Abstract
Biochar has altered plant yields and soil nutrient availability in tropical soils, but less research exists involving biochar additions to temperate cropping systems. Of the existing research, results vary based on soil texture, crop grown, and biochar properties. The objective of this study was to determine the effects of pine (Pinus spp.) woodchip biochar at 0, 5, and 10 Mg·ha−1 rates combined with urea nitrogen (N) on soil chemical properties and corn (Zea mays L.) yield under field conditions in the first growing season after biochar addition in a silt-loam alluvial soil. Biochar combined with fertilizer numerically increased corn yields, while biochar alone numerically decreased corn yields, compared to a non-amended control. Corn nitrogen uptake efficiency (NUE) was greater with 10 Mg·ha−1 biochar compared to no biochar. There were limited biochar effects on soil nutrients, but biochar decreased nitrate, total dissolved N, and Mehlich-3 extractable sulfur and manganese concentrations in the top 10 cm. Pine woodchip biochar combined with N fertilizer has the potential to improve corn production when grown in silt-loam soil in the mid-southern U.S. by improving NUE and increasing yield. Further research will be important to determine impacts as biochar ages in the soil.
Highlights
Fertile and carbon-rich soils have been discovered throughout the Amazon River basin, an area where soils are typically nutrient leached and weathered [1,2]
Corn yields decreased with the addition of 10 Mg·ha−1 biochar in the no fertilizer treatment compared to the no fertilizer and no biochar treatment combination
Pine woodchip biochar applied at rates of 5 and 10 Mg·ha−1 in combination with N fertilizer to a fertile silt loam in northwest Arkansas numerically increased corn yields compared to fertilizer application without biochar
Summary
Fertile and carbon-rich soils have been discovered throughout the Amazon River basin, an area where soils are typically nutrient leached and weathered [1,2]. Terra Preta soils, or Amazonian dark earth soils, occur in locations classified as Oxisols and Ultisols with similar mineralogical properties as surrounding soils. The Terra Preta soils are differentiated by their darker color due to large amounts of organic matter (reportedly nearly 90 g·kg−1 in the surface horizon or 250 Mg·ha−1·m−1 compared to around 30 g·kg−1 or 100 Mg·ha−1·m−1 in surrounding Oxisols), charcoal, and A horizons ranging from 30 to 60 cm opposed to the typical 10- to 15-cm depths in adjacent soils [1,3,4,5]. In light of the observed fertility of Amazonian dark earth soils, presumably due in part to the presence of charcoal, research is ongoing to determine the effects of charcoal addition in different soils and charcoal’s agronomic impact as a soil amendment. Pyrolysis is the thermal conversion of biomass under no or minimal oxygen conditions with temperatures generally between
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