No-till Effects on the Loss of Different Forms of Phosphorus from Agricultural Landscapes: A Meta-Analysis.

The impact of no-till (NT) farming on soil health is well documented, but there remain uncertainties about whether NT could mitigate the water quality problems associated with phosphorus export from agricultural landscapes. Contrasting results are reported in the literature. To gain a greater insight into the published data, we conducted a meta-analysis to investigate physical (rainfall variability, transport pathways, slope) and management (NT duration, crop species) factors that may contribute to that variability. In comparison to conventional tillage (CT), the analysis showed that NT generally resulted in a reduction of 45% and 55% respectively in the concentration and load of particulate P, but also produced higher concentration and load of dissolved P. Higher total P concentration was most noticeable in fields under NT for periods >10 years, likely due to subsoil compaction, P stratification and surface accumulation of organic matter. Therefore, NT-induced changes in soil properties need to be considered when assessing the potential environmental impact of NT farming. We suggest combining NT with other land management practices (e.g., cover crops) to reduce the loss of dissolved P.