The evaluation of the compatibility of cereal and green manure on the basis of nutrients

Research was carried out at the Lithuanian Research Centre for Agriculture and Forestry’s (LAMMC) Joniškėlis Experimental Station on a clay loam Endocalcari Endohypogleyic Cambisol. The study was aimed to explore the aboveground mass of perennial forage legumes: red clover (Trifolium pratense L.) and lucerne (Medicago sativa L.), and their mixtures with festulolium (x Festuliolium), used as green manure, qualitative parameters and compatibility with cereals on the basis of nutrients nitrogen (N), phosphorus (P) and potassium (K). The deficiency of other nutrients (P, K) and intensity of green manure mineralization can lead to N absorption. It has been determined that winter wheat takes one kg of N together with 0.2 kg P and 0.6 kg K. Spring wheat requires a similar amount of P but a higher amount of K. Average winter wheat grain yield can be 4.0 t ha-1 on a clay loam Cambisol in organic cropping system. NPK content – 134 kg ha-1 is needed for such productivity (grain + straw). This content is lower for spring winter growing. P:N and K:N ratios are more favourable in perennial forage legume mixture with festulolium, as compared to legume alone. To obtain grain yields of 4 t ha-1 of winter wheat and 3 t ha-1 of spring wheat in balanced organic crop rotation it is sufficient to apply 3.0 and 2.0 t ha-1 DM of pure legume mass as green manure. “Cut-and-carry” fertilisers do not satisfy the wheat demand for P

Long-term crop rotation and fertilisation effect on soil organic matter dynamics in sustainable agriculture management systems

https://doi.org/10.7220/9786094674662; https://zua.vdu.lt/wp-content/uploads/2020/12/Agroeco_2020_Abstracts-Book.pdfOne of the most important indicators of soil fertility is the soil organic matter and/or humus content. Humus content has the greatest importance for plant nutrition. Organic fertilisers is a key sustainable technology that needs to be integrated into agricultural practices to make agricultural management systems more efficient, as well as less negative for the environment. Long-term field experiments were conducted at the Lithuanian Research Centre for Agriculture and Forestry in 2006–2017. The objective of this research was to determine the impact of long-term crop rotation and organic and mineral fertilisation on soil humus content, humic and fulvic acids, organic matter humification in organic and sustainable agricultural management systems with low (1.90–2.01 %) and medium (2.10–2.40 %) humus levels. Results of the long-term use of organic and sustainable agricultural management systems with different crop rotations and fertilisation revealed the positive effect of the applied agro-means on soil humus, especially that of farmyard manure in combination with green manure. Analysis of humification showed that in organic system II where nitrogen rich biomass of white mustard was incorporated, which stimulated more intensive decomposition of organic matter, it was found significantly lower degree of humification in comparison to other agricultural management systems. In soil with low humus level the degree of humification under all agricultural management systems was significantly higher on average by 0.9 percentage points compared to that in soil with moderate humus level. Different forms of organic fertilisers are the main sustainable technology that should be integrated with other agricultural practices in order to make organic and sustainable agricultural management systems more productive and efficient and less negative to the environmentAgronomijos fakultetasLietuvos agrarinių ir miškų mokslų centras, Joniškėlio bandymų stotisVytauto Didžiojo universitetasŽemės ūkio akademij

Protonation of [FeFe]-hydrogenase sub-site analogues: revealing mechanism using FTIR stopped-flow techniques

The formation of transient metal hydride(s) at the metallo-sulfur active sites of [FeFe]-hydrogenase is implicated in both hydrogen evolution and uptake reactions. Stopped-flow spectroscopic techniques can provide insight into the reactivity patterns of model {2Fe2S} sub-sites towards protons, and this information contributes to understanding the nature of the biological systems. In this study we have focussed on the influence of the nature of the bridging dithiolate ligand in influencing the kinetics and activation energy parameters for protonation in synthetic sub-sites including Fe2{µ-[S(CH2)nS]}(CO)4(PMe3)2 [n = 2, ethane-1,2-dithiolate (edt) or n = 3, propane-1,3-dithiolate (pdt)], Fe2[(µ-SCH2)2NH](CO)4(PMe3)2 and (NEt4)2{Fe2[(µ-SCH2)2NH](CO)4(CN)2}. Notably we find that (i) the presence of a nitrogen in the dithiolate bridge does not accelerate metal–metal bond protonation, and that (ii) immobilisation of (NEt4)2[Fe2(µ-pdt)(CO)4(CN)2] in a polymer matrix stabilises otherwise short-lifetime protonation products

