Nitrogen deficiency in maize fields of the Southern Pampas does not affect kernel number but reduces weight per kernel

• Published in: Field crops research 2024-05, Vol.312, p.109394, Article 109394
• Main Authors: Moises, Clara, Andrade, Fernando H., Monzon, Juan P., Reussi Calvo, Nahuel I., Cerrudo, Anibal
• Format: Article
• Language: English
• Subjects: Nitrogen - Maize yield gap - Grain filling period - Yield components - N deficiency - On-farm experiment
• ISSN: 0378-4290; 1872-6852
• DOI: 10.1016/j.fcr.2024.109394

Nitrogen (N) requirement of maize has been increasing over the past decades, but there has been a lack of adjustment in fertilization management practices across different regions in Argentina. The higher N requirement in modern hybrids is associated with a higher post-flowering N accumulation. Additionally, soil fertility in the Argentina Pampas has consistently decreased in recent years. Whether the effects of N deficiency are expressed in the post-flowering period is still unclear at field level. The objective of this work was to quantify the yield reduction attributed to N deficiency and to identify the physiological basis of this effect at the field level for typical high-tech farms across the south-eastern Pampas of Argentina. Nineteen experiments were conducted during the 2020/2021 growing season in the south-eastern Pampas, evaluating two N managements i) Farmers' N level; ii) High N input. Results showed that the additional N input increased grain yield by an average of 6.4% (average grain yield difference of 712 kg ha−1). Weight per kernel was the only yield component that responded to N fertilization. Farmers' N management did not affect N accumulation or growth-related variables such as leaf area index, green leaves per plant, PAR interception, nitrogen sufficiency index until flowering, but the farmers' N level reduced these variables during the grain filling period leading to differences in aerial biomass and N accumulated at physiological maturity. Farmers' N level led to decreased post-flowering N uptake during grain filling period, which reduced the photosynthetic capacity of the canopy. These findings suggest that N management strategies and models need to be reviewed for high-tech maize systems. •N management limited grain yield in a significant portion of the assessed fields.•N deficiency under farmers' N level occurred only during the grain filling period.•N deficiency resulted in less post-flowering N uptake, and reduced C assimilation.•Weight per kernel was the only yield component affected.•N deficiency could not be detected at flowering.