Effects of variable rate fertiliser application on selected macronutrients leaching from the ploughed layer

The changes in total phosphorus (P) accumulation in the plow layer and in the contents of several P compounds in an upland Andosol with time and the effects of these changes on biomass production at the field level were investigated in relation to the continuous application of farmyard manure and compost (referred to as “farmyard manure”) and inorganic P for 9 y. 1) Inorganic P applied continuously without farmyard manure accumulated only in the plow layer of the upland Andosol, whereas the combined application of inorganic P and farmyard manure P led to the leaching below the plow layer, with a constant level (3.3–3.5 g kg-1) of P accumulation in the plow layer within several decades. In order to reach a constant P accumulation level, higher application of P shortened the time required for the accumulation. 2) Bray No. 2-P value in the plow layer increased with time and tended to become maximum only under the application of both inorganic P and farmyard manure. 3) Aluminum (AI) bound-P (AI-P) fraction in the plow layer of the Andosol increased continuously and quadratically with the cultivation, along with an accelerated decrease in the amount of iron bound-P (Fe-P) and residual-P fractions (Res-P) during the 9-y period. 4) Continuous application of farmyard manure accelerated the decrease in the organic P (Org-P) fraction, presumably due to promoting microbial activity in the plow layer. 5) During the 9-y period, differences in crop growth with and without continuous application of P became attenuated, suggesting that the availability of accumulated P in the plow layer of the Andosol farm field before the experiment increased for the subsequent crop cultivation. Continuous increase in the AI-P fraction with time was closely correlated with the increase in P availability of accumulated P for crop growth.

Improving poor physical structural components has been gaining increasing recognition for its role in enhancing soil fertility. This study was conducted to identify the key physical structural barriers for soil fertility and their effects on crop productivity in Aquic Inceptisol. Based on the strip sampling in Fengqiu County, arable soils from 0–0.40 m profile pits were collected to determine the physical structural components including plough layer thickness, textural composition, soil aggregation and bulk density, as well as stocks of soil organic matter (SOM), total nitrogen (TN) and total phosphorus (TP). The grain yields of wheat and maize and amounts of fertilizer applications were also investigated. The tested soil was dominated by a plough layer of 0.15–0.18 m and sandy loam texture, which constituted 50% and 59%, respectively, of the studied profile pits. Compared to the soil with < 0.15 m plough layer, the bulk density was 4–11% lower in the plough layer and 4–12% lower in subsoil with increasing the thickness of plough layer. The soil with ≥ 0.15 m plough layer had over 21-fold macroaggregation at the expense of microaggregation, whereas the high content of sand particle in soil restrained macroaggregation. Increasing the plough layer thickness averagely improved the stocks by 176% in SOM, 153% in TN and 59% in TP at the 0–0.40 m depth. Soil macroaggregation was also significantly positively correlated with these nutrient accumulations. The factor analysis revealed that soil fertility was significantly influenced by the plough layer thickness and soil texture. The soil with 0.20–0.25 m plough layer and loam clay texture displayed the highest integrated fertility index and consequently, was beneficial to increasing the grain yields of wheat and maize and nutrient use efficiency from applied N fertilizer in the study area. These results would be informative to improve soil fertility and then crop productivity during a long-term cultivation.

