AGRONOMIJAS VĒSTIS - Latvijas Lauksaimniecības universitāte

AGRONOMIJAS VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008ResultsIn this paper we present the results of the second experimental period (2000-2003) whenthe complex of practices was investigated once more in the field.Physical properties of soils. While applying segment ploughing at 0.40 m depth for theincorporation of amendments we observed the decrease of bulk density and the increase of the totalporosity in the subsoil during the whole three-year period. However, in the first year after suchtillage the soil structure (according to the structural coefficient) at the bottom (0.15-0.25 m) of thetopsoil was 19.0% poorer, compared with conventional ploughing (the structural coefficient –0.21). While incorporating farmyard manure, green manure and lime mud by the segment plough at0.40 m depth the water conductivity in the subsoil in the first year of influence increased by 2.95,3.17 and 3.65 times respectively, as compared to conventional ploughing without the incorporationof amendments (hydraulic conductivity – 1.93). Segment ploughing increased the waterconductivity in subsoil by 3.26 times, however, the water conductivity in the topsoil was 44.8%poorer compared with conventional ploughing (data not shown).Reduced ploughless soil tillage used after the incorporation of amendments determined theincrease of soil bulk density and the decrease of total porosity only in the first year, however, thesoil structure was poorer every year, compared with moldboard ploughing (Table 1).Table 1. Effect of reduced primary tillage on soil physical propertiesTillage method Layer, mTotalPorosity, %Coefficientof structurality2002 2003 2002 2003Moldboard ploughing at0.25 m depth0-0.150.15-0.2547.743.744.941.51.390.390.900.48Ploughless loosening at0.25 m depth0-0.150.15-0.2546.642.244.141.70.740.250.740.26Ploughless loosening at0.15 m depth0-0.150.15-0.2545.842.844.142.20.770.280.980.37LSD 050-0.15 1.651.880.230 0.2020.15-0.25 1.381.610.053 0.098The results of our investigations suggest that after reduced ploughless primary tillage, thesoil in spring before sowing was tilled shallower, the roughness of the seedbed bottom was greatercompared with moldboard ploughing. All the same the content of soil structural aggregates >5 mmincreased and the content of valuable (2-5 mm) soil aggregates decreased in the seedbed. Thestructure of the seedbed (according to the coefficient of structurality) was worse because ofploughless tillage at 0.25 and 0.15 m depths for spring barley by 9.2% in both cases, for peas – by24.0% and 16.0% respectively as compared to ploughing (data not shown).Energy evaluation. Segment ploughing at 0.40 m depth was less efficient by 34.1%, dieselfuel costs for it were higher by 33.5%, ploughless soil tillage at 0.25 and 0.15 m depth was moreefficient by 58.1% and 2.02 times, and fuel costs were lower by 23.4% and 38.7% respectively,than for conventional ploughing at 0.25 m depth (data not shown).Crop yield. The application of soil amendments increased the winter wheat (2001), springbarley (2002) and peas (2003) grain yield: farmyard manure – by 9.2, 12.7 and 15.3%, greenmanure – by 6.1, 7.2 and 8.7%, lime mud – by 4.5, 8.0 and 9.3% respectively, as compared to thesoil where the amendments were not applied. Segment ploughing at 0.40 m depth had a positiveeffect on the winter wheat yield, however negative – on the yield of peas. When growing cerealsaccording to ploughless soil tillage technology at 0.25 and 0.15 m depths, the spring barley grainyield was lower by 13.5% and 15.6%; grain yield of peas – by 26.9% and 30.7% respectively,compared with moldboard ploughing (Table 2).75