Aleksandra Perčin

Reducing sampling intensity in order to investigate spatial variability of soil pH, organic matter and available phosphorus using co-kriging techniques. A case study of acid soils in Eastern Croatia

ABSTRACT Soil pH, hydrolytic acidity (HA), organic matter (OM) and plant available phosphorus (AP) are factors controlling the environmental-friendly soil management in agroecosystems. These parameters are highly variable in space. The objective of this work is to study spatial variability of pH, HA, OM and AP using several interpolation methods in Eastern Croatia. A total of 1004 (0–30 cm) soil samples were collected, and several univariate and multivariate interpolation performances were tested. The results showed that soils of the study area had high HA and AP, while pH and OM were low. The variogram analysis revealed different spatial structures among studied soil properties and demonstrate a need for variable-rate management. Soil pH and OM had lower spatial variability compared to AP and HA. Ordinary kriging was the most accurate method to estimate the studied variables. The incorporation of auxiliary variables increased the precision of the estimations for HA. Soil AP and OM showed different results for spatial prediction obtained by co-kriging. Overall, the incorporation of pH as auxiliary variable increased the prediction of the models. However, more co-variates should be incorporated in further models, in order to identify with more precision areas that need to be restored.

Soil compaction in vineyards of different ages in Pannonian Croatia. Part I. Influence of machinery traffic and soil management on compaction of individual horizons.

Soil compaction is one of the most important problems in agricultural production. Tillage system with frequent machinery traffic due protection, agrotechnic operation and harvesting has effect on different soil compaction levels in the vineyards. The aim of this study was to determine and compare the soil resistance, soil bulk density and soil moisture within and between rows in the seven-year and thirty-year vineyard due to tillage and compacting by machinery traffic. Results show statistically lower soil resistance to a depth of 40 cm in tilled interrow position in all vineyards as a direct effect of tillage. The values of bulk density in both vineyards are lowest in row position which is convenient for root growth. Increased values of bulk density that can restrict root development are recorded in interrows position in all vineyards. The moisture content of all vineyards increases with depth. Greater deviation in compaction between seven-year and thirty-year vineyard is not recorded. The research results indicate that the soil management is more important factor than the number of machinery passes. Soil resistance values does not give a complete information about compaction because of all the factors it is most depend on current soil moisture.

Radioactivity of Selected Agricultural Soils in Croatia: Effects of Soil Properties, Soil Management, and Geological Parameters

We present a study on the radioactivity of selected Croatian agricultural soils that vary considerably with respect to geological background; physical, chemical, and biological characteristics; soil type; land use; and soil management. Our investigation is focused on the main naturally occurring radionuclides (40K, 238U, 226Ra, 232Th, 235U) and 137Cs as the most threatening long-lived anthropogenic radionuclide. We find that the radioactivity level is not influenced by the application of different soil amendments, at least in moderate quantities, and that no effect of soil management can be detected as well. In contrast, geological and location-specific properties influence radionuclide content in soil, especially regarding the naturally occurring ones. Moreover, physical and chemical soil properties such as texture and soil adsorption complex, respectively, seem to be the main factors regarding fixation of 137Cs in soil. Calculated dose rates for external exposure to the gamma radiation originating from soil have been found to be generally low, except for two locations where they are higher but not at a level that would lead to health problems for workers on the field.

Visible and near infrared reflectance spectroscopy for field-scale assessment of Stagnosols properties

Spectral data contain information on soil organic and mineral composition, which can be useful for soil quality monitoring. The objective of research was to evaluate hyperspectral visible and near infrared reflectance (VNIR) spectroscopy for field-scale prediction of soil properties and assessment of factors affecting soil spectra. Two hundred soil samples taken from the experiment field (soil depth: 30 cm ; sampling grid: 15 × 15 m) were scanned using portable spectroradiometer (350–1050 nm) to identify spectral differences of soil treated with ten different rates of mineral nitrogen (N) fertilizer (0–300 kg N/ha). Principal component analysis revealed distinction between higher- and lower-N level treatments conditioned by differences in soil pH, texture and soil organic matter (SOM) composition. Partial least square regression resulted in very strong correlation and low root mean square error (RMSE) between predicted and measured values for the calibration (C) and validation (V) dataset, respectively (SOM, %: RC2 = 0.75 and RV2 = 0.74 ; RMSEC = 0.334 and RMSEV = 0.346 ; soil pH: RC2 = 0.78 and RV2 = 0.62 ; RMSEC = 0.448 and RMSEV = 0.591). Results indicated that hyperspectral VNIR spectroscopy is an efficient method for measurement of soil functional attributes within precision farming framework.

Land use change and soil fertility assessment in the vicinity of Zagreb landfill

The aim of this study was to give quantification of the present land use, land use change and assessment of agricultural soil in the area surrounding Jakusevec landfill in Zagreb, Croatia. A map of land use types of approximately 2 km zone around the landfill was created, based on photointerpretation during 2012 and according to Corine Land Cover 2000, 2006 and 2012 database. For soil fertility evaluation, soil was sampled at four locations at a distance of up to 300 m around the landfill. Spatial analysis revealed thirteen land use categories of total size around 3,161 ha. These categories were divided into three larger groups based on land use types (water: 5%, agricultural land: 50% and city: 45% of the total analysed area). Mixed agriculture is very important in this urban area regardless of the closeness of the waste landfill, because it relies on fertile soil and vicinity of large market of the capital city. The main land use changes included increase in industrial or commercial units and transport infrastructure, and decrease of agricultural land.