Rhizosphere nutrient availability and nutrient uptake of soybean in response to biochar application

Biochar application in agricultural soils can be highly beneficial to crop productivity in numerous ways. Rhizosphere nutrient dynamics and its relation to nutrient uptake of crops under biochar amendment remain unclear. Therefore, the present study investigated the combined effect of biochar application and incubation on growth, yield, and rhizosphere nutrient availability of soybean (Glycine max L.) plant. A pot experiment was conducted with two biochar applications (with and without biochar) and two incubation conditions (with and without incubation) in a glasshouse. A separate soil column leaching experiment was conducted to test the nutrient retention ability of soil once biochar is amended. Irrespective of the incubation condition, biochar application made a significant increase in pod dry weight. The total nutrient uptake by soybean greatly increased under biochar amendment compared with the plants grown without biochar. When incubation is not done, soybean increased its P and K uptake respectively by 52% and 48% under biochar amendment compared to those without biochar. With incubation, the relevant increases were 42% and 32% respectively. The results from soil column leaching experiment suggest that the application of biochar in planting media could be an effective way to retain soil N by reducing the leaching losses.