AGRONOMIJAS VĒSTIS - Latvijas Lauksaimniecības universitāte

AGRONOMIJAS VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008properties pf soil. In contemporary agriculture soil must be resistant to all degradation factors andsoil properties must meet the requirements of sustainable and input-saving crop cultivationtechnologies.Compaction as the main type of soil physical degradation is especially typical on clayeysoils, because they do not resist soil compaction well. Great compaction of heavy soils results in aconsiderable worsening of their physical and technological properties. With increased soilcohesion, hardness, plasticity, and stickiness soil resistance to tillage as well as energy inputincrease. Therefore it is vital to improve the clayey soils physical properties by the incorporation ofvarious amendments as ameliorants, apply the proper soil tillage methods, choose the best-suitedalternative soil and crop management practices (Maiksteniene, 1997; Balesdent et al., 2000; Hornet al., 2000; Lapins et al., 2001; Palojarvi and Nuutinen, 2002).Great compaction of clayey soils increases its high comparative resistance to mechanicaltillage and much energy input is required to overcome this problem. Energy input for soil tillage ismarkedly decreased by the replacement of conventional ploughing by ploughless tillage. Mostauthors maintain that tillage without inversion of the plough layer results in improved physical,chemical and biological properties of the upper topsoil layer, however the soil properties tend todeteriorate at the bottom of the topsoil (Rasmussen, 1999; Tebrugge and During, 1999; Feiza andCesevicius, 2006). Therefore, the aim of this study is to evaluate the feasibility to improve theclayey soil‘s physical properties by the incorporation of amendments and to apply the sustainabletillage technologies for grown crops.Materials and MethodsSite and soil description. The study was conducted at the Joniskelis Experimental Stationof the Lithuanian Institute of Agriculture situated on the soils of the northern part of CentralLithuania’s lowland (56 o 21’ N, 24 o 10’ E) during the period of 1997-2003. The experiments werecarried out on drained, clay loam on silty clay with deeper lying sandy loam Endocalcari-Endohypogleyic Cambisol, whose parental rock is glacial lacustrine clay. Clay particles< 0.002 mm in Aa horizon (0-0.30 m) made up 27.0%, in B1 horizon (0.31-0.51 m) – 59.6%, in Bkhorizon (0.52-0.76 m) – 51.6%, in C 1 horizon (0.77-1.05 m) – 10.7%.Experimental design. The experiments were performed according to the scheme: Factor A.Amendments for soil improvement: 1. Without amendments; 2. Farmyard manure – 60 t ha -1 ;3. Green manure – 27 t ha -1 ; 4. Lime mud – 10 t ha -1 . Factor B. Incorporation of the methods ofamendments: 1. With a moldboard plough at 0.25 m depth; 2. With a segment plough at 0.40 mdepth. Factor C. Primary soil tillage technologies after the incorporation of the amendments:1. Moldboard ploughing at 0.25 m depth; 2-3. Reduced ploughless tillage at 0.25 and 0.15 mdepths. The plots were 6 m wide and 20 m long. Replications 4.Measurements and assessments. Every experimental year the following was estimated: a)soil agrophysical properties at the end of the growing season of crops: 1) soil bulk density andporosity (Kachinski method); 2) soil structure (Savinov method); 3) seedbed physical parameters(Kritz and Hakansson method); b) soil hydrophysical properties: 1) moisture content (weighingmethod); 2) water conductivity (Nesterov method); c) the yield of the primary production of allcrops. The experimental data were processed by ANOVA and STATENG. Significant differencesare presented at a 95% probability level.Field operations, crops and environmental conditions. The incorporation of soilamendments was carried out twice (in 1997 and 2000) during the experimental period. Segmentploughing, while incorporating soil amendments, was performed with special accessories (a bendedshare of the moldboard type and a knife for cutting) attached to the moldboard plough. Whileperforming the segment ploughing, the bended share cuts out the cracks (0.15 m deep and 0.08 mwide) in the subsoil. For the reduced ploughless tillage a combined stubble breaker was used. In theexperiment we grew winter wheat (Triticum aestivum Host) (1998 and 2001), spring barley(Hordeum vulgare L.) (1999 and 2002), vetch (Vicia sativa L.) and oat (Avena sativa L.) mixture(2000) and peas (Pisum sativum L.) (2003). The growing seasons in 1998 and 2001 werecharacterized by moisture excess, in 2003 – by optimum moisture, whereas the years 1999, 2000and 2002 were characterized by drought.74