Abstracts of Nippon Dojo-Hiryogaku Zasshi 93 - 2

Original Paper

Estimating available nitrogen using total carbon content and spectral reflectance obtained from aerial photography of paddies with continuous organic matter application

Kazuki Togami, Akira Takamoto and Tomoki Takahashi

Daisen Research Station, Tohoku Agricultural Research Center, NARO

Based on the fact that humus is dark and stable against microbial degradation, we hypothesized that stable humus content can be estimated by the soil carbon content predicted from spectral reflectance. Furthermore, the difference between the total carbon content and the predicted value can be attributed to easily-decomposable organic matter, representing available nitrogen. Thus, we suggest a new method to estimate available nitrogen based on total carbon content and spectral reflectance. To test this method, we conducted drone-based remote sensing using a four-wavelength multispectral camera at paddies, where livestock manure compost and rice straw has been continuously applied, and paddies where no organic matter has been added after puddling. Using spectral reflectance, the model tended to underestimate the predicted carbon content in such paddies. Coefficients of determination were higher in paddies without added organic matter, suggesting that the value predicted via spectral reflectance may measure stable humus. We found a significant correlation between the available nitrogen and the difference between the predicted value from the spectral reflectance and the total carbon content. This finding indicates that total carbon content and spectral reflectance can be used to estimate available nitrogen. Using both the spectral reflectance and the total carbon content in the predictive formula, the coefficient of determination increased from 0.70 to 0.90 in air-dried soil incubated for 4 weeks and from 0.45 to 0.74 in wet soil incubated for 10 weeks. The applicability of this method should be verified in different soil and humus types.

Key words: available nitrogen, total carbon content, spectral reflectance, continuous use of organic matter, drone-based remote sensing

(Jpn. J. Soil Sci. Plant Nutr., 93, 69–76, 2022)

Current Topic

Techniques to promote the nitrogen mineralization of organic fertilizer in rice paddy field by moving ahead of fertilization timing

Satoshi Kumagai, Toshinari Igarashi^† and Hiroshi Nakamoto^‡

Kamikawa Agric. Exp. Stn., HRO

^†Present address: Central Agric. Exp. Stn., HRO

^‡Present address: Tokachi Agric. Exp. Stn., HRO

(Jpn. J. Soil Sci. Plant Nutr., 93, 77–82, 2022)

Miscellaneous

What is the tastiness and safety that comes from soil?

Itsuo Goto^a, Tetsuji Yanagihara^b,†, Keiki Okazaki^c, Yuzo Manpuku^c, Mayumi Hachinohe^d, Ryota Koyama^e, Yo Toma^f and Takuro Shinano^f

^aTokyo University of Agriculture

^bHokkaido Research Organization, Industrial Technology and Environment Research Department, Food Processing Research Center

^cInstitute of Agro-Environmental Sciences, NARO

^dInstitute of Food Research, NARO

^eFaculty of Food and Agricultural Sciences, Fukushima University

^fGraduate School of Agriculture, Hokkaido University

^†Present address: ADD-ONE Co., Ltd.

(Jpn. J. Soil Sci. Plant Nutr., 93, 83–88, 2022)

Miscellaneous

2021 IS-MPMI Congress: eSymposia Series participation report

Shin-Ichiro Agake

United Graduated School of Agriculture, Tokyo University of Agriculture and Technology

(Jpn. J. Soil Sci. Plant Nutr., 93, 89, 2022)

Miscellaneous

Exhibition report of the EcoPro 2021

Taku Kato

Tokyo University of Agriculture, Faculty of Applied Biosciences, Department of Agricultural Chemistry

(Jpn. J. Soil Sci. Plant Nutr., 93, 90, 2022)

Miscellaneous

Regional trends: Tohoku

Chiharu Ito^a and Mizuhiko Nishida^b

^aAkita Prefectural Agricultural Experiment Station

^bGraduate School of Agricultural Science, Tohoku University

(Jpn. J. Soil Sci. Plant Nutr., 93, 91, 2022)