engleski

Influence of soil tillage upon the characteristics of erosional drift on Luvic stagnosols in Central Croatia

Conservation tillage and crop rotation are powerful tools that enable us to control erosional processes and keep erosion within tolerated limits. Efficient soil conservation is the conditio sine qua non of sustainable land management of highly erodible soils. One of such soil types is Luvic stagnosol in central part of Croatia. During five years of stationary investigations at the experimental station in Daruvar – central Croatia, the total quantity of erosional drift was measured on Luvic stagnosol under six tillage treatments - variants ; 1. Standard plot, according to USLE, (black fallow, ploughing up/down the slope) ; 2. Ploughing up/down the slope ; 3. No-tillage, sowing into dead mulch, weed control by total herbicides ; 4. Ploughing across the slope ; 5. Very deep ploughing across the slope (to 50 cm) ; 6. Subsoiling to the depth of 60 cm + ploughing across the slope. The paper presents the results on the texture of tilled soil in particular trial variants and in erosional drift from the same plots. Average soil samples were taken from the surface layer of tilled soil on each plot of a trial variant in order to determine the particle size distribution. Samples of erosional drift removed from tilled plots were used to determine the particle size distribution of the drift. The intention was to establish whether there was a difference between the particle size distribution of tilled soil and erosional drift removed by erosion from the same soil. The results obtained point to the conclusion that erosional drift was always richer in clay particles. Approximately the same quantity of coarse sand was recorded in natural soil and in erosional drift in all tillage variants. As regards the content of fine sand, sometimes more and sometimes less such particles were found in erosional drift than in tilled soil. In most cases, more silt particles were determined in erosional drift than in tilled soil. As clay particles, i.e., the colloid soil fraction, adsorb nutrients and cations of organic and inorganic pollutants such as pesticide residues, polycyclic aromatic hydrocarbons - PAH and heavy metals, the results indicate that erosion causes a selective or erosional redistribution of agrochemicals - nutrients and pollutants in agricultural soil. As a consequence, the zones of soil removal by erosion gradually get depleted of nutrients and less polluted. In contrast, nutrients as well as diverse pollutants accrete in the zone of erosional drift accumulation. Investigation results show that an adequate choice of the method, that is, tilling direction on Luvic stagnosol, may efficiently protect the soils at the slope base as well as water accumulating in fishponds of the catchement area from pollution due to erosion of agricultural soils. In other words, the choice of the method and tilling direction is a key issue in creation of sustainable, that is, acceptable and environment-friendly land management.

texture of erosional drift; selective redistribution of agrochemicals and pollutants; tillage direction; sustainable land management practice.

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