Calderón Francisco J, Benjamin Joseph, Vigil Merle F
USDA-ARS, 40335 Co Rd GG., Central Great Plains Research Station, Akron, Colorado, United States of America.
PLoS One. 2015 Apr 2;10(4):e0121006. doi: 10.1371/journal.pone.0121006. eCollection 2015.
In order to properly determine the value of charring crop residues, the C use efficiency and effects on crop performance of biochar needs to be compared to the un-charred crop residues. In this study we compared the addition of corn stalks to soil, with equivalent additions of charred (300 °C and 500 °C) corn residues. Two experiments were conducted: a long term laboratory mineralization, and a growth chamber trial with proso millet plants. In the laboratory, we measured soil mineral N dynamics, C use efficiency, and soil organic matter (SOM) chemical changes via infrared spectroscopy. The 300 °C biochar decreased plant biomass relative to a nothing added control. The 500°C biochar had little to no effect on plant biomass. With incubation we measured lower soil NO3 content in the corn stalk treatment than in the biochar-amended soils, suggesting that the millet growth reduction in the stalk treatment was mainly driven by N limitation, whereas other factors contributed to the biomass yield reductions in the biochar treatments. Corn stalks had a C sequestration use efficiency of up to 0.26, but charring enhanced C sequestration to values that ranged from 0.64 to 1.0. Infrared spectroscopy of the soils as they mineralized showed that absorbance at 3400, 2925-2850, 1737 cm-1, and 1656 cm-1 decreased during the incubation and can be regarded as labile SOM, corn residue, or biochar bands. Absorbances near 1600, 1500-1420, and 1345 cm-1 represented the more refractory SOM moieties. Our results show that adding crop residue biochar to soil is a sound C sequestration technology compared to letting the crop residues decompose in the field. This is because the resistance to decomposition of the chars after soil amendment offsets any C losses during charring of the crop residues.
为了正确确定炭化作物残渣的价值，需要将生物炭的碳利用效率及其对作物生长性能的影响与未炭化的作物残渣进行比较。在本研究中，我们将玉米秸秆添加到土壤中，并与添加了同等量的炭化（300℃和500℃）玉米残渣进行了比较。进行了两项试验：一项长期实验室矿化试验，以及一项针对黍稷植物的生长室试验。在实验室中，我们通过红外光谱测量了土壤矿质氮动态、碳利用效率以及土壤有机质（SOM）的化学变化。与未添加任何物质的对照相比，300℃生物炭降低了植物生物量。500℃生物炭对植物生物量几乎没有影响。通过培养，我们测量到玉米秸秆处理的土壤中NO3含量低于生物炭改良土壤，这表明秸秆处理中黍稷生长减少主要是由氮限制驱动的，而其他因素导致了生物炭处理中生物量产量的降低。玉米秸秆的碳固存利用效率高达0.26，但炭化将碳固存提高到了0.64至1.0的范围。随着土壤矿化，土壤的红外光谱显示，在3400、2925 - 2850、1737 cm-1和1656 cm-1处的吸光度在培养过程中下降，可视为不稳定的SOM、玉米残渣或生物炭波段。1600、1500 - 1420和1345 cm-1附近的吸光度代表了更难分解的SOM部分。我们的结果表明，与让作物残渣在田间分解相比，向土壤中添加作物残渣生物炭是一种可靠的碳固存技术。这是因为土壤改良后炭对分解的抗性抵消了作物残渣炭化过程中的任何碳损失。
