The Effect of Biochar on Sweet Corn Production and Nitrate Leaching

The rising operational cost and the environmental impact of agriculture are current concerns of agriculturalists and environmentalists.  Nitrogen fertilizers are costly and are lost easily through leaching.  Effective methods to increase nitrogen-use efficiency are needed.  Biochar, also called activated carbon or black carbon, has gained attention because of its potential environmental advantages and economic value as a soil amendment.  A two-year field experiment was conducted to determine the effect of biochar on sweet corn production and on nitrate leaching.  Two treatments (no biochar, biochar) were used.  Treatments were replicated four times in a randomized complete block design. All blocks were fertilized with a chemical fertilizer (15–3.5–12 NPK) to provide 120 kg N–28 kg P–80 kg K/ha.  In year one, biochar at 12 Mg/ha was applied. No biochar was applied in year 2 to determine the residual effect of biochar.  Samples of soil from all blocks were collected, four times (on four different dates) in year one and once in year two.  Soil samples were collected from three different depths, 0 to 20, 20 to 40, and 40 to 60 cm from the soil surface. Samples were tested for nitrate concentration.  Nitrate from the 40 to 60 cm depth was considered as leached N.  At harvest, a random 2 m² from each block was used to collect data on yield and plant growth parameters.  Plant height, number of plants per hectare, number of ears per hectare, and total fresh weight of ears per hectare were determined.  Biochar had no effect on yield or plant growth parameters in the first year but resulted in a slight increase of plant height the second year.  Small decreases in nitrate leaching occurred with biochar treatment in both years.  Our data suggest that biochar may increase nitrogen use efficiency.