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The effects of organic carbon (OC) additions from farm manures and crop residues on selected soil biophysical and physico-chemical properties were measured at seven experimental sites, on contrasting soil types, with a history of repeated applications of farm manure or differential rates of inorganic fertilizer nitrogen (N). Repeated (> 7 years annual additions) and relatively large OC inputs (up to 65 t OC ha À1 ) were needed to produce measurable changes in soil properties, particularly physical properties. However, over all the study sites, there was a positive relationship between OC inputs and changes in total soil OC and 'light' fraction OC (LFOC), with LFOC providing a more sensitive indicator of changes in soil organic matter status. Total soil OC increased by an average of 3% for every 10 t ha À1 manure OC applied, whereas LFOC increased by c. 14%. The measured soil OC increases were equivalent to c. 23% of the manure OC applied (up to 65 t OC ha À1 applied over 9 years) and c. 22% of the crop residue OC applied (up to 32 t OC ha À1 over 23 years). The manure OC inputs (but not crop residue OC inputs) increased topsoil porosity and plant available water capacity, and decreased bulk density by 0.6%, 2.5% and 0.5% with every 10 t ha À1 manure OC applied, respectively. Both OC sources increased the size of the microbial biomass (11% increase in biomass C with 10 t OC ha À1 input), but only manure OC increased its activity (16% increase in the soil respiration rate with 10 t OC ha À1 input). Likewise, the potentially mineralizable N pool only increased with manure N inputs (14% increase with 1 t manure total N ha À1 ). However, these soil quality benefits need to be balanced with any potential environmental impacts, such as excessive nutrient accumulation, increased nitrate leaching and phosphorus losses and gaseous emissions to the atmosphere.

To facilitate the maintenance and restoration of semi‐natural grasslands, it is important to understand their relationships with soil properties. Semi‐natural grasslands typically have a high incidence of stress‐tolerant species (measured here by high stress radius values), but not all have high species richness. Species richness and stress radius values were related to soil pH, Olsen extractable phosphorus (P), extractable potassium (K) and magnesium (Mg), total nitrogen (N) and organic matter (OM) at 571 sites representing a wide range oftemperate grasslands. Highest species richness (>30 m−2) occurred at pH > 6 and 4–15 mg l−1 P, but species richness was also highly variable at 4–15 mg l−1 P. At pH < 5, species richness was low (<20 m−2). Stress radius values were highest (mainly calcareous and heath grasslands and mires) at pH c. 8·0 and < 5·0, and at the lowest soil P levels (<5 mg l−1). A wide range of stress radius values occurred at low soil P levels because appropriate management is also needed to maintain semi‐natural grasslands. Reducing soil P is difficult in practice, so grassland restoration in the presence of elevated soil‐extractable P levels merits re‐assessment.

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