AGRONOMIJAS VÄSTIS - Latvijas LauksaimniecÄ«bas universitÄte

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AGRONOMIJAS VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008Table 3. The influence of crop sequence in crop rotation on weed fresh weight before theharvesting of crops, 2004-2006, g m -2Number Years Crops The fresh weight of weedsof field1. 2004.2005.2006.triticale/ ryeoil radish/ryepotatoes247.251.441.0Average2. 2004.2005.2006.Average3. 2004.2005.2006.Average4. 2004.20052006.Average5. 2004.2005.2006.Average6. 2004.2005.2006.Averagerye/white mustardpotatoesoatspotatoesoatsvetch-oats mix.oatsvetch-oats mix.red clover, timothyvetch-oats mix.red clover, timothytriticale/ rye113.2-37.43.020.272.432.545.750.218.962.621.834.452.949.045.649.2red clover, timothy-triticale/ rye47.8oil radish/rye51.349.6LSD 0.05 97.5In 2004 in the rye/ white mustard stand, and in the red clover and timothy stand the biomass ofweeds was not determined. There were not sygnificant differnces among the crop rotation links.ConclusionsThe number of weeds in the fields of crop rotation in organic farming systems is dependent oncultivated crops, the succession of crops in the crop rotation links and crop cultivationtechnologies.We agree with opinion of researchers who indicated that weed infestation is the major cropprotection problem in organic farming systems, and the development of weed managementstrategies requires detailed information on weed population dynamics. Therefore, long termresearch is necessary to analyse this problem accurately.The investigations will be continued at least up to the end of a rotation period.References1. Albrecht H. (2005) Development of arable weed seedbanks during the 6 years after the change fromconventional to organic farming. Weed Research, 45, 339-350.2. Baumann D. & Slembrouck I. (1994) Mechanical and integrated weed control systems in row crops.Acta Horticulturae 372, Engineering for Reducing Pesticide Consumption and operator Hazards, 245-252.3. Baumann D., Kroff M. & Bastiaans L. (2000) Intercropping leeks to suppress weeds. Weed Research, 40(4), 359-374.4. Bond W. & Grundy A. (2001) Non-chemical weed management in organic farming system. WeedResearch 41 (5), 383-405.5. Delate K. (2002) Using an agroecological approach to farming systems research. HortTechnology, 12(3), 345-354.6. Doucet C., Weaver S., Hamill A. and Zhang J.(1999) Separating the effects of crop rotation from weedmanagement on weed density and diversity. Weed Science, 47 (6), 729-735.30
AGRONOMIJAS VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 20087. Kurstjens D. & Perdock U. (2000) The selective soil covering mechanism of weed harrows on sandysoil, Soil & Tillage Research, 55, 193-206.8. Lampkin N. (1994) Organic Farming. Farming Press Books. Ipswich, U.K., 161.9. Liebman M. & Davis A. (2000) Integration of soil, crop and weed management in low-external-inputfarming systems. Weed Research, 40, 27-47.10. Maiksteniene S. and Arlauskiene A. (2005) The influence of different crop management practices onsoil fertility and crop rotation productivity. Agronomijas vēstis, 8, 216-220.11. Weed Control Handbook: Principles (1990) Edit. by Hance R. & Holly K. Blackwell ScientificPublications. British Crop Protection Council. Oxford, 329-365.DYNAMICS OF SOIL ORDER AND PENETRATION RESISTANCE IN SOIL WITH ANDWITHOUT SPRING BARLEYAUGSNES SAKĀRTAS UN PENETROMETRISKĀS PRETESTĪBAS IZMAIĥUDINAMIKA AUGSNĒ AR UN BEZ VASARAS MIEŽIEMBērziĦš A., LapiĦš D., Dinaburga G., Plūme A., Melngalvis I., Sprincina A., Sanžarevska R.Latvijas Lauksaimniecības universitāte, Lielā iela 2, Jelgava, Latvija, LV-3001Tel.: +371 63005632, e-mail: Dainis.Lapins@llu.lvAbstractChanges in the dynamics of soil bulk density as well as soil penetration resistance with andwithout spring barley has been investigated in the 30 stationary observation points in the Researchand Study farm “Vecauce” of the Latvia University of Agriculture in 2005-2006. the distancebetween points was 5 m. Observations were made at the stage of 2 till 3 leaves of spring barley, atthe end of tillering, at the stem elongation stage (2 till 3 node stage), as well as before harvesting.Soil penetration resistance and moisture was determined till 50 cm deep. Yield and its structureelements were determined with sample sheafs from 0.1 m 2 . It was established that in areas sownwith spring barley soil moisture losses from topsoil and also from subsoil besauce of the plants’transpiration promoting soil penetration resistance increase substantially in the conditions of 2005and 2006. Essential differences in soil penetration resistance in plant root action zones wereestablished when compared with observation points without plants in the development stage ofspring barley after tillering. It means that plants with their own root action restrict the placementdepth of roots.Key wordsSpring barley, soil moisture, soil penetration resistance, yield formationIevadsLatvijā jau iepriekšējos gados ir veikti pētījumi par augsnes apstrādes pasākumuoptimizēšanas iespējām, lietojot augsnes pretestības mērījumus ar GPS noteiktos stacionārospunktos ziemas kviešu sējumos (Lapins, Vilde, Berzins, et. al. 2006), kā arī izmēăinājumos vasarasmiežos (Lapins, Berzins, et. al. 2005). Konstatētas būtiskas augsnes penetrometriskās pretestībasrādītāju atšėirības sezonās. Viens no augsnes penetrometriskās pretestības izmaĦu cēloĦiem bijanokrišĦu daudzums un augsnes mitrums. Pētījumu mērėis bija pārbaudīt hipotēzi par auga sakĦusistēmas iedarbību uz augsnes penetrometrisko pretestību un skaidrot sakarības starp augsnesmitrumu, pretestību un sakārtas blīvumu.Materiāli un metodesLauka izmēăinājumi veikti LLU MPS „Vecauce” 2005. – 2006. g., vasaras miežus audzējotatkārtotā sējumā. Meteoroloăiskie apstākĜi abos gados bija atšėirīgi: 2005.g. raksturojās arpazeminātām gaisa temperatūrām, bet 2006.g. – ar izteikti zemu nokrišĦu daudzumu un līdz ar toarī mitruma deficītu augsnē (1. un 2. att.).31
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