In sugar beet cultivation, fully automatic transplanting by a transplanter into "chain pots" is used to reduce labor. Each chain pot is made from two-ply sheets of decomposition-resistant paper joined together with water-resistant adhesive. Individual pots can be linked to form a "chain" of paper pots, which can be fed continuously into the transplanter. In order to enable both continuous feeding into the transplanter and plant growth for 45 days, the paper from which the pot is made needs to be strong. For this purpose, we have developed a chemically modified paper treated with dimethyloldihydroxyethyleneurea (DMDHEU), which is capable of cross-linking wood polysaccharide. To examine the effects on the growth and yield of sugar beet, we compared seedlings raised in pots made of our chemically modified paper with those raised in previously used synthetic fiber blend pots. The results were as follows: 1) Our chemically modified paper pots, unlike previous synthetic fiber blend pots, prevented microorganism pests from damaging the beet roots, both in the pot and in the soil. The inhibition of microbial growth increased seedling growth at the time of transplanting and led to better growth in mid-June after transplanting. 2) At harvest, however, no significant differences in root weight or sugar yield were found between the plants raised in the pots made of our chemically modified paper and previous synthetic fiber blends. Plants grew better initially in our paper pots soon after transplanting. The growth differential, however, decreased after mid-June (when root pressure tore the paper pots). At the time of harvest there was no difference in the yield between the pot types.

View full abstract

We studied how addition of granulated higher fatty acids (GHFA) would affect nitrate and ammonium leaching out of pots planted with tea plants. In Wagner pots (1/5000a, height 30cm) filled with tea field soil, we mixed GHFA into the upper soil layer (depth 10cm) at 0 (control, without GHFA), 0.5, 1, or 5% (0, 10, 20, 100g per pot), and cultivated tea plants (Camellia sinensis (L.) var. sinensis) for approximately one month. We measured the leaching of nitrate and ammonium from the pots over this period by monitoring ^<15>N-labeled potassium nitrate or ammonium sulfate that had been applied to the pots. We found the following: 1) GHFA applied at 5% reduced leaching of nitrate in drainage water by 40% and ammonium concentrations in drainage water by 20%, compared to control pots. 2) At the end of treatments, the content of inorganic nitrogen in the upper soil layer with GHFA was higher than that of the soil without GHFA. In addition, the content of ^<15>N retained in soil was also higher in GHFA treatment. These results suggest that the decline of leached nitrogen from pots with GHFA was caused mainly by immobilization of nitrogen rather than denitrification. 3) The growth of tea plants cultured in the pots with GHFA applied at 5% was not suppressed, but was vigorous compared to that of control pots. The content of total nitrogen of tea plants also increased in the 5% GHFA treatment. Therefore, we suggest that the application of GHFA up to 5% is useful to increase nitrogen uptake, stimulate tea plant growth, and reduce nitrogen leaching by retaining it in the soil.

View full abstract

We studied three aspects of animal manure: first, whether the nitrogen (N) decomposition pattern of animal manure could be estimated by a decomposition model (Hayami, 1985); second, the relationship between the ratio of organic N extracted from manure using four different methods and the coefficients of the decomposition model; third, the effect on yield and N uptake in paddy fields by applying the amount of compost calculated with our model to predict the N decomposition pattern. To build our model, we examined N decomposition patterns of 13 different manure types (five from cattle, three from swine, and two from poultry, two from both cattle and swine, and one from cattle, swine and poultry; some manures included supplementary ingredients such as chaff, straw, saw dust, and wood chips) in paddy fields by burying unwoven cloth bags filled with manure in the field. Our results were the following: 1. After two months of burial (at about 1000℃ of cumulative air temperature), decomposition rates were highest in poultry manure, followed by swine and cattle manure. In addition, the decomposition rates of all manure tended to decrease when the cumulative air temperature exceeded about 1000℃, the inflection point. 2. We created a decomposition model where coefficients of the model were determined from decomposition patterns of the manure. D=eT^r (where D is N-decomposition rate (%); e is acceleration coefficient of N decomposition; T is cumulative air temperature×10^<-3>; and r is difficulty level coefficient of N decomposition). Decomposition patterns of N for all manure could be explained by the model with a determination coefficient of 0.93 or higher. In addition, since the inflection point was at cumulative air temperature of about 1000℃, where T=1, at that point, D and e became equal. Therefore, we suggest that the acceleration coefficient is equivalent to easily decomposable organic N at the inflection point. 3. The relationship between the acceleration coefficient and the difficulty level coefficient was well explained by the following equation: y=2.1x^<-0.77>. 4. The ratio of organic N extracted from the manures varied depending on the extraction method and the solutions used: 6-42% for extraction with phosphate buffer, 3-31% for extraction with diluted sulfuric acid, 18-48% for extraction with hot water, and 32-65% for extraction with an acidic detergent. 5. The correlation coefficient between the ratio of extracted N and the acceleration coefficient was highest (r=0.97) for extraction with a phosphate buffer: the ratio of the extracted N to the acceleration coefficient was about 1:1. Therefore, we suggest that extracting organic N with a phosphate buffer is a preferable method to estimate the ratio of easily decomposable N in paddy field soils. 6. Measured N decomposition patterns of the three different manures (cattle, swine, and poultry) were well explained by our predicted models. Root mean square errors between the measured N decomposition rate and the predicted rate were 2.4-2.7. 7. We applied our model to calculate the amount of N supply during the time between three manure applications and the full heading date of rice. We then calculated the amount of manure needed to equal the amount of N supply from chemical fertilizer. When the corresponding manure amount was added to the field, the rice yield and N uptake were slightly less than those of chemical fertilizer plots.