Legume-based cropping systems could help to increase crop productivity and soil organic matter levels, thereby enhancing soil quality, as well as having the additional benefit of sequestering atmospheric C. To evaluate the effects of 35 yr of maize monoculture and legume-based cropping on soil C levels and residue retention, we measured organic C and 13C natural abundance in soils under: fertilized and unfertilized maize (Zea mays L.), both in monoculture and legume-based [maize-oat (Avena sativa L.)-alfalfa (Medicago sativa L.)-alfalfa] rotations; fertilized and unfertilized systems of continuous grass (Poa pratensis L.); and under forest. Solid state 13C nuclear magnetic resonance (NMR) was used to chemically characterize the organic matter in plant residues and soils. Soils (70-cm depth) under maize cropping had about 30-40% less C, and those under continuous grass had about 16% less C, than those under adjacent forest. Qualitative differences in crop residues were important in these systems, because quantitative differences in net primary productivity and C inputs in the different agroecosystems did not account for observed differences in total soil C. Cropping sequence (i.e., rotation or monoculture) had a greater effect on soil C levels than application of fertilizer. The difference in soil C levels between rotation and monoculture maize systems was about 20 Mg C ha-1. The effects of fertilization on soil C were small (~6 Mg C ha-1), and differences were observed only in the monoculture system. The NMR results suggest that the chemical composition of organic matter was little affected by the nature of crop residues returned to the soil. The total quantity of maize-derived soil C was different in each system, because the quantity of maize residue returned to the soil was different; hence the maize-derived soil C ranged from 23 Mg ha-1 in the fertilized and 14 Mg ha-1 in the unfertilized monoculture soils (i.e., after 35 maize crops) to 6-7 Mg ha-1 in both the fertilized and unfertilized legume-based rotation soils (i.e., after eight maize crops). The proportion of maize residue C returned to the soil and retained as soil organic C (i.e., Mg maize-derived soil C/Mg maize residue) was about 14% for all maize cropping systems. The quantity of C3-C below the plow layer in legume-based rotation was 40% greater than that in monoculture and about the same as that under either continuous grass or forest. The soil organic matter below the plow layer in soil under the legume-based rotation appeared to be in a more biologically resistant form (i.e., higher aromatic C content) compared with that under monoculture. The retention of maize residue C as soil organic matter was four to five times greater below the plow layer than that within the plow layer. We conclude that residue quality plays a key role in increasing the retention of soil C in agroecosystems and that soils under legume-based rotation tend to be more “preservative” of residue C inputs, particularly from root inputs, than soils under monoculture. Key words: Soil carbon, 13C natural abundance, 13C nuclear magnetic resonance, maize cropping, legumes, root carbon

Assessing the effect of long-term crop cultivation on distribution of Cd in the root zone

Long-term effects of fertilization on the forms and availability of soil phosphorus in rice paddy

Variable rate fertilization is one of the core technologies of precision agriculture, and it is particularly important to develop a representative field sampling scheme with less workload. A grid sampling of 1 m × 1 m was conducted on a pomegranate garden of 414 m2 in Nanzhuang Town, Jianshui County, Honghe Hani and Yi Autonomous Prefecture, Yunnan Province, and set up 7 groups of sample point deletion schemes to study the reasonable sampling spacing of soil nutrients. Based on the grading standard of soil nutrients in plow layer, the distribution of soil nutrients was statistically analyzed by using classical statistical methods to reveal the spatial distribution variability of soil nutrients. We then utilized a geostatistical method to interpolate the soil nutrient to obtain the soil nutrient distribution map, and compared the soil nutrient distribution map of the deletion sampling scheme with the original sampling scheme A in shape and area. Results revealed that the deletion scheme E was the most consistent with the sampling results of the full coverage sampling scheme A, and the number of soil sampling could be reduced by half under the premise of meeting the requirements of precise fertilization. The field experiment showed that the variable rate fertilization could save 26%, 54% and 34% nitrogen, phosphorus and potassium fertilizer compared with the farmers’ conventional fertilization, the total yield of soft seed pomegranate increased by 41.52%, and the sugar content, sugar–acid ratio and vitamin C content of pomegranate grain increased by 11.79%, 51.26% and 31.59%. The results also provide support to determine sampling spacing, spatial variability of soil nutrients and variable rate fertilization in precision farming.

The changes in the organic P fractions and microbial activity related to P transformation in the plow layer of paddy soil with long-term fertilization were investigated, in relation to the continuous application of chemical fertilizers (NPK), straw-based compost (Compost), and chemical fertilizers and compost (NPK + Compost) for 31 years. Continuous fertilizer application and rice cultivation led to a continuous decrease in ratio of organic P to total P in the plow layer with the lapse of years. In particular, the combined application of chemical fertilizers and compost accelerated the decrease in the organic P fractions, presumably due to the promotion of microbial activity in the plow layer, even though a high amount of organic P was inputted by compost. In this paddy soil, moderately labile organic P (MLOP) was the main organic P compound, which accounted for 70-90% of organic P, and showed the same tendency as that of the total organic P fraction during the test, irrespective of the treatments. Microbial P content and phosphatase activity, which were determined in the fresh soil collected in April 2003, were higher for the combination of chemical fertilizers and compost than for the single application of compost or chemical fertilizers, and showed a strong correlation with the amount of plant available P. In conclusion, the combined application of chemical fertilizers and compost could be an effective method to increase the plant availability of P in soils by promoting microbial activity.

