Vesna Vukadinović

Winter wheat yield responses to mineral fertilization

The yield of arable crops may be influenced by many factors such as water, temperature and nutrient deficiency. The winter wheat (variety Zitarka) field trials were set up in the autumn of 2002 on silty loam stagnic luvisol at site Donji Miholjac and loessive pseudogley at site Krizevci in continental Croatia. The results of the triennial experiments show big influence of climate conditions (year) and sites on usage of nutrients from fertilizer and forming of wheat yield. The highest fertilization dosage (N5P2K2) in average almost doubled the total mass yield and wheat grain yield comparing to the control. Fertilization with nitrogen, which according to the phosphorus input in average increased the grain yield 3.5 times and above ground mass yield 10 times, and according to the potassium 4 and 20 times, had the biggest influence on both yields. Non appropriate fertilizer use may result in non sustainable plant nutrition.

Influence of different soil tillage systems on yield of maize

Maize is one of the most important crops in Croatia, especially for the Panonian part - Slavonia and Baranja region, which is producing, in average, 30% of total maize production in the country (Kovacevic and Josipovic, 1998). The practice is mainly conventional, based on standard soil tillage including ploughing as primary tillage operation, which is the most expensive, slow, with high demands for fuel and labour. Also, it can be ecologically unfavourable and non-sustainable. Meanwhile, in the latest twenty years the knowledge about soil tillage in Croatia and its vicinity (Birkas and Gyuricza, 2000) has been changed, as in many countries in the world, toward simplification, reduced, rational tillage, which was the subject of research by Croatian authors, for instance Zugec (1984), Culjat and Tabakovic (1991) and Jug et al. (2006). Diskharrowing or chiselling, as a primary tillage operation, was not researched thoroughly enough, especially in the light of other reduced tillage systems, such as no-till, where equipment price of special no-till planters and heavier tractors can be limit for average farmers, especially in the changing climate conditions, as emphasised by Dobo et al. (2006). The scope of this paper was to optimise soil tillage for maize in longer period of time.

Excessive iron and aluminum uptake and nutritional stress in corn (Zea mays L.) plants

Abstract Disorders of corn growth were observed at 6–9 leaf stage in the growing season of 1986. They were manifested as growth retardation and chlorosis. Chlorotic corn showed signs of either P, Zn or K deficiency. Excessive Fe and Al uptake in the leaves (4.7, 3.1, 1.9 and 2.2 times higher Fe concentrations than in normal plants for chlorosis induced by P, Zn and K deficiency and in the cases of atypical chlorosis, respectively). Depending on the form of chlorosis, the dry matter of chlorotic plants was 4.6 to 10 times lower than in normal plants.

Influence of liming on soil acidity and iron availability

Abstract The influence of liming and phosphorus application (in the range to 20 t of hydrated lime and to 480 kg P2O5/ha, respectively) on the status of plant available Fe was studied in acid soil of East Croatia. Due to application of the highest rate of line, Fe content in soil decreased from 34.1 ppm (unlimed plot) to 14.1 ppm Fe. At the same time, titratable acidity decreased from 16.0 to 1.5 raequ/100 g of soil and exchangeable acidity from 3.0 to 0.1 mequ/100 g of soil, while soil pH in KCl increased from 4.03 to 5.42. Phosphorus application did not significantly affect these soil characteristics.

Mapping soil organic matter in the Baranja region (Croatia): Geological and anthropic forcing parameters

Spatial mapping of soil organic matter (SOM) and evaluation of the related natural and anthropic influencing factors are crucial to monitor the extent of degraded land and the evolution of soil functions. The objective of this work is to study the spatial distribution of SOM in a highly exploited agricultural area in the Baranja Region (Croatia). The spatially dense dataset available (4825 top-soil samples from 0 to 30 cm) allowed to produce reliable SOM maps using geostatistical interpolation kriging algorithms and to study the relationships with possible influencing factors. The interpolation has been conducted by means of two approaches. In one approach, the overall data set is considered for computing a global variogram and performing a direct interpolation of SOM values. In the second approach, the data are stratified according to two different geological and morphogenetic domains, Holocene Domain (HD) and Pleistocene Domain (PD), and a distinct geostatistical analysis is performed in each domain. The results showed that average SOM in the studied region was 2.29%, indicating a future need for adopting sustainable soil management practices in this region. SOM was significantly higher in HD (2.64%) than PD (1.97%) domain. SOM in PD generally had a much lower global variability. Global dataset analysis reveals that regional intrinsic factors prevail over local intrinsic and extrinsic factors in determining SOM spatial patterns. In contrast, the stratified approach can filter the effect of regional variability related to the main geological and geomorphological setting. The structural spatial correlation in PD is weaker than in HD, as manifested by spatial patches of low and high SOM content with smaller extension in PD with respect to HD. The strong relationships between SOM spatial patterns and geological/geomorphological factors suggest the possibility of adopting finer subdivision criteria in future research.

Liming of acid soils in Osijek-Baranja County.

