AGRONOMIJAS VĒSTIS - Latvijas Lauksaimniecības universitāte

AGRONOMIJAS VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008used for all experiments. The impact of the weed infestation was investigated comparing herbicideSecator 0.3 kg ha -1 usage and a no herbicide treatment (factor C).Meteorological conditions were different in all trial years with great differences in thelong-term observations. That was a reason for the variation in the obtained results.Traditional soil tillage has advantages in years with great amount of precipitation (growingseason 2000 - 2001 and especially 2001 - 2002) but in dry conditions (autumn 2002) asignificanthy higher yield was produced by direct sowing.Comparing additional expenses for soil tillage and additional obtained yield bothtreatments – minimal tillage and traditional tillage – gave additional profit on average in threeyears. The highest increase of winter wheat grain yield from additional investments was observedin treatment with minimal soil tillage growing winter wheat in recurrent sowing and usingherbicides – 81.2 kg from 1 additionally expended LVL. A higher profit is realized fromadditionally expended resources in this treatment on average in three years.Key wordsWheat, tillage, previous crop, economical evaluation.IntroductionThe tendency of using reduced soil tillage technologies is beecoming more important andpopular in Latvia and in EU countries (Romaneckas, 1999; Satkus, 2000; Simanskaite, 2000). It ismainly caused by a more economical use of production sources in agriculture. Many newagricultural machines for minimal soil tillage and no-till are now offered from producers ofagricultural machinery. Many experiments about those methods were done in EU counties duringthe period of years 1970 – 1988 when many different soil cultivation and tillage methods onvarious crops were compared (Cannel, 1985; Finney and Knight, 1973; Ellis and Hause, 1980;Lutch and Vaidyanathan, 1983). On those results presently are done the main part of engineering ofagricultural machinery and recommendations of use.Research and experiments on different technological solutions for soil tillage systems andtheir impact on the productivity of different crops happens in many places in Latvia. Research insoil tillage systems in winter wheat production after different previous crops, together with theefficiency of herbicide use, were not done previously in Latvia. Also agricultural machinery usedfor those experiments Simba Discs 34C 4.6 + Simba double press 4.6 were not compared inLatvian conditions, especially on heavy clay soils.The target of the scientific work is to clarify benefits or disadvantages of minimal soiltillage and no-till against traditional soil ploughing with stubble reversing. Also to find thedifferences in costs of those technologies and the economical profit or loss using them. The resultswill create the possibility to find optimal ways of using those technologies and work outrecommendations on practical production.Materials and MethodsThe three years experiments (2001 – 2003) were carried out at the farm SIA Dobele Agralocated in the Dobele region of Latvia. The soil there is heavy clay. Trials were established in twodifferent crop rotations: 1. winter wheat sown after winter wheat, 2. winter wheat sown after winterrape (Factor A). Three different soil tillage and sowing methods were compared: 1.minimalconservation soil tillage 10 – 15 cm deep with mixing of soil, 2. direct sowing into stubble withoutany soil cultivation, 3.traditional soil tillage with ploughing on 25 cm with cultivation beforesowing (Factor B). Additionally compared impact of those soil tillage methods on weed infestationin winter wheat: 1. with herbicide, 2. without herbicide treatment (Factor C). The field trials weredesigned with sizes 24 x 100 m.The winter wheat variety ‘Zentos’ was sown on 25.09.2000., 29.09.2001. and 30.09.2002at optimal soil conditions. Sowing was done with the pneumatical cultivator seed drill VaderstadRapid 600P which is equipped with 2 rows of cultivator tines (Agrilla system) and one row oflevelling tines (crossboard system). Soil ploughing was done with the 6 furrow conventionalplough Kverneland, soil cultivation prior to ploughing was done with the equipment VaderstadRexius which consist of levelling board (crossboard) and rollers (Cambridge type). Minimal soil69