Kinji Tanaka

CIELAB color variables as indicators of compost stability

The composting process of different organic wastes both in laboratory and on a large-scale was characterized using CIELAB color variables to evaluate compost stability for the better application in agriculture. The time courses of the CIELAB variables of composting materials were determined directly from the bottom of a glass petri dish filled with dried and ground samples using a Minolta Color Reader (CR-13) calibrated with clean empty petri dishes placed on a white tile. To compare the proposed method with conventional methods, the same materials were also evaluated using commonly used compost stability evaluation indices. Most of the CIELAB variables of a compost made from a mixture of green tea waste and rice bran reached a plateau after 84 days of composting and showed strong relationships with the commonly used compost stability evaluation indices. The time needed for CIELAB variables, especially the L*and b* values, to stabilize at large-scale composting plants of cattle litter, farmyard manure, kitchen garbage and bark compost, were more or less similar to the times of maturation evaluated by the respective compost producers. The CIELAB color variable offers a new, simple, rapid and inexpensive means of evaluating compost stability and its quality prior to agricultural use.

Evaluation of the Physio-Chemical and Microbial Properties of Green Tea Waste-Rice Bran Compost and the Effect of the Compost on Spinach Production

Abstract To study the physio-chemical and microbial properties of green tea waste-rice bran compost (GRC), and feasibility of GRC as the alternative of agrochemicals for quality spinach production, five types of compost were prepared by mixing green tea waste and rice bran. The compost temperature was increased by adding rice bran to the green tea waste. The compost GC made from green tea waste alone contained a relatively large amount of nitrogen (7.55%). On the other hand, the compost RC made from rice bran alone contained a relatively large amount of minerals, such as phosphorus (0.49%), potassium (4.96%) and magnesium (2.28%). Addition of rice bran increased the total number of bacteria, viable bacteria and organic matter decomposing bacteria as well as actinomycetes population in the mature compost. The frequency of organic matter decomposing bacteria in GRC was in the following order: cellulolytic bacteria < pectolytic bacteria < lipolytic bacteria < amilolytic bacteria except RC. The growth of spinach was significantly increased over the untreated control (only soil) when GRC was applied in the field and growth pattern was depended on the nature of the composting materials. The highest fresh weight of 27.5 g plant-1 and 45.4 g plant-1 were obtained by applying the compost with 30% green tea waste + 70% rice bran (GRC-3) under field condition in autumn of 2004 and 2005, respectively. The highest growth enhance effect was also obtained from GRC-3 when three spinach varieties were grown with GRC under greenhouse condition. The amount of nitrate and oxalate in the spinach grown with GRC were ranged from 114.0 to 146.0 mg 100 g-1 and 612.0 to 748.0 mg 100 g-1 fresh weight, respectively. These values were below from the safety standard of health level of nitrate and oxalate for spinach. The amount of ascorbic acid, glutamic acid and iron in the spinach were increased by applying the compost. Among the five combinations of GRC, GRC-3 provided the best results in spinach production.

Comparison of the symptoms on rice sheath caused by several sclerotial fungi and the occurrences of the disease in paddy fields.

近年,収穫期のイネに,紋枯病によく類似した病斑を形成する,いわゆる疑似紋枯病が多く発生して問題となっている。この病斑は褐色紋枯病菌,赤色菌核病菌および褐色菌核病菌によって形成される場合が多く,これらの菌の人工接種によって病斑を形成させ,その特徴を詳細に検討した。また,一般水田から採集した疑似紋枯病斑について菌の分離を行った結果,褐色紋枯病菌と褐色菌核病菌が多く分離された。

Several sclerotial fungi isolated from sheath blight-like lesions and their properties

1979年,日本各地から採集したイネの紋枯病様病斑から,紋枯病菌(Pellicularia sasakii)以外の数種の菌核病菌がしばしば分離された。紋枯病菌以外の菌核病菌はRhizoctonia oryzae(赤色菌核病),Rhizoctonia solani培養型IIIB(褐色紋枯病)およびSclerotium oryzae-sativae(褐色菌核病)であった。これらの菌のイネに対する病原性を比較した結果,紋枯病菌>赤色菌核病菌>褐色菌核病菌>褐色紋枯病菌の順であった。褐色紋枯病菌は基準菌との菌糸融合と菌糸の核数により同定した。Rhizoctonia属菌(P. sasakii, R. solani IIIB, R.oryzae)の菌糸細胞は多核(平均5.7),Sclerotium属菌(S, oryzae-sativae, S, fumigatum, S. hydrophilum)のそれは2核からなっている。