Optimizing Nitrogen Management: The Role of Sorghum Cultivars and Urease Inhibitors in Sustainable Crop Rotations

A study conducted by researchers from the University of the Basque Country and AN S. Coop. found that integrating the Vilomene sorghum cultivar with urease inhibitors improves nitrogen retention, reduces environmental impact, and enhances wheat yield and quality in crop rotations.

Keywords: Sorghum bicolor, Triticum aestivum, ammonia‐oxidizing bacteria, ammonium, biological nitrification inhibition, catch‐crop

Our findings reinforce the role of sorghum not only as a resilient crop, but also as an active contributor to sustainable nitrogen management in cereal rotations, thanks to its biological nitrification inhibition (BNI) capacity. This natural trait helps reduce environmental nitrogen losses while promoting more efficient and productive farming systems – Vega-Mas (https://orcid.org/0000-0002-9794-7078)

Nitrogen (N) fertilizers, particularly urea, are widely used in agriculture to meet increasing food demands, but their efficiency is limited by N losses due to leaching, volatilization, and nitrification, which negatively impact the environment. Sorghum, a stress-tolerant C4 crop, shows promise as a cover crop for improving soil N retention, especially in fertilization systems employing urease inhibitors like NBPT (N-(n-butyl) thiophosphoric triamide). Researchers from University of the Basque Country, in collaboration with the agri-food cooperative at AN S. Coop., evaluated the potential of four sorghum cultivars (including S. bicolor hybrids) to enhance soil N dynamics and benefit wheat in rotation under urea and urea+NBPT fertilization. The results underscored the importance of cultivar selection, revealing that two of the cultivars—both highly suitable for grain and silage exploitation—exhibited a capacity to enhance soil N retention among the cultivars.The Vilomene (VL) cultivar, demonstrated superior ammonium (NH4+) retention, even without NBPT, suggesting inherent biological nitrification inhibition (BNI) potential. VL also showed increased sorghum productivity when combined with NBPT. In contrast, Voyenn (VY) appeared to exert its BNI capacity through the reduction of soil nitrifying bacteria populations.

The benefits of sorghum as a catch crop extended to the subsequent wheat phase, with the VL precedent showing enhanced performance compared to others. Soil NO3− levels remained low, suggesting sustained BNI effects, while enhanced NH4+ availability supported wheat growth and yield, particularly when NBPT was used. The VL sorghum-wheat rotation achieved higher biomass and grain quality compared to other cultivars, demonstrating its ability to enhance NH4+ retention, and mitigate the environmental impacts of N losses. This emphasizes the importance of pairing urease inhibitors with suitable sorghum cultivars for sustainable agriculture. Further research is needed to explore the underlying mechanisms of VL’s benefits and its long-term impact on crop rotations.

SorghumBase example:

**Figure 1:** Expression tab view of NiR from the SorghumBase search page. Transcription profiling using high-throughput sequencing highlights the expression of the NiR gene across 15 different tissues in Sorghum bicolor (BTx623). The “All Studies” tab provides insights into the gene’s expression patterns across various experiments. Notably, high expression levels are observed in the leaf tissue.

Reference:

Vega-Mas I, Ascencio-Medina E, Menéndez S, González-Torralba J, González-Murua C, Marino D, González-Moro MB. Selecting an optimal sorghum cultivar can improve nitrogen availability and wheat yield in crop rotation. J Sci Food Agric. 2024 Oct 26. PMID: 39460499. doi: 10.1002/jsfa.13969. Read more

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