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The projected intensification of agriculture to meet food targets of a rapidly growing world population are likely to accentuate already acute problems of soil compaction and deteriorating soil structure in many regions of the world. The key role of soil structure for soil functions, the sensitivity of soil structure to agronomic management practices, and the lack of reliable observations and metrics for soil structure recovery rates after compaction motivated the establishment of a long-term Soil Structure Observatory (SSO) at the Agroscope research institute in Zürich, Switzerland. The primary objective of the SSO is to provide long-term observation data on soil structure evolution after disturbance by compaction, enabling quantification of compaction recovery rates and times. The SSO was designed to provide information on recovery of compacted soil under different post-compaction soil management regimes, including natural recovery of bare and vegetated soil as well as recovery with and without soil tillage. This study focused on the design of the SSO and the characterization of the pre-and post-compaction state of the field. We deployed a monitoring network for continuous observation of soil state variables related to hydrologic and biophysical functions (soil water content, matric potential, temperature, soil air O 2 and CO 2 concentrations, O 2 diffusion rates, and redox states) as well as periodic sampling and in situ measurements of infiltration, mechanical impedance, soil porosity, gas and water transport properties, crop yields, earthworm populations, and plot-scale geophysical measurements. Besides enabling quantification of recovery rates of compacted soil, we expect that data provided by the SSO will help improve our general understanding of soil structure dynamics.

The effects of mineral fertilizers and organic amendments on soil properties, carbon (C) sequestration, and crop yields are studied in a 37‐year field experiment, Phosphorus–Potassium‐balanced design, in Switzerland. Treatments included a control (mineral fertilization) without nitrogen (N) fertilizers (Min‐N0) and with optimal N (Min‐Nopt) and 5 organic amendments (green manure [Gm], cereal straw [Str], fresh cattle manure in 2 doses 35 and 70 t ha−1 [Ma35 and Ma70] and cattle slurry [Slu]) all receiving the same optimal N fertilization as Min‐Nopt. All mineral and organic treatments received optimum P–K fertilization. Nitrogen fertilization (Min‐Nopt vs. Min‐N0) increased soil organic C, microbial activity, and microporosity but decreased pH, magnesium, and macroporosity. All organic treatments with optimal mineral N resulted in higher soil organic C content compared with Min‐Nopt, however, these effects were significant only for the highest dose of manure. The organic amendments supplied 25% to 80% additional C input to the soil compared with Min‐Nopt, and their amendment‐C retention coefficients ranged from 1.6% (Gm) to 13.6% (Ma70). Chemical, physical, and biological soil properties were not or slightly significantly different among organic treatments. Nevertheless, soils fertilized with farmyard manure produced generally higher grain yield (up to 7.3%) compared with Min‐Nopt whereas the opposite effect was noted for Gm (−2.2%) and Str (−5.2%) treatments due to their negative effect on N availability. In conclusion, Gm and Str treatments were as effectives as Ma35 and Slu treatments to prevent soil degradation but required higher chemical fertilizer to maintain crop yield.