Correction and diagnosis of boron deficiency in corn

Field experiments were conducted during the 1985 growing season on six soils in the Atlantic Coastal Plain region and one from the Piedmont region to determine the response of irrigated corn (Zea mays L.) to boron application. Two treatments applied to each of the soils consisted of 1) a control and 2) both band and foliar boron applied at rates of 2.0 and 0.5 kg ha⁻¹, respectively, as Solubor when corn plants were in the V5 to V6 growth stage. Corn grain yields averaged 13,485 kg ha⁻¹ across treatments on the seven soils. Based on published calibration data for the hot water soluble boron procedure, a corn grain yield response to boron application was not expected on any of the seven soils. Nevertheless, boron application increased corn grain yield from 13,485 kg ha⁻¹ on the control treatment to 14,300 kg ha⁻¹ on the plus boron treatment for one of the seven soils, an Altivista loamy sand. This soil had a hot water soluble boron concentration of 0.56 mg kg⁻¹ and a Mehlich 3 extractable boron concentration of 0.78 mg kg⁻¹. The six soils for which boron application did not increase yields had hot water soluble boron concentrations from 0.55 to 0.92 mg kg⁻¹ and Mehlich 3 extractable boron concentrations from 1.02 to 1.33 mg kg⁻¹. The boron concentration in whole corn plants sampled at the V5 to V6 growth stage was 6.7 mg kg⁻¹ on the Altivista soil where boron application increased corn grain yields and ranged from 9.6 to 103.1 mg kg⁻¹ on the six soils where boron application did not increase yields. The boron concentrations in ear leaves sampled at the early silk growth stage ranged from 8.5 to 18.6 mg kg⁻¹ and in corn grain from 0.66 to 3.31 mg kg⁻¹ on the control treatments of the seven soils. Ear leaf and grain boron concentrations were 10.7 and 0.74 mg kg⁻¹ for plants grown on the control treatment on the Altivista loamy sand, respectively. It can be concluded that, of the plant tissue and soil test procedures evaluated, boron concentration in whole young plants and Mehlich 3 extractable B were the most promising for diagnosis of boron deficiency in corn plants. Nevertheless, research is required on more soils before boron concentrations in young plants and Mehlich 3 extractable B can be used as a routine procedure for detection of boron deficiency in corn plants.