View full abstract

Japanese 'Fuji' apples are exported almost exclusively to the Taiwanese market, where they compete mainly with apples from South Korea and the USA. The objective of this study was to determine the geographical origin of 'Fuji' apples on the basis of their elemental composition. Concentrations of 10 elements (B, Mn, Fe, Cu, Zn, Sr, Ba, Ni, Ti, Al) were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) from the peduncles and seeds of 63 domestic samples originating from Japan and 40 foreign samples from the USA, South Korea and China. Because concentrations of these elements in the apple peduncles and seeds were higher than those in the rinds or sarcocarps, we determined that peduncles and seeds were more suitable parts for measuring the elemental concentrations to distinguish the geographical origins. By using the linear discriminant analysis results for 7 elements (B, Mn, Fe, Cu, Zn, Sr, Ba) measured either in the peduncles or in the seeds, we classified the origin of the apples (domestic or foreign) with 96.1% accuracy. By using canonical discriminant analysis results for all 10 elements of the peduncles and 8 elements of the seeds, we classified the origins of foreign apples (China, South Korea or the USA) with 97.5% accuracy. By using canonical discriminant analysis of the results for 7 elements of both the peduncles and the seeds, we classified the origins of apples found in the Taiwanese market (Japan, South-Korea, or the USA) with 98.9% accuracy. Based on these results, we attained a reliable determination method of the Japanese geographical origin of 'Fuji' apples.

View full abstract

This study was conducted to evaluate the effect of increasing soil pH on cadmium (Cd) uptake by soybean. We conducted our experiment in the Jinzu River basin in a low pH (around 5) soil in an upland field that was converted from paddy field and was slightly polluted with Cd. Base application was applied to some plots increasing the soil pH as high as 7; in the pH range above 6, the soybean seed Cd concentration decreased from around 0.5mg kg^<-1> to around 0.25mg kg^<-1>. The Cd concentration and accumulation in the shoots decreased linearly with increasing soil pH in the full bloom stage and the full seed stage. Therefore, soil pH amendment was effective in restricting Cd uptake in the early reproductive stage. The Cd concentration in the soil solution decreased exponentially with increasing soil pH; we attribute the reduced Cd uptake by soybean roots to the decreased Cd concentration in the soil solution. The soil pH amendment often increased the dry matter production, main stem length, and grain yield. However, there remains a possibility that grain yield was not as high as it could have been because of the rough weather conditions during the reproductive stage or manganese deficiency when pH was around 7. In conclusion, amending soil pH with base effectively restrained Cd uptake by soybean in a field slightly polluted with Cd.

View full abstract

We examined the impacts on water, air, and soil qualities of heavy application of anaerobically digested cattle slurry (ADS) to whole crop rice cultivation by using a lysimeter (1×1×0.5m). Four treatments were prepared in triplicate: A) chemical fertilizer (CF) was applied three times at 10g-Nm^<-2> each time (CF30), B) ADS was applied three times at 10g-Nm^<-2> each time (ADS30), C) ADS was applied seven times evenly with a total of 60g-Nm^<-2> (ADS60), D) ADS was applied six times in an increasing application pattern for a total of 60g-Nm^<-2> (ADSapt). Our findings were the following: 1) Rice growth was not inhibited by the ADS applications compared with that in CF30. With ADS application, the yield was high with biomass production over 1.9kg (dry basis) m^<-2>. 2) A total amount of N leaching was less than 4% of the N applied in all the treatment: the treatments. 3) More ammonia volatilized in the ADS treatments than in CF30; however, the ratio of soil ammonia volatilization to total N application was less in the ADS60 and ADSapt treatments than in the ADS treatments. 4) Methane emission was markedly higher in the ADS treatments than in CF30. With more ADS (ADS60 treatment) it increased to 1.5 to 1.7 times higher than in ADS30. Yet, methane emission was reduced by 10% in ADSapt treatment, compared with that of ADS60 in spite that both the treatments received the same amount of total ADS application. 5) There were no significant differences in the soil physico-chemical properties between before and after cultivation. In contrast, amounts of exchangeable K and Na in the soil after cultivation were higher with the ADS treatment than in the CF treatments. The same increasing trend was found in ADS60. 6) Applying ADS based on the growth stage of rice plant (ADSapt) was more environment-friendly and resulted in higher fertilization efficiency than even application of ADS during the growing period (ADS60).

View full abstract