The suitability map for barley in Kanazawa area was taken as an example of an interpretative soil map using a Soil Information System for arability in Japan (JAPSIS). The map was made through the following process. (1) The analysis of the relationships between yields of barley and natural environment factors was executed. the results of the analysis, the soil conditions, are a very important factor for barley cultivation. In the Gley soil area, the yield of barley was greatly influenced by the weather condition. (2) The statistical analysis (multidimensional quantification I analysis) of the relationships between the suitability rank data for barley cultivation and soil survey data in the model area was executed using a computer. the result of the analysis, the yield of barely, was strongly correlative to the depth of topsoil, the macro porosity of subsoil, and bulk density of topsoil. (3) The estimated value on the suitability soil for barley cultivation was shown by the following numerical formula : [numerical formula]where, P=synthetic estimated value, r_i=weight of i item, B_<iK>=weight of i factor and k category, and ki=category quantity of i factor. According to these results, the estimated value could be divided into three groups : 1) Suitable areas for barley cultivation. 2) Moderately suitable areas for barley cultivation. 3) Unsuitable areas for barley cultivation. The area of poorly drained paddy fields were ranked as unsuitable areas. (4) The soil map and suitability map for barley cultivation (scale 1 : 50000) were made using soil name files and cartographic files of JAPSIS. They were printed out on the topographic base maps directly using an autodrafter. (5) The accuracy of the suitability map was checked by the actual barely yield data in some agricultural cooperative substations. The results confirmed that the maps were appropriate.

View full abstract

Cupric chloride was dissolved in two kinds of soil solutions obtained with a centrifuge. their toxicity on the elongation of seminal roots of rice were compared with that of cupric chloride in distilled water. The results showed that the soil solutions effected a decrease in the toxicity of copper ; these was a clear difference in the strength of this effect between these two kinds of solutions. To clarify this mechanism, the two soil solutions were treated with activated carbon, ultrafilter, and ion-exchanged resin, and cupric chloride solutions were made with these treated soil solutions. The toxicity of copper in these solutions on seminal roots of rice was compared. The results showed that the organic compounds and nutrient elements ions in the soil solutions effected the decrease in the toxicity of copper and also showed that the strength of this effect depends on the amounts of these substances in the soil solutions.

View full abstract

Two kinds of soils were contaminated with cupric chloride and these soils were incubated at 20℃ for more than a month. Soil solutions were obtained from these soils with a centrifuge method. The toxicity of these soil solutions on the elongation of seminal roots of rice were compared with each other and that of cupric chloride in distilled water. The results showed that the soil solutions effected a decrease in the copper's toxicity, and there was a clear difference in the strength of this effect between these two kinds of solutions. This result was the same as that of the last paper, so it was assumed that the organic compounds and nutrient elements ions in the soil solutions effected a decrease in the copper's toxicity and also that the strength of these effects depends on the amounts of these substances in the soil solutions. There was a large difference in the copper concentration in soil solutions between these two kinds of soil-alluvial soil and volcanic ash soil. Copper concentration in soil solution of the former soil was more than ten times higher than that of the latter for the same added concentration of cupric chloride. It was assumed that this phenomenon depends on the difference in clay mineral content of these two kinds of soils, because there was no difference in the content of fumus between both soils.

View full abstract

It is time-consuming to determine free oxides in soils. This paper describes a rapid method for the determination of iron, silicon, and aluminum in MEHRA-JACKSON's and TANN's extracts using X-ray fluorescence spectroscopy. In order to concentrate the elements, measurement of X-ray intensities was carried out on droplets of the extracts on filter papers. Internal standards were used to diminish variation of X-ray intensities (NiKα for FeKα, RbLα for SiKα and AlKα). Matrix effect was overcome by addition of sodium citrate in large quantities. Procedure and results are as follows. After 2 g of sodium citrate and 0.5 ml of internal standard solution (Ni 6 mg/ml, Rb 25 mg/ml) are added to 10 ml of the extract, 80 μl of the mixture solution is dropped on a filter paper (Toyo No.7), followed by drying with hot wind using a hair dryer. Calibration curves are prepared from solutions which have similar reagent composition to that of the extracts. Reproducibility (C. V.%) of this method is 2.7 to 5.1 and 0.6 to 2.0 at the levels of 20 to 50 ppm and 50 to 200 ppm, respectively. Lower limit of determination is about 10 ppm for each element in the extracts. The results fro soil samples by this method were in good agreement with those obtained by spectrophotometry (Fe and Si) or graphite furnace atomic absorption spectrophotometry (Al).

