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See more from this Session: Professional Oral Presentation: III
Ruiyu Lin1, 2 and Chengci Chen2*
(1. Institute of Agroecology, School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, P.R. China, 350002; 2. Central Agricultural Research Center, Montana State University, Moccasin, MT 59462, USA)
ABSTRACT
Crop rotations have been a successful strategy in managing wheat-based agroecosystem. Several rotation systems, including wheat-legume, wheat-oil crop and wheat-potato etc., have been setup in such a typically cold dry weather region in the Northern Great Plains of central Montana. The objective of this study was to estimate 1) winter wheat biomass and grain yield and nitrogen use efficiency (NUE) affected by rotation and tillage, and 2) if introducing legume to the rotation will increase winter wheat yield and NUE in till and no-till practices. Four crop rotations were initiated in a) long-term no-till field and b) long-term tilled field for 6 years. The treatments included four crop rotations (fallow-winter wheat, spring pea-winter wheat, spring wheat-winter wheat, and winter pea-winter wheat) and two tillage regimes (till and no-till), four N rates (0 kg ha-1, 45 kg ha-1, 90 kg ha-1 and 135 kg ha-1). When the experiment was initiated in the long-term no-till field (Experiment I), winter wheat biomass(BM) and grain yields were consistently greater in FW-WW rotation than in the others, showing in the order of FW–WW(5.585 Mg ha-1)> WP–WW(5.169 Mg ha-1) > SP–WW(4.619 Mg ha-1) > SW–WW(2.910 Mg ha-1). After converting no-till to till, ABMs of WW were enhanced by 9.4%, 8.2%, 13.0% and 13.1% for FW–WW, SP–WW, SW–WW and WP–WW, respectively, and grain yield increased 8.5%, 11.0%, 19.6%, and 14.1%. Similar results were found on long-term tilled field (Experiment II), however, the ABMs in the four rotations increased by 21.4%, 25.4%, 24.5% and 52.9% and the grain yields were by 22% times, 27% times, 30% and 1.62% in experiment II, respectively, and no significant differences were found after converting till to no-till. The total N uptake was consistently greater in till than in no-till, especially in Experiment I, Nitrogen use efficiency was consistently higher in till than in no-till in Experiment I, but was not different between the tillage regimes in Experiment II. The NUEs were in the order of FW-WW (0.492)>SP-WW (0.454) ≈WP-WW(0.452)>SW-WW(0.291) in experiment I. After converting no-till to till, NUEs were significantly enhanced, showing in the order of FW-WW (0.578)>SP-WW (0.534)>WP-WW(0.472)>SW-WW(0.341). The lowest NUE was 0.462 observed in SP-WW rotation in experiment II, following by SW-WW(0.513), FW-WW(0.523) and FW-WW (0.558) rotations. Introducing peas in rotation with winter wheat greatly increased winter wheat yield and N use efficiency compared with spring wheat-winter wheat mono-cropping. Winter wheat following winter pea harvested for hay produced similar yield at low N level compared with winter wheat following fallow. However, fallowed field conserves more water than the field after growing winter pea for hay, therefore, winter wheat yield was higher in the fallow-winter wheat rotation than in winter pea-winter wheat rotation at higher N levels. Adding legume to the rotation can add more crop residues with low C:N ratio, which may expedite the residue decomposition and N cycling in no-till system. Further study is needed to determine N cycling in different crop rotations in no-till systems.
Keywords: winter wheat, pea, crop rotation, tillage, nitrogen use efficiency, Abbreviations: FW, Fallow; SW, Spring Wheat; WP, Winter Pea for Hay; WW, Winter Wheat; BM, Biomass; NUE, Nitrogen Use Efficiency.
*Corresponding author: Chengci Chen, Montana State University, Central Agricultural Research Center, 52583 U.S. Hwy 87, Moccasin, MT 59462; E mail:cchen@montana.edu.
See more from this Session: Professional Oral Presentation: III