CAJ | 학술논문

土壤含水率直接测量是相关研究和应用的基础,在土壤力学、作物栽培、农田灌溉、生态环境等研究和实践中十分重要.该文提出了一种与传统烘干称质量法相当的体积置换法直接测量土壤质量含水率及土壤容重.该方法在假设一定土壤颗粒密度的前提下,用一定体积的标准取样环刀取得土样后,通过向待测量土体补充水分使土壤达到饱和,用一定体积的水置换土壤中的充气空隙,直到土样达到饱和状态;再通过测量得到的初始/原始土样质量、饱和后土壤的质量以及已知土壤颗粒密度和水密度,计算得到被置换的充气空隙的体积,进而由此计算得到土壤质量含水率和土壤容重.采用3种不同土壤,即陕西杨凌黏黄土、北京粉壤土和江西黏红土,分别预配制成7种不同初始土壤体积含水率,含水率约为:风干土(含水率2%~3%)、5%、10%、15%、25%、30%和饱和含水率,以及3种不同土壤容重:1.25、1.35和1.45 g/cm3进行室内试验.用类似的土样,采用传统方法烘干土样8、12、24、48 h后,测量确定土壤的质量含水率,通过延长烘干时间测得数据表明,传统方法烘干8 h所测得的质量含水率仍有1%~3.2%的含水率误差.最终试验结果表明体积置换方法测得的土壤含水率比传统烘干土样8 h 所测得的结果大2%~3%,比烘干土样48 h所测得的结果大1%左右.体积置换方法测量操作过程简单,耗时较少,节约能源,测量结果具有较高精度.
토양함수솔직접측량시상관연구화응용적기출,재토양역학、작물재배、농전관개、생태배경등연구화실천중십분중요.해문제출료일충여전통홍간칭질량법상당적체적치환법직접측량토양질량함수솔급토양용중.해방법재가설일정토양과립밀도적전제하,용일정체적적표준취양배도취득토양후,통과향대측량토체보충수분사토양체도포화,용일정체적적수치환토양중적충기공극,직도토양체도포화상태;재통과측량득도적초시/원시토양질량、포화후토양적질량이급이지토양과립밀도화수밀도,계산득도피치환적충기공극적체적,진이유차계산득도토양질량함수솔화토양용중.채용3충불동토양,즉협서양릉점황토、북경분양토화강서점홍토,분별예배제성7충불동초시토양체적함수솔,함수솔약위:풍간토(함수솔2%~3%)、5%、10%、15%、25%、30%화포화함수솔,이급3충불동토양용중:1.25、1.35화1.45 g/cm3진행실내시험.용유사적토양,채용전통방법홍간토양8、12、24、48 h후,측량학정토양적질량함수솔,통과연장홍간시간측득수거표명,전통방법홍간8 h소측득적질량함수솔잉유1%~3.2%적함수솔오차.최종시험결과표명체적치환방법측득적토양함수솔비전통홍간토양8 h 소측득적결과대2%~3%,비홍간토양48 h소측득적결과대1%좌우.체적치환방법측량조작과정간단,모시교소,절약능원,측량결과구유교고정도.
Direct measurement of soil moisture and bulk density is the foundation of related research and applications, which is of great importance in such studies and applications as soil mechanics, crop production, irrigation and ecological environments. This paper presents a new method for direct measurement of soil moisture and soil bulk density based on volume replacement, which is equivalent to the conventional oven-dry method. The measurement principle is based on the model of soil three-phase composition, soil particles, water and air. Its volume and mass are partitioned into three fractions of these substances. The initial soil mass is approximately determined by the soil particles and water when the air mass is neglected. The measurement principles are as the follows. The samples used for measurements of moisture content and bulk density were taken by corers of known volumes and were weighted to determine their initial masses before they were filled with water to saturation state to replace all the air-filled spaces in the soil samples. The initial/original weight of the soil sample and that after saturation were used to compute the water mass required to replace the air-filled volume. Under the known soil particle density, the given volume as defined by the corer and the determined air-filled space volume, the original soil water content and soil bulk density can be calculated. An experimental system and the related algorithm procedures were proposed for the direct measurement of water content and soil bulk density. The standard soil corers were used to prepare the soil samples under designed bulk densities. The saturators were used to pre-saturate the soil samples. The samples were dripped with water to ensure their saturation during the measurement. Three soil materials, a clay loam from Yangling of Shaanxi province, a silt loam from Beijing and a red clay from Jiangxi province, were used for the demonstrational experiments to illustrate the measurement procedures and to verify the method. Seven different initial soil water contents, about 2%-3%, 5%, 10%, 15%, 25%, 30%and saturated water content, and three bulk densities of about 1.25, 1.35 and 1.45 g/cm3 were adopted in the experiments. These samples of the different initial water contents and soil bulk densities were used to measure the soil moisture by the volume replacement method. Detailed experimental procedures were presented to illustrate the experimental procedures. Conventional oven-dry method was used to determine parallelly the moisture contents of the soil samples similarly prepared. The water content changes when samples were oven-dried for 8, 12, 24, 48 h were measured to determine the influences of oven-dry period. The measured data showed that the soil water contents measured by the volume replacement were 2%-3%higher than those by the oven-dry method for a drying period of 8 h and were about 1%higher than those by the conventional oven-dry method for a drying period of 48 h. In addition, the traditional drying method is more time-consuming and not suitable for the field work. This indicates oven-dry method needs extended period of time to dry the soil sample. The results verify the newly-suggested measurement method and the experimental procedures. In general, the experimental operation of the volume replacement method is simple, time efficient, low energy consumption and high accuracy.