Dataset associated with the manuscript: Soil management legacy interacts with wheat genotype to determine access to organic N in a dryland system

Organic nutrient management through the application of compost and/or
cover crops provides mineralizable sources of nutrients for plants while
often building soil organic matter (SOM) and various aspects of soil
health. Variability in nutrient acquisition strategies between crop
genotypes may confer advantages under different soil health contexts and
could be important for crop selection and breeding, but crop response
under field conditions remains unexplored. We investigated the ability of
different genotypes of winter wheat (Triticum aestivum L.) to
access nitrogen (N) from newly added cover crop residues in two soils with
contrasting levels of SOM and biological activity. We planted three
previously characterized wheat genotypes in a long-term dryland compost
amendment field trial: 1) Byrd (modern, deep roots, low exudation), 2)
Cheyenne (historic, drought susceptible, intermediate exudation), and 3)
Snowmass (modern, drought-susceptible, high
exudation). 15N-labelled cover crop residue was added to each
plot and traced into wheat tissue. In the low SOM soil, the high exudate
genotype Snowmass and historic genotype Cheyenne took up the most
residue-derived N (6.4-8.1 kg N ha-1) compared to the low-exudate genotype
Byrd (4.4 kg N ha-1), suggesting a strong exudate effect in the more
carbon-limited soil. However, the low-exudate, deep rooted genotype, Byrd,
took up the most residue N in the high SOM soils (4.6 kg N
ha-1 vs. 2.8 and 3.3 hg N ha-1 for Cheyenne and Snowmass,
respectively), which indicated higher native N cycling activities and
great importance of drought resistance. Enzyme activity, inorganic N, and
microbial communities were not influenced by genotype, though did show
strong effects of compost application legacy. Our results show that
belowground allocation strategies that favor microbial stimulation may be
less successful under water limitation, especially when high SOM can
support mineralization of residue N without added investment in root
inputs. Increased soil health through SOM-building management likely
enhances nutrient cycling, and may better support root strategies that
invest less in microbial stimulation in favor of other limiting resources.