No-till (NT) affects dynamics of phosphorus (P) applied. Wheat response to P fertilization can be affected by available soil P, grain yield, placement, rate, and timing of fertilization. Furthermore, mycorrhizal associations could contribute to improving plant P uptake. Three experiments were used to evaluate P rate (0, 25, and 50 kg P ha⁻¹) and fertilizer placement (broadcasted or deep-banded) effects in NT wheat on P recovery efficiency (PRE) yield and arbuscular mycorrhizal colonization (AMC) which was assessed in one experiment. Fertilization increased dry matter (DM) and accumulated P. Broadcasted P produced lower P accumulation than deep-banded P only at tillering. Phosphorus rate decreased PRE, and placement method did not affect it. Grain yield response was increased by P rate (857 and 1805 kg ha⁻¹for 25 and 50 kg P ha⁻¹, resp.) and was not affected by placement method (4774 and 5333 kg ha⁻¹for broadcasted and deep-banded, resp.). Deep-banded P depressed root AMC compared with broadcast applications. Highest AMC in P broadcasted treatments could help to explain the lack of differences between placement methods. These results indicate that Mollisol have low P retention capacity. Therefore, broadcasted P could be used as an alternative of fertilizer management for NT wheat.

Maize (Zea mays L.) is highly susceptible to zinc (Zn) deficiency. Different application strategies (AS) can be utilized to improve grain yield (GY) and quality (Zn biofortification) by combining Zn fertilizer rate, source, timing, and placement techniques. This study aimed to evaluate whether different Zn-AS (soil, seed, and foliar) affect maize GY and grain Zn concentration in Mollisols with contrasting soil Zn availability and pH. Five site-years field experiments were carried out. Treatments (Zn-AS) were compared to a control, and included: seed-Zn, 0.3 kg Zn ha⁻¹; foliar-Zn, 0.7 kg Zn ha⁻¹ at V6 stage; and soil-Zn, 2.1 kg Zn ha⁻¹ surface banded. Zinc fertilization increased GY (response ranged from 892 to 2519 kg ha⁻¹) in four of five sites (p < 0.05). The evidence indicates that in scenarios of very low soil Zn availability (<0.9 mg kg⁻¹ Zn-DTPA) greater Zn rates are required, and therefore soil-Zn and foliar-Zn are the more suitable AS. Grain Zn concentration ranged from 19.5 to 43.1 mg kg⁻¹ and was not affected by Zn-AS. At all sites, even those showing GY response to Zn fertilization, grain Zn concentration in the control treatment was above the sufficiency threshold for maize GY (18 mg kg⁻¹), indicating that this threshold needs to be updated for the current maize hybrids. Grain Zn concentration was predicted by the model: grain Zn concentration = 39.56 − 0.002 × GY + 9.62 × Zn-DTPA (R² = 0.38).