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

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

Buenos Aires

Congreso; XXVIII Congreso Argentino de la Ciencia del suelo; 2022

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 of a 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 on the 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 was negatively 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.