Distribuição do fósforo e potássio em Latossolos do cerrado sob diferentes sistemas de cultivo

Abstract

Cropping systems and the management of phosphorus and potassium fertilization influence the availability of these nutrients in the soil, their uptake by plants, and consequently, crop productivity. Therefore, it is essential to evaluate the distribution and dynamics of these elements throughout the soil profile to understand the impact of each management system. The experiment was conducted on a Latosol in the rural region of Uberlândia, Minas Gerais, comparing different land uses: T1. Native Cerrado; T2. Grain cultivation under no-tillage system; T3. Grain cultivation under conventional tillage; and T4. Various crops under center-pivot irrigation. The treatments followed a 4 × 6 factorial scheme, with four cultivation systems and six depths, in a completely randomized design with four replicates. For each system, four trenches (60 cm deep) were opened to collect undisturbed soil samples at every 10 cm. The distribution of P and K was determined using the Mehlich-1 extractor, with readings performed by molecular absorption spectrophotometry and flame emission spectrophotometry. Data were subjected to analysis of variance (p ≤ 0.05), and means were compared using Tukey’s test (p ≤ 0.05). Results showed that soil depth had no significant interaction with the cultivation system in phosphorus dynamics, confirming the low mobility of this nutrient and its reduced concentrations in deeper layers. However, phosphorus availability varied significantly only in the 0–10 cm layer, where the no-tillage and irrigated systems showed the highest concentrations. On the other hand, irrigation significantly affected potassium mobility, promoting its redistribution along the soil profile and differing from the no-tillage and conventional systems, in which potassium remained concentrated in the surface layers. The high K values observed in irrigated soils indicate that more intensive land use increases the availability of this nutrient. It is concluded that management systems directly influence potassium dynamics in the soil, and these interactions must be considered to optimize fertilization strategies and promote more efficient nutrient use in agricultural environments.