Determining the effects of two different biochars on crop yields and soil quality

The aim of this study was to determine the effects of two different biochar sources on yields and nutrient uptake of winter wheat, red paper and red cabbage and physical, chemical and bio-chemical properties of a clayey soil. The study was carried out in the Bafra Experimental Station of the Black Sea Agricultural Research Institute during two rotation periods. The layout of field expeirment was split plots in randomized blocks. Six different doses (0, 10, 20, 30, 40 and 50 t ha-1) of rice husk and poultry manure biochars were splitted into the plots of the two blocks. The experiment was carried out with 3 replications in the same field. Winter wheat, red cabbage and red pepper were grown in two different rotation periods. The biochars were only applied at the begining of the experiment and the residual effects of biochars were investigated in the second rotation period. In addition to the biochar doses, appropriate fertilizers were also applied based on the requirements of the crops in the rotation. Soil samples were collected from 0-20 cm depths of each plot at the end of each rotation period. Physical, chemical and bio-chemical properties of soils, crop yields and nutrient concentrations of leaf samples were determined after each rotation. Crop yields increased with increasing the doses of two biochar types, however, the increases were not statistically significant. The increase in biochar doses caused a decrease in bulk density (3.5%) of the soil, while porosity (3%), moisture content at field capacity (5.3%), permanent wilting point (1.26%) and available water content (1.26%) increased. The changes in aggregate stability with the increase in biochar doses were not statistically significant. The pH, electrical conductivity, lime, organic matter, nitrogen, phosphorus, cupper, manganese and zinc contents were not changed, while total carbon C (7%) content increased depending on period and biochar application dose. Potassium concentration of soils was increased (49%) depending on rotation period and dose increase, while iron concentration decreased (34%) with the increase in biochar doses. Mineralizable nitrogen and microbial biomass carbon contents, alkaline phosphatase, dehydrogenase and urease enzyme activities did not significantly change with biochar type and application doses, whereas CO2 release and beta glucosidase enzyme activity were decreased with the increase in biochar doses. Biochar had a significant impact on soil functions by improving soil physical properties while managing organic wastes. The use of biochar alone does not seem possible to meet the nutrients needed by the crops. However, although not statistically significant, the increase in yield indicated that application of biochar contributes to the increase of the nutrient availability in the soil with an appropriate fertilization.