Life cycle assessment of Swiss farming systems: II. Extensive and intensive production

Extensive or low-input farming is considered a way of remedying many problems associated with intensive farming practices. But do extensive farming systems really result in a clear reduction in environmental impacts, especially if their lower productivity is taken into account? This question is studied for Swiss arable cropping and forage production systems in a comprehensive life cycle assessment (LCA) study. Three long-term experiments (DOC experiment comparing bio-dynamic, bio-organic and conventional farming, the "Burgrain" experiment including integrated intensive, integrated extensive and organic systems and the "Oberacker" experiment with conventional ploughing and no-till soil cultivation, are considered in the LCA study. Furthermore, model systems for arable crops and forage production for feeding livestock are investigated by using the Swiss Agricultural Life Cycle Assessment method (SALCA). The analysis covers an overall extensification of cropping systems and forage production on the one hand and a partial extensification of fertiliser use, plant protection and soil cultivation on the other. The overall extensification of an intensively managed system reduced environmental impacts in general, both per area unit and per product unit. In arable cropping systems medium production intensity gave the best results for the environment, and the intensity should not fall below the environmental optimum in order to avoid a deterioration of eco-efficiency. In grassland systems, on the contrary, a combination of both intensively and extensively managed plots was preferable to medium intensity practices on the whole area. The differences in yield, production intensity and environmental impact were much more pronounced in grassland than in arable cropping systems. Partial extensification of a farming system should be conceived in the context of the whole system in order to be successful. For example, the extensification solely of fertiliser use and soil cultivation resulted in a general improvement in the environmental performance of the farming system, whereas a reduction in plant protection intensity by banning certain pesticide categories reduced negative impacts on ecotoxicity and biodiversity only, while increasing other burdens such as global warming, ozone formation, eutrophication and acidification per product unit. The replacement of mineral fertilisers by farmyard manure as a special form of extensification reduced resource use and improved soil quality, while slightly increasing nutrient losses. These results show that a considerable environmental improvement potential exists in Swiss farming systems and that a detailed eco-efficiency analysis could help to target a further reduction in their environmental impacts.Farming systems Intensive production Extensive production Low-input farming Life cycle assessment Environmental impacts

Two decades of no-till in the Oberacker long-term field experiment: Part I. Crop yield, soil organic carbon and nutrient distribution in the soil profile

This is the first in a series of papers describing the impact of two decades of no-till in the Oberacker long-term field experiment in Switzerland. The experiment was established in 1994 on a sandy loam and compares two tillage systems, conventional tillage with mouldboard ploughing (MP) and no-till (NT). Crops are grown in a six-year rotation, namely peas (Pisum sativum L.) − winter wheat (Triticum aestivum L.) − field beans (Phaseolus vulgaris L.) − winter barley (Hordeum vulgare L.) − sugar beet (Beta vulgaris L.) − silage maize (Zea mays L.). This study investigated the impact of the two tillage systems on (i) nutrient distribution and storage in the soil profile, (ii) the depth distribution of soil organic carbon and (iii) crop productivity. Soil samples were collected layer-by-layer following cultivation layers and natural soil horizons in a metal frame (0.5 m × 0.5 m cross-sectional area) down to 0.5 m depth. The layer boundaries were approximately 0.02, 0.05, 0.15, 0.25, 0.30, 0.40, and 0.50 m for NT, and 0.15, 0.25, 0.30, 0.40, and 0.50 m for MP. Soil organic carbon (SOC), total nitrogen (TotN), phosphorus (P), calcium (Ca), potassium (K), magnesium (Mg), pH, and bulk density were measured for each layer. The nutrient distribution was rather uniform within the plough layer in MP. In NT, there was strong stratification, with higher nutrient concentrations in the upper layers for TotN, K and Mg. This was associated with crop residue retention on the surface and reduced plant uptake due to low pH. In contrast, the distribution of P and Ca in NT was rather uniform in the 0–30 cm layer, with a trend towards maximum concentrations at around 20 cm depth. Total storage of nutrients per ha in the whole soil profile was similar in NT and MP for all nutrients. SOC stocks did not differ between NT and MP, although the depth distribution of SOC concentration was significantly different. The long-term average crop yield was slightly higher in NT than in MP, but the difference was not significant. Crop yield was significantly higher in NT for winter cereals (winter wheat, winter barley) and legumes (field beans and peas), but lower for root and tuber crops (sugar beet, potatoes). It can be assumed that the high crop yields in NT in the Oberacker long-term field experiment are due to the wellbalanced crop rotation

Loss of soil organic carbon in Swiss long-term agricultural experiments over a wide range of management practices

Soil carbon sequestration (SCS) is one of the cheapest and technically least demanding carbon dioxide (CO2) removal (CDR) or negative CO2 emission technologies. For a realistic assessment of SCS, it is critical to evaluate how much carbon (C) can be stored in soil organic matter under actual agricultural practices. This includes typical crop rotations and fertilization strategies, depends on resources that are available (e.g. farmyard manure (FYM)) and are affordable for farmers. Furthermore, it is important to assess SCS based on given climatic and soil conditions. Here, we evaluate changes in soil C storage for Switzerland using data from eleven long-term field experiments on cropland and permanent grassland that include common local practices. At all sites, changes in soil organic carbon (SOC) stocks were measured in topsoil (∼0-0.2 m) in response to a total of 80 different treatments including different types of mineral or organic fertilization (e.g. FYM, slurry, peat, compost) or soil management (tillage vs. no-till). The treatments were applied to different, diverse crop rotations or grass mixtures that are representative for Switzerland. We found that topsoils lost C at an average rate of 0.29 Mg C ha−1 yr−1, although many of the investigated treatments were expected to lead to SOC increases. Based on a linear mixed effects model we showed that SOC change rates (ΔSOC) were driven by C inputs to soil (harvest residues and organic fertilizer), soil cover and initial SOC stocks. The type of land use or soil tillage had no significant effect. Our analysis suggests that current efforts to manage soils sustainably need to be intensified and complemented with further techniques if Switzerland wants to achieve the goal of the 4 per 1000 initiative