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In the temperate-humid region of Argentina, nitrogen (N) fertilisers in maize (Zea mays L.) are mainly applied around sowing, whereas N-splitting is rare and occurs during early vegetative stages. Splitting and late N fertilisation, even up to silking (R 1), effects on yield have been recently studied. However, to the extent of our knowledge, these studies have mainly focused on the effect of these strategies on maize yield, but less on the crop N economy. The aims were to study the mechanisms explaining the effect of i) splitting N and ii) additional N application at R 1 on yield, post-flowering N uptake, kernel weight, N uptake efficiency, and the relationship of these variables with the N nutrition index (NNI). Seven experiments were carried out throughout the humid temperate region of Argentina, evaluating seven treatments: a control without N fertilisation, N rate entirely applied at sowing or split between sowing, eight leaf (V 8), and R 1 , an additional N rate at R 1 , and an N sufficiency treatment. The scenario with split N application had no adverse effect on either yield or N uptake at maturity (P > 0.05), with less pre-flowering N uptake compensated with more post-flowering N uptake in late N applications. In turn, increases in both yield and kernel weight were related to increases in post-flowering N uptake. Positive yield responses to N-splitting (plateauing at 450 kg ha-1) were obtained with yield responses to N greater than 3107 kg ha-1. Likewise, yield responses to additional N at R 1 (plateauing at 1107 kg ha-1) were evident with yield responses greater than 2943 kg ha-1. The NNI at R 1 accounted for variations in post-flowering N uptake and yield, as well as yield responses to additional N at R 1 and their impact on kernel weight. Results show that N-splitting and late N fertilisation are promising strategies that, combined with crop N status monitoring, could lead to improvements in both maize yield and N economy. • Split and late N fertilisations were evaluated for maize in the humid-temperate region of Argentina. • Grain yield (GY) responses to N-splitting and to additional N at R 1 were recorded. • GY responses to N-splitting and to additional N at R 1 were higher for the most responsive sites. • N-splitting did not reduce GY and increased N uptake efficiency. • GY response to additional N at R 1 was negatively associated with crop N status at R 1. [ABSTRACT FROM AUTHOR]

Wheat plants were cultivated in pots with the objective of evaluating the effect of two sulfur (S) rates (+S and −S) on (i) shoot growth, S and nitrogen (N) uptake and nitrogen use efficiency (NUE) and (ii) root growth and architecture and its relations with S and N uptake. Plant samplings were at Z39, Z51 and Z92 stages. Shoot mass and NUE were greater in +S treatment at the three stages. −S treatment increased root growth at Z39 (14% more length and 16% more tips) in comparison with +S, but the opposite occurred at Z51 (31% less area and 42% less mass). S uptake per unit root mass, area and length were greater in +S treatment at Z39 and Z51. A similar pattern was determined for nitrogen uptake (Nu) at Z39, but the opposite occurred at Z51. This indicates that Nu is mainly controlled by shoot growth and not by root growth. [ABSTRACT FROM PUBLISHER]

• Over the season, shoot N concentration was only affected by N supply. • Over the season, N deficiency decreased shoot S concentration. • Shoot N:S stoichiometry could diagnose N status independently from S supply. • N should not be limiting when using N:S stoichiometry for diagnosing S status. • N and S fertilization increased their nutrient use and recovery efficiencies. Nitrogen (N) and sulfur (S) critical dilution curves and the N:S stoichiometry are useful tools for evaluating nutrient status in maize (Zea mays L.). Nutrient supply for both N and S impact plant nutrient uptake, consequently influencing the overall performance of fertilization diagnostic tools. Interaction between these nutrients has not been studied relative to their nutrient use efficiencies (NUE and SUE), agronomic efficiencies (NAE and SAE), and components of these. The aim of this study was to analyze the effect of N and S fertilization on: i) N and S uptake (N U and S U) dynamics, ii) N and S dilution curves, iii) N:S stoichiometry, and iv) NUE, SUE, NAE, SAE, and their components in maize. Five maize field trials were conducted evaluating the effect of N and S fertilization with two levels for each nutrient (unfertilized and fertilized). Maize shoot biomass and its N and S concentrations were measured from six-leaf to physiological maturity. The main outcomes of this study were: i) averaged across sites, N fertilization increased yield by 41% and S fertilization by 10%; ii) S U was delayed relative to N U ; iii) S fertilization increased shoot S concentration when N was not limiting; iv) N dilution curve was not affected by S supply; v) N:S ratio decreased with increasing shoot biomass and varied with N and S supply; vi) N fertilization improved SUE and SAE via greater S recovery, with a similar S fertilization effect on NUE and NAE. This study demonstrated that both the critical S dilution curve and N:S stoichiometry are useful tools to characterize S status when N is not deficient. Simultaneous N and S management is critical for increasing their use efficiencies, improving crop productivity, and reducing environmental footprint. [ABSTRACT FROM AUTHOR]