Soil organic phosphorus mineralisation rate in cropped fields receiving various P sourcesrnative cropping systems and organic waste product application? A multi-method evaluation

https://doi.org/10.1007/s10705-024-10377-2

Abstract :

Phosphorus (P) is a major nutrient for crops, and its application to agricultural soils as inorganic or organic fertiliser is crucial for optimising P availability to plants to sustain food production. The mineralisation of soil organic phosphorus (SOP) may play a significant role in supplying plant-available P. This study aimed to determine the SOP mineralisation rate in soils cropped under contrasting agropedoclimatic conditions. By applying the modelling approach developed by Hénin and Dupuis in 1945 for soil organic carbon, to SOP, we were able to determine the rate of SOP mineralisation. We used three French long-term field experiments (LTFEs) on P fertilisation, which combine different P doses (0–112 kg P ha⁻¹ yr⁻¹), applied for decades (14–18 years) as superphosphate or various organic waste products (OWPs), on different soil types, and different annual crop successions. These databases include long time-series data of SOP and soil inorganic phosphorus (SIP) stocks and annual crop measurements. For the three LTFEs, the initial SOP stocks were 446, 595, and 1145 kg P ha⁻¹. During the post-harvest year, 2.5, 7.9, and 11.0 kg P ha⁻¹ yr⁻¹ were incorporated into SOP by the decomposition of crop residues and OWPs. Conversely, 12.5, 27, and 46 kg P ha⁻¹ yr⁻¹ were released as phosphate ions and contributed significantly to the plant-available soil P. The rates of SOP mineralisation, 2.1, 5.4, and 11.2 kg P ha⁻¹ yr⁻¹, differed significantly across the LTFEs. The SOP stocks remained stable across time, and during repeated crop production and fertilisation, irrespective of P treatments. The SIP stocks closely corresponded to the cumulative P budget. Overall, the average SOP mineralisation rate is low and appears to play a minor role in the plant-available soil P and its uptake.

Keywords : Long-term field experiment; Organic waste fertilisers; Organic phosphorus mineralisation; Modelling phosphorus dynamics; Soil–plant nutrient cycling