Soil compaction causes important physical modifications at the subsurface soil, especially from 10 to 30 cm depths. Compaction leads to a decrease in infiltration rates, in saturated hydraulic conductivity, and in porosity, as well as causes an increase in soil bulk density. However, compaction is considered to be a frequent negative consequence of applied agricultural management practices in Slovakia.
Detailed determination of soil compaction and the investigation of a compaction impact on water content, water penetration depth and potential change in water storage in sandy loam soil under sunflower (Helianthus annuus L.) was carried out at 3 plots (K1, K2 and K3) within an experimental site (field) K near Kalinkovo village (southwest Slovakia). Plot K1 was situated on the edge of the field, where heavy agricultural equipment was turning. Plot K2 represented the ridge (the crop row), and plot K3 the furrow (the inter–row area of the field). Soil penetration resistance and bulk density of undisturbed soil samples was determined together with the infiltration experiments taken at all defined plots.
The vertical bulk density distribution was similar to the vertical soil penetration resistance distribution, i.e., the highest values of bulk density and soil penetration resistance were estimated at the plot K1 in 15–20 cm depths, and the lowest values at the plot K2. Application of 50 mm of water resulted in the penetration depth of 30 cm only at all 3 plots. Soil water storage measured at the plot K2 (in the ridge) was higher than the soil water storage measured at the plot K3 (in the furrow), and 4.2 times higher than the soil water storage measured at the most compacted plot K1 on the edge of the field. Results of the experiments indicate the sequence in the thickness of compacted soil layers at studied plots in order (from the least to highest compacted ones): K2–K3–K1.
Soil compaction in agricultural areas inhibits plant root growth through increased mechanical resistance, altered water and nutrient supply. The main objective of this study was to evaluate spatial distribution of roots and its effect on water uptake of maize grown on field with subsoil compaction. Two treatments were examined: complex melioration consisting of deep loosening in combination with drainage and control without applied meliorations. Root observations were conducted on vertical and superposed horizontal planes covered with a 2 cm grid short after silking. Root distributions expressed as index of density and/or dry mass density were estimated down to 1m soil depth and with a distance to a plant base. For analysis of root distribution pattern on the horizontal planes, a Variance to Mean Ratio (VMR) test was applied. Soil water monitoring were conducted during the vegetation period. On the vertical planes, root densities were similar in the topsoil of both treatments, but the results were significantly higher in the subsoil of the meliorated one showing deeper allocation of root density. In contrast, the control had more squares with lots of roots (i.e. higher indexes) just at the top- subsoil boundary owing to bunching of roots in macropores. The horizontal planes in the control generally consisted larger areas without visible roots and thus great distances for water and nutrient transmission, especially in the subsoil. The estimated VMR also pointed toward different levels of root clustering. Consequently, an inhibited water extraction from the subsoil in the control, a delay in crop ontogenesis and a less biomass production was established during the observed period. and Zhutnenie poľnohospodárskej pôdy bráni rastu koreňov; je to spôsobené zvýšeným mechanickým odporom pôdy, a zníženým prítokom vody a živín. Cieľom tejto štúdie je zhodnotenie priestorovej variability koreňov, ich vplyvu na odber vody koreňmi kukurice na poli so zhutnenou podorničnou vrstvou. Boli hodnotené dva spôsoby obrábania: komplexná meliorácia pozostávajúca z hlbokého podrývania v kombinácii s drenážou a obrábanie (kontrola) bez melioračných zásahov. Identifikácia rozdelenia koreňov bola vykonaná vo vertikálnych a horizontálnych rovinách s 2-cm sieťou, krátko po metaní. Rozdelenie koreňov bolo vyjadrené ako index hustoty alebo ako hustota suchej biomasy koreňov do hĺbky 1 m; v horizontálnom smere až k susedným rastlinám. Bol použitý test ''Variance to Mean Ratio'' (VMR) na určenie rozdelenia koreňov v horizontálnom smere počas vegetačného obdobia. Hustota koreňov vrchnej vrstvy pôdy vo vertikálnej rovine bola podobná pre obidve varianty, ale pre meliorovanú pôdu boli hodnoty hustoty koreňov v podloží podstatne vyššie a korene zasahovali hlbšie. Ako protiklad, na kontrolnom pozemku bolo viac štvorcov s mnohými koreňmi (t.j. vyššie indexy) práve na hranici orničnej a podorničnej vrstvy, pre enormný rast koreňov v makropóroch. V horizontálnej rovine tento kontrolný pozemok obsahoval veľké oblasti bez viditeľných koreňov, a to znamená veľké vzdialenosti pre prenos vody a živín v podorničnej vrstve. Výsledky aplikácie VMR naznačujú tiež rozdielne úrovne zhlukov koreňov. Z toho vyplýva znížený odber vody koreňmi rastlín na kontrolnom pozemku, ako aj pomalšia ontogenéza a nižšia produkcia biomasy, ktorá bola identifikovaná počas sledovaného obdobia.