生物炭对京郊沙化地土壤性质和苜蓿生长、养分吸收的影响

通过田间试验研究了施用生物炭(14 t·hm^-2)和种植苜蓿对京郊沙化地的改良作用。试验设裸地(BL)、裸地添加生物炭(BLB)、种植苜蓿不加生物炭(A)和种植苜蓿添加生物炭(AB)四个处理。结果表明:添加生物炭使土壤容重显着减小11.5%~11.6%,pH值显着增加0.1~0.2个单位,田间持水量和总孔隙度分别增加9.1%~10.3%和7.6%~11.3%,土壤总氮、有机碳含量和氮、磷、钾、锌的有效含量分别增加10.3%~25.8%、52.8%~71.7%、12.7%~23.5%、141.7%~233.3%、47.7%~81.1%、94.2%~95.2%,有效铁含量最高减小29.1%,阳离子代换量(CEC)和钙、镁、锰、硼的有效含量无显着变化;种植苜蓿没有显着影响土壤pH值、容重、总孔隙度、田间持水量、CEC和氮、钙、镁、锌、硼的有效性,总体上显着减小了土壤含水量和总氮、速效磷、速效钾的含量,增加了铁和锰的有效含量。BLB处理土壤含水量比BL显着增加13.9%(P<0.05);添加生物炭使苜蓿地上部生物量、含水量和氮、磷、钾、钙、镁、铁、锌、锰、硼的吸收累积量分别显着增加91.1%、3.6%、110.0%、130.9%、200.4%、82.6%、44.8%、89.5%、102.7%、99.5%、104.7%.生物炭与苜蓿种植相结合可在短期内改善京郊沙化地土壤的理化性质、提高养分有效性和恢复植被。

Effects of Biochar on Soil Properties and Alfalfa Growth and Nutrient Uptake in Desertified Land in Beijing Suburb

Biochar has potential to improve soil properties and enhance plant growth. A field experiment was conducted to investigate the effects of biochar additions(14 t·hm^-2) on soil properties and alfalfa growth and nutrient uptake in desertified land in Beijing suburb. Four treatments were designed, including bare land(BL), bare land amended with biochar(BLB), alfalfa without(A) and with biochar addition(AB). Results showed that biochar additions significantly decreased soil bulk density by 11.5%~11.6%, but increased soil pH by 0.1~0.2 units, field capacity by 9.1%~10.3%, and soil total porosity by 7.6%~11.3%. Soil water content was 13.9% higher in BLB treatment than in BL treatment(P<0.05). Compared to no biochar treatment, biochar additions also increased contents of total nitrogen(TN), organic carbon(OC), available nitrogen, available phosphorus, available potassium, and available zinc by 10.3%~25.8%, 52.8%~71.7%, 12.7%~23.5%, 141.7%~233.3%, 47.7%~81.1%, and 94.2%~95.2%, respectively, while decreased available iron by up to 29.1%. Cation exchange capacity(CEC), and available calcium, magnesium, manganese and boron concentrations were not significantly affected by biochar amendment. Alfalfa did not show significant impacts on soil pH, soil bulk density, total porosity, field capacity, CEC and available nitrogen, calcium magnesium, zinc, and boron, but decreased soil water content, TN concentration, available phosphorus and potassium, while increased available iron and manganese. Biochar addition enhanced dry biomass, water content, nitrogen, phosphorus, potassium, calcium, magnesium, iron, zinc, manganese, and boron contents of alfalfa shoot by 91.1%, 3.6%, 110.0%, 130.9%, 200.4%, 82.6%, 44.8%, 89.5%, 102.7%, 99.5% and 104.7%, respectively. These results suggest that a combination of biochar amendment and alfalfa planting could improve soil physicochemical properties, enhance phytoavailability of soil nutrients, and restore vegetation for desertified land in Beijing suburb.