacteria, making them more vulnerable to washout at shorter HRTs. The effects of solid:liquid ratio on hydrolysis and acidogenesis were examined with sludge:water ratios ranging from 1:1 to 1:0.25. The addition of larger volumes of water resulted in improved acidogenesis with the 1:1 sludge:water mixture producing a liquor with 245% more VFA mass (635 mg) than reactors with a 1:0.25 sludge:water mixture (184 mg). Addition of rumen contents was shown to have little or no effect on either acidogenesis or hydrolysis. This may have been due to a masking effect of an increased organic load through the addition of undigested grass in the rumen. A mix, settle and decant (MSD) system and an unmixed flow-through leachbed separator system were trialled and compared as hydrolytic/acidogenic reactors. The MSD system produced 0.033gVFA/gTSadded and 0.315gCOD/gTSadded compared with 0.015gVFA/gTSadded and 0.155gCOD/gTSadded in the unmixed leachbed separator. It was hypothesised that improved mixing and longer solid-liquid contact times in the MSD system provided greater surface contact and transfer of organics to the liquid phase thereby enhancing hydrolysis. A two-stage (acidogenic/hydrolytic and methanogenic) system was tested at bench scale. A partially mixed leachbed separator was fed with manure slurry. This retained solids while leaching out a treated feed high in organic content to be fed into a variety of methanogenic systems. The leachbed separator produced a treated feed with a VFA concentration of 562 mg/L, 120% higher than the influent slurry (255 mg/L). Soluble COD increased 60% from 1,085 mg/L in the slurry to 1,740 mg/L in the treated feed. 20-day HRT and 10-day HRT unmixed unheated methanogenic reactors, both fed with treated feed from the leachbed separator, had lower specific methane yields (0.14 and 0.11 LCH4/gVS respectively) than a 50-day HRT reactor fed with untreated slurry (0.17 LCH4/gVS). However, both the 20-day HRT reactor and the 10-day reactor had higher volumetric methane yields (0.033 and 0.057 LCH4/Lreactor/day respectively) than the 50-day HRT reactor fed with slurry (0.024 LCH4/Lreactor/day). Gas production was shown to rise as the VFA levels in the treated feed rose. Fermentation in the leachbed followed by separation was shown to improve average gas production by up to 57% compared to separation alone. Field-scale trials of a leachbed separator system followed by a 20-day HRT methanogenic reactor were undertaken. VFA concentrations increased from 100 mg/l in the influent to 1,260 mg/l in the treated feed, while the soluble COD increased from 2,766 mg/L to 5,542 mg/L. The methanogenic reactor produced 0.08 m3 CH4/ m3reactor/day, four times higher than that which would be expected from a covered pond of the same size. This was hypothesised to be due to the increased biodigestability of the feed to the tank digester as well the increased organic loading rate. This study indicates that the use of a leachbed separator would be an effective low-tech strategy for reducing the HRT of farm anaerobic ponds, and reducing the size of covers required for biogas energy recovery.

