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プロファイル土壌水分計PR2/6 は，対象土壌の破壊を最小限に抑えつつ，100cm 深のうち6 層の平均土壌水分量を測定できるが，土壌毎に校正式を得る必要がある．本稿では， 6 土壌に対する校正作業の結果に基づいて，出力値の誤差を解析し，①各センサーの出力値の時間的バラツキ・位置によるバラツキはともに小さいこと，②各センサーの出力値のバラツキよりもセンサー間のバラツキの方が大きいこと，③センサー個別の校正式を決定した場合に適合性が最も高くなるが，全センサーの平均出力値を用いて校正式を決定した場合や3 番目のセンサーの校正式をすべてのセンサーに使用した場合も高い適合性が得られること，④プローブ間のバラツキは小さく，1 本のプローブに対して得られた校正式は，他のプローブにも使用できること，が明らかになった, The PR2/6 moisture profile probe (Delta-T) allows measurement of the average soil moisture contents in each of six layers to a 100-cm depth with minimum soil disturbance, but it requires a calibration equation for each soil. In this study, we analyzed the device’s measurement errors based on calibration equations for six Japanese converted paddy soils. The variability among measurements by each sensor was so small, C.V.

We investigated two soil profiles 3-m deep in the Sambe Forest and determined some physico-chemical and biological properties of soils to describe the characteristics of deeper soil layers that were hard to reach. Deeper soil layers are expected to play important roles in the potential ecological services of forest ecosystems. One profile was made at the ridge part of a slope under a secondary forest. Another was made at the lower slope under a cedar plantation. Soil type was Cambisols at the ridge and Andisols at the lower slope. The two soil types are typical ones in the forest. Both soils reserved more than 1000 mm of water within a profile. Organic carbon stored in the soils was 20 kg m^ at the ridge and 39 kg m^ at the lower slope. Fine root was found even at the deepest layer and the biomass of fine roots was 1.3 kg m^ at the ridge and 0.8 kg m^ at the lower slope. Soil water distributed evenly from the top soil to the deepest layer. Soil organic carbon and fine root biomass concentrated mostly to the top soil. Deep soil water might contribute to the stability of stream discharge running through the forest and to water supply for the deep rooting trees during draught.

北海道大雪山系では融雪時期の早期化や土壌乾燥化などの影響で，乾燥化の指標種とされているチシマザサ（Sasa kurilensis，以下，ササ）やハイマツ（Pinus pumila）などの低木が分布域を拡大している。それと対応して，高山湿生植物群落の分布域が縮小し，高山植物の局所的な絶滅が危惧されている。本研究では北海道大雪山国立公園の五色ヶ原を解析モデル区とし，植生変動の定量化と変動のメカニズムを明らかにするために，現地調査，現地計測，航空機，及びマイクロ波衛星観測の手法を用いて，植生判別と植生変動地域の抽出，植生変動地域における地表面特性の抽出，植生変動地域における土壌水分の分布と季節変動の抽出，及びササ侵入危険地域の予測などを行った。特に土壌水分の季節変動の推定の研究では，植生密生地域において植物の下層にある土壌水分の季節変動の推定に初めて成功した。研究対象地では，ササの拡大が最も顕著な木道周辺で，1977年から2009年までの31年間で30％拡大していた。またハイマツも14％増加し，樹高生長も見られた。ササの増加地域は，斜面方位が主として東斜面であり，傾斜度が0-20度以下，日射量が高い（80-90 KWh/m^2）場所で選好性を示した。マイクロ波を用いた植生変動地域における土壌水分の季節変化は，ササ分布域では土壌水分の減少（乾燥化）が顕著に現れた。GISの解析により，アナログ空中写真とマイクロ波データを重ねあわせて解析することにより，植生変化と環境変動を詳細に把握することが可能となった。

陸面過程モデルSiBUCを用いた陸面オフライン計算によって，GSWP2の枠組みにおいて全球にわたる土壌水分分布が推定されている。本稿では，土壌水分の推定精度を検証した。GSMDBの土壌水分現地観測値との月平均値・年偏差間の相関係数を算出し，モデル推定値の季節変動・年々変動の精度評価を実施した。その結果，イリノイ・ロシア西部・華北平原で良好な精度が得られていることが明らかとなった。一方，乾燥・半乾燥地域を中心に，精度が十分でない領域が存在することが明らかとなった。次に，土壌水分の精度向上を目的とし，土壌水分の推定精度に寄与する要素や条件を明らかにするために，水収支解析を実施した。その結果，土壌水分に十分な年内変化が存在するか，降水と蒸発散の差が十分あるか，が重要となることが示された。, Integration of one-way uncoupled SiBUC (Simple Biosphere including Urban Canopy) land surface model has produced global soil moisture field under the framework of the 2nd Global Soil Wetness Project. Soil moisture estimation by SiBUC is evaluated against soil moisture observations derived from Global Soil Moisture Data Bank. Results show SiBUC reproduces reasonably inter-annual variability and seasonal cycle of soil moisture except a part of stations. What are the essential factors for reproducing seasonal cycle soil moisture? To answer this question, water balance components were analyzed. As a result, two typical regions were found: one region with high accuracy on soil moisture estimation is located where soil moisture has clear seasonal cycle because the seasonal cycle of precipitation is different from that of evapotranspiration, another region with low accuracy is located where precipitation are almost converted to evaporation.

