Ammonia emissions from outdoor fattening pigs on concrete pad – a farm case study

Keeping organic fattening pigs indoors with access to an outdoor concrete pad is common in EU countries. The main environmental impact is related to a risk of high ammonia emissions from excretions on the concrete pad. The objective was to evaluate the effect of frequency of scraping the pigs’ toilet, on ammonia (NH3) emissions. The experiment was conducted at an organic pig farm in southern Sweden over three consecutive days in August. The experiment included four groups of 68 fattening pigs per group, 24 weeks old. Each group had access to an outdoor concrete area (116,4 m2) divided into two sections with a wall

Vattenflöden i djurstallar

Manure quality and quantity have been shown to change a lot through dilution from identified and diffuse water sources. Knowledge of the dry matter contents (DM) of the manure is needed for effective use of the manure as fertilizer and to avoid too high doses causing losses of nutrients to the surrounding water bodies. Based on this, water flow measurements were carried out at the five Swedish pilot farms. All water ending up in the manure storage was included. The measurement took note of drinking (indoor and outdoor), milk room (dishing etc), washing (stable, milk room, field equipment), feeding, staff areas and total consumption. The results were used for discussion on improving the handling of water in VERA, the Swedish calculation tool for manure quantity and quality on farms. The water amount from the different water categories differed between the animal categories, where dairy cows used in total 30-35 m3 per animal and year and the fatteners and sows around 8-10 m3 per animal and year. Out of the total water to the dairy cows, around 75-80% of the water was drinking water and the rest other technological water (e.g. cleaning of milk room, milking pit and dishes). For pigs the ratio was higher for drinking water, 95-almost 100 %. Here the largest amount of water was from wet foddering making up 80 % of the drinking water. Water through water cups per dairy cow amounted to around 25 m3 per year depending on if drinking water on pasture was included or not. This gives a daily consumption of 65-75 litres per animal and day which is a bit low compared to the literature. A concluding remark is that neither technical water (except for washing water at dairy farms) nor a variability in precipitation did have any major effect on the DM contents in slurry ex-storage. Instead, the water supply from faeces and urine was what determined the DM content. Additional water flow measurements on farms would provide data that should be used for generating improved default values for the calculation tools

Development of a mobile organic piggery for outdoor pork production – function, productivity, animal behaviour and environmental risk assessments

Pens in outdoor pig systems in general become permanent during the grazing period. The excretion behaviour of the pigs creates plant nutrient hotspots within pens. In this study we developed a mobile organic piggery (MOP) without electric fencing that can be moved to a new grazing area each day. The aims were to distribute plant nutrients evenly, provide the pigs with continuous access to fresh herbage, and improve productivity and the working environment. Initially, 25 fattening piglets were installed in the MOP on a clover/grass ley. Nitrogen, P and K flows to and from the MOP were monitored during 87 days. The purchased feed included 80% of the energy norm for pigs in indoor systems and the pigs were automatically fed. The MOP was moved 65 times. Behavioural studies including excretion behaviour were conducted during a two-week period. Net nutrient accumulation was 88 kg N, 31 kg P and 10 kg K ha-1 for the total grazing area (4212 m2). Average liveweight gain was 675 g day-1. Average feed conversion rate was 2.7 kg feed kg-1 liveweight gain. The pigs grazed, on average, almost half the day. With the MOP system it was possible to use a lower quality concentrate feed in terms of energy and protein supply in combination with regular access to fresh herbage. The MOP system also allowed a more even distribution of animal manure within the total grazing area, compared with permanent pens. Avoiding harmful point loads of nutrients decrease the risk of nutrient losses

Precisionssådd av höstoljeväxter

Precision seeding of winter oilseed rape The project aimed at increasing knowledge of precision establishment of oil seed rape. The hypothesis was that precision sowing in rows with low seed rates and close placing of N will optimize crop autumn development, overwintering, and seed pay-off. In total 12 field trials were conducted in southern and middle Sweden during the harvest years 2019–2022. Treatments included seeding with Väderstad Tempo, 45 cm row spacing, and seeding rates of 20, 35, 50 and 65 plants per m2. As a reference seeding was also done traditionally with a Väderstad Rapid, 12,5 cm row spacing and 50 plants per m2. In average there were no effect of neither seed rate nor row spacing on yield. In individual field experiments where low seed rates yielded better than high seed rates, this followed on a well-developed oil seed rape plant with a high shoot- and root biomass and a large root neck diameter in late autumn. Physiological plant development was affected by seed rate. Number of leaves, root neck diameter and above and below ground biomass was negatively correlated to the seed rate while there was a tendency for the growing point being positively correlated to the seed rate. The number of leaves per plant, shoot and rot biomass and to some extent also root neck diameter and the height of growing point was positively correlated to accumulated day degrees during autumn

Ammoniakavgång från flytgödsellager : orötad och rötadnötflygödsel, med och utan surgörning