The negative trend of soil degradation process increases with intensive agricultural production. Therefore, there is a need for soil conditioning like liming, humification, fertilization, etc. to improve soil quality. One of the major problems that occur on agricultural soils of Croatia is acidification. A downward trend of soil pH is mainly present in soils of poor structure with intensive agricultural production. In agricultural practice liming often needs to rely only on the pH value, without determining the hydrolytic acidity, CEC or soil texture. Due to the above mentioned facts, calculation of liming for Osijek-Baranja County was conducted with the help of ALRxp calculator, which takes CEC, soil pH in KCl, hydrolytic acidity, bulk density of soil, soil textural class and depth of the plow layer to 30 cm into account. Low soil pH values have a great influence on soil suitability for crops as well as on the deficit of calcium and magnesium. All of these lead to the degradation of soil structure, and can even lead to disturbances of plant nutrition in some production areas. On such soils, liming would be imperatively required, but with caution because an excessive intake of lime materials, especially without the necessary analysis, causes a decline in organic matter and reduces accessibility for plant uptake of microelements.

The effect of year, genetic and morphologic specificity at the kernel mass, chemical composition and vigour of the maize seed

Oil rape is a valuable fodder because in early spring and late autumn it produces green forage used for the nutrition of domestic animals. It has been replacing sunflower and soy in colder and wetter regions. It is additionally advantageous because it leaves behind more nitrogen in soil, which is beneficial to other plants in plant rotation. There are some possible ways for the fixation of nitrogen in soil and they are as follows: by the means of oil rape straw ; by relatively long roots ; by the action of nitrogen bacteria, which perform the nitrogen synthesis within their root system, which is the case in some leguminous plants. Oil seed rape is expected to be wider used in crop rotation of West and Middle Europe, Croatia included. Due to this various sorts have been introduced and potential positive impacts have been studied in order to boost the process. This paper presents information on barley and wheat yield in case when they were sown after oil seed rape and corn. The aim of the research is to determine the presence of positive impacts upon the soil with special attention paid to a potential increase of nitrogen content after oil seed rape was grown. The preceding crops had statistically significant effect. Rape yield was significantly higher compared to the one with corn as preceding crops. Very similar results were obtained in 2007.The maize hybrids seed from three different FAO groups (FAO 400, FAO 500 and FAO 600) in four fractions (KO, KP, SO and SP) produced in two climatically different years (extremely dry 2000 and extremely wet 2001) had been different in quality and chemical composition. The effects of year, genetic specifity and seed fraction at the kernel mass, chemical composition (starch, proteins, cellulose, oil and moisture content) and seed vigour have been evaluated. The influence of agroecological conditions during two production years have been exposed at seed chemical composition and vigour indicators (cold test – CT and bulk seed electrical conductivity - EC). The genetic specificity and seed fraction had significant influence at all tested indices, with the exception of the influence of the fraction at the starch content

The influence of the temperature, genetic specificity and seed size at early growth and development of the maize in controlled conditions

The optimal planting terms, which contain favorable conditions for emergence and early growth, are one of the most important preconditions for achieving high grain yields. During this period, the most important environmental factors are temperature and soil moisture, which have a key role for optimal conditions needed for the young plants genotype potential expression. Beside genetic specificities which are preconditioning plants growth and development, the seed size is one of the very important biological factors which has strong influence at faster sprouting and intensive growth within the heterotrophic stage, when seed reserves have the key role for supplying young plant with the nutrients. The tolerance of the maize hybrids at suboptimal temperatures which can frequently occur in early spring has been observed by Szundy et al. (2005) through the number of days to emergence and individual dry shoot mass. According to Pommel et al. (1995), plants developed from greater seed had higher leaf area if compared with plants from smaller seed. Gilbert et al. (1995) concluded that the dry weight of plants shoot and root is positively correlated with the seed size. Batistella et al. (2002) found out in their research that there were significant differences between hybrids and seed category and their influence at shoot and root length, together with shoot dry weight in favor of larger seed fractions. After Grzesiak (2001) smaller ratio of shoot and root length is indicating higher hybrid resistance on the induced stress. The aim of this research was to determine the influence of the temperature, genetic specificity and seed size fractions at phenologic and physiologic features of the maize in early growth.

Potassium fixation in heavy soils of east Croatia

Bioavailability of potassium is strongly affected by present alkaline earth ions Ca and Mg and fixation of potassium into interlayer zones of some clay minerals. Soil fixation ability strongly affects the efficiency of fertilization. The research has been conducted on 6 hydromorphic and gleysoils in eastern Croatia. Soil fertilization with 450-4500 kg ha-1 K2O was simulated in lab-conditions. After one day the samples were extracted with NH4OAc 6 times, shaked, centrifuged and transferred into flasks. Fixation of potassium was calculated according to the formula: Kf = Ka – Ke + Ko, in which Kf is fixated K2O in mg 100g-1 soil ; Ka is K2O added as fertilizer in mg 100g-1 ; Ke is K2O determined in the eluate and Ko is K2O in the sample without fertilization. Fertilizing simulation of heavy soils in eastern Croatia with medium or very high dosages of potassium (450-4500 kg ha-s ; ), deducted in lab-conditions, showed that AL method of potassium extraction gives relatively high values of available potassium (two times higher than extraction in NH4OAc). Also, highest relative amount of potassium is fixated at lower fertilizing dosages (approximately 76%), the increase in fertilization increases absolute, but reduces relative fixation. Some heavy soils have high ability of fixation (above 70-90%) and very low desorption, and require special attention when establishing dosages for fertilization and ameliorative fertilization with potassium. Results obtained by soil analyses show connection between high fixation of potassium added by fertilization and higher amount of clay in the soil as well as lower level of available potassium before fertilization.