The influence of four main tillage systems and four fertilization systems on biological reactivity of a plow layer of typical chernozemic soil under agrophytocenosis of five crops was investigated during four year research (2016–2019) of the stationary field grain row crop rotation. Loss of mass of flax linen in a plow layer of soil during two months of the study characterizing the intensity of cellulose-decomposing microorganisms under beard, beardless, differential and disc tillage made correspondingly 24.5; 22.7; 23.4 and 23.3 % – for soybeans; 16.3; 15.7; 15.9 and 16.2 % for winter wheat, 24.1; 22.8; 24.7 and 22.6 % – for sunflowers, 27.7; 24.1; 25.1 and 23.7 % – for spring barley, 21.9; 19.9; 22.4 and 19.0 % – for corn. Steady surface and beardless tillage strengthen the differentiation of a plow layer according to the intensity indices of flax linen decomposing while the beard one tillage decreases. The most heterogenic plow layer was observed under beardless tillage; it was a bit lower under disk tillage in a crop rotation. The intensity of flax linen decomposing on the top of a plow layer (0–10 cm) is the highest under beardless tillage and the lowest under beard tillage, while in the bottom (20–30 cm) of a plow layer an inverse relation can be observed. The intensity of carbon dioxide production by the soil under soybeans, winter wheat and spring barley is the highest under beard tillage and the lowest it is for soybeans under beardless and differential tillage, for winter wheat, sunflowers and spring barley under beardless tillage and for corn under disc tillage. For sunflowers and corn this index is higher under differential rather than under beard tillage in a crop rotation. The biological reactivity of a plow layer of a typical chornozemic soil increases as the fertilizers application rates increase. Crop rotation productivity is almost at the same level under beard and beard-beardless tillage in a crop rotation. Systematic beardless and surface disc tillage decreases this index significantly. Key words: soil, crop, crop rotation, tillage, fertilizers, flax linen, carbon dioxide, plow layer, heterogeneity.

The fractionation method of CHANG and JACKSON (2) was used for the analysing of the distribution of inorganic phosphorus in the topsoil and subsoil of twelve virgin and twelve cultivated soils from various parts of the country; two virgin soils and twenty cultivated soils were studied down to the depths of 60 cm or 70 cm, one even to 2 m. In the more intensively podsolized virgin soils the surface layers, particularly the A2-horizon, are very poor in all the forms of inorganic phosphorus while the enrichment layer will contain fairly high amounts of iron and aluminium bound phosphorus. The application of fertilizers and the other cultivation managements tend to accumulate aluminium and iron bound phosphorus in the plough layer. In some soils the minimum content of calcium bound phosphorus occurs in the layer below the plough layer, but an increase with the depth seems to be typical to it in all the non-Litorina soils, while the first two fractions usually decrease with the depth. In the Litorina soils the iron bound phosphorus is dominant in all the layers studied, but the content of reductant soluble phosphorus is low in these soils, and their content of calcium bound phosphorus is higher than the content of phosphorus bound by aluminium. The predominance of calcium phosphate in the subsoil and the rather low content of reductant soluble and occluded fractions indicate that the chemical weathering in most of our soils is not yet at an advanced stage. The test values determined were in accordance with the results of the fractionation and the estimation of ammonium oxalate soluble aluminium and iron.

Revisiting the involvement of ammonia oxidizers and denitrifiers in nitrous oxide emission from cropland soils

Abstracts of Nippon Dojo-Hiryogaku Zasshi

We evaluated an air-assisted strip seeder, developed by the Hokuriku research center, in farmers’ fields for four years. Plantings using the seeder had more panicles and a higher yield than those using a shooting hill-seeder. The early growth of planting using the air-assisted strip seeder was promoted by increasing the rate of seedling establishment because the seeding depth of plantings using the air-assisted strip seeder was shallower than that of plantings using the shooting hill-seeder. Tillering in this planting was also promoted, which boosted the yield, while simultaneous seeding with fertilizer application using the air-assisted strip seeder was also compared with conventional practice over two years in a field at the Hokuriku research center. During simultaneous seeding with fertilizer application, the rate of seedling establishment was equivalent to that in conventional practice. After seedling establishment, growth and yields in the simultaneous seeding with fertilizer application were equivalent to or exceeded those in conventional practice. Discipline: Crop production Additional key words: rice, seeding depth, seedling establishment, simultaneous seeding with fertilizer application, yield *Corresponding author: e-mail furuhata@ affrc.go.jp Received 26 February 2014; accepted 3 September 2014. Introduction The Hokuriku research center has developed an air-assisted strip seeder (Chosa et al. 2009b, Fig. 1.) The seeding base width of the seeder is 10 m (base width of one side is 5 m.) The blower of the seeder conveys seeds to the injection ports; powered by the PTO of the tractor and can deposit seeds in rows with interval spacing of 30 cm. The effective field capacity is 2 ha/h, assuming a base speed of 0.8 m s-1 and field efficiency of 70%. Because the seeder allows planting of large fields, its technology may promote labor-saving and low-cost technologies for direct seeding culture in the near future. In the mechanical transplanting method, a labor-saving technology for rice planting, involving the application of fertilizer or pesticide has already been developed, while in direct seeding culture, systematized techniques, such as seeding with fertilization or pesticide application, have also been introduced. In cultures using a shooting hill-seeder (Togashi et al. 2001a) and coated urea, technology simultaneously seeded with fertilizer application has been reported (Yoshinaga et al. 1997, Morita et al. 2005, Furuhata et al. 2006) In this technology, a decreased seedling emergence rate and delay in early growth was observed, compared with fertilizer incorporation into the plow layer (Furuhata et al. 2006) Furthermore, the runoff of nitrogen from the soil surface following basal dressing containing quick-acting Base width (one side 5m) Injection port Interrow space (0.3m) Spray pipe Electric motor cylinder Blower Feed roll Hopper 1980mm PTO transmission system Fig. 1. Schematic diagram of air-assisted strip seeder

