| Institution: | 1.Faculty of Agriculture and Life Sciences,Lincoln University,Christchurch,New Zealand;2.Institute of Applied Ecology, Chinese Academy of Sciences,Shenyang,China;3.Key Laboratory of Tropical Agro-Environment,South China Agricultural University,Guangzhou,China;4.Bio-Protection Research Centre,Lincoln University,Christchurch,New Zealand;5.Scion Research,Christchurch,New Zealand |
| Abstract: | The objective of this study was to quantify the combined effects of long-term plant biomass retention/removal and environmental conditions on soil microbial biomass phosphorus (P), bioavailable P, and acid phosphomonoesterase activity. Topsoil samples (0–2.5 and 2.5–5 cm) were collected from replicate field-based plots that had been maintained under contrasting plant biomass retention and removal regime for 21 years. Samples were collected on 14 occasions over a 17-month period and assessed for microbial P, bioavailable P, and phosphomonoesterase activity. All P measurements were consistently and significantly higher under plant biomass retention compared with biomass removal. Temporal variations in microbial P and phosphomonoesterase activity were evident in top soil (0–2.5 cm) and were driven by environmental conditions, mainly soil moisture, rainfall, and potential evapotranspiration, while bioavailable P had no temporal variation. Detailed analysis of microbial P data for the top 2.5-cm soil depth revealed that annual P flux through this pool was two times greater under biomass retention (10.3 kg P ha?1 year?1) compared with plant biomass removal (5.0 kg P ha?1 year?1). Similar and consistent trends were observed in soil from 2.5- to 5-cm sampling depth; however, differences were not significant. The findings of this study confirm the importance of the microbial biomass in determining the bioavailability of P in temperate grassland systems. |
