Long-term phosphorus management enhances crop productivity and soil organic carbon under no-tillage in the Brazilian Cerrado

Long-term phosphorus (P) management influences crop productivity and soil organic carbon (SOC) dynamics primarily through the distribution of P within the soil profile rather than fertilizer rate alone. This study evaluates the effects of initial P correction strategies and annual maintenance fertilization on cumulative soybean (Glycine max (L.) Merr.) and maize (Zea mays L.) productivity and their implications for SOC stocks in a long-term no-tillage experiment established in 2010 on a tropical Oxisol in the Brazilian Cerrado. The experiment combined surface P application and deep incorporation at 20 and 40 cm with annual maintenance fertilization (50 and 100 kg ha⁻¹ of P₂O₅), applied either by broadcasting or in-furrow, in addition to an unfertilized control. Over 15 years, treatments with P incorporation associated with annual strip fertilization resulted in higher cumulative grain yields. Soybean productivity increased by up to 16.7% (44,073 kg ha⁻¹) when P was incorporated at 20 cm and by 11.9% (42,271 kg ha⁻¹) when incorporated at 40 cm, compared with the treatment without initial P correction. Maize productivity increased by 16.1% (58,915 kg ha⁻¹) when P was incorporated at 20 cm and by 9.6% (55,639 kg ha⁻¹) when incorporated at 40 cm, compared with the treatment without initial P correction. Regarding soil C stocks, regardless of treatment, C was mainly concentrated in the subsurface layers, with about 63% of C accumulated below 10 cm, ~31% between 10–20 cm, and ~33% between 20–40 cm, while the surface layers (0–10 cm) contributed ~37% of the total stock.