N2O and NO emissions from an Andisol maize field were studied. The experimental treatments were incorporation of urea into the plough layer at 250 kg N ha–1 by two applications (UI250), band application of urea at a depth of 8 cm at 75 kg N ha–1 plus incorporation of urea into the plough layer at 75 kg N ha–1 (UB150), band application of polyolefin-coated urea at a depth of 5 cm at 150 kg N ha–1 (CB150), and a control (without N application). N2O fluxes from UI250 and UB150 peaked following the incorporation of supplementary fertilizer, and declined to the background level after that, while the N2O flux from CB150 was relatively low but remained at a constant level until shortly after harvest. Accordingly, the total N2O emissions during the whole cultivation period from the three treatments were not significantly different. The fertilizer-derived N2O-N losses from UI250, UB150 and CB150 were 0.15%, 0.27% and 0.28% of the applied N, respectively. However, it was suggested that, due to the low plant N recovery, UI250 had a significantly larger potential for indirect N2O emission than the other treatments. On the other hand, NO emissions from UI250 and UB150 were 12 times higher than that from CB150, and the fertilizer-derived NO-N losses from the three treatments were 0.16%, 0.27% and 0.026% of the applied N, respectively. Significant NO fluxes were detected only when urea-N fertilizer was surface-applied and incorporated into plough-layer soil.

Abstract. Variable rate (VR) fertilizer application has the potential to improve fertilizer use efficiency, reduce cost of production, and reduce environmental impacts. Two wild blueberry fields were selected in central Nova Scotia to examine the effect of VR fertilization on plant growth and fruit yield as compared to uniform fertilization. The field boundaries, weeds, and bare spots were mapped using real-time kinematics global positioning system (RTK-GPS). The variation in slope was mapped and management zones were delineated. Both fields were divided into two sections (VR and uniform). The GPS-guided prescription maps were generated in ArcGIS 9.3 for VR treatment sections. Three fertilization rates 200, 150, and 100 kg ha -1 were applied in Z1, Z2, and Z3, respectively, with a VR fertilizer spreader. The bare spots and weeds were mapped and classified as a separate class in the prescription maps and zero rate was allocated. For comparison, growers uniform fertilizer rate of 200 kg ha -1 was applied in uniform treatment section of both fields. Soil samples were taken from selected sampling points from each field before and after the fertilization, and soil properties and levels of soil nutrients were determined. Plant growth parameters and fruit yield were also collected from selected points in each field. Plants in uniform treatment sections were taller than VR treatment sections in low lying areas. Plant density, number of branches, and number of buds were non-significantly affected with fertilizer treatments. Plant growth parameters were significantly correlated with soil properties and soil nutrients in both VR and uniform treatments. The fruit yields in VR treatment sections were non-significantly different than uniform treatment section, although mean fruit yield was higher in VR section. VR fertilization saved 39% and 41% fertilizer in Fields 1 and 2, respectively. Results of this study suggested that VR fertilization could increase fruit yield and reduce fertilizer usage in wild blueberry fields.

