Evaluation of cultivation, legume undersowing and nitrogen interventions on wheat development

  • Karen E. Rial Lovera

    Student thesis: Doctoral ThesisDoctor of Philosophy


    Agriculture is facing increasing pressures to produce food that meets specific market and/or nutrition requirements, while using inputs in such a way that can ensure economic and environmental goals more efficiently. Two field experiments were conducted in 2013 and 2014 at the Royal Agricultural University’s Harnhill’ Manor Farm, Cirencester, UK to evaluate the influence of selected cultivation techniques, N fertilisation and undersowing legumes on spring wheat growth and development. To explore, in particular, the yield components contributing to grain yield and quality, as well as weed pressure influences together with changes in soil mineral N (SMN) content. Cultivation techniques included conventional tillage (CT), high intensity non-inversion tillage (HINiT) and low intensity non-inversion tillage (LINiT); mineral N fertilisation rates of 0, 70, 140 and 210 kg N ha-1 and two undersown legume species, black medic and white clover, plus no undersowing treatment. The performance of the management practices was strongly influenced by the weather. In 2013, under dry weather conditions, LINiT seems to be a suitable alternative to CT, while N fertilisation did not encourage greater grain yield. In 2014, CT appears to be a more reliable practice, while the application of up to 140 kg N ha-1 seemed to be enough to increase grain yield. Dry weather conditions at the time of broadcasting did not allow the undersowing species to be fully established, resulting in no effects on weed control and crop growth. In 2013, the initial poor plant establishment and slow crop growth under LINiT was compensated for by the soils ability to retain moisture, and thereby reducing crop water stress during the dry periods. This finally resulted in statistically similar grain yield to CT. In 2014 when water was not a limiting factor, poor plant establishment and crop growth, low SMN content and high weed pressure under LINiT resulted in lower grain yield than CT. In both years, HINiT resulted in low SMN content and high weed pressure resulting in poor grain yield. Across experiments, HINiT and LINiT saved energy-use and production costs, but CT could be more energy-use efficient and have high economic return if higher grain yield is assured. N fertilisation significantly promoted wheat growth, although under dry conditions with higher residual soil N, the N fertilisation did not increase yield. Under low SMN level applying up to 140 kg N ha-1 increased grain yield produced, but N fertilisation is energy consuming and its use does not always ensure a higher economic return.
    Date of Award2015
    Original languageEnglish
    Awarding Institution
    • Coventry University
    • Royal Agricultural University
    SupervisorNicola Cannon (Supervisor), Paul Davies (Supervisor) & John S. Conway (Supervisor)


    • Grain
    • Soil fertility
    • Legumes
    • Nitrogen

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