Bojan Stipešević

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.

Reduced soil tillage systems for crop rotations improving nutritional value of grain crops

The trial for winter wheat ( Triticum aestivum L. ) or spring barley ( Hordeum vulgaris L. ) in rotation with maize ( Zea mais L. ) on lessive-pseudogley in semiarid to semihumid climate of Eastern Croatia was set up during years 1996–1999 with five soil tillage systems: PL) Conventional tillage based on ploughing; PD) Conventional tillage after diskharrowing for previous crop in preceding season; DP) Diskharrowing after conventional tillage for previous crop in preceding season; DD) Continuous diskharrowing, and CD) Chiselling and diskharrowing. During first and second season (1996/97 and 1997/98), recorded winter wheat grain yields were not different, with PL having the highest and DD the lowest yield. Maize showed next differences in first season: PL=PD>CH=DD=DP, and in second season PD=PL=DP=CH>DD. In 1999, spring barley replaced winter wheat, and yields were: PL>DP>PD>CD>DD. Maize yields recorded were: PL>PD>DP>CH>DD. The grain yield results, together with hectoliter mass and mass of 1000 grains, sup...

Effects of conventional and reduced tillage systems in winter wheat — soybean crop rotation on crops biomass development

Croatian Baranja region contains soils with highly quality crop production properties, but the knowledge of the effects of reduced tillage systems is lacking. Our investigations were conducted under field conditions at Knezevo site chernozem in four replications. They included four soil tillage systems (CT: conventional tillage, with ploughing up to the 30 cm as a primary tillage; DS: diskharrowing up to the 15 cm; CH: chiselling up to the 30 cm + diskharrowing; NT: no-till seed drilling), both for winter wheat ( Triticum aestivum L. )-soybean ( Glycine max L. ) in crop rotation during three growing seasons (2002–2004). All measured crop properties were strongly affected by different seasons, especially with the season of 2003 with extreme drought. Crop biomass in five growth stages for winter wheat showed that at the beginning DS and CH had stronger growth than CT and NT, but differences vanished toward final stages. Winter wheat grain yield achieved by reduced tillage systems was in average either highe...

Influences of soil tillage and fertilization on maize yield and weed infestation

The field experiment was conducted after wheat harvesting (July 1997) on Zemun Polje chernozem. Maize was grown under dry farming system (without irrigation) for three growing seasons (the factor A: 1998, 1999 and 2000). Soil tillage systems (the factor B) included three treatments as follows: B1) zero tillage (direct sowing in non-cultivated soil), B2) minimum tillage (tillage with a soil miller only and sowing) and B3) conventional tillage (stubble field shallow ploughing, ploughing in autumn, presowing soil preparing and sowing). In each soil tillage treatment three levels of fertilization were used as follows: Cl) unfertilized (control), C2) the first level of fertilization (kg ha−1: 150 N + 105 P2O5 + 75 K2O) and C3) the second level of fertilization (kg ha−1: 300 N + 211 P2O5 + 150 K2O). The field experiment was conducted in four replicates. Area of base plot was 25 m2. Under drought stress of the 2000 growing season it was only 6.08 t ha−1 or 35% lower compared to 1999. The conventional tillage (yield 9.86 t ha−1) resulted by 24% and 84% yield increases compared to reduced tillage and zero-tillage, respectively. Using the second rate of fertilizer (yield 8.86 t ha−1) increased yields by 17% and 32% compared to the first rate and non-fertilized treatments, respectively. Weeds infestations (weeds m−2) under conventional tillage was considerably lower (7) compared to reduced (39) and zero-tillage (46).

Winter wheat and soybean zinc uptake in different soil tillage systems

Winter wheat and soybean were grown under field conditions on chernozem soil of Knezevo, Croatia, for four years (from 2002 to 2005) in three applied soil tillage treatments: a) CT — conventional soil tillage, based on mouldboard ploughing, b) DH — soil tillage based on diskharrowing instead of ploughing; and c) NT — no-tillage. Both crops showed decreasing concentration of Zn within the plant tissue as a result of the soil tillage reduction in the order CT>DH>NT, presumably due to the limited roots growth in lesser disturbed soil at DHand NT treatments. Winter wheat recorded generally lower than optimal Zn concentrations and higher P:Zn ratios at reduced soil tillage treatments, as a result of lower Zn uptake. The recommendation for the winter wheat production by reduced soil tillage is additional Zn fertilization, whose exact amounts and way of application shall follow further research.

Tillage and nitrogen effects on winter wheat yield and selected soil physical properties on hypogley of Eastern Croatia

The field research was conducted on hypogley in Vrbanja, Croatia, during four growing seasons from 1992/1993 to 1995/1996. They included five soil tillage systems and three nitrogen fertilization levels in four replications for winter wheat (Triticum aestivum L.) after soybeans (Glycine max L.) as a preceding crop. Tillage treatments were: PL=conventional tillage (ploughing to 20 cm depth, diskharrowing and standard sowing); DS=diskharrowing and standard sowing; MC=tillage by multitiller and chisel, standard sowing; RS=soil tillage and sowing by RAU-Rotosem; PR=ploughing to the depth of 20 cm + RS. Nitrogen fertilization treatments were 140 (N1), 170 (N2) and 200 kg N ha−1 (N3). Wheat grain yields effects by tillage were as follows: 6.00 (PL), 5.79 (DS), 5.65 (MC), 5.61 (RS) and 5.90 t ha−1 (PR). Significant differences of yields were found only in the first year of testing. Nitrogen fertilization resulted by non-significant differences of yields as follows: 5.56 t ha−1 (N1), 5.85 t ha−1 (N2) and 5.96 t ha−1 (N3). The conclusion is that under certain environmental conditions it is possible to apply reduced soil tillage and moderate N fertilization.

Soil tillage impacts on nutritional status of wheat

Soybean were grown under field conditions on chernozem soil for four growing seasons (from 2002 to 2005). Three treatment of soil tillage were applied as follows: a) conventional tillage, b) reduced tillage (diskharrowing instead of ploughing) and c) no-till (zero-tillage). In general, the characteristics of growing season (the factor „year“) were more influencing factor of soybean nutritional status (aerial part in stage of full-developed pods) in comparison with the soil tillage. In our study, low influences of applied soil tillage treatments on nutritional status of soybean were found because significant differences on soybean composition were found only for four (Cu, Cr, Sr and Ba) from total 20 analysed elements. For example, conventional tillage resulted by the higher plant Cu (by 15% and 18% in comparison with DH and NT, respectively), and the lower plant Sr (by 12% and 16%, respectively) and Ba (by 26% and 23%, respectively), while under DH conditions by 22% lower plant Cr was found. Main nutrient...

Influence of soil tillage and weed suppression on winter wheat yield.

Modern soil tillage systems based on different tools than mouldboard plough have very often stronger weed occurrence, which can be a serious problem for achieving high yields. An obvious solution for weed suppression is a herbicide, whose improper use can deteriorate environment and lead toward serious ecological problems. In order to investigate the interaction between soil tillage and herbicide, trial was set up in Valpovo in seasons 2008/09 - 2010/11. Two soil tillage systems (CT-conventional tillage, based on mouldboard ploughing, and CH-chiselling and disk harrowing, without ploughing) and five herbicide treatments (NH-control, no herbicides; H10- recommended dose of Herbaflex (2 l ha-1); H05-half dose of Herbaflex; F10- recommended dose of Fox (1.5 l ha-1); and F05-half dose of Fox) were applied to winter wheat crops. Results showed similar effects of soil tillage on the winter wheat yield, whereas different herbicide dosages showed similar weed suppression and influence on winter wheat yield.

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.