Vol. 80 (2009) No. 2 (pp. 109–218 ) Original Papers Effect of surface application timing of crushed fibrous-bamboo and intertillage and ridging on N2 fixation and production of soybean (Glycine max L. Merr.) cv. Fukuyutaka Yuki NAKAGAWA*1, Takeo YAMAKAWA*2 and Yoshinori KAJIHARA*3 *1Grad. Sch. Bioresour. Bioenviron. Sci., Kyushu Univ., *2Dept. Plant Resour., Fac. Agric., Kyushu Univ., *3University Farm, School of Agric., Kyushu Univ. (Jpn. J. Soil Sci. Plant Nutr., 80, 109–115, 2009) Field experiments were performed on agricultural farm of Kyushu university to investigate the effect of surface application timing of crushed fibrous-bamboo (bamboo powder) and intertillage and ridging on N2 fixation and production of soybean (Glycine max L. Merr.) cv. Fukuyutaka in 2005 and 2006. Moso bamboo (Phyllostachys pubescens Mazel) of 3 to 4 age was crushed in fiber-shaped and used as a bamboo powder. Treatments in 2005 were non-multi, early stage mulching, and late stage mulching, which bamboo powder was not applied, applied just after sowing or applied just after the cultivating and ridging, respectively. Treatments without cultivating and ridging in 2006 were F0, F40 and F80, which 0, 40 and 80 kg 10a−1 of commercial chemical fertilizer (N; P2O5; K2O = 3.0; 10.0; 10.0%) without bamboo powder was applied on the surface of soil just after sowing, respectively and M0, M40 and M80, which 0, 40 and 80 kg 10a−1 of compound fertilizer was applied on the surface of bamboo powder spread on soil just after sowing, respectively. All treatments had three replicates. The results in 2005 indicated that the surface application of bamboo powder decreased the soybean yield regardless of the application timing. Therefore, it was concluded that the cultivation method with cultivating and ridging was not suitable for the soybean production under the application of bamboo powder. The results in 2006 indicated the surface application of bamboo powder without cultivating and ridging increased the soybean yield. Because, the surface application of bamboo powder improved the germination and facilitated the growth from late vegetative to flowering stage. Furthermore, this method increased N2 fixation (relative abundance of ureides). Key words: bamboo powder, N2 fixation, relative abundance of ureides, soybean, surface application. Phytoremediation of cadmium by rice in low-level of Cd contaminated paddy field Toshimitsu HONMA*1,2, Hirotomo OHBA*1, Ayako KANEKO*1, Takashi HOSHINO*1, Masaharu MURAKAMI*3 and Takuji OHYAMA*2,4 *1Niigata Agric. Res. Inst., *2Graduate School. Sci. and Tech., Niigata Univ., *3Natl. Inst. Agro-Environ. Sci., 4Facul. Agric. Niigata Univ. (Jpn. J. Soil Sci. Plant Nutr., 80, 116–122, 2009) Phytoremediation using hyperaccumulator wild plants has been proposed as a promising, environmentally-friendly, low-cost technology for decontaminating toxic metals from soil. However, it may be difficult to use hyperaccumulator wild plants for practical phytoremediation of Cd-contaminated paddy fields because of their several drawbacks. Several rice varieties that accumulate high-Cd in their shoots have been found. To select rice variety practicable for phytoremediation of low-Cd-contaminated paddy field, we examined the decrease effect of Cd concentration in soil and brown rice of food rice variety by phytoremediation using six rice varieties. Six rice varieties (Kusayutaka, LAC 23, Milyang 23, Habataki, Moretsu, and IR 8) were planted for 3 years in Andosol, in which plow layer contained 0.44–0.50 mg Cd kg−1 extracted with 0.1 mol L−1 HCl (1:5 w/v). The order of the shoot Cd uptakes by these rice varieties was as follows: Kusayutaka < LAC 23 < Milyang 23 < Habataki < Moretsu < IR 8. IR 8 absorbed 158 g Cd ha−1 in its shoot from soil by 3-year phytoremediation. Soil Cd concentration in the IR 8 plot has been decreased from 0.48 mg Cd kg−1 to 0.33 mg Cd kg−1. Cd concentrations in brown rice of food rice variety (Koshihikahi) grown after the phytoremediation by IR 8, Habataki and Moretsu were lower than those by Kusayutaka and LAC 23. Judging from these results, we conclude that IR 8 is the most promising in the six varieties for phytoremediation of Cd from paddy fields contaminated with relatively low Cd concentration. Key words: cadmium, paddy