QUANTITATIVE AND QUALITATIVE WHEAT RESPONSE TO NITROGEN FERTILIZATION IN THE ARGENTINEAN PAMPAS: A SYNTHESIS ANALYSIS

DAMIANIDIS, D; REUSSI CALVO NAHUEL; GARCÍA, FERNANDO; ALVAREZ, C; BARBIERI, PABLO ANDRÉS; SAINZ ROZAS, HERNÁN RENÉ; BARRACO, MIRIAM; BRACH, A; BOERO, J; CASTELLARIN, JULIO; FERRARIS, NESTOR GUSTAVO; GOMEZ, F; GUDELJ, VICENTE; GUTIÉRREZ BOEM, FLAVIO; KRUGER, HUGO; LOEWY, TOMAS; MANLLA, A; DELION, D; VIDELA MENSEGUE, H; PAGNAN, L.; PAUTASSO, JUAN; PRYSTUPA, P.; PUGLIESE, G; VENTIMIGLIA, LUIS; DIAZ ZORITA, M; CORRENDO, ADRIÁN; SALVAGIOTTI, FERNANDO

Buenos Aires

Congreso; XVIII Congreso Argentino de la Ciencia del Suelo; 2022

AACS

Nitrogen (N) management in wheat is crucial to sustain high yields and maintain/improve grain protein content. Wheat response to N management has been extensively studied in Argentina under particular soil-crop-climate conditions, thus, limiting the space for inference and decision-making. A database was compiled with nitrogen fertilization experiments in wheat conducted between1990 and 2021. The experiments included at least one control and one N fertilized (Nf) treatment with a minimum of two replicates. Information on yield, grain protein, soil nitrates at planting (60 cm; Ninit), management practices, and soil type were collected. The database comprised 182 environments (year-location-experiment combinations), each characterized by a maximum yield (Rmax). Relative yield (RY) per environment was calculated as the ratio between the yield ofa fertilization treatment and the yield obtained with the maximum dose of Nf. The average yield was 4809 (range: 881-9799; interquartile range (IQR) 3715-5959) kg ha-1, while Nfs (Nf + Ninit) ranged between 9-419 kg N ha-1 with a mean equal to 128 kg N ha-1. The RY range was 37-125% (mean: 86%; IQR: 78-97%) and grain protein content 7.02-18.00% (average: 11.13%; IQR: 9.71-12.40%). Global analysis indicated that both the quadratic-plateau and linear-plateau models explained more than 34% of the variability between RY and Nfs, with Nfs thresholds of 243 and 164 kg N ha-1. To investigate the effect of environment, soil type, and management on wheat RY response to Nfs the database was divided into: 1) three potential yield environments based onthe cumulative probability distribution of Rmax (low < 4600, medium: 4600 – 6230, and high > 6230 kg ha-1); 2) three soil textural groups (coarse, medium, and fine), and 3) the previous crop in the crop sequence (corn, soybean, and sunflower). The quadratic-plateau (linear-plateau) model explained 29 (30), 33 (34), and 55 (55)% of the observed variability in the RY for the low, medium, and high Rmax groups, with Nfs thresholds equal to 215 (115), 235 (132), and 247 (174) kg ha-1. The linear-plateau model fit by soil group showed Nfs thresholds of 253, 142, and 170 kg N ha-1 for fine (R2 = 0.26), medium (R2 = 0.34), and coarse (R2 = 0.34) textures. Grouping by the previous crop improved the fit of the linear-plateau model (R2 between 38 and 64%) for RY response to Nfs, with Nfs thresholds of 141 (sunflower), 173 (soybean), and 180 (corn) kg ha-1. Wheat grain protein wasnegatively associated with yield (global analysis, R2 = 0.06); grouping by cultivar quality index (1 = high, 2= intermediate, 3 = inferior quality) indicated a positive (slope = 0.00043 % kg-1 ha) and negative (slope = -0.00063 % kg-1 ha) linear relationship for groups 1 and 2. A positive linear relationship between grain protein concentration and Nfs was observed for all three groups. This synthesis-analysis suggests that modern wheat cultivars may respond to higher levels of available N than previously determined. A further investigation of the interactions between soil texture, potential environment, and management may further fine-tune the N fertilization prescriptions in wheat.