Phosphorus organic forms release in long term field experiment depending on maize fertilization and growing systems

Abstract

Since phosphorus is a non-renewable resource and one of the main pillars of modern agriculture the majority of global studies are directed toward more efficient use of phosphorus fertilizers, its recycling, and the use of alternative sources. Soil samples for the study were taken from long-term trial of the Institute of Field and Vegetable Crops at the experimental station at Rimski Šančevi. The trial was set up in 1965 as two-factorial, and replicated four times, according to the plan of divided plots (split-plot design with randomized variants). This study is based on monitoring the effect of crop rotation and fertilizers (manure, harvest residues and mineral fertilizers) on the presence of phosphorus and its organic fractions in different layers of rhizosphere by long-term use of particular maize growing and fertilization systems. The following factors were analysed: 1. Fertilizing systems: single-crop system (Ø, NPK, NPK+maize remains, NPK+manure) and two-crop rotation – maize/barley (manure, NPK+manure); 2. Soil depth: 0-20 cm; 20-40 cm; 40-60 cm. Chemical parameters, which was monitored on 324 number of soil samples, during the this investigating period was: basic chemical characteristics of soil, content of total phosphorus, content of total organic phosphorus, fractionation of organic phosphorus, activity of acid and alkaline phosphatase and yield. Organic matter content ranges from 1.88% to 2.98%. The highest values are characteristic for the treatments where manure was included together with mineral fertilizer. The highest content of total and organic phosphorus was found in the treatments with manure application, increase ranging from 27% to 70% depending of the variant. Characterisation of different types of organic phosphorus (labile, moderately labile, nonlabile) showed clear demarcation among studied treatments. Significant differences in all studied fractions and depths divided two basic groups, with and without use of organic fertilizers, wherein the highest values were actually found in the treatments with manure application. This was also proved by achieved statistical significances of LSD test between analysed components. In the year of the study, as well as for the long-term period, the lowest yields were achieved in the control variant of maize cultivation in single-crop system. Treatment two-crop rotation NPK+manure has statistically significantly highest yield comparing to all investigated variants.