Macro- and microscale gaseous diffusion in a Stagnic Luvisol as affected by compaction and reduced tillage

Intensification of mechanical agriculture has increased the risk for soil compaction and deformation. Simultaneously, reduced tillage practices have become popular due to energy saving and environmental concerns, as they may strengthen and improve the functioning of structured soil pore system. Soil aeration is affected by both compaction and reduced tillage through changes in soil structure and in the distribution of easily decomposable organic matter. We investigated whether a single wheeling by a 35 000 kg sugar-beet harvester in a Stagnic Luvisol derived from loess near Göttingen, Germany, influenced the gas transport properties (air permeability, gaseous macro- and microdiffusivities, oxygen diffusion rate) in the topsoil and subsoil samples, and whether the effects were different between long-term reduced tillage and mouldboard ploughing. Poor structure in the topsoil resulted in slow macro- and microscale gas transport at moisture contents near field capacity. The macrodiffusivities in the topsoil under conventional tillage were slower compared with those under conservation treatment, and soil compaction reduced the diffusivities by about half at the soil depths studied. This shows that even one pass with heavy machinery near field capacity impairs soil structure deep into the profile, and supports the view that reduced tillage improves soil structure and aeration compared with ploughing, especially in the topsoil

Selluloosatehtaan jätelietteen lannoitusvaikutus

vKirjasto Aj-kFertilizer effect of sludge from a sulphate and paper mil

Allocation of added selenium in lettuce and its impact on roots

Allocation of selenium (Se) in lettuce and its impact on root morphology were studied to better understand the growth responses of plants to added Se. Lettuce was grown in vermiculite under controlled growing conditions for seven weeks, and the allocation in the shoots and roots of selenate added in increasing dosages (0, 1, 10, 100, 500 and 1000 µg Se per 3.5-litre pot) as well as morphological variables of the roots were determined. The intermediate additions of 100 and 500 µg Se per pot seemed to produce the highest biomasses, although this was nearly masked by large scatter in the data. The Se contents both in roots and shoots increased roughly proportionally to the amount of Se added. However, at small additions Se was preferentially allocated to roots, whereas at larger additions the contents in roots and shoots (mg kg-1 dry matter) were roughly equal. Se treatments did not change the morphology of hypocotyls. On the contrary, the specific length and area of basal and lateral roots were smallest at intermediate Se additions, whereas the specific volume was largest at the largest Se addition. These effects of Se on root morphology were, however, not unambiguously related to plant growth. As the Se contents in roots increased, the roots grew thicker and the specific volume of lateral roots increased in agreement with a hypothesis of increased endogenous ethylene production

Tuloksia hiesumaan syväkynnöstä ja maanparannuksesta

vokKirjasto Aj-

Hiesun viljelytekniikka

vokKirjasto Aj-

Genomic Analysis of Staphylococcus aureus Isolates Associated With Peracute Non-gangrenous or Gangrenous Mastitis and Comparison With Other Mastitis-Associated Staphylococcus aureus Isolates

Staphylococcus aureus is a highly prevalent cause of mastitis in dairy herds worldwide, capable of causing outcomes that vary from subclinical to peracute gangrenous mastitis. We performed a comparative genomic analysis between 14 isolates of S. aureus, originating from peracute bovine mastitis with very severe signs (9 gangrenous, 5 non-gangrenous) and six isolates originating from subclinical or clinical mastitis with mild to moderate signs, to find differences that could be associated with the clinical outcome of mastitis. Of the 296 virulence factors studied, 219 were detected in all isolates. No difference in the presence of virulence genes was detected between the peracute and control groups. None of the virulence factors were significantly associated with only a single study group. Most of the variation in virulence gene profiles existed between the clonal complexes. Our isolates belonged to five clonal complexes (CC97, CC133, CC151, CC479, and CC522), of which CC522 has previously been detected only in isolates originating from caprine and ovine mastitis, but not from bovine mastitis. For statistical analysis, we sorted the CCs into two groups. The group of CCs including CC133, CC479, and CC522 was associated with gangrenous mastitis, in contrast to the group of CCs including CC97 and CC151. The presence of virulence genes does not explain the clinical outcome of mastitis, but may be affected by allelic variation, and especially different regulation and thus expression in the virulence genes.Peer reviewe

Tuloksia ohran ja kauran lajikokeista Keski-Suomessa Lannoitustaso ja ohran sato

vokKirjasto Aj-

Rikkakasvien siementen määrä ja elinvoima Satakunnan ja Etelä-Pohjanmaan tutkimusasemien maanäytteissä

VokKirjasto Aj-

Yksivuotisen lupiinin nystyräbakteerien eristäminen ja valikoitujen siirroskantojen testaus kenttäolosuhteissa

VokLoppuunmyyt