AGRONOMIJAS VĒSTIS - Latvijas Lauksaimniecības universitāte

AGRONOMIJAS VĒSTIS (Latvian Journal of Agronomy), No.10, LLU, 2008Materials and MethodsExperiments were conducted at the Joniskelis Experimental Station of the LithuanianInstitute of Agriculture located in the northern part of Central Lithuania Lowland during the period2001-2004. The soil of the experimental site is characterised as Endocalcari-EndohypogleyicCambisol (CMg-n-w-can), according to the texture – clay loam on silty clay, whose parental rock islacustrine clay. The soil agrochemical properties in the 0–25 cm layer are presented in 1 table.Experiments involved the following design: 1. Without catch crop; 2. Oil radish (Raphanussativus L.); 3. White mustard (Sinapis alba L.); 4. Red clover (Trifolium pratense L.); 5. Cocksfoot(Dactylis glomerata L.); 6. Italian ryegrass (Lolium multiflorum Lamk.). Two analogousexperiments were set up in 2001 (Experiment 1) and 2003 (Experiment 2) and lasted for two years(2001-2002 and 2003-2004) each. Red clover, cocksfoot and Italian ryegrass were undersown inspring barley – shortly after sowing. Catch crops as post-crops: white mustard and oil radish wasdirect drilled by a stubble drill after cereal harvesting (on the same day). N 30 was applied aftercereal harvesting for optimal growth and the development of oil radish, white mustard, cocksfootand Italian ryegrass. The next year spring barley was grown after the incorporation of the catchcrops biomass as green manure. Nitrogen, organic carbon and crude fibre in the green material ofcatch crops was determined by the following methods: by Kjeldahl and by the analyser „Heraeus“respectively. The total soil nitrogen was determined by the Kjeldahl method, organic carboncontent- after picking out visible rootlets from the soil samples - by the Tyurin method. Theexperimental data was processed by methods of dispersion and correlation analysis, applying theprogrammes ANOVA and STATENG for statistical data treatment (Tarakanovas and Raudonius,2003).Results and DiscussionThe highest overground biomass was produced by the undersown crops – red clover,cocksfoot and by postcrops –white mustard. Of all catch crops red clover was noted for the highesttotal dry matter content, which was 1.6 -2.4 times higher compared with the other catch crops.Table 1. Soil chemical characteristics of the experiments (Jonišk÷lis, 2001, 2003)Total Organic carbon, Mobile, mg kg -1Experiments pH KClNitrogen, g kg -1 g kg -1 P KExperiment 1 6.0 1.50 12.8 63.8 211.7Experiment 2 6.4 1.69 14.2 60.3 195.8The nitrogen content in the biomass has a decisive effect on the mineralization of biomassincorporated into the soil (Velička et al., 2006). Higher nitrogen concentrations and greatervariations were identified in the overground plant mass compared to the underground plant mass(Table 2).Table 2. Nitrogen content in the biomass of catch crops, kg ha -1 (Jonišk÷lis, 2001, 2003)Underground massOverground massCatch cropexperimentI, 2001 II, 2003 average I, 2001 II, 2003 averageOil radish 14.9 15.8 15.4 59.0 64.2 61.6White mustard 6.6 9.6 8.1 78.5 82.9 80.7Red clover 61.7 42.0 51.9 161.0 119.1 140.1Cocksfoot 22.1 21.2 21.7 65.2 65.1 65.2Italian ryegrass 17.2 14.7 16.0 44.2 60.3 52.3Average 24.5 20.7 22.6 81.6 78.3 78.0LSD 05 6.64 3.53 5.98 21.63 18.72 17.4879