Perennial forage legume cultivation and their above-ground mass management methods for weed suppression in arable organic cropping systems

Abstract Background In organic crop farms, growing crop yields are limited by insufficient nitrogen supply to plants and crop weediness. In such farms, legume swards are proposed as a service crop to improve nitrogen cycling. However, a positive effect of nitrogen is not only on cereals but also on weeds. In crop rotation, legume swards can stimulate the competition of cereals using the above-ground mass of legume to control the spread of weeds. The effects of the following methods for weeds control were analyzed: (i) forage legumes (Trifolium pratense L. and T. repens) undersown in cereals, (ii) forage legumes (T. pratense L., Medicago sativa L.) and their mixture with festulolium (x Festuliolium) and their above-ground mass management methods, and (iii) plant-based fertilizers (red clover above-ground mass fermented and composted). Results Oat with red clover undersown reduced weediness more than red clover monocrops, pea, and their mixture with oats. Incorporated undersown white clover mass increased spring barley competitiveness with weeds. When growing legume swards for a longer period of time (green fallow), red clover and their mixture with festulolium are the most suitable for this purpose. The lowest weed dry weight (average 34%, compared with the removal from the field) was obtained while using the mixed management. The cultivation of cereals after forage legumes and their mixtures with festulolium (as a preceding crop) increases its grain yield and competitive ability against weeds. Fermented red clover and fermented pea and spring wheat mixture mass, as a manure, did not increase weediness. Conclusions It was concluded that the effectiveness of the perennial forage legumes is determined by the uses of the above-ground mass: soil cover, mulching, application of green manure, and intensity of mass mineralization. Type of activity of forage legumes on weeds were competition for environmental resources, disruption/promotion of germination, destruction of above-ground mass, reduction of the amount of matured seeds, creation of a physical barrier (mulch), and increase of competitiveness of cereals. Growing forage legumes in pure crops usually leads to a loss of marketable production. Graphic abstrac

Mechanistic aspects of the protonation of [FeFe]-hydrogenase subsite analogues

The formation of transient metal hydride(s) at the metallo-sulfur active sites of [FeFe]-hydrogenase is implicated in both hydrogen evolution and uptake reactions. Using a combination of time-resolved NMR, stopped-flow UV and stopped-flow IR, we have begun to unravel the mechanisms for protonation of synthetic electron-rich analogues of the di-iron subsite of the enzyme: Fe2(µ-pdt)(CO)4(PMe3)2, Fe2(µ-edt)(CO)4(PMe3)2, (NEt4)2[Fe2(µ-pdt)(CO)4(CN)2], (NEt4)2[Fe2(µ-edt)(CO)4(PMe3)2] and (NEt4)[Fe2(µ-pdt)(CO)4(CN)(PMe3)] (pdt = propane-1,3-dithiolate, edt = ethane-1,2-dithiolate). The mechanistic role of isomer interconversion and how this critically relates to steric access to the di-iron bridge are revealed.)] (pdt = propane-1,3-dithiolate, edt = ethane-1,2-dithiolate). The mechanistic role of isomer interconversion and how this critically relates to steric access to the di-iron bridge are revealed

Electronic Control of the Protonation Rates of Fe–Fe Bonds

Protonation at metal–metal bonds is of fundamental interest in the context of the function of the active sites of hydrogenases and nitrogenases. In diiron dithiolate complexes bearing carbonyl and electron-donating ligands, the metal–metal bond is the highest occupied molecular orbital (HOMO) with a “bent” geometry. Here we show that the experimentally measured rates of protonation (kH) of this bond and the energy of the HOMO as measured by the oxidation potential of the complexes (E1/2ox) correlate in a linear free energy relationship: ln kH = ((F(c – βE1/2ox))/(RT)), where c is a constant and β is the dimensionless Brønsted coefficient. The value of β of 0.68 is indicative of a strong dependence upon energy of the HOMO: measured rates of protonation vary over 6 orders of magnitude for a change in E1/2ox of ca. 0.55 V (ca. 11 orders of magnitude/V). This relationship allows prediction of protonation rates of systems that are either too fast to measure experimentally or that possess additional protonation sites. It is further suggested that the nature of the bridgehead in the dithiolate ligand can exert a stereoelectronic influence: bulky substituents destabilize the HOMO, thereby increasing the rate of protonation