Abstracts of nippon dojo-hiryogaku zasshi, Vol. 89 (2018) No. 4

Original Paper

Rate of atmospheric carbon sequestration by Japanese tea plantations

Toshiyuki NAGUMO and Akio MORITA

Faculty of Agriculture, Shizuoka University

Tea plantations can act as a sink for atmospheric carbon. Although a few studies have estimated carbon stocks in tea plants and soil, the annual rate of carbon sequestration by tea plantations in Japan has not yet been estimated. In this study, we aimed to estimate the rate of carbon sequestration by a tea plantation using reported data from a compartment model consisting of tea plants and soil. For a stand age of up to 50 years, the annual rate of carbon sequestration was estimated to be 83–237 g carbon m⁻² y⁻¹. This rate was higher for younger plants (<10 years) and was lower for mature plants (>30 years). These results indicate that tea plantations have the same carbon sequestration ability as forests and that high levels of greenhouse gas (e.g., nitrous oxide) emissions from tea fields could be partly offset by their carbon sequestration abilities.

Key words: carbon sequestration, atmospheric carbon sink, greenhouse gas, tea plantation

(Jpn. J. Soil Sci. Plant Nutr., 89, 283–294)

Original Paper

Characterization of hot-water extracts from co-compost of dried sewage sludge and bamboo chips and effect of compost application on the growth of black soybean (Glycine max)

Hiroyuki KIKUKAWA¹, Morimaru KIDA², Madoka ENSO¹, Yukako INAMOTO¹, Ken-ichi KISHIMOTO³, Taku KATO⁴ and Nobuhide FUJITAKE²

¹ Sasayama Shinonome High School

² Graduate School of Agricultural Science, Kobe University

³ Sasayama City Water Supply and Sewerage Division

⁴ Faculty of Applied Bioscience, Tokyo University of Agriculture

Sewage sludge is generated 2.26 million Mg annually in Japan, and its dealing is one of the social problems. This study aimed to promote the application of dried sewage sludge in farmlands for recycling purposes. We composted sludge and bamboo chips in the ratios of 5 : 5, 7 : 3, and 9 : 1. Characteristics of hot water extracts during composting were analyzed approximately every week until the end of composting process (41 days) by testing inhibition of germination of Japanese mustard spinach (Brassica rapa var. perviridis) and by chemical analyses such as those using UV-vis spectroscopy and those involving dissolved organic carbon measurement. The concentration of ammonia, which is one of the strongest odor sources, decreased by about 60％ in the first 2 weeks of composting. The pH, electrical conductivity, and E2/E3 tended to decrease, whereas specific UV absorbance (SUVA₂₅₄) tended to increase during composting, suggesting the progression of humification and maturation of composts. Although the 7 : 3 and 9 : 1 compost extracts demonstrated considerable germination inhibition in the early stages of composting, the inhibition was alleviated as maturation progressed to 28 days. Inhibition was not observed in the 5 : 5 compost extract, and heavy metals did not exceed the safety standard, so the compost did not exhibit harmful effects on crop growth or safety. We also performed three replicates of a field growth experiment using Tanbaguro black soybean (Glycine max) with and without addition of 50-day-old compost (5 : 5, 7 : 3, and 9 : 1). Results showed that addition of the composts significantly increased the main stem length and the number of pods (p < 0.01). Soybean yield was the highest in the 9 : 1 compost addition group, although this difference was not significant. These results suggest that composting of dried sewage sludge and bamboo chips is effective in agricultural production as it recycles local resources, reduces odor, and does not inhibit germination.

Key words: black soybean, dissolved organic matter, E2/E3, odor, SUVA₂₅₄

(Jpn. J. Soil Sci. Plant Nutr., 89, 295–301)

Original Paper

Effects of controlled-release nitrogen fertilizer on soil nitrous oxide emissions from broccoli (Brassica oleracea var. italica) autumn-cultivation field

Yo TOMA¹, Mayu ONISHI², Yutaka SHIRATORI³, Shigeto SUDO⁴, Seiichi NISHIMURA⁵ and Hideto UENO¹

¹ Graduate School of Agriculture, Ehime University

² Faculty of Agriculture, Ehime University

³ Niigata Agricultural Research Institute

⁴ Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization (NARO)