The fate of the carbon and nitrogen in dairy farm effluent (DFE) applied onto soil was investigated through laboratory experiments and field lysimeter studies. They resulted in the development and testing of a complex carbon (C) and nitrogen (N) simulation model (CaNS-Eff) of the soil-plant-microbial system. To minimise the risk of contamination of surface waters, regulatory authorities in New Zealand promote irrigation onto land as the preferred treatment method for DFE. The allowable annual loading rates for DFE, as defined in statutory regional plans are based on annual N balance calculations, comparing N inputs to outputs from the farming system. Little information is available, however, to assess the effects that these loading rates have on the receiving environment. It is this need, to understand the fate of land-applied DFE and develop a tool to describe the process, that is addressed in this research. The microbially mediated net N mineralisation from DFE takes a central role in the turnover of DFE, as the total N in DFE is dominated by organic N. In a laboratory experiment, where DFE was applied at the standard farm loading rate of 68 kg N ha⁻¹, the net C mineralisation from the DFE was finished 13 days after application and represented 30% of the applied C, with no net N mineralisation being measured by Day 113. The soluble fraction of DFE appeared to have a microbial availability similar to that of glucose. The low and gradually changing respiration rate measured from DFE indicated a semi-continuous substrate supply to the microbial biomass, reflecting the complex nature and broad range of C compounds in DFE. The repeated application of DFE will gradually enhance the mineralisable fraction of the total soil organic N and in the long term increase net N mineralisation. To address the lack of data on the fate of faecal-N in DFE, a ¹⁵N-labelled faecal component of DFE was applied under two different water treatments onto intact soil cores with pasture growing on them. At the end of 255 days, approximately 2% of the applied faecal ¹⁵N had been leached, 11 % was in plant material, 11 % was still as effluent on the surface, and 40% remained in the soil (39% as organic N). Unmeasured gaseous losses and physical losses from the soil surface of the cores supposedly account for the remaining ¹⁵N (approximately 36%). Separate analysis of the total and ammonium nitrogen contents and ¹⁵N enrichments of the DFE and filtered sub-samples (0.5 mm, 0.2µm) showed that the faecal-N fraction was not labelled homogeneously. Due to this heterogeneity, which was exacerbated by the filtration of DFE on the soil surface, it was difficult to calculate the turnover of the total faecal-N fraction based on ¹⁵N results. By making a simplifying assumption about the enrichment of the ¹⁵N in the DFE that infiltrated the soil, the contribution from DFE-N to all plant available N fractions including soil inorganic N was estimated to have been approximately 11 % of the applied DFE-N. An initial two-year study investigating the feasibility of manipulating soil water conditions through controlled drainage to enhance denitrification from irrigated DFE was extended a further two years for this thesis project. The resulting four-year data set provided the opportunity to evaluate the sustainability of DFE application onto land, an extended data set against which to test the adequacy of CaNS-Eff, and to identify the key processes in the fate of DFE irrigated onto soil under field conditions. In the final year of DFE irrigation, 1554 kg N ha⁻¹ of DFE-N was applied onto the lysimeters, with the main removal mechanism being pasture uptake (700 kg N ha⁻¹ yr⁻¹ removed). An average of 193 kg N ha⁻¹ yr⁻¹ was leached, with 80% of this being organic N. The nitrate leaching decreased with increasing soil moisture conditions through controlled drainage. At the high DFE loading rate used, the total soil C and N, pH and the microbial biomass increased at different rates over the four years. The long-term sustainability of the application of DFE can only be maintained when the supply of inorganic N is matched by the demand of the pasture. The complex simulation model (CaNS-Eff) of the soil-plant-microbial system was developed to describe the transport and transformations of C and N components in effluents applied onto the soil. The model addresses the shortcomings in existing models and simulates the transport, adsorption and filtration of both dissolved and particulate components of an effluent. The soil matrix is divided into mobile and immobile flow domains with convective flow of solutes occurring in the mobile fraction only. Diffusion is considered to occur between the micropore and mesopore domains both between and within a soil layer, allowing dissolved material to move into the immobile zone. To select an appropriate sub-model to simulate the water fluxes within CaNS-Eff, the measured drainage volumes and water table heights from the lysimeters were compared to simulated values over four years. Two different modelling approaches were compared, a simpler water balance model, DRAINMOD, and a solution to Richards' equation, SWIM. Both models provided excellent estimation of the total amount of drainage and water table height. The greatest errors in drainage volume were associated with rain events over the summer and autumn, when antecedent soil conditions were driest. When soil water and interlayer fluxes are required at small time steps such as during infiltration under DFE-irrigation, SWIM's more mechanistic approach offered more flexibility and consequently was the sub-model selected to use within CaNS-Eff. Measured bromide leaching from the lysimeters showed that on average 18% of the bromide from an irrigation event bypassed the soil matrix and was leached in the initial drainage event. This bypass mechanism