Guido Haas

Life Cycle Assessment framework in agriculture on the farm level.

Life Cycle Assessment (LCA) is a method that can be used to assess the environmental impact of agriculture, but impact categories and the functional unit of classical LCA’s must be adapted to the specific agricultural production process. Serving as an example, the framework of a LCA of 18 grassland dairy farms covering three farming intensity levels and carried out in the Allgäu region in southern Germany is presented. By focussing on the chosen impact categories and the respective, suitable functional units, the specific needs and backgrounds of conducting an agricultural LCA are discussed in general.

Farm-gate nutrient balance assessment of organic dairy farms at different intensity levels in Germany

Organic farms are characterized as low external input agro-ecosystems. Currently, some organic dairy farmers feed higher amounts of concentrates and succulent feed, some of which is purchased, to increase the dairy performance of their cows. To assess the environ¬mental impact of this practice, nutrient balances at the farm-gate level of 26 organic dairy farms located in two different regions in Germany were compiled and analysed. The farms are characterised by different production features and feeding intensity levels (0 - 2.72 t DM of concentrates per cow and year, which was 0 - 378 g kg-1 milk) yielding 5,150 - 8,790 kg milk on average per cow and year. The area- and product- (milk) related farm-gate nutrient budgets for P and K are almost balanced (mean -3 kg P ha-1, range (R): -14 to 4 kg P ha-1; -0.5 g P kg-1 milk, R: -2.8 to 0.9 g P kg-1 milk and 1 kg K ha-1, R: -13 to 15 kg K ha-1; 0.1 g K kg-1 milk, R: -2.4 to 3.9 g K kg-1 milk). The N surplus averages only 43 kg ha-1 (R: 8 to 85 kg N ha-1) and 8.2 g kg-1 milk (R: 2.1 to 17.1 g kg-1 milk), but the correlation between the amount of feed purchased on a net basis and N surplus is significant (r = 0.56, p = 0.003). Average area-related nutrient use efficiency for all farms calculated as the proportion of input to output is high for N (45%), P (164%) and K (91%). The share of nutrient input and output components and correlations between parameters are presented. To classify the results, investigations comparing organic and conventional dairy farming in Europe are listed, indicating an N surplus for organic farms, which is often only half or a third of the surplus of conventional farms. However, intensification in organic dairy farming has, in some cases, significant impacts that need to be assessed to determine its environmental performance and profile.

Nutrient cycling in organic farms: stall balance of a suckler cow herd and beef bulls

In organic agriculture, the internal farm nutrient cycle must bequantified to ensure high system productivity accompanied by environmentallysound production processes. In contrast to common farm-gate and field balances,budgeting at the stall level is seldom undertaken. When budgeting mixed farmingsystems, a substantial lack of nutrients can be detected in the “forageand straw input – stall – manure output” nutrient flow chain.Therefore, stall balances focus on a central component of whole-farm nutrientbudgets for developing efficient nutrient management strategies. At theexperimental farm for organic agriculture at Wiesengut in Hennef, Germany, allsolid mass flows for a suckler herd and a herd of beef bulls were measured.Relative balance values obtained for dry matter and C (45 to 56%), N (16to 36%), P (−7 to 22.5%), K (0 to 13%) and ash(−4 to 7%) varied over a wide range. Balances are very sensitive tovariations in mass flow and nutrient content for components with high nutrientcontents and/or a large contribution to total mass flow (e.g. manure, silage).In developing strategies to minimise N losses, by reducing N surplus in theration, one must consider, that, in contrast to dairy farms, a suckler herd forbeef production integrated in an organic farm has to adapt to crop productiondemands.

Nitrogen from Hairy Vetch (Vicia villosa Roth) as Winter Green Manure for White Cabbage in Organic Horticulture

ABSTRACT The effect of the nitrogen (N) supply from hairy vetch, grown as winter green manure, on white cabbage was investigated in field trials performed on an organic farm in north-west Germany over two years. Hairy vetch was either used as green manure or harvested. One of two bare soil fallow treatments was supplied with hairy vetch shoot mass to serve as a reference. In 2002 and 2003, hairy vetch and weeds accumulated 136 and 178 kg ha−1 of shoot N and yielded 3.79 and 4.721 ha−1, respectively. After ploughing and planting white cabbage (Brassica oleracea L. convar, capitata var: capitata f. alba) at the beginning of June, the amount of soil mineral N (SMN) in the topsoil layer was investigated biweekly for about 6–8 weeks until canopy. In 2002, a maximum of 121 kg SMN ha−1 for the green manure hairy vetch treatment was reached within 2 weeks, whereas in 2003 a maximum of only 60 kg SMN ha−1 was observed, due to an exceptionally dry and warm season. In 2002, white cabbage shoot yielded an average 4.4 t DM ha−1 (range 3.9–5.1 t ha−1 DM) and had accumulated 153 kg N ha−1 (range 129–178 kg N ha−1). Mean fresh matter yield (FM) of a single head was only 1.2 kg ± 0.1 kg due to severe pest damage. In the following year, the mean head yield was 5.1 kg FM (range 3.4–6.4 kg) and head yield per hectare was 5.8 t DM (range 4.6–7.5 t DM ha−1) with a mean head N uptake of 182 kg ha−1 (range 136–237 kg N ha−1). The relationship between the weighted arithmetic daily mean of SMN for the first 6–8 weeks after the hairy vetch harvest date and the N uptake of cabbage at two sampling dates was significant, as were most correlations between presented core parameters. Although only about 27% of the N supplied in the green manure was apparently recovered in cabbage shoot at final harvest, a balanced field N budget can be ensured by using hairy vetch as a basic N source for a subsequent white cabbage cash crop.