A Comparative Nitrogen Balance and Productivity Analysis of Legume and Non-legume Supported Cropping Systems: The Potential Role of Biological Nitrogen Fixation

Abstract

The potential of biological nitrogen fixation (BNF) to provide sufficient N for production has encouraged re-appraisal of cropping systems that deploy legumes. It has been argued that legume-derived N can maintain productivity as an alternative to the application of mineral fertilizer, although few studies have systematically evaluated the effect of optimizing the balance between legumes and non N-fixing crops to optimize production. In addition, the shortage, or even absence in some regions, of measurements of BNF in crops and forages severely limits the ability to design and evaluate new legume–based agroecosystems. To provide an indication of the magnitude of BNF in European agriculture, a soil-surface N-balance approach was applied to historical data from 8 experimental cropping systems that compared legume and non-legume crop types (e.g., grains, forages and intercrops) across pedoclimatic regions of Europe. Mean BNF for different legume types ranged from 32 to 115 kg ha−1 annually. Output in terms of total biomass (grain, forage, etc.) was 30% greater in non-legumes, which used N to produce dry matter more efficiently than legumes, whereas output of N was greater from legumes. When examined over the crop sequence, the contribution of BNF to the N-balance increased to reach a maximum when the legume fraction was around 0.5 (legume crops were present in half the years). BNF was lower when the legume fraction increased to 0.6–0.8, not because of any feature of the legume, but because the cropping systems in this range were dominated by mixtures of legume and non-legume forages to which inorganic N as fertilizer was normally applied. Forage (e.g., grass and clover), as opposed to grain crops in this range maintained high outputs of biomass and N. In conclusion, BNF through grain and forage legumes has the potential to generate major benefit in terms of reducing or dispensing with the need for mineral N without loss of total output.

CLE peptide tri‐arabinosylation and peptide domain sequence composition are essential for SUNN‐dependent autoregulation of nodulation in Medicago truncatula

“…A multi‐stepped symbiosis between soil rhizobia and legumes results in the production of new root organs called nodules where inert atmospheric nitrogen (N) is converted into ammonia. This symbiosis sustainably provides the largest source of N to ecosystems (Bullock, ; Vitousek et al ., ; Jensen et al ., ; Iannetta et al ., ). Rhizobia infect root hair cells in the model legume Medicago truncatula by inducing and colonizing membrane invaginations called infection threads and they also simultaneously trigger cell divisions in several inner root layers which eventually form the nodule (Timmers et al ., ; Xiao et al ., ).…”

The introduction of soybean in an organic crop rotation in the Nemoral zone: the impact on subsequent spring wheat productivity

“…Biological N fixation varies in relation to the ability of legume species to fix N in different environmental conditions (Peoples et al, 2009). Across varying pedoclimatic regions of Europe it was shown that biological N fixation for different legume species ranges from 32 to 115 kg ha -1 annually (Iannetta et al, 2016). Our results show that the allocation of biologically fixed N in straw differed between forage and grain legumes.…”

“…Our results show that the allocation of biologically fixed N in straw differed between forage and grain legumes. Forage as opposed to grain crops in this range maintain high outputs of biomass and N tot (Iannetta et al, 2016). In Baltic region, clover was shown to accumulate up to 6.4-14.9 t ha -1 DM yield biomass and up to 118-327 kg ha -1 of N (Ingver et al, 2019).…”

“…In such systems, production of grain legumes offers multiple environmental benefits and can enhance sustainability of European farming, but their production area is declining constantly (Preissel et al, 2015). The decrease in legume cultivation in most of European agriculture remains poorly understood (Iannetta et al, 2016), but legume production in Lithuania is currently increasing. Lithuania is among the leaders in European Union's field pea market with a high increase of pea acreage and production since 2015 (FAOSTAT, 2019, http://www.…”

Processing Tomato–Durum Wheat Rotation under Integrated, Organic and Mulch-Based No-Tillage Organic Systems: Yield, N Balance and N Loss

“…The N balance (Table 1) allows the comparison between the three systems as it was computed by averaging the variations related to the conditions in individual years and crops [30]. The adoption of TIC in ORG+ considerably improved the N self-sufficiency of this system [31], raising (+35%) the Ndfa as compared to ORG. As expected, the Noutput values confirmed the gap between organic and conventional farming systems [32]; the Noutput values observed in ORG+ were the lowest in accordance with the finding of Knapp and van der Heijden [33] and Cooper et al [34].…”