Mario Sraka

Influence of drainpipe spacing on nitrate leaching and maize yield

The objectives of the study were to determine the extent of nitrate leaching and maize yields in four drainpipe spacing variants (15 m, 20 m, 25 m and 30 m). The study was carried out at an experimental reclamation field during a period of five years (growing seasons). Maize was grown as the trial crop and the same agricultural practices were applied in all drainpipe spacing variants in all trial years. Nitrogen fertilization rates varied in different trial years (from 145 kg/ha/year to 175 kg/ha/year). The results indicate that nitrate concentrations in drainage water exceeded the allowable values in a larger part of the year (four to seven months) in all drainpipe spacing variants and maximum values were from 18.15 mg.dm−3 (drainpipe spacing of 15 m in 1999/00) up to 34.71 mg.dm−3 (drainpipe spacing of 25 m in 2002/03). Quantity of nitrogen leached differed from year to year and corresponded to the total nitrogen added with fertilization and annual precipitation. Statistically significant higher maize yields were achieved in most years with the drainpipe spacing of 15 m compared to other drainpipe spacing variants.

Herbicides in the soil and waters of river Drava catchment area

The objective of this paper is to present the results of the 15 years long research into the influence of agriculture on soil and water contamination by herbicide residues in a part of the Drava catchment area. The status of triazine herbicides - atrazine, simazine, prometrine and ametrine, and chlortoluron, isoproturon, dicamba, metolachlor, metamintron, terbuthylazine, MCPA and 2, 4-D was monitored in agricultural soil and water of this area in the conditions with or without regular application of herbicides. Amont the 206 plough layer samples analyzed, herbicides were detected in 50 samples (24%) with concentrations varying from 3-119 ng/g. The most frequently detected herbicides were triazine herbicides (atrazine and simazine) owing to their persistence as well as application frequency. The results indicate that, as a rule, alkaline or potentially alkaline herbicides persist longer in soil ; atrazine residues were found as late as 10 months after its application. Acid or potentially acid herbicides were not detected in soil even within one month of their application. Among the total number of analyzed samples of surface and ground watwers, the recorded herbicide concentrations exceeded the maximum allowable concentration, MAC, for single herbicides in drinking water (100 ng/l) in 42% of samples for atrazine, 23% for simazine, 9% for prometrine, 13% for ametrine, 24% for chlortoluron, 25% for isoproturon, 17% for dicamba, 60% for metolachlor, 20% for metamitron, while terbuthylazine, MCPA and 2, 4-D were not detected.

Influences of pipe drainage and fertilization on nitrate leaching

Introduction Leaching of nitrates from soil depends on the amount, frequency and intensity of precipitation, soil properties, crop and crop development stage, evapotranspiration, and nitrogen fertilization, Vidacek et.al. (1996,1999); Nadasy and Nadasy (2006); Nemeth T. (2006) and Josipovic et al. (2006). The problem of nitrate leaching is even more expressed in agroecosystems of hydroameliorated, especially drained, soils because of changed infiltration and filtration capabilities of these soils. Total hydroameliorated areas cover 600,054 ha in Croatia, including 117,856 ha of pipe drainage system area, Vidacek (2006). The objective of this study was to assess the influence of pipe drainage and increasing application of nitrogen fertilizers on leaching of nitrates from soil in winter barley and maize production.