rice, phytoremediation. The influence of no-tilled direct seeding cultivation on greenhouse gas emissions from rice paddy fields in Okayama, Western Japan 5. Annual emission of CH4, N2O and CO2 from rice paddy fields under different cultivation methods and carbon sequestration into paddy soils Eiji ISHIBASHI*1, Syogo YAMAMOTO*1, Naohiko AKAI*1, Toru IWATA*2 and Haruo TSURUTA*3 *1Okayama Pref. Gen. Agric. Cent., *2Faculty of Environ. Sci. and Tecnol. , Okayama Univ., *3Natl. Inst. Agro-Environ. Sci., Present address: Cent. for Climate Sys. Res., Univ. of Tokyo (Jpn. J. Soil Sci. Plant Nutr., 80, 123–135, 2009) In order to clarify any difference in the emission of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2), from two rice paddy fields under the continuation of no-tilled direct seeding cultivation (ND), two rice paddy fields under the conventional tilled transplanting cultivation (TT), and one rice paddy field under the tilled direct seeding cultivation (TD), we measured CH4, N2O and CO2 fluxes from these fields with gray lowland paddy soils in Sanyoh of Okayama Prefectural General Agriculture Center, by using a closed chamber method for 2–5 years (1998–2002). We estimated the Net Ecosystem CO2 Exchange (NEE) during rice-growing seasons by using a model based on the eddy covariance flux measurement made at a rice paddy field in Hachihama of Okayama University, a 23 km-distance from Sanyoh. Consequently, the following results were obtained. 1) A clear trade-off relationship was shown between CH4 and N2O fluxes in all the rice paddy fields. 2) The sum of annual CO2 equivalent emission of CH4 and N2O was a little bit higher in ND than in TT but not significantly different between ND and TT, possibly due to the long-term continuation of ND, although the emission of CH4 was much lower in ND than in TT during a few or several years after TT was converted to ND. 3) The averaged annual emission ratio of N2O to the sum of CH4 and N2O on the CO2 equivalent basis was 9.0%, 7.3%, and 1.8% in ND, TD and TT, respectively. The highest ratio in ND was caused by sporadic enhancements of N2O flux in fallow seasons due to an organic matter layer only formed on the surface soil of ND. 4) As a result, the N fertilizer-induced emission factor of N2O in a three-year average was 0.48% and 2.5% in TT and ND, respectively. 5) During fallow and no-flooded seasons, the CO2 flux from the surface soil to the atmosphere was higher in ND than in TT. An annual NEE in TD was estimated to be -294 and -311 g CO2 m−2 y−1 in 1998 and 1999, respectively. 6) The organic matter layer formed on topsoil increased with the continuation of ND , and the carbon sequestration rate to the surface soil was 86.2 g C m−2 y−1, equal to about 30% of the total annual CO2 equivalent emission rate of CH4 and N2O. 7) According to the carbon neutral principle, the annual net CO2 emission in ND was -268 g CO2 m−2 y−1 by adding the CO2 emission through the slow decomposition of soil organic matter to the carbon sequestration rate. 8) Hence, the total CO2 equivalent greenhouse gas emission (the sum of CH4, N2O, and CO2) in ND was 811 and 648 g CO2 m−2 y−1 in 1998 and 1999, respectively, and which were lower by 20% than those in TT, mainly due to carbon sequestration to soils in ND. 9) The conversion to TD or TT from ND with the continuation for 8 years, by incorporating the surface organic matter into the plowed layer, did not show any increase in the emission of CH4 or N2O during the following two years. 10) A possible and effective option for mitigation of greenhouse gas emissions in ND is that ND fields should be converted to TT or TD fields after the continuation of ND for 4–5 years. Key words: paddy soil, no-tilled direct seeding, methane, nitrous oxide, rice straw. Effectiveness of silica application at the panicle formation stage on the rice production Shizuka MORI1 and Hiroshi FUJII2 1Yamagata General Agric. Res. Cent., Dept. of Agro-Prod. Sci., Shonai Branch. 