View full abstract

(1) Grain yield of wheat plant consists of several yield components. Correlation between these yield components and the amount of nitrogen absorbed by wheat plant at each growth stage was investigated. (2) The amount of nitrogen absorbed by wheat plant at the maximum tiller number stage was closely related to the number of panicles per unit area and the number of spikelets per unit area. And there was a high positive correlation between the amount of nitrogen absorbed at the panicle formation stage and the number of spikelets per unit area, and also between the amount of nitrogen absorbed at the maturing stage and the grain yields per unit area. (3) The amount of nitrogen (F') taken up by wheat plants during the ripening periods were closely related to the grain yield (J') and to the leaf area index (y) at the heading stage. These correlations were shown as follows : F'=0.0221 J'-1.15y-1.29 (4) From these results, the optimum amount of nitrogen to be absorbed by wheat at each growth stage was determined. It is estimated to be 2.4~3.0 kg/10a at the panicle formation stage, 6.5~7.5 kg/10a at the maximum tiller number stage, 9~10.5 kg/10a at the heading stage, and 13~14 kg/10 a at the maturing stage.

View full abstract

[in Japanese]

View full abstract

Yacon (Polymnia sonchifolia or P. edulis), a root crop native to the Andean Highlands, was introduced into Japan via New Zealand in 1985. the chemical compositions of yacon were determined and the following results were obtained. 1) Compared with the tubers such as potato, taro, Jerusalem artichoke, and Japanese yam, yacon has high moisture, low nitrogen, phosphorus and intermediate iron, and high calcium contents. 2) Free sugars in yacon were only fructose, glucose, and sucrose. These three sugars amounted to 29% of the total dry weight. 3) Twenty-one free nitrogenous compounds (amino acids, and amides) were detected. The nitrogen content of asparagine, glutamine, proline, proline, and arginine accounted for 87% of the nitrogen in the 21free nitrogenous compounds. Nitrogen derived from the 21 free nitrogenous compounds reached about 65% of total nitrogen. 4) The hydrolysate of the polysaccharide fraction contained nearly the same mole of glucose and fructose, suggesting that polysaccharides other than inulin should exist in yacon.

View full abstract

Change of chemical and physical soil properties and rice plant's nitrogen-uptake patterns were investigated by field experiment in Hachirogata reclaimed fields. The results obtained are summarized as follows : 1) The oxidized soil layer of rotated paddy fields was thicker than that of continuously rice-cultivated paddy fields. And, the thickness of the oxidized layer decreased by 10 cm each year in paddy fields which were converted from the state of upland fields. At the subsoil in rotated paddy fields, soil structure developed and gaseous phase ratio increased. 2) In rotated paddy fields, root of rice plant extended more deeply and this activity was higher than that in paddy fields. 3) The 2nd year of wetland cultivation after upland use, the amount of absorbed nitrogen in rotated paddy fields by rice plants was more than that in paddy fields. Particularly, the amount of absorbed nitrogen n rotated paddy fields was large at the panicle formation stage and the harvest stage. The recovery rates of basal application were 37.5% in rotated paddy fields and 21.3% in paddy fields. 4) There is a close relationship between the number of spikelets per unit area and the yield of rice. In rotated paddy fields, the increase in rice yield approached a plateau when the number of spikelets exceeded 45,000/m^2. In paddy fields, the increase in rice yield approached a plateau when the number of spikelets exceeded 38,000/m^2. In rotated paddy fields, the percentage decrease of ripened grains was lower than in paddy fields. It is concluded that productivity of rice plants can be enhanced by paddy-upland rotation management in Hachirogata reclaimed fields.

