Organic materials as sources of nitrogen in organic production of lettuce. [M.Sc. thesis] | Organski materijali kao izvori azota u organskoj proizvodnji salate. Magistarska teza
2009
Cabilovski, R.
In order to determine the mineralization potential of different organic materials (OM), manure (ST), guano (G), soy seed (S), forage pea seed (P), the kinetics of release of mineral nitrogen (N) and correlation between OM content and the amount of mineralized N, an incubation experiment was set up. The results of the incubation experiment were checked in field conditions. The highest values of mineralization constant k (0.127/d) and net mineralization (NM) (76.37% of total applied N) were recorded for guano, whereas the lowest values of k (0.098/d) and NM (30.12% of total applied N) were recorded for manure. Negative linear correlation between NM of organic materials and C/N ratio (r=-0.97*), and a positive linear correlation between NM and total N content in OM (r=0.99%). Between k and NM, caused a significant increase in the content of mineral forms of N in the soil during the vegetation period of lettuce, when compared to the control. Linerar correlation was found between the content of mineral N in the soil and nitrate content in the green mass of lettuce at the moment of harvesting, in both years. Biannual average fresh matter (SvM) of lettuce on fertilized plots ranges from 45.447 kg SvM/ha (P) to 46.385 kg SvM/ha (ST) and was significantly higher than fresh matter yield of the control (39.343 kg SvM/ha, biannual average). Total amount of uptaken N in the above-ground part of lettuce organic materials was recorded with guano, where lettuce plants uptook 39% of total applied amount of N (biannual average), and the lowest with ST (12.5%). The highest additional profit from the application of OM was made with ST (1597 EUR/ha), for which the lowest price per N unit was found too (0.8 EUR/kg N).
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