Abstract:An instrument used to measure the content of soil organic matter was developed based on spectroscopy. The instrument consists of an optical unit and an electronic unit. The optical unit is used to collect the reflecting light from soil surface and change the filtered light into the electrical signal. The electronic unit includes an amplifying circuit, an A/D circuit, and a display and storage circuit. Three wavebands of filters, 530, 765, and 850 nm, were selected in the performance test in order to determine the optimal one. The soil samples tested include two types, dried soil and air-dry soil. The result shows that there is highest correlation between the reflectance and the content of soil organic matter at the wavelength of 850 nm (r2=0.930) for dried soil. While the coefficient of determination r2 is abouu 0.711 for air-dry soil at the same wavelength. Although the actual precision is lower because of the soil moisture, it is practical in real-time measurement in the field.
[1] WANG Mao-hua(汪懋华). Transactions of the Chinese Society of Agricultural Engineering (农业工程学报), 1999, 15 (1): 1. [2] BAO Shi-dan(鲍士旦). Soil and Agricultural Chemistry Analysis (土壤农化分析). Beijing:China Agriculture Press(北京:中国农业出版社),2000. [3] Sudduth K A, Hummel J. Transactions of the ASAE, 1991, 34(4): 1900. [4] Li Minzan, Sasao A, Shibusaw a S, et al. Journal of the JSAM, 2000, 62 (3): 111. [5] WANG Duo-jia, ZHOU Xiang-yang, JIN Tong-ming, et al(王多加, 周向阳, 金同铭, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2004, 24(4): 447. [6] Krishnan P, Alexander J D, Butler B J, et al. Science Society of American Journal, 1980, 44: 1282. [7] SHA Jin-ming, CHEN Peng-cheng, CHEN Song-lin(沙晋明, 陈鹏程, 陈松林). Research of Soil and Water Conservation(水土保持研究), 2003, 10(2): 21. [8] SUN Jian-ying, LI Min-zan, ZHENG Li-hua, et al(孙建英, 李民赞, 郑立华, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2006, 26(3): 426. [9] Sudduth K A, Hummel J. Transactions of the ASAE, 1993, 36(1): 185. [10] Sudduth K A, Hummel J. Transactions of the ASAE, 1993, 36(6): 1571. [11] Reeves III J B, McCarty G, Meisinger J. J. Near Infrared Spectrosc., 1999, 7: 179. [12] Reeves III J B, Van Kessel J S. J. Near Infrared Spectrosc., 1999, 7: 195. [13] XU Guang-tong, YUAN Hong-fu, LU Wan-zhen(徐广通, 袁洪福, 陆婉珍). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2000, 20(2): 134. [14] WAN Feng, SUN Hong-wei, FAN Shi-fu(万 峰, 孙宏伟, 范世福). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2006, 26(4): 779. [15] DING Xiao-ping, WANG Wei, FU Lian-chun (丁小平, 王 薇, 付连春). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2006, 26(6): 1176. [16] ZHANG Xi-jie, LI Min-zan, CUI Di, et al(张喜杰, 李民赞, 崔 笛, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2006, 26(5): 887. [17] GAO Rong-qiang, FAN Shi-fu, YAN Yan-lu, et al(高荣强, 范世福, 严衍禄, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2004, 24(12): 1563.