accounted for the high amount of organic N leached under DFE-irrigation onto these soils and a description of this bypass process needed to be included in CaNS-Eff. Between 80 and 90% of the N and C leached from the lysimeters was particulate (> 0.2 µm in size), demonstrating the need to describe transport of particulate material in CaNS-Eff. The filtration behaviour of four soil horizons was measured by characterising the size of C material in a DFE, applying this DFE onto intact soil cores, and collecting and analyzing the resulting leachate using the same size characterisation. After two water flushes, an average of 34% of the applied DFE-C was leached through the top 0-50 mm soil cores, with a corresponding amount of 27% being leached from the 50-150 mm soil cores. Most of the C leaching occurred during the initial DFE application onto the soil. To simulate the transport and leaching of particulate C, a sub-model was developed and parameterised that describes the movement of the effluent in terms of filtering and trapping the C within a soil horizon and then washing it out with subsequent flow events. The microbial availability of the various organic fractions within the soil system are described in CaNS-Eff by availability spectra of multiple first-order decay functions. The simulation of microbial dynamics is based on actual consumption of available C for three microbial biomass populations: heterotrophs, nitrifiers and denitrifiers. The respiration level of a population is controlled by the amount of C that is available to that population. This respiration rate can vary between low level maintenance requirements, when very little substrate is available, and higher levels when excess substrate is available to an actively growing population. The plant component is described as both above and below-ground fractions of a rye grass-clover pasture. The parameter set used in CaNS-Eff to simulate the fate of DFE irrigated onto the conventionally drained lysimeter treatments over three years with a subsequent 10 months non-irrigation period was derived from own laboratory studies, field measurements, experimental literature data and published model studies. As no systematic calibration exercise was undertaken to optimise these parameters, the parameter set should be considered as "initial best estimates" and not as a calibrated data set on which a full validation of CaNS-Eff could be based. Over the 42 months of simulation, the cumulative drainage from CaNS-Eff for the conventionally drained DFE lysimeter was always within the 95% CI of the measured value. On the basis of individual drainage bulking periods, CaNS-Eff was able to explain 92% of the variation in the measured drainage volumes. On an event basis the accuracy of the simulated water filled pore space (WFPS) was better than that of the drainage volume, with an average of 70% of the simulated WFPS values being within the 95% CI for the soil layers investigated, compared to 44% for the drainage volumes. Overall the hydrological component of CaNS-Eff, which is based on the SWIM model, could be considered as satisfactory for the purposes of predicting the soil water status and drainage volume from the conventionally drained lysimeter treatment for this study. The simulated cumulative nitrate leaching of 4.7 g NO₃-N m⁻² over the 42 months of lysimeter operation was in good agreement to the measured amount of 3.0 (± 2.7) g NO₃-N m⁻². Similarly, the total simulated ammonium leaching of 2.7g NH₄- N m⁻² was very close to the measured amount of 2.5 (± 1.35) g NH₄- N m⁻² , however the dynamics were not as close to the measured values as with the nitrate leaching. The simulated amount of organic N leached was approximately double that measured, and most of the difference originated from the simulated de-adsorption of the dissolved fraction of organic N during the l0-month period after the final DFE irrigation. The 305 g C m⁻² of simulated particulate C leached was close to the measured amount of 224 g C m⁻² over the 31 months of simulation. The dissolved C fraction was substantially over-predicted. There was good agreement in the non-adsorbed and particulate fractions of the leached C and N in DFE. However, the isothermic behaviour of the adsorbed pools indicated that a non-reversible component needed to be introduced or that the dynamics of the de-adsorption needed to be improved. Taking into account that the parameters were not calibrated but only "initial best estimates", the agreement in the dynamics and the absolute amounts between the measured and simulated values of leached C and N demonstrated that CaNS-Eff contains an adequate description of the leaching processes following DFE irrigation onto the soil. The simulated pasture N production was in reasonable agreement with the measured data. The simulated dynamics and amounts of microbial biomass in the topsoil layers were in good agreement with the measured data. This is an important result as the soil microbial biomass is the key transformation station for organic materials. Excepting the topsoil layer, the simulated total C and N dynamics were close to the measured values. The model predicted an accumulation of C and N in the topsoil layer as expected, but not measured. Although no measurements were available to compare the dynamics and amounts of the soil NO₃-N and NH₄-N, the simulated values appear realistic for an effluent treatment site and are consistent with measured pasture data. Considering the large amount of total N and C applied onto the lysimeters over the 42 months of operation (4 t ha⁻¹ of N and 42 t ha⁻¹0f C), the various forms of C and N in dissolved and particulate DFE as well as in returned pasture, and that the parameters used in the test have not been calibrated, the simulated values from CaNS-Eff compared satisfactorily to the measured data.