application/pdf, 論文(Article)

資料番号: PA0810089000

GSWP2の枠組みにおける陸面過程モデルSiBUCの陸面オフライン計算によって全球土壌水分分布が推定されている。これらプロダクトの推定精度の検証を実施した。GSMDBの土壌水分現地観測値との月平均値・年偏差間の相関係数を算出し，モデル推定値の季節変動・年々変動の精度評価を実施した。イリノイ・ロシア西部・華北平原で良好な精度が得られていることが明らかとなった。一方，精度が十分でない領域が存在することが明らかとなったが，これら領域は内陸部の年降水量の少ない乾燥・半乾燥地域であった。, Integration of one-way uncoupled SiBUC (Simple Biosphere including Urban Canopy) land surface model has produced global soil moisture field under the framework of the 2nd Global Soil Wetness Project (GSWP2). One of advantages of GSWP2 products is the most accurate global land surface hydrological data set in available. Thus, these global products should be applied to land-atmosphere interaction study. To do this, it is important to understand spatial or temporal accuracy on calculated soil moisture field. Global soil moisture field calculated by SiBUC is compared with soil moisture observation data provided from Global Soil Moisture Data Bank. It is confirmed that estimated soil moisture has adequate accuracy on inter-seasonal or annual scale.

In semiarid areas of Mexico, lack of organic matter is a major constraint for production of corn and frijol beans, the main crops of the region. A multi-year experiment was carried out at the CENGUA Experiment Station, Guanajuato State, Mexico. Soil moisture was highest in the treatments with 100% or 67% of corn residues. Yields of frijol beans increased as the proportion of corn residues increased in all three years, but there was no significant difference between the treatment with all corn residues and the treatment with one-third reduction of corn residues in two of the three years. The harvest index was highest in the same two treatments with higher proportions of corn residues in the last years. These results suggest that corn residues can be reduced by one third in fertilization of corn-frijol bean systems while maintaining adequate frijol bean yields. This could assist in establishment of sustainable corn-frijol bean-cattle integrated agriculture in semi-arid areas of Mexico.

Ground cover plants are useful for the management of levee vegetation. In order to elucidate the effects of slope aspects on the growth of ground cover plants and their soil conservation abilities, 12 kinds of ground cover plants were grown on north- and south-facing slopes. Lysimachia nummularia L., Ajuga reptans L. and Potentilla verna L. died in summer on south-facing slope, and the regrowth of Arctotheca calendula Levyns. in spring was worse on north-facing slope. The dry weights of underground organs of Verbena tenera Spreng., Phyla nodiflora L. and Potentilla verna L. were greater on south-facing slope than on north-facing. Weed number of treatment area were few as the coverage of ground cover plants was high. The soil erosion from the slope where ground cover plants covered was few compared to bare slope. The amount of soil erosion from the slope was few as the coverage of ground cover plants was high.

本研究では，日本のような湿潤地域における短時間で局所的な降水に対して現実に起こりうる範囲の土壌水分量の変化が影響を与えうるかについて，非静力数値気象モデルを用いた数値実験によって検討した。具体的には，2001年8月15日に琵琶湖周辺で観測された対流性降水について，土壌水分量初期値を2001 年8 月に琵琶湖流域で観測された最も湿潤な状態と最も乾燥した状態に設定し，非静力学数値気象モデルを用いた数値実験を行った。その結果，現実に起こりうる範囲の土壌水分量の変化が湿潤な地域における短時間で局所的な対流性降水に影響を与えうることが示された。, In this study, the effect of soil moisture to convective precipitation in humid region is investigated by numerical simulations. Two numerical simulations are carried out in mountainous region around the Lake Biwa on 15th Aug. 2001 (during the intensified observation period of the Lake Biwa Project). One of them has the wettest soil moisture and the other has the driest soil moisture in Aug. 2001. It is found that realistic difference of soil moisture can affect convective precipitation in humid region.

