Optimal Planting Date of Kernza Intermediate Wheatgrass Intercropped with Red Clover

Intermediate wheatgrass (IWG) is a new perennial dual-use crop for grain and forage with growing interest among farmers. Intercropping IWG with red clover may increase yield and nutritive value through nitrogen transfer. IWG and red clover planting timing can affect grain and forage yield, and there has not been previous research on this management practice. At two locations (Arlington and Lancaster, WI, USA) a factorial experiment was established two years with two factors: (1) IWG planting date (August through October, and April) and (2) red clover planting season (in the fall with IWG or frost seeded in the next spring). Yield data were collected for two subsequent years. Grain yield was maximized at 515 kg ha−1 and 423 kg ha−1 at Arlington and Lancaster when planted by 26 August and 13 September, respectively. Planting date influenced grain yields in the first harvest year but not in the second. Seeding red clover in the spring increased IWG and red clover biomass compared to seeding it in the fall. In Wisconsin, planting IWG by early September at the latest and planting red clover in the spring is recommended to maximize grain yield.

Bidirectional Nitrogen Transfer and Plant Growth in a Mixed Plantation of N2-Fixing Species and Eucalyptus urophylla × E. grandis under Different N Applications

N2-fixing species play a crucial role in mixed-plantations as they improve stand productivity. To quantify the N transfer from N2-fixing species to Eucalyptus (Eucalyptus urophylla × E. grandis) in N2-fixing species/Eucalyptus plantations, we established a pot experiment and confirmed the occurrence of this process under natural conditions. The 15N was traced in labeled species as well as in neighboring tree species after labeling, and the growth was evaluated in short-term natural trials. Our results showed that a bidirectional N transfer occurred. The amount of net N transfer was 21.8–127.0 mg N plant−1, which was equal to 1.5–21.2% of the total nitrogen (TN) that accumulated in Eucalyptus plants under pot conditions, was transferred from Dalbergia odorifera to Eucalyptus. The amount of N transferred significantly decreased with the increasing N application rate but increased with time after labeling. Compared with the results for the Eucalyptus monocrop, the soil N concentration (including NO3−-N and NH4+-N) greatly improved when D. odorifera was introduced together with Eucalyptus under both field and pot conditions. Furthermore, the results under field conditions were consistent with the results of the pot experiment. The dry matter (DM) yield (14.5–16.4%) and the N content (5.1–9.6%) in Eucalyptus increased when mixed together with D. odorifera, but the N content in and DM yield of D. odorifera slightly decreased. It is concluded that the N transfer between Eucalyptus and D. odorifera is a much more important dynamic process than previously recognized, and Eucalyptus and legume intercropping is a successful management practice because N transfer provides a significant amount of N required for Eucalyptus productivity.

Biological N Fixation and N Transfer in an Intercropping System between Legumes and Organic Cherry Tomatoes in Succession to Green Corn

The aim of this study was to investigate the transfer of N from different legumes to cherry tomatoes in the intercropping system under residual straw of the previous green corn crop using the 15N natural abundance method. We also investigated the temporal variation in nitrogen transfer to a cherry tomato, the biological nitrogen fixation (BNF) of legumes, and the N concentration of green corn cultivated in the intercrop succession. The experimental design was a complete randomized block with eight treatments and five replications, described as follows: two controls consisting of a monocrop of cherry tomato with or without residual straw, cherry tomato and jack bean, sun hemp, dwarf velvet bean, mung bean, and white lupine or cowpea bean in intercropping system. The BNF was responsible for more than half of the N accumulated in the legumes. The N of legumes was transferred to cherry tomato in similar quantities, and the leaves and fruits of cherry tomato received more N transfer than shoots. It was shown that N transfer increases with the growth/development of cherry tomatoes. The intercropping system with legumes did not affect the 15N natural abundance of leaves and the aboveground biomass of green corn cultivated in succession.

A Theoretical Approach to Demystify the Role of Copper Salts and O2 in the Mechanism of C-N Bond Cleavage and Nitrogen Transfer

<b>C≡N bond scission accomplished by protonation, reductive cleavage and metathesis techniques are well-known to execute nitrogen transfer reactions. Herein, we have conducted an extensive computational study, using DFT and molecular dynamics simulations, to unravel the mechanistic pathways traversed in CuCN and CuBr₂ promoted splitting of coordinated cyanide anion under a dioxygen atmosphere, which enables nitrogen transfer to various aldehydes. Our detailed electronic structure analysis using <i>ab initio</i> multi-reference CASSCF calculations reveal that both the promoters facilitate radical pathways, in agreement with the experimental findings. This is a unique instance of oxygen activation initiated by single electron transfer from the nitrile carbon, while the major driving force is the operation of the Cu^II/Iredox cycle. Our study reveals that the copper salts act as the “electron pool” in this unique nitrogen transfer reaction forming aryl nitrile from aryl aldehydes.</b><br>

A Theoretical Approach to Demystify the Role of Copper Salts and O2 in the Mechanism of C-N Bond Cleavage and Nitrogen Transfer

<b>C≡N bond scission accomplished by protonation, reductive cleavage and metathesis techniques are well-known to execute nitrogen transfer reactions. Herein, we have conducted an extensive computational study, using DFT and molecular dynamics simulations, to unravel the mechanistic pathways traversed in CuCN and CuBr₂ promoted splitting of coordinated cyanide anion under a dioxygen atmosphere, which enables nitrogen transfer to various aldehydes. Our detailed electronic structure analysis using <i>ab initio</i> multi-reference CASSCF calculations reveal that both the promoters facilitate radical pathways, in agreement with the experimental findings. This is a unique instance of oxygen activation initiated by single electron transfer from the nitrile carbon, while the major driving force is the operation of the Cu^II/Iredox cycle. Our study reveals that the copper salts act as the “electron pool” in this unique nitrogen transfer reaction forming aryl nitrile from aryl aldehydes.</b><br>