⁵ Hokkaido Agricultural Research Center, National Agriculture and Food Research Organization (NARO)

Nitrous oxide (N₂O) is one of the important greenhouse gases emitted from agricultural field. We investigated nitrous oxide (N₂O) emissions following the application of coated urea (CU) and calcium nitrate in autumn broccoli cultivation field. The experiment was conducted in Ehime University Farm from September to November 2016 and comprised four treatments: non-fertilized (C), urea (U), CU, and coated calcium nitrate (CN) applications. In CU and CN treatments, we applied only 80％ of the nitrogen (N) fertilizer used in treatment C; of this, 40％ was replaced with coated fertilizer. We measured the N₂O flux and N₂O emission factor (EF) induced by applied N as well as soil environmental factors including soil temperature at 5-cm-depth, soil pH, and soil ammonium and nitrate concentrations. We also measured yield, concentration of N leaching from the top 20-cm soil layer, N uptake by plant, and N use efficiency. EFs of the CU (0.62％) and CN (0.23％) treatments were higher than that of the U (0.06％) treatment. Application of CU or CN instead of U did not reduce N₂O emissions from the autumn cultivation of broccoli. In the early stages of the experiment, N elution from the coated fertilizer following nitrification and denitrification might have been enhanced due to higher temperatures and precipitation. In addition, N₂O emission from the applied supplemental N was low because of lower temperature and precipitation conditions following the supplemental fertilization in U. Lower yield and higher levels of leached N in CN treatment may have been due to the loss of N with higher precipitation after basal fertilization. Our study demonstrates that application of coated U could increase N₂O emissions relative to the application of U under higher temperature and precipitation conditions following the application. Furthermore, application of CN may decrease the yield and increase leaching of N.

Key words: nitrous oxide, emission factor, coated urea, coated calcium nitrate, broccoli

(Jpn. J. Soil Sci. Plant Nutr., 89, 302–310)

Note

Improvement of a simplified method for measuring exchangeable soil potassium by using a compact potassium ion meter for improvement its accuracy

Hidetaka NAKAYAMA, Shohei SATO, Yoshimitsu ARAI and Mutsuto SATOU

Fukushima agricultural technology center

(Jpn. J. Soil Sci. Plant Nutr., 89, 311–316)

Note

Using digital image analysis to improve a simple colorimetric kit for COD and to estimate the content of available nitrogen in paddy soils from the measurement of COD in the water extracts of oven-dried soil samples

Tomonori ABE¹, Jiro SASAKI¹, Kenji KANAZAWA², Michio KOMADA² and Shigeru TAKAHASHI^{2, †}

¹ Miyagi Furukawa Agricultural Experiment Station

² National Agricultural Research Center

^†Tohoku Agricultural Research Center

(Jpn. J. Soil Sci. Plant Nutr., 89, 317–320)

Note

Characteristics of nitrogen mineralization from the organic matter applied to the organic vegetable farm soil. I. Comparison of N mineralization from rice bran applied to the soil of organic, organic transition and conventional farm

Toshihiko KARASAWA, Kazunari NAGAOKA, Yasufumi URASHIMA and Tomoyoshi HASHIMOTO

Central Region Agricultural Research Center, NARO

(Jpn. J. Soil Sci. Plant Nutr., 89, 321–325)

Note

Characteristics of nitrogen mineralization from the organic matter applied to the organic vegetable farm soil. II. Comparison of N mineralization from various organic matter applied to the soil of organic and conventional farm

Toshihiko KARASAWA, Yuko SUGA^†, Yasufumi URASHIMA and Tomoyoshi HASHIMOTO

Central Region Agricultural Research Center, NARO

^† Headquater, NARO

(Jpn. J. Soil Sci. Plant Nutr., 89, 326–329)

Miscellaneous

Report on European Geosciences Union General Assembly (EGU) 2018

Mayuko SEKI

Tokyo University of Agriculture and Technology

(Jpn. J. Soil Sci. Plant Nutr., 89, 330)

Miscellaneous

Report on iMMM2017 and ICOM9

Hayato MARUYAMA

Graduate School of Agriculture, Hokkaido University

(Jpn. J. Soil Sci. Plant Nutr., 89, 331)