Fertilization and tillage effects on soil properties and maize yield in a Southern Pampas Argiudoll

Agricultural management practices, such as tillage and fertilization alter soil physical, chemical and biological properties over the medium term, which has a direct impact on the system's sustainability and crop performance. The aim of this work was to evaluate how fertilization with nitrogen (N), phosphorus (P), sulphur (S), micronutrients (Mi), liming (Li) and tillage systems affect soil properties in the medium term, and to measure the impact of these changes on maize (Zea mays L.) yield.A seven-year experiment on a Typic Argiudoll in the Southern Pampas region of Argentina using seven fertilizations treatments (Control, N P, NS, PS, NPS, NPS + Mi, and NPS + Mi + Li) and two tillage systems – conventional tillage (CT) and no-till (NT) – was evaluated. Each sub-plot was analyzed to determine physical parameters – bulk density (BD) and aggregate stability (AS)-, biological parameters – total organic carbon (TOC), carbon in the particulate fraction (COP), anaerobically incubated nitrogen (AN), total nitrogen (TN) and nitrogen in the particulate fraction (PN) – and chemical parameters – nitrate, available phosphorus, sulphate and pH – at different depths. Also, maize yield was measured in the final year without fertilizer application, in order to evaluate the effects of soil changes on this crop.Among the physical parameters, the only differences found were in BD between tillage systems in the 0–5 cm layer (1.28 g cm−3 in NT and 1.15 g cm−3 in CT). Biological parameters were unaffected by fertilization treatments. However, tillage systems modified many of them in the 0–5 cm layer: COT (17 Mg ha−1 in CT and 21 Mg ha−1 in NT), POC (2.4 Mg ha−1 in CT and 4.5 Mg ha−1 in NT), TN (1.4 Mg ha−1 in CT and 1.8 Mg ha−1 in NT), PN (0.3 Mg ha−1 in CT and 0.5 Mg ha−1 in NT) and AN (56 mg kg−1 in CT and 79 mg kg−1 in NT). These differences were not significant when the 5–20 cm depth was analyzed. Chemical properties such as pH (5.7 in treatments with N; 6.1 without N, and 6.4 with N and lime) and P Bray content were modified (35 mg kg−1 in treatments with P and 13 mg kg−1 without P). In both cases, there was interaction with the tillage system, with significant stratification under NT.Maize yield was only affected by residual P; there were no other effects of medium-term fertilization or tillage systems.

► Long term N and P fertilization enhanced C input but did not affect soil C content.
► Tillage practices affected C accumulation, and P and pH stratification.
► N fertilization reduced pH, and this trend was reverted by the application of lime.
► S and micronutrients did not affect any soil property nor increased maize yield.
► Among soil properties affected by fertilization, only available P altered maize yield.