The effects of biochar types application on the concentration of silicon and some essential nutrients in the soil with silty clay loam texture

Most of the Iranian soils are poor in organic matter due to poor management; including monoculture system and lake of crop rotation, removal of plant residues from the field, arid and semi-arid climates and non-utilization of organic fertilizers and organic amendment. Improper use of chemical fertilizers to increase agricultural production has initiated environmental issue and diminish soil fertility. Nowadays, with the development of organic farming, the use of organic amendments to replace the application of chemical fertilizers took a pay attention. The sugarcane is a plant that accumulates silicon. The poor management of sugarcane cultivation can reduce available silicon. Biochar is one of the most important organic compounds for improving soil properties, carbon content and improving the concentration of available silicon. The aim of this study was to investigate the effects of biochar types application on the concentrations of silicon and some essential elements of the sugarcane field soil.

In order to investigate the effects of biochar types application on the concentration of silicon and some essential nutrients in the sugarcane field soil, an experimental design was carried out as a factorial experiment based on a randomized complete design with two factors including biochar and chemical fertilizer in a completely randomized design with three replications in the greenhouse of Imam Khomeini Agro-Industrial Company in Khuzestan. The applied biochar was included sugarcane bagasse, rice husk, rice straw, wheat straw and dicer wood chips, which were produced at 300 °C for 3 hours in a pyrolysis furnace. Experimental treatments included the control (soil without any biochar or chemical fertilizers), biochar, chemical fertilizers and mixture of biochar and chemical fertilizers. Biochar was added to the soil based on one percent weight and the treatments were incubated for three months in the field capacity water content. At the end of the incubation period, the concentrations of nitrogen, phosphorus, potassium, silicon, iron, manganese, copper and zinc were measured.

The results showed that the effects of treatments on the concentration of nitrogen, phosphorus, potassium, silicon, iron, manganese, copper and zinc in the soil was significant. The mixture of rice straw biochar and nitrogen, phosphorus and potassium from chemical fertilizer sources (RSB + NPK) treatment had the highest available concentration of nitrogen, phosphorus and potassium in the soil. The highest available soil silicon concentrations were related to the treatments of mixture of rice straw biochar and nitrogen, phosphorus and potassium from chemical fertilizer sources (RSB + NPK), mixture of rice straw biochar and nitrogen and phosphorus from chemical fertilizer sources (RSB + NP) and mixture of rice straw biochar and phosphorus from chemical fertilizer sources (RSB + P). There was no significant difference between these treatments and treatments of rice straw biochar along with phosphorus and potassium (RSB + PK) and rice straw biochar (RSB).

In general, the results of this study showed that treatments with biochar (either biochar alone or mixture of biochar and chemical fertilizer) increased the available concentration of soil nutrients more than treatments without biochar (control and chemical fertilizer). Among the biochars, rice straw biochar, sugarcane bagasse biochar and rice husk biochar were most useful to increase the available concentration of nutrients. In general, it can be concluded that because biochar is a rich source of the nutrients and has a positive effect on soil properties, Hence, it can be used as useful material factor to improve soil fertility.