Spring wheat nitrogen-use indicators responses to cropping sequence and nitrogen fertilization

Authors: Sainju, Upendra

Submitted to: Journal of Crop Improvement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2024
Publication Date: 7/15/2024
Citation: Sainju, U.M. 2024. Spring wheat nitrogen relations responses to cropping sequence and nitrogen fertilization. Journal of Crop Improvement. 1-23. https://doi.org/10.1080/15427528.2024.2377362.
DOI: https://doi.org/10.1080/15427528.2024.2377362

Interpretive Summary: Novel management practices are needed to enhance nitrogen-use efficiency and recovery in dryland spring wheat production so that negative impacts of nitrogen fertilizers on soil and environmental quality can be reduced. An ARS researcher in Sidney, MT examined the effects of cropping sequence and nitrogen fertilization rate on nitrogen relations in spring wheat from 2012 to 2019 and reported that spring wheat-fallow with or without nitrogen fertilization increased spring wheat nitrogen concentration and uptake, but reduced nitrogen-use efficiency and nitrogen recovery compared to continuous spring wheat with low to high N fertilization rates. In contrast, continuous spring wheat with reduced nitrogen fertilization rate increased nitrogen-use efficiency and nitrogen recovery. However, neither spring wheat-fallow nor continuous spring wheat are effective at both enhancing crop yields and sustaining soil and environmental quality. While the former can negatively impact soil and environmental quality, the latter reduces wheat yield due to increased infestation of weeds and pests. As a result, the researcher reported that spring wheat-pea rotation with half of the recommended nitrogen fertilization rate can sustain spring wheat nitrogen yield and nitrogen-use efficiency without having a severe impact on the soil and environment. Producers can use a spring wheat-pea rotation with from one-half to the full recommended nitrogen fertilization rate to enhance dryland spring wheat nitrogen use efficiency.

Technical Abstract: Spring wheat (Triticum aestivum L.) N-use efficiency and recovery with N fertilization rates in crop rotations need further exploration. The effect of cropping sequence and N fertilization rate were evaluated on spring wheat N concentration and uptake, N harvest index (NHI), N-use efficiency (NUE), and N recovery index (NRI) from 2012 to 2019 in the northern Great Plains, USA. Cropping sequences were conventional till spring wheat-fallow (CTWF), no-till spring wheat-fallow (NTWF), no-till spring wheat-pea (Pisum sativum L.) (NTWP), and no-till continuous spring wheat (NTCW), and N fertilization rates to spring wheat were 0, 50, 100, and 150 kg N ha-1. Straw N concentration and N uptake were greater for CTWF than NTWP and NTCW in 4 out of 8 yr and increased with increased N fertilization rate. Grain N concentration and NHI varied with treatments and years. Grain N uptake was greater for CTWF and NTWF than NTWP and NTCW at most N fertilization rates and years. In contrast, NUE was greater for NTCW than CTWF and NTWF at all N fertilization rates in most years. The NRI was greater for NTWP or NTCW than CTWF or NTWF in most years. Increasing N fertilization rate increased grain N uptake for most cropping sequences in all years, but had a variable effect on NUE and NRI. Although spring wheat N concentration and N uptake were superior for CTWF and NTWF, and NUE for NTCW, NTWP with 50 to 100 kg N ha-1 can be used to sustain N relations.