本研究では、夏季の対流性降雨の発生に対する地表面加熱や土壌水分状態の重要性を調べることを目的として、2001 年8 月14 日と15 日の事例に関して琵琶湖周辺の山岳域を対象に6 つの数値実験が実行された。その結果、地表面条件（土地利用、サブグリッドの都市の効果）や土壌水分状態は非常に短期間の数値予報においても対流性降雨に影響を与えることが示された。, In this study, six numerical experiments are carried out in mountainous region around the Lake Biwa on 14th and 15th August in 2001. These experiments are intended to see the importance of surface heating and soil moisture status for the formation of convective rain in the summer time. It is found that landcover condition and soil moisture condition can affect the amount of convective rain even in a very short-term prediction.

モンゴル高原の広大な試験域において, 半乾燥地域の地下水涵養の実態を探るべく, 気象・水文モニタリングを複数点で実施した。2001年夏から2002年夏までのモニタリングデータ解析の結果, 夏季に集中的に降雨があり, それに応じて下方への水分移動が生じた。発散ゼロフラックス面(DZFP)は常時地表面薄層付近にあり, それより上方は蒸発散に, それより下方は地下水涵養に寄与している。しかしDZFPより下層の年間の土壌水分貯留量は非常に少なく, 降水量の数％であり, 蒸発散がほとんど占め, 地下水涵養は夏季に極くわずかであることが明らかとなった。, To grasp the real state of groundwater recharge in the large area of the semi-arid land, we carried out monitoring of meteorological and hydrological elements at several sites of the study area that was set up in the Mongolian plateau. The monitoring data analysis in 2001-2002 showed some interesting results to understand real states of downward soil water movement. The divergent zero flux plane (DZFP) occurred at the 10 cm depth from spring to summer in each site. Intensive downward soil water movement with rainfall event in late spring and early - mid summer in the zone below DZFP can be considered to contribute mostly the shallow groundwater recharge. However, the amount of the shallow groundwater recharge was estimated to be less than 10 % of the annual precipitation.

application/pdf, At present, a large number of methods are put into practical measurement of soil moisture. Among them, from view points of agricultural, engineering and environmental field survey, three methods are selected to compare respective availability for simple and quick measurement of soil moisture. They are microwave oven dry method, infrared drying method and glycerin extraction method. 8 specimens differing in physical properties are taken to the research, and analysis of time-moisture curves, estimated from experimental points of each drying process, shows the following results. 1. As microwave oven dry method is proven practically most convenient and inexpensive, the method is most suitable for simple and quick measurement of soil moisture. 2. Under the power source is unavailable condition, only glycerin extraction method is able to put to practical use. 3.Inlfrared drying method can be measured soil moisture with the most high accuracy among them.

微視的観点から粒径分布を有する球形粒子内のサクションと保水量推定のモデルを構築する. まず最初に, 粒子接合部においてリング水が独立して存在するとの仮定により, 2球間のサクションと保水量算定式の誘導がなされている. これらの関係は2球間の粒子の距離と粒径比の関数として表される. 次に, 一般の土壌に対し, サクションと保水量を求めるには, 任意の土粒子における配意数を決定しなければならない. 本論文では粒径分布と間隙率が既知であるとし, 配位数を推定する方法を提案している. 最後に本モデルと硅砂を用いた実験結果を比較検討することにより, リング水が独立して存在する低含水域において両者の傾向がよく一致し, その有用性が示された.

形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: PA1810079000

マルチ資材の種類による土壌物理性、地温、土壌水分量、作物の生長への影響を夏季，冬季について調べた。固相率・透水係数・硬度など土壌物理性においては，マルチ資材の影響は見られなかった。地温については、夏季において、黒ビニールは地温上昇効果、他のマルチ資材は地温低下効果を示した。冬季において、黒ビニール、わら、紙シートは地温上昇効果、古紙は地温低下効果を示した。土壌水分量は、すべてのマルチ資材で夏季・冬季いずれにおいても水分保持効果を示した。作物の生長については、夏季についてはマルチングの水分保持効果により、生長を促した。一方、冬季では、古紙マルチ区では地温低下により生長を阻害されたが、他の資材では、地温上昇効果により生長を促進した。, Impacts of mulciling on soil physics were tested in summer and winter seasons, using four materials, i. e. black vinyl sheet, paper sheet, straw and shredded paper. Field tests showed that there were few impacts on apparent gravity, permeability and soil hardness but very clear impacts on soil moisture and temperature which behavior depended on seasons and materials. It was investigated how physical circumstances acted on the soil physics.

本研究では、GAMEHUBEXのモデリング研究の一環として、気象庁数値予報モデル88年度版JsM88の陸面過程に、田中らが開発した陸面過程モデルsiBucを導入する。また、国土数値情報KS202とAARS植生分布図から土地利用面積率データを作成し、これを用いて1988年7月15日を対象としてJsM88siBuc結合モデルのテストランを行ない、SiBUCモデルの導入効果を検討する。, In this study, we have coupled land‐surface processes model (SiBUC) developed by authors into numerical weather prediction model (JSM: Japan Spectral Model) developed by JMA(Japan Mete‐orological Administration). We have made landuse fraction data from Japanese GIS (KS‐202) and AARS(Association for Asian Remote Sensing) world vegetation map. Preliminary test simulation was carried out by SiBUC‐J5M88 coupled model for 15th July in 1988. Although land surface flux shows much difference from original result, simulated rainfall is almost same. This result was brought by thestrong influence of SST and boundary conditions from global analysis data.

