Exploringmaize grain yield response to boron fertilization in Mollisols: Critical thresholds and predictive models

Abstract

Background: There are no extractable boron (B) thresholds for maize (Zea mays L.) inMollisols determined by field calibrations.Aims: Our objectives were to: (1) explore maize grain yield response to B fertilization, (2)calibrate the soil hot water extractableB(HW-B) as a predictor of maize response toBfertilizationunder field conditions, and (3) assess the contribution of clay, pH, and soil organicmatter (SOM) as predictive variables of maize response to B fertilization.Methods:We conducted 53 field trials with 2 treatments: with andwithoutBfertilization.At all sites, wemeasured clay, SOM, pH, and HW-B at a 0–20 cm depth.Results: Maize grain yield ranged from 5.34 to 17.35 Mg ha−1. Grain yield response tofertilization was observed in 6 out of 53 sites (11.3%). In responsive sites, average grainyield response was 1.0 Mg ha−1. Multiple regression models to predict yield response toB addition that included soil, pH, and SOM only explained 19% of the variability. The criticalsoil HW-B concentration threshold was 0.78 mg kg−1, correctly diagnosing 79% of thesite-years.Conclusion: The critical threshold for maize B levels resulting from our field study is thefirst of its kind inMollisols. This threshold will improve the identification of soils deficientin B