Different nitrogen and biochar sources’ application in an alkaline calcareous soil improved the maize yield and soil nitrogen retention

We investigated effect of biochars (BCs) and nitrogen (N) fertilizers on soil selected characteristics, growth of maize, and soil N transformations in a pot experiment. Maize was grown in soil amended with control (no BC), and three BCs different in feedstock (rice-straw biochar (RSBCC), vegetable-waste biochar (VMBC), poultry-manure biochar (PMBCC), and N application (control, 0.25 g N kg−1 soil using urea and NH4NO3). At harvest, agronomic parameter, soil (pH, EC, SOM, total N, and NO3-N), and plant analyses were done. The results showed the improvement in soil nutrient contents and yield with application of BC and N. The soil pH diminished in BC treatments where N was used. The soil EC was increased in RSBC treatment than the control but decreased in NH4NO3 application irrespective of all BC treatments. The SOM was improved in all BC treatments under N. The NH4 concentration in plants and total soil N were significantly enhanced in BC treatments even without N. The plant growth and nutrient uptake were more influenced in NH4NO3 than urea. Comparing BCs showed overall better performance of PMBC than RSBCC and VWBC. Overall, the combined supply of PMBCC and NH4NO3 has advantages of improving plant growth, and soil fertility by changing N dynamics.