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NCHAIN – Forging strong links in the organic nitrogen chain

Posted by | February 21, 2021

Principal Investigators: Stig Uggerhøj Andersen, Aarhus University; Peter Young, The University of York; Torben Asp, Aarhus University; Luc Janss, Aarhus University; Bjarni Vilhjalmsson, Aarhus University

Associated with: DLF-Trifolium; Legume Technology

Project Summary:

In agriculture, nitrogen (N) is an important macronutrient critical for plant yield. Without access to synthetic N fertilizers, many Danish organic farmers face a severe challenge in providing sufficient amounts of nitrogen for optimal crop yield. The main N contribution often comes from clover/grass swards, which both generate feed for livestock and provide N fertilization and soil improvement for successive crops in a crop rotation scheme. The N chain in this production system has four main links: 1) Symbiotic N2 fixation by rhizobia; 2) Transfer of fixed N to legume hosts (clover); 3) Transfer of fixed N to other plant species (grasses); 4) Transfer of plant N to cattle. Overall, the efficiency depends heavily on interspecies interactions between rhizobium/clover and clover/grass. The state of the art is to assume that rhizobia already present in the soil provide effective nitrogen fixation with all clover varieties: essentially, that genetic variation between rhizobia is insignificant or that optimal rhizobia for all clover varieties are present in all soils. In terms of plant interactions, it is assumed that the performance of clover and grass varieties determined in monoculture reflects their performance as mixed crops. We hypothesize that gains in N fixation and biomass yield can be obtained using genomic prediction of interspecies interactions, and we will test this hypothesis by capturing and analyzing genotype and phenotype data for rhizobium/clover/grass crops.