November Reducing greenhouse gas emissions. Case study 6

Transcription

1 November 2009 Reducing greenhouse gas emissions Case study 6

2 Farm Details Location - West Midlands Farm size ha Farm type - Dairy with arable contracting 330 cows, all-year round calving with an average yield of 9000 litres per cow/year, and 300 youngstock. There are straw bedded cubicles for 200 cows, with the remainder of the cows and youngstock housed in straw yards. All stock are housed during the winter and turned out to grass during the spring and summer months. In addition to the dairy unit and associated arable land, a contracting business is operated within the farming system. The soil type is predominantly medium loam over clay, which is well suited to grassland and arable cropping, but with some heavy belts of clay areas which are used for grazing youngstock in the summer. Cropping Winter Oats Winter Wheat Maize Grassland Area 20 ha (50ac) 36 ha (88ac) 31 ha (76ac) 156 ha (386ac) Key areas of the farming system that are helping to reduce greenhouse gas emissions by good practice: 1. Reducing carbon dioxide emissions The following methods are employed on the farm to cut fuel and energy costs and associated carbon dioxide emissions from the farm: Eco power tractors have been used on the farm for 2 years. The maximum engine speed is lowered by 400 rpm and the average piston speed is reduced by 20%. This has resulted in a reduction in fuel consumption of 10% (and reduced engine noise) Minimum tillage - wheat is direct drilled into maize stubble, reducing the number of tractor passes Cows are encouraged to graze for as long as possible during the year, reducing the amount of silage needed and the use of machinery associated with feeding and slurry spreading The use of a high-forage ration reduces the amount of purchased feed transported to the farm

3 2. Cow rations The dairy cow ration has recently been reformulated following a change of milk buyer. The ration now consists of maize and grass silage, haylage, rolled wheat, maize germ, soya hulls, soya bean meal, rapeseed meal and molasses. This has resulted in an increase of 2.5 litres of milk per cow/day, and an increase to 3.8% butterfat content, at no extra cost. Silage sampling is undertaken on an annual basis. Cow cubicles There has been a reduction in ammonia N as a % of total N in the silage (now less than 4%) since reducing manufactured nitrogen applications to grassland. The silage dry matter has also increased. As less of the plant protein is degraded to ammonia in the clamp, there is more chance of it being utilised by the cow, and therefore less N is excreted. 3. Manure storage and use Both dairy cow slurry and farm yard manure (FYM) are produced on the farm. FYM is stored in a heap under cover (see picture). All slurry is scraped by a tractor into a reception pit at the end of the scraping yard and is pumped regularly to the uncovered slurry store which has a maximum capacity of 2273 m 3 (500,000 gallons). FYM storage

4 Applications of manure and slurry The farm utilises both FYM and slurry in order to provide nutrients for growing crops and reduce reliance on manufactured fertilisers. Standard nutrient values are used for FYM and slurry management. Hydrometers have been used in the past to analyse slurry, but the figures have been so close to typical values that standard values are now used. The FYM is applied to the maize ground in April or onto the cereal ground using a standard rear discharge spreader. All spring applications of FYM are incorporated by ploughing within 24 hours of application to minimise ammonia losses. The slurry store is emptied by the end of March and again after 1 st cut silage, and the amount stored is kept low during the summer months with regular applications on the grazing ground. No applications are made during the winter when N utilisation is known to be poor. The slurry is applied using an injector at a rate of m 3 per hectare. The lower rate is used on the grazing land and highest rate on cutting land. The use of a slurry injector does not reduce the palatability of the grass as the slurry is placed on the soil surface leaving clean grass for grazing. Injector application is also believed to promote benefits in terms of soil aeration each time it is used, along with reduced ammonia emissions and improved crop N recovery.. 4. Nutrient planning Manure is applied to the maize fields to provide nutrients for the maize and following winter wheat crop. Soil analyses are carried out for the whole farm every 4-5 years. These figures are used to assess the ph, P and K status of the soil, and manure applications (and manufactured fertiliser if required) are planned on the basis of the results. By taking better account of the nutrients in manures over the last 10 years, fertiliser purchases have been reduced - with positive financial benefit to the business and no reductions in crop quality or yields. Reduced use of manufactured N fertiliser will have reduced nitrous oxide emissions. There has been a reduction of 40 tonnes in the amount of manufactured nitrogen purchased on the farm, amounting to a saving of 10,800 per year. There has also been a saving of 20,000 on P and K by better use of manures and soil sampling, giving a total saving of 30,800 per year. This has been a huge financial benefit to the business. The savings made have been used to finance capital investment in slurry storage and the slurry injector, which have both been financially worthwhile for the business and are currently helping the farm comply with Nitrate Vulnerable Zone regulations.

5 Conclusions Strengths Regular soil testing to better match crop requirements and nutrient applications has reduced manufactured N use and associated nitrous oxide emissions Use of injection for slurry applications to grassland reduced ammonia emissions Eco Power tractors used to reduce carbon dioxide emissions through reduced fuel consumption Opportunities Reduce the winter housing period and associated GHG emissions for silage making and manure management Storage of slurry - could be covered to reduce emissions On farm anaerobic digestion of manures to reduce methane losses but capital costs remain a barrier While AHDB, operating through its DairyCo division, seeks to ensure that the information contained within this document is accurate at the time of printing no warranty is given in respect thereof and, to the maximum extent permitted by law the Agriculture and Horticulture Development Board accepts no liability for loss, damage or injury howsoever caused (including that caused by negligence) or suffered directly or indirectly in relation to information and opinions contained in or omitted from this document. Agriculture and Horticulture Development Board All rights reserved.