The last decade has been a period of great expansion and land use intensification for the New Zealand dairy farming industry with a 44% increase in national dairy cow numbers. Intensive dairy farming is now considered to be a major contributor to the deterioration in the quality of surface and ground water resources in some regions of New Zealand. Previous research has demonstrated intensive dairy farming is responsible for accelerated contamination of wateways by nutrients, suspended solids, pathogenic organisms and faecal material. A number of common dairy farming practices increase the risk of nutrient leaching. In particular, farm dairy effluent (FDE) has been implicated as a major contributor to the degradation of water quality. With the introduction of the Resource Management Act in 1991, the preferred treatment for FDE shifted away from traditional two-pond systems to land application. However, on most farms, irrigation of FDE has occurred on a daily basis, often without regard for soil moisture status. Therefore, it has been commonplace for partially treated effluent to drain through and/or runoff soils and contaminate fresh water bodies. The objectives of this thesis were to design and implement a sustainable land application system for FDE on difficult to manage, mole and pipe drained soils, and to assess the impacts of FDE application, urea application and cattle grazing events on nutrient losses via artificial drainage and surface runoff from dairy cattle grazed pasture. To meet these objectives a research field site was established on Massey University's No.4 Dairy farm near Palmerston North. The soil type was Tokomaru silt loam, a Fragiaqualf with poor natural drainage. Eight experimental plots (each 40 x 40 m) were established with two treatments. Four of the plots represented standard farm practice including grazing and fertiliser regimes. Another four plots were subjected to the same farm practices but without the fertiliser application and they were also irrigated with FDE. Each plot had an isolated mole and pipe drainage system. Four surface runoff plots (each 5 m x 10 m) were established as subplots (two on the fertilised plots and two on the plots irrigated with FDE) in the final year of the study. Plots were instrumented to allow the continuous monitoring of drainage and surface runoff and the collection of water samples for nutrient analyses. An application of 25 mm of FDE to a soil with limited soil water deficit - simulating a 'daily' irrigation regime - resulted in considerable drainage of partially treated FDE. Approximately 70% of the applied FDE left the experimental plots with 10 mm of drainage and 8 mm of surface runoff. The resulting concentrations of N and P in drainage and runoff were approximately 45% and 80% of the original concentrations in the applied FDE, respectively. From this single irrigation event, a total of 12.1 kg N ha-1 and 1.9 kg P ha-1 was lost to surface water representing 45% of expected annual N loss and 100% of expected annual P loss. An improved system for applying farm dairy effluent to land called 'deferred irrigation' was successfully developed and implemented at the research site. Deferred irrigation involves the storage of effluent in a two-pond system during periods of small soil moisture deficits and the scheduling of irrigation at times of suitable soil water deficits. Deferred irrigation of FDE all but eliminated direct drainage losses with on average <1 % of the volume of effluent and nutrients applied leaving the experimental plots. Adopting an approach of applying 'little and often' resulted in no drainage and, therefore, zero direct loss of nutrients applied. A modelling exercise, using the APSlM simulation model, was conducted to study the feasibility of practising deferred irrigation at the farm scale on No 4 Dairy farm. Using climate data for the past 30 years, this simulation exercise demonstrated that applying small application depths of FDE, such as 15 mm or less, provided the ability to schedule irrigations earlier in spring and decreased the required effluent storage capacity. A travelling irrigator, commonly used to apply FDE (a rotating irrigator), was found to have 2-3 fold differences in application depth and increased the risk of generating FDE contaminated drainage. New irrigator technology (an oscillating travelling irrigator) provided a more uniform application pattern allowing greater confidence that an irrigation depth less than the soil water deficit could be applied. This allowed a greater volume to be irrigated, whilst avoiding direct drainage of FDE when the soil moisture deficit is low in early spring and late autumn. A recommendation