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The purpose of the study was to examine biochar amendment, phosphorus (P) fertilizer and arbuscular mycorrhizal fungi (AMF) on the yield, nutrient and cadmium (Cd) absorption of Lolium multiflorum in acidic soil. It was shown that mycorrhizal inoculation had no positive influence on the plant shoot biomass and the contents of nitrogen (N), P, potassium (K), calcium (Ca) and magnesium (Mg) in plants at all biochar and P level treatments. Irrespective of mycorrhizal inoculation and P level, biochar amendments markedly elevated the soil available P and K uptake in plant tissues. In contrast, biochar significantly decreased the translocation factor of plants, soil exchangeable Cd, and acid and neutral phosphatase activities, regardless of the mycorrhizal inoculation and P fertilizer. Without P fertilization, biochar amendments significantly promoted shoot P content, while biochar amendments significantly reduced shoot P content when P fertilizer was applied. Without biochar application, P fertilizer application significantly promoted the biomass and N uptake of shoots in both AMF inoculation treatments, while P fertilizer increased these only in the presence of biochar and mycorrhizal inoculation. The increased N content induced by the biochar amendment elevated the shoot N:P ratio and alleviated the N deficiency with P fertilizer input. Thus, we concluded that the addition of biochar and P fertilizer showed more positive effects on the promotion of growth and nutrient uptake of L. multiflorum than AMF grown in acidic Cd-contaminated soils. Image 1 • AMF had no positive influence on shoot biomass and nutrient uptakes. • Biochar markedly elevated soil P level and plant K uptake. • Biochar decreased translocation factor. • Biochar increased shoot N:P ratio with P fertilization. • Biochar and P fertilizer had more positive effects on ryegrass than AMF. [ABSTRACT FROM AUTHOR]

Phosphorus (P) loss from highly fertilised grazed pastures can impair surface water quality. High P concentrations in grazed pastures are maintained to boost legume production, but systems that use monocultures of grass and clover can be more profitable and decrease P losses by lowering soil P in grassed areas. In contrast with using a direct drill to establish new pastures, conventional cultivation can lower topsoil P quickly and can be used as part of a farm re-grassing programme every six years. We tested if the potential for low P losses (measured by water extractable P; WEP) could be maintained over six years in pastures (ryegrass and white clover monocultures and a ryegrass and clover mixed sward) despite being fertilised (10, 35 and 100 kg P ha-1) and grazed. Cultivation (0–20 cm) decreased WEP and Olsen P in all three pastures and P rates by 30–50 % compared to direct drill and maintained this decrease for six years. A threshold in Olsen P (22 mg L-1) was noted where WEP concentrations increased at a greater rate relative to Olsen P than below. This threshold was like the critical point in Olsen P for 97 % relative yield in the pastures (22–28 mg L-1) and could be used to advise on cultivation and P fertiliser strategies to help avoid the potential for P loss without significantly compromising yield. The data indicated that cultivation could be used to quickly establish and maintain lower soil P concentrations as part of a strategy to decrease P losses and improve profit by using a split grass-clover system. • Phosphorus runoff from land can impair surface water quality. • Splitting pastures into monocultures maintains production and enables low P plants to grow in runoff prone areas. • Conventional cultivation can be used to quickly decrease enriched soil P for low P plants. • Potential for runoff was maintained despite fertiliser P and grazing returns over 6-year period. • Conventional cultivation is a suitable method for re-grassing programme to lower runoff P losses. [ABSTRACT FROM AUTHOR]

Biosolids derived organo-mineral fertilisers (OMF) are designed to reduce fertiliser inputs, but may lead to excessive accumulation of soil P. Two OMF formulations comprised of biosolids (BS), urea and potassium at NPK ratios of 10:4:4 (OMF 10 ) and 15:4:4 (OMF 15 ) were investigated. Effects of OMF on ryegrass ( Lolium perenne L.) yields and crop P content, together with soil nutrients (total C and N, organic matter, pH) were explored and compared to BS and urea in a three year field trial. In addition the soil microbial community (biomass C, phospholipid fatty acid – PLFA and multiple substrate induced respiration – MSIR) were assessed at the end of the experiment. All fertilisers (rates 0–250 kg N ha −1 ) produced similar yields with the exception of urea, which had reduced yield at 250 kg N ha −1 . Soil total carbon increased where BS and OMF 10 were applied but not with OMF 15 and urea. Crop P was not affected by fertiliser applications and no organic matter accumulation were observed with urea. Comparable yields produced by the application of OMF compared to urea suggest that OMF is a promising alternative to inorganic fertiliser. Soil microbial biomass was greater in BS plots compared to urea indicating an increased supply of substrates for microorganisms in the former. Soil microbiological analysis indicates change in the community PLFA profile in autumn, but an altered MSIR functional profile in spring. Changes in available P suggest OMF replenished supplies of utilised nutrient and maintains soil P levels. [ABSTRACT FROM AUTHOR]