Variability of Selected Physical and Mechanical Properties of Soil in Alfalfa Crop Production
Abstract
In recent years, studies have focused on monitoring soil compaction caused by agriculture. The aim of the research presented in this article was to examine the impact of forage cultivation (organic farming) on soil properties. Field measurements focused on monitoring the variability of soil moisture content (SMC) and penetrometric resistance (PR) during alfalfa cultivation across 3 soil horizons. The study area was a 47.64-hectare plot (Oponice, Slovak Republic) with a total of 21 monitoring points (MP). Standardized methodologies and measurement techniques were used to monitor soil properties (WET sensor with HH2 logger, Eikelkamp penetrometer). Statistical evaluation of the results was performed using descriptive statistics, one-way ANOVA, deterministic spline interpolation (ArcGIS 10.0), and cluster analysis (Orange). The results for soil moisture content indicate significant changes in variability (horizons, dates). The coefficient of variation (CV) values for soil moisture content ranged from 8.47% to 23.12%. A significant depth dependence of the measurements was observed (pilot measurements: P<0.05, F=7.51). An examination of the relationship between individual measurement periods showed that in selected horizons they were dependent (SMC01→SMC02, 0-20 cm, 21-40 cm; SMC02→SMC03, all horizons) and in the others they were independent (SMC01→SMC02, 41-60 cm). The average PR values showed the lowest heterogeneity in the deep soil horizon (CV: PR01, 59.81→16.52%; PR02, 41.97→31.25%; PR03, 38.86→21.22%). Comparisons of measured penetrometer resistance values between irrigated and non-irrigated areas or between different measurement dates showed weak to strong correlations (0.02-0.87; 1.68 to 2.72 MPa). The obtained results were also subjected to deterministic and cluster analyses of penetrometric resistance, with the results indicating significance among the measurements. The results obtained from soil moisture monitoring indicate that soil moisture levels are balanced, but there are negative effects on soil compaction.