View full abstract

The soil amended with nitrate was incubated for 24 hr by the method previously reported. Effects of organic compounds on NO_3 metabolism and related biochemical reactions in the soil were examined. It was found that the effects widely fluctuated according to both the kind and the amount of added organic compounds. On the basis of changes in the amount of CO_2 and N_2O production with increasing amount of the added organic compounds, various organic compounds were classified into the following 5 groups. 1) Glucose, sucrose, etc.: They were converted quickly and completely into CO_2 and strengthened reduced state of the soil at any level of their addition. Denitrification was enhanced only when their addition was small and was taken over by dissimilatory reduction of NO_3 into NH_3 when their addition became large. 2) Fumarate, lactate, etc.: When their addition was large, their conversion into CO_2 and enhancement of reduced state of the soil were somewhat retarded. Denitrification was not taken over by dissimilatory reduction of NO_3 into NH_3 even when a large amount of these compounds was added to the soil. 3) Xylitol, glycerol, etc.: They were not good substrates for any biochemical reaction. 4) Methanol, leucine, etc.: They were not utilized for any biochemical reaction. 5) Formate, acetate, etc.: They suppressed almost all the biochemical reactions. This was especially remarkable when their addition was large.

View full abstract

Fracional factorial experiment using 8 lysimeters was applied to compare the effects of four operational factors in rice culture on the nitrogen outflow and balance (input by irrigation-outflow). Four factors and the two levels allocated to each factor are as follows : irrigation flow rate (10 and 20 mm/day) ; nitrogen concentration in irrigation water (+0 and +20 mg/l) ; phosphorus concentration (+0.0 and +2.0 mg/l) ; soil condition (fertilized in the past three years, not fertilized before). The lysimeters had little volume of percolated flow. The irrigation period was divided into 4 sub-period by their characteristics observed in the factorial effects on nitrogen outflow. Period I : high nitrogen concentration mainly affected positively, and in this particular level high flow rate had much outflow. Period II : high N concentration increased outflow significantly. Perion III : high flow rate, high N concentration, and non-fertilized soil increased outflow. Period IV : the most significant factor on increasing outflow was high flow rate. In no-irrigation period, nitrogen outflow was free from all factorial effects. Throughout those periods, no effects of P were observed. From the viewpoint of effects on nitrogen balance, in Periods I and II the high N concentration affected positively. Period III : high flow rate, high N concentration, and fertilized soil increased balance. Period IV : high N concentration and high flow rate increased balance. Throughout the irrigation period, effects by P were not significant. The conditions which increased the balance (removal), increased the crop. The conditions which promote the balance contradicted the conditions for decreasing outflow in many periods.

View full abstract

Soils reclaimed for 7-10 years were surveyed at Yasugi area of Lake Nakaumi to investigate the microbiological aspect of the forming process of acid sulfate soils. Contents of water-soluble (WS) Na^+ and Cl^- gradually increased with depth, indicating that remnant of sea water was being removed with percolating water due to rainfall. On the contrary, contents of WS Ca^<2+> and SO_4^<2+> widely fluctuated in the profile. This was probably caused by dissolution of shell with sulfuric acid formed by oxidation of pyrite. Soil pH was low in the upper oxidized layers in the profile while it remained about 7 in the lower reduced layers. The results demonstrated that oxidation was proceeding from the top to the bottom of the profile. It was found that the number of Thiobacillus ferrooxidans became large in parallel with lowering of soil pH. The number of T. thiooxidans reached a maximum at a shallower layer than that of T. ferrooxidans. This fact suggested that pyrite was oxidized at first by T. thiooxidans and then by T. ferrooxidans : Microbial succession from T. thiooxidans to T. ferrooxidans was going on during pyrite oxidation in the reclaimed soils.

View full abstract