2Yamagata Univ. (Jpn. J. Soil Sci. Plant Nutr., 80, 136–142, 2009) The effects of silica application on the yield and quality of rice were compared among the following plots: (A) a new silicate fertilizer A was applied at the panicle formation stage at 12 g m−2, (B) a new silicate fertilizer B was applied at the panicle formation stage at 12 g m−2, (C) a conventional silicate fertilizer was applied before transplanting as a basal fertilizer at 36 g m−2, and (N) no silicate fertilizer was applied. The results obtained were as follows: 1. The relative yields at the experimental plots A, B, C and N were 106, 104, 104, and 100, respectively. The effectiveness of applied silicate ((yield at A, B, or C - yield at N) / the amount of Si applied) for A, B, and C were 2.58, 2.17 and 0.67 g m−2, respectably. In addition, higher cost performances were achieved in A and B than in C. 2. The numbers of grains were as follows: 30,400 grains m−2 for C > 30,100 for A and B > 28,900 for N. On the other hand, no significant difference was found in the 1,000-grain weight and the percentage of ripened grains among those experimental plots. 3. The amounts of Si in the leaves plus stems were as follow: 65.0 for A and B (110) >63.0 g m−2 for C (107) > 59.3 for N(100). The amount of Si in the grains were as follows: 35.3 g m−2 for C (116) > 33.2 for A and B (109) > 30.4 for N (100). This fact indicates that the top-dressed Si was more effectively used by the rice plant than the basal Si. 4. Total amount of N acquisition and the recovery rate of top-dressed N by the rice plants were higher in Si-applied plots than in non-Si-applied plot. It is likely that the application of Si enhances the N acquisition, resulting in increase of the number of grains. Key words: nitrogen, rice yield, rice plant, silicic acid, panicle formation stage. Time course transition of soil solution composition and its cation balance during vegetable cultivation using salt-concentrated compost (1)— In the case of mini tomato cultivation - Munehiro EBATO1, 2 and Mitsue KURIBARA3 1National Institute of Livestock and Grassland Science, Nasu Research Station, 2Present address: National Institute of Livestock and Grassland Science, Miyota Research Station, 3Livestock Industry Research Center, Fukushima Agricultural Technology Center (Jpn. J. Soil Sci. Plant Nutr., 80, 143–151, 2009) Recently, Japan has placed a legal restriction on the stacking of livestock manure in the fields owned by livestock farmers. As a result, compost containing a large amount of sodium and potassium (salt-concentrated compost), has been made from the manure. Due to the high amount of salt, it is difficult to determine the suitable amount of salt-concentrated compost to use for vegetable cultivation in the field. This study aimed to clarify the effects of salt-concentrated compost on mini tomato (Solanum lycopersicum) growth and on soil by investigating the time course transition of soil solution composition and its cation balance. Mini tomatoes were cultivated in pots filled with an Andosol and a Brown lowland soil (Fluvisol) applied with chemical fertilizer, normal compost or salt-concentrated compost. The concentration of soil solution transited at a low level after normal compost application. However, the concentration of soil solutions increased in accordance with the amount of salt-concentrated compost applied, and was maintained at a high level during mini tomato cultivation. The application of salt-concentrated compost to the Andosol caused a blossom-end rot disease to the mini-tomato fruits. Blossom-end rot is known as a response to calcium deficiency. Since the application of the salt-concentrated compost drastically increased the concentration of potassium and sodium in the soil solution, it was suggested that the relative ratio of calcium to monovalent cations was a key factor causing the symptom. By introducing a new index for the activity ratio for potassium plus sodium, i.e. ARK+Na, composition of cations in the soil solution could be evaluated quantitatively. Based on the analyses using ARK+Na, it was found that blossom-end rot occurred when ARK+Na value became too low and exceeded some level (-0.1 in the present case) while mini tomato fruit was constituted at the first branch. In the case that the amount of salt-concentrated compost applied to the Andosol was reduced to be 20 Mg ha−1 or less, the values of ARK+Na were higher than the value when blossom-end rot had occurred, and the blossom-end rot did not occur. Key words: ARK+Na, blossom-end rot, mini tomato, salt-concentrated compost, soil solution composition. Notes