【摘要】 红壤是华南地区典型的土壤类型之一,其质地粘重,易于板结,尤其保水性差,易干旱,改善红壤的持水能力对于提高红壤的农业产出具有重要意义。近年来生物质炭被广泛应用于红壤的酸性改良,而对红壤水分特征影响规律研究较少。为了探究生物质炭对红壤水分特征的影响机制,以南方典型红壤为研究对象,设置稻壳炭-红壤的比例分别为0(CK)、3%(RHC-3)、5%(RHC-5)、10%(RHC-10),采用土柱模拟试验研究了生物质炭对红壤水分渗透特性的影响,结果表明,在同一入渗条件下,添加生物质炭处理均降低了土壤水分的入渗率,且随着生物质炭添加量的增加,水分入渗率不断降低,入渗起始阶段水分入渗率表现为:RHC-10<RHC-5<RHC-3<CK,最后入渗率趋于稳定。采用离心机法研究了不同炭土比(W0-0;W1-1%;W3-3%;W5-5%;W10-10%)红壤的水分特征曲线,并运用Gardner和Van Genuchten模型进行拟合,结果表明,这两个模型都可以很好地描述红壤的持水特征,拟合系数分别在0.928和0.998以上。当生物质炭添加比例为5%(W5)时,Gardner模型参数A值最大,表明持水能力最强。Van Genuchten模型表明,W5处理土壤饱和含水率最高,随着炭土比增加,α值不断降低,说明土壤保水性增强。从拟合曲线可以看出,在较低的土壤吸力(<1 000 kPa)作用下,各处理含水率下降较快,当土壤吸力为1 000 kPa时,5个处理土壤含水率分别下降了25.86%、38.15%、38.27%、36.88%、31.64%;而在较高土壤吸力(1 000-6 000k Pa)时,土壤质量含水率下降速率减慢,当土壤吸力>6 000kPa时,各处理土壤含水率逐渐趋于平缓,并且在此吸力范围内,W10处理土壤质量含水率最高。另外,红壤的毛管持水量表现为W10>W5>W3>W1>W0。总之,生物质炭添加到红壤后降低了水分的入渗率,添加适量生物质炭可提高红壤的饱和含水率,增强红壤的持水性能。更多还原

【Abstract】 Red soil is one of the typical soils in South China with the characteristic of heavy texture, low output, easily hardening and poor water capacity. Therefore, it is significant to increase the agricultural output of the red soil by improving the water retention capacity. Recently, biochar is used widely as one new soil amendment to improve the red soil acidity, while there is less research about its water characteristics. This study investigated the effect of biochar application on water infiltration and retention of red soil. To this end, a soil column experiment was set for water infiltration, and biochar was applied to red soil with the rates of0(CK), 3%(RHC-3), 5%(RHC-5) and 10%(RHC-10), respectively. The results indicated that: biochar application greatly reduce water infiltration, moreover, the water infiltration was decreased constantly with the increase of biochar application rates. Besides,a centrifugal model test was employed to analyze the water characteristic curve of different biochar application rates(W0-0;W1-1%;W3-3%; W5-5%; W10-10%). The result corroborated with the predictions of both Gardner equation and the Van-Genuchten equation, with r2 values of 0.928 and 0.998, respectively. The highest value of parameter A of the Gardner model was observed in the W5 treatment, indicated the water retention capacity of W5 was the highest. The parameter α value of Van Genuchten model decreased gradually with the increase of biochar application, suggested an increase in the water holding capcity.The fitting curves of Van Genuchten model demonstrated that the moisture of the red soil decreased rapidly at low soil water suction pressure(<1 000 k Pa). Soil moisture content of W0, W1, W3, W5 and W10 treatments decreased 25.86%, 38.15%,38.27%, 36.88% and 31.64%, respectively at 1 000 kPa soil water suction pressure. At higher suction pressure(1 000 kPa to 6 000 kPa), loss rate of soil moisture decreased. The loss rate of soil moisture flattened at suction pressure higher than 6 000 kPa, with the highest soil moisture measured in W10 treatment. Moreover, with the increase in the biochar application rate, the capillary moisture of the red soil was increased gradually(W10>W5>W3>W1>W0). In summary, the water infiltration rate of the red soil was significantly improved by the moderate application of biochar. The Suitable amount of biochar application can increase the saturated water content and enhance the water retention capacity of the red soil.更多还原