The study concerns acidification at the beginning of storage to reduce ammonia emissions during storage. The aim of the study was to evaluate the reduction of ammonia emissions by the acidification of cattle slurry, digested and non-digested, in storage under summer conditions. Cattle slurry (CS) and digested cattle slurry (DCS) were taken from a dairy farm with a digester plant. The sulphuric acid required for acidification to pH 5.5 was determined by titration before the pilot-scale experiment began. In the pilot-scale experiment, each slurry type was divided into two containers. One batch was acidified to pH<5.5 by adding sulphuric acid (96%) slowly with gentle mixing. The other batch was not acidified. During acidification, the pH was measured frequently and the total amounts of acid added were noted. Temperatures were measured during the four-month storage period with loggers at 0.1 m from the bottom and 0.1 m from the surface of each container. Data were continuously recorded hourly. Ammonia emissions were measured using a micrometeorological mass balance method with passive flux samplers. There were five measuring periods during the warm storage period from May to August. The length of the measuring periods ranged from 3 to 14 days, with the shortest period at the start of storage. On a pilot scale, the acid consumption for reaching pH< 5.5 was 1.1 L/m3 for CS and 6.2 L/m3 for DCS. The change in pH after acidification was rather limited and the pH stayed <6 throughout the four-month storage period for both CS and DCS. On a laboratory scale, more acid was needed to reach pH 5.5, and the pH increased more, with less buffering, than on a pilot scale. The reasons for this could be higher temperatures, frequent mixing, small volumes, and the use of diluted acid on a laboratory scale compared with on a pilot scale. On a laboratory scale, it was possible to show differences in acid demand between slurry types, but the amounts of acid needed seem to be different (higher) compared with pilot scale. The estimated cumulative NH3-N emissions corresponded to about 19% of total-N for CS and about 26% of total-N for DCS. The estimated cumulative NH3-N emissions were about the same as a percentage of TAN for CS and for DCS (57.8 and 53.9% respectively). Emissions from the acidified batches of slurry were overall negligibly low. The addition of acid decreased ammonia emissions very effectively, for both CS and DCS.Denna studie handlar om hur surgörning av flytgödsel vid start av lagringen kan minska ammoniakavgången under lagringsperioden maj till augusti. Målet var att bestämma minskningen av ammoniakavgången genom att surgöra nötflytgödsel, både orötad och rötad och se effekten jämfört med gödsel utan syratillsats. Flytgödsel (CS) och rötad nötflytgödsel (DCS) hämtades från en mjölkkogård med en biogasanläggning. För att få ett riktvärde för den syramängd som skulle åtgå för att sänka pH hos respektive gödseltyp till 5,5, utfördes titreringar i laboratorium innan uppstart av lagringsförsöket i pilotskala. Lagrings­anläggningen bestod av fyra behållare á 3 m3. Vid fyllningen av lagren, delades varje gödselslag upp mellan två behållare, varav det i en av behållarna tillsattes svavelsyra (96 %-ig) samtidigt som gödseln rördes om försiktigt med en eldriven propeller. Den andra behållaren rördes om också men utan tillsats av syra. Under syratillsättningen mättes pH vid upprepade tillfällen och totala mängden syra noterades. Gödseln lagrades under fyra månader från maj till augusti samtidigt som gödseltemperaturen registerades på två nivåer i varje behållare, vid gödsel­ytan och nära botten, och temperaturvärdena registrerades varje timme. Under lagringen mättes ammoniakavgången med en mikrometeorologisk massbalansmetod med passiva fluxprovtagare. Fluxprovtagarna var monterade på master runt varje behållare under exponeringen. Totalt var det fem mät­perioder, som varade 3 till 14 dagar, med den kortaste perioden direkt efter fyllningen i maj. För att sänka pH till 5,5 åtgick 1,1 liter per m3 för CS och 6,2 liter  per m3 för DCS. Under lagringen steg pH hos de surgjorda gödselslagen obetydligt och låg i slutet av lagringen på pH mindre än 6 hos båda gödselslagen. Vid titreringen i laboratorium före start av lagringsförsöket behövdes det betydligt mer syra för att nå pH 5,5 än i pilotskalan. Orsaker till det kan vara att i laboratoriet var temperaturen högre, gödselvolymerna små, gödseln blandades om ofta, samt att vid titreringen användes utspädd syra. Men även i laboratorieskalan var det stora skillnader mellan CS och DCS i syraförbrukning, så titrering kan användas som en grov uppskattning och för att se skillnader mellan olika gödselslags syrabehov. Däremot kan det vara svårt att förutse behovet av mer exakta syramängder i större skala. Totalt uppskattades den kumulativa ammoniakavgången i kvävemängd uppgå till ca 19 % av totala kväveinnehållet hos nötflytgödsel (CS) och 26 % av kväve­innehållet i den rötade gödseln (DCS) när ingen syra hade tillsatts.  Motsvarande siffror i procent av innehållet av det lättlösliga ammoniumkvävet var 57,8 % för CS och 53,9 % för DCS. Ammoniakavgången från den surgjorda CS och DCS gödseln var mycket liten och i stort negligerbar. Det betyder att tillsats av syra minskade ammonia-kavgången mycket effektivt, både för CS och DCS