Long-Term Tillage and Nitrogen Fertilization for Soybean on Gley Soil

Abstract

During three years (2007, 2008 and 2009), multidisciplinary stationary research of reduced soil tillage and nitrogen fertilization was conducted for soybean [Glycine max (L.) Merr.], on Gley soil type of Croatian Baranya region. Research was carried out with four soil tillage treatments and three nitrogen fertilization level, set up as split-plot design in four repetitions. Tillage treatments (TT) were: CT- conventional tillage (autumn plowing 30 cm), DT- multiple disk-harrowing (autumn disk-harrowing 10-12 cm), LT- chiselling and disk-harrowing (autumn soil loosening 30 cm), NT- no-tillage. Nitrogen fertilization treatment (NF) for soybean was NF-1 = 35, NF-2 = 70, NF-3 = 110 kg N/ha. Weather conditions during the study were adverse with considerable aberrations, respectively significantly different from long-term mean. Thus, 2007 was extremely dry, 2008 was moderately humid and 2009 dry. Significant differences of soil water content (SWC) were identified in all years of research: NT had higher SWC in 2007 and 2008, while DT had hogher SWC in 2009 compared to CT. The yield was negatively statistically significant correlated with bulk density (BD), i.e. with increase of compaction yield decreased. Significant differences among years were recorded regarding soybean grain yield, whereas soil tillage systems showed following decreasing order, on average: CT (2.59 t/ha) > LT (2.46 t/ha) > NT (2.46 t/ha) > DT (2.41 t/ha). Nitrogen fertilization on average did not influence soybean yield. On average, compared to CT, only DT had significantly lower soybean grain yield. The study showed a very successful application of reduced soil tillage systems in soybean production with the optimal nitrogen fertilization.