Effect of combined application with 15N-labeled ammonium sulfate and swine or poultry manure compost on mineralization of compost nitrogen Masahiko KATOH*, Yasuhito HAYASHI* and Hiromasa MORIKUNI* *JA ZEN-NOH R&D Cent. (Jpn. J. Soil Sci. Plant Nutr., 80, 152–156, 2009) A new protocol to identify soil ciliates through movie data and DNA extracted from one soil ciliate Chikako SHIMAYA* and Tomoyoshi HASHIMOTO* *National Agricultural Research Center for Kyusyu Okinawa Region (Jpn. J. Soil Sci. Plant Nutr., 80, 157–160, 2009) Bacterial direct count with the wash-sonic method in water dispersed small soil particles Nobuyuki KOHNO*1,2 and Tomoyoshi HASHIMOTO*1 *1National Agricultural Research Center for Kyusyu Okinawa Region, *2Present address: Institute for Environmental Studies, Fukuyoshi Engineering Co. Ltd., Hiroshima 732–0045, Japan. (Jpn. J. Soil Sci. Plant Nutr., 80, 161–164, 2009) Characteristic of chicken manure compost produced in Mie Prefecture Keiichi MURAKAMI*1, Sachiko KOSAKA*1,2, Takayuki FUJIWARA*1,3 and Masayuki HARA*1 *1Mie Prefecture Agricultural Research Institute, Present addresses: *2Iga Agriculture Forestry Commerce Industry and Environment Office, *3Mie Prefecture Industrial Research Institute (Jpn. J. Soil Sci. Plant Nutr., 80, 165–167, 2009) Effect of composition of sewage sludge incinerated ash mixing rate of alkali on phosphate fertilizer efficiency of fused sludge ash compound fertilizers Shuko KUBOYAMA*1, Yoshiko KUBOTA*1, Takashi KOMATSU*2 and Itsuo GOTO*1 *1Tokyo University of Agriculture, *2SANKI (Jpn. J. Soil Sci. Plant Nutr., 80, 168–172, 2009) Current Topics Estimation of available nitrogen content in upland soil by a boiling decoction method Atsushi YAMAKI Chiba prefectural agriculture and forestry research center (Jpn. J. Soil Sci. Plant Nutr., 80, 173–176, 2009) Decision support system for application of manure and fertilizer to grassland and forage corn field based on nutrient recycling Teruo MATSUNAKA*1, Toshiya SAIGUSA*2, Hiroyuki SASAKI*3, Takehiko MATSUMOTO*4, Kazunori KOHYAMA*5, Akihiro FURUDATE*6 and Shu MIURA*7 *Rakuno Gakuen Univ., *2Hokkaido Konsen Agric. Exp. Stn., *3National Institute of Livestock and Grassland Science, *4Hokkaido Central Agric. Exp. Stn., *5National Institute of Livestock and Grassland Science (present, National Institute for Agro-Environmental Sciences), *6Hokkaido Kamikawa Agric. Exp. Stn. Tenpoku Branch, *7Hokkaido Kamikawa Agric. Exp. Stn. Tenpoku Branch (present, Hokkaido Kitami Agric. Exp. Stn.) (Jpn. J. Soil Sci. Plant Nutr., 80, 177–182, 2009) Lecture Recent development in the plant nutritional diagnosis by non-destructive methods: 3. Utilization of diagnosis of crop plant using a chlorophyll meter for forage crop productions Yoshihito SUNAGA National Institute of Livestock and Grassland Science (Jpn. J. Soil Sci. Plant Nutr., 80, 183–187, 2009) Nutritional diagnosis technique of apple tree using the image analysis Yoshinori TAKAHASHI*1,2 *1Iwate Agric. Res. Cent., *2Present address: Ministry of Agriculture, Forestry and Fisheries General Food Policy Bureau (Jpn. J. Soil Sci. Plant Nutr., 80, 188–191, 2009) Miscellaneous Food and Health: The necessity of minerals and fatty acids Toshihiro KATO*1, Harumi OKUYAMA*2, Sinkan TOKUDOME*3, Hisao ODA*4, Kazuhiko WATANABE*5, Makoto KIMURA*6 *1Aichi Agricultural Research Center, *2Kinjo Univ., *3Nagoya City University Graduate School of Medical Sciences and Medical School, *4Eisai Seikaken Co.,Ltd., *5Tokyo University of Agriculture, 6Nagoya University Graduate School of Bioagricultural Sciences (Jpn. J. Soil Sci. Plant Nutr., 80, 192–200, 2009) Studies of protozan and nematode dynamics and diversity for soil quality evaluation Tomoyoshi HASHIMOTO*1, Susumu ASAKAWA*2, Jun MURASE*2, Satoshi SHIMANO*3, Tadao TAKAHASHI*4, Hiroaki OKADA*5, Erika SATO*6, Koki TOYOTA*6 *1Natl. Agri. Res. Cent. Kyushu Okinawa Reg., *2Grad. Sch. Bioagric. Sci., Nagoya Univ., *3Miyagi Univ. Educ., *4Nishikyushu Univ., *5Natl. Inst. Agro-Environ. Sci., 6Tokyo Univ. Agri. Technol. (Jpn. J. Soil Sci. Plant Nutr., 80, 201–206, 2009) Challenges of soil sciences to climate change-international meetings in Beijing and Nanjing, China, October 2008 Kazuyuki INUBUSHI Graduate school of Horticulture, Chiba Univ. (Jpn. J. Soil Sci. Plant Nutr., 80, 207, 2009)