Yield and protein gaps in barley: Quantifying nitrogen and sulfur contributions

Abstract

Malting barley requires management that simultaneously attains high yield and grain protein concentrations required by the industry, but the impact of nitrogen and sulfur limitations on these variables remain unclear. Yield and protein gaps under rainfed conditions have not been quantified or nutritionally decomposed for barley at the farm scale. This study aimed to i) quantify yield and grain protein gaps in malting barley, ii) evaluate the contribution of N and S to these gaps, iii) examine the relationship between yield and protein gaps, and iv) analyze the relationship between yield, grain protein , and their respective gaps with crop N uptake in the central Pampas region of Argentina. On-farm experiments (42, factorial design with two or three replications) with N and S fertilization treatments combined with crop modeling were used to estimate barley yield potential (Yp), water-limited yield potential (Yw), actual yield (Ya), yield gap (Yg = Yw - Ya), actual grain protein concentration (Pa), and protein gap (Pg = Pi - Pa, where Pi is the average 11 % protein required by the brewing industry). Mean Yg represented 26.2 % of Yw and was mainly due to N limitation (97.6 % of cases), while S limitation was less frequent (< 23.5 %). Pa was below the 11 % required by the brewing industry. Mean Pg was 26.5 % of Pi and was mainly due to N limitation (some limitation was observed in all the cases). Pg showed a weak association with Yg. Crop N uptake influenced both gaps, with higher N requirements needed to achieve Pi than to maximize yield. The findings indicated that N management is crucial to closing yield and protein gaps in malting barley, while S limitation is less frequent. Future research should integrate stress interactions with other nutrients to better understand and optimize yield and quality gaps.