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

Report of the work of the expert group on maintaining the ability of biodiversity to continue to support the water cycle

rapport d'expertise pour l'UNEP (Programme des Nations Unies sur l'Environnement)The work of the expert group was based on peer-reviewed scientific or technical literature, supplemented by peer-reviewed examples of practice. Section II provides an overview of the processes that underpin ecosystem functions in relation to hydrology, and how these support the delivery of ecosystem services. Specific examples of these relationships, and how they can be managed in practice, are elaborated for agricultural systems and cities in section III . Social and economic aspects of this topic are largely self-evident and briefly discussed in section IV. Section V discusses the recent international policy landscape, highlighting the profile of this topic in the outcomes of the United Nations Conference on Sustainable Development 2012 (Rio+20). It also discusses some institutional constraints to managing the biodiversity-water cycle relationship and identifies simple ways of enabling more rapid uptake of biodiversity-based solutions to water-related problems. Section VI identifies the immediate opportunity available to the Conference of the Parties to strengthen cooperation and partnerships on this subject as a means to enhance implementation of the Strategic Plan for Biodiversity (2011-2020)