Optimizing phosphorus rates for peanut: The role of soil P, water availability, and cultivar

Peanut (Arachis hypogea L.) cultivars (cv) have different root morphology, which, combined with soil water availability, can change the response to phosphorus (P). This study evaluated peanut yield, P uptake, and P agronomic efficiency – kg kg⁻¹ as affected by cv maturity group and soil P availability. Four field experiments were carried out from 2021 to 2023 in sandy soils in southeastern Brazil. An early- and a late-maturing cv were grown with P rates of 0, 17, 35, 52, and 70 kg ha⁻¹. In the driest year, the maximum yield was approximately 4000 kg ha⁻¹, whereas with higher water availability, it reached around 8,000 kg ha⁻¹. Under P and water deficiency, the late cv yielded 7–32 % more than the early cv, but this did not result in higher P agronomic efficiency. Although the late cv accumulated more P and had higher yields, the P-resin content in the topsoil after harvest was higher than that of the early cv. The optimum P rate was 52 kg ha⁻¹ under low initial P in both years. However, when soil P content was medium, maximum yield was observed with 17 kg ha⁻¹ in the wet year and between 17 and 35 kg ha⁻¹ in the dry year, depending on the cv. High P rates (> 52 kg ha⁻¹) reduced P agronomic efficiency because P uptake and peanut yield was not increased. Maximum P exports ranged from 12 to 28 kg ha⁻¹. The optimum P levels ranged from 2.2 to 3.8 g kg⁻¹ in peanut leaves and 8–25 mg kg⁻¹ in soil. The optimum P rate for peanuts depends on the initial soil P level, water availability, and cultivar. The late cv was better adapted to P-deficient soil and less responsive to P.