Phosphorus balances for arable soils in Southern England 1986–1999

Abstract

The behaviour of P in a range of English arable soils was examined by plotting the change in resin P in the topsoil (ΔPres) at the end of a 3‐ to 5‐year period, against the P balance over the same period (fertilizer P applied minus offtake in crops, estimated from farmers’ reported yields and straw removal). Based on the assumption that values for offtake per tonne of crop yield used for UK arable crops are valid averages, 20–60% of ΔPres was explained by the balance. Applying excess P fertilizer increased Pres, and reducing P fertilizer use decreased it; typically 3–4 kg P ha−1 was required for each mg L−1ΔPres (6–8 kg ha−1 for each mg L−1 of Olsen P). About half the P balance seems to be resin extractable and this differed little between soil groups, except in cases of very low P (index 0) in which the P buffering was stronger, and on very high P soils (index 4/5) when buffering was less. However, on calcareous soils and red soils, when fertilizer was applied in accord with offtake, Pres fell by up to 4 mg L−1 year−1 (2 mg L−1 yr−1 olsen P) and to prevent this an extra 3–10 kg P ha−1 year−1 fertilizer was required. But on most non‐calcareous soils, replacing offtake maintained Pres, with perhaps slight rises on soils of low clay content or greater organic matter content. In soils under arable rotations, the apparent recovery of P from fertilizer was often around 100%, falling to 85% on Chalk soils and 75% on medium–heavy soils on limestone or Lower Chalk. The fate of the ‘missing’ P needs clarification. The case for corrections to current P fertilizer recommendations in the UK on certain soil types is discussed.

Risk of Phosphorus Desorption from Canadian Agricultural Land: 25‐Year Temporal Trend

“…Long‐term experiments using excessive P fertilization show soil P enrichment (McCartney et al, 1998; Giroux et al, 2002; Chang et al, 2005; Heming, 2007). Therefore, we estimated the annual amount of residual P (P_Balance) that contributed to the soil P enrichment for each SLC agricultural polygon using the following equation: where P_Man and P_Min are applied P (kg P) from animal manure and mineral fertilizers, respectively, and P_Rem is P removed (exported) by harvests (kg P).…”

“…Long-term experiments using excessive P fertilization show soil P enrichment (McCartney et al, 1998;Giroux et al, 2002;Chang et al, 2005;Heming, 2007). Th erefore, we estimated the annual amount of residual P (P_Balance) that contributed to the soil P enrichment for each SLC agricultural polygon using the following equation:…”

Field‐Scale Evaluation of Biosolids‐Derived Organomineral Fertilizers Applied to Winter Wheat in England

“…Combined effects of the relatively low N/P ratio of biosolids (typically less than 1) with soil application rates based primarily on crop N requirements (Withers et al, 2016) often results in over-application of P relative to crop need. Soil application of P at rates exceeding offtake is known to raise extractable P levels, particularly in low (e.g., <20%) clay content soils (Heming, 2007). Surplus P applied to soils in biosolids influences soil P dynamics, and can enhance the adverse effects of P in surface water when P is transferred on eroded soil (Smith et al, 2006;Withers et al, 2009;Wang et al, 2016).…”

Regional trends in Scottish advisory soil acidity and phosphorus results: significance of management history, land use and soil attributes

“…The considerable potential for many soils to buffer change in extractable P concentrations and minimize any apparent detrimental impact on crop yields is also evident. A buffer factor was introduced by Heming () for different soil groups for arable areas in southern England, but the influence of soil type was limited except for very light or stony soil. The conclusion from this study was to suggest that in this situation fertilizer recommendations would not be improved by including soil type.…”