Improved Method of Boron Fertilization in Rice (<i>Oryza sativa</i> L.)–Mustard (<i>Brassica juncea</i> L.) Cropping System in Upland Calcareous Soils

• Main Authors: Ranjan Laik, Santosh Kumar Singh, Biswajit Pramanick, Vandana Kumari, Debabrata Nath, Eldessoky S. Dessoky, Attia O. Attia, Mohamed M. Hassan, Akbar Hossain
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Sustainability
• Subjects: boron fractions; boron fertilization; boron transformation; boron uptake; rice–mustard system
• Online Access: https://www.mdpi.com/2071-1050/13/9/5037

Calcareous soils are highly deficient in boron (B) due to having high levels of free CaCO₃ and low organic matter. This has become one of the most important deficient micronutrients in Indian soil after zinc (Zn). For various rice (<i>Oryza sativa</i> L.)-based cropping systems, B fertilization is essential for increasing crop productivity and the biofortification of the crop, thus a suitable soil application protocol for B fertilization is required for B-deficient soils. In a six-year experiment, different rates of B application, namely, 0.5, 1.0, 1.5, and 2.0 kg ha⁻¹ y⁻¹, were evaluated to determine the effects of three different modes of B fertilization, i.e., applied only in the first year, applied in alternating years, and applied every year, in a rice (<i>Oryza sativa</i> L.)–Indian mustard (<i>Brassica juncea</i> L.) cropping system. It was observed that the application of B at 1.5 kg ha⁻¹ every year or 2 kg ha⁻¹ in alternate years resulted in the highest yield of rice and mustard, as well as the maximum system productivity of the rice–mustard cropping system. Application of 2 kg ha⁻¹ of B in the initial year showed the maximum B uptake by rice, while application of 1.5–2.0 kg ha⁻¹ of B every year resulted in the maximum B uptake by the mustard crop. Application of B at 2 kg ha⁻¹ in alternate years or 1.5 kg ha⁻¹ every year was the best B-application protocol in B-deficient calcareous soils for ensuring the highest productivity of the rice–mustard cropping system and B availability in the soil.