arising from this work is that during this period of low soil water deficits, all irrigators should be set to travel at their fastest speed (lowest application depth) to minimise the potential for direct drainage of partially treated FDE and associated nutrient losses. The average concentrations of N and P in both 2002 and 2003 winter mole and pipe drainage water from grazed dairy pastures were all well above the levels required to prevent aquatic weed growth in fresh water bodies. Total N losses from plots representing standard farm practice were 28 kg N ha-1 and 34 kg N ha-1 for 2003 and 2004, respectively. Total P losses in 2003 and 2004 were 0.35 kg P ha-1 and 0.7 kg P ha-1, respectively. Surface runoff was measured in 2003 and contributed a further 3.0 kg N ha-1and 0.6 kg P ha-1. A number of common dairy farm practices immediately increased the losses of N and P in the artificial drainage water. Recent grazing events increased NO3--N and DIP concentrations in drainage by approximately 5 mg litre-1 and 0.1 mg litre-1, respectively. The duration between the grazing and drainage events influenced the form of N loss due to a likely urine contribution when grazing and drainage coincide, but had little impact on the total quantity of N lost. Nitrogen loss from an early spring application of urea in 2002 was minimal, whilst a mid June application in 2003 resulted in an increased loss of NO3--N throughout 80 mm of cumulative drainage suggesting that careful timing of urea applications in winter is required to prevent unnecessary N leaching. Storage and deferred irrigation of FDE during the lactation season caused no real increase in either the total-N concentrations or total N losses in the winter drainage water of 2002 and 2003. In contrast, land application of FDE using the deferred irrigation system resulted in a gradual increase in total P losses over the 2002 and 2003 winter drainage seasons. However, this increase represents less than 4% of the P applied in FDE during the lactation season. An assessment of likely losses of nutrients at a whole-farm scale suggests that it is standard dairy farming practice (particularly intensive cattle grazing) that is responsible for the great majority of N and P loss at a farm scale. When expressed as a proportion of whole-farm losses, only a very small quantity of N is lost under an improved land treatment technique for FDE such as deferred irrigation. The management of FDE plays a greater role in the likely P loss at a farm scale with a 5% contribution to wholefarm P losses from deferred irrigation.

This book is the first detailed and comprehensive guide to the use of feedpads in the dairy industry, from planning and construction to day-to-day management, written especially for farmers. With ongoing droughts and access to water driving up the cost of conserved forages and feeding concentrates, feedpads offer flexible and efficient systems to maximise returns on feeding expensive supplements to grazing dairy cows, and form part of the risk management strategy for dairy farms. Feedpads for Grazing Dairy Cows covers all the aspects of animal husbandry involved in running a successful system and addresses key issues such as formulating rations to balance grazed pasture, management of farm labour and effluent management. The key principles of dairy nutrition are explained along with the concept of partial mixed rations and the range of potential ingredients. The authors also cover the physical features of feedpad design and construction and provide a checklist for planning a feedpad. They discuss important issues such as cow welfare, animal health and the management of effluent, including cleaning the pad, storing and recycling these solids and liquids on farm while minimising feedpad odours, flies and vermin. This book demonstrates a wide range of long-term economic benefits and will play an important role in helping dairy farmers achieve higher farm profitability.

In this paper, we design a supply-side infrastructure for data centers that runs primarily on energy from digested farm waste. Although the information technology and livestock industries may seem completely disjoint, they have complementary characteristics that we exploit for mutual benefit. In particular, the farm waste fuels a combined heat and power system. The data center consumes the power, and its waste heat feeds back into the combined system. We propose a resource management system to manage the resource flows and effluents, and evaluate the direct and indirect economic benefits. As an example, we explain how a hypothetical farm of 10,000 dairy cows could fulfill the power requirements of a 1MW data center.