The rain-induced surface failure is a phenomenon under the action of the gravity force due to the interacting between geotechnical properties of the slope and the rainwater infiltration. For predicting accurately the time and places of rain induced slope failures, to make clear the behaviors of rainfall infiltration at 1-2 m thickness of in-situ slope is still the urgent problem. Therefore, a field monitoring of rainfall infiltration is being carried out at the natural Masado slopes where a debris flow was triggered during the event of June 29, 1999. The authors have already discussed in the past papers about field monitoring system and rain water infiltration processes on depths of 0.5m to 2.0m of those slopes. In this paper, newly added monitoring system to measure the change of pressure of soil moisture and moisture content at shallow part from the surface such as 0.1m- 0.3m will be introduced. And then, soil moisture behaviors on these shallow parts will be elucidated.

The rain-induced surface failure is a phenomenon under the action of the gravity force due to the interacting between geotechnical properties of the slope and the rainwater infiltration. For predicting accurately the time and places of rain induced slope failures, to make clear the behaviors of rainfall infiltration at 1-2 m thickness of in-situ slope is still the urgent problem. Therefore, a field monitoring of rainfall infiltration is being carried out at the natural Masado slopes where a debris flow was triggered during the event of June 29, 1999. The authors have already discussed in the past papers about field monitoring system and rain water infiltration processes on depths of 0.5m to 2.0m of those slopes. In this paper, newly added monitoring system to measure the change of pressure of soil moisture and moisture content at shallow part from the surface such as 0.1m- 0.3m will be introduced. And then, soil moisture behaviors on these shallow parts will be elucidated.

To study the feasibility of crop production on Moon and Mars, theoretical considerations on water movement in porous media under low gravity conditions were organized., 資料番号: AA0063706103

Due to rainfall during the snowmelt season in May 2012, landslides occurred at Nakayama Pass, which is on the main route between Sapporo and Southern Hokkaido, and all lanes there were temporarily closed for the first time since the route opened in 1969. Quantitative evaluation for the risk of landslide such as that at Nakayama Pass during the snowmelt season has remained an issue. In this study, we proposed a method for quantifying the soil moisture of potential landslide sites by comprehensively estimating the long-term water cycle of the watershed. As the result of applying the proposed method to the Nakayama Pass landslide site, it was clarified that the soil moisture of the landslide site at the time of the May 2012 disaster was the highest in the previous 33 years. This proposal was considered effective for quantitative evaluation of the soil moisture associated with landslide during the snowmelt season.

本研究では,モンゴル草地における植生調査とパターン展開法を応用した土壌水分推定手法について,現地調査データへの適用を試みた。調査はモンゴルのトブ県,ドンドゴビ県とヘンティ県における牧草地や耕作放棄地など多様な土地利用状況における全10箇所を対象地とした。植生調査は,植被率の算出と坪刈りによる植物種の同定を行った。次に,可視・近赤外波長域(350-1050nm)が観測可能なセンサを持つ分光放射計を用いて,土壌分光反射率を測定した。分光反射率は,衛星画像への適用を考慮に入れ測定波長域を4バンドに分類し,解析では各バンドの平均値を利用した。植生調査の結果,いずれの調査地においてもイネ科植物が生息していた。また,植被率が同程度の地域でも,土壌水分量に差異が認められた。著者らは,既にパターン展開法を応用した土壌水分推定手法を報告している。屋外実験により測定した土壌分光反射曲線(反射パターン)が,土壌含水比の低下に伴い直線形状に近づいたことから,パターン展開法を応用し,土壌含水比が低い場合の特性を示す直線モデルパターンを考案したものである。現地調査で測定した土壌分光反射率データを用いて土壌水分推定を行った結果,パターン展開により算出した直線モデルパターン展開係数と土壌含水比の間に有意な関係が示された(r^2=0.72)。この際,土壌タイプの考慮は行わなかったことから異なるタイプの土壌を対象にした場合でも良好な精度の土壌水分推定値が得られることが示された。, In this study, we conducted the measurements of soil spectral reflectance and soil moisture content, and vegetation surveys over ten plots within the prefectures of Tov, Dundgovi and Henti of Mongolian grasslands. We attempted to apply a method for estimating soil moisture content to the field measured data. We also collected the data of vegetation species by the quadrate method, and calculated the vegetation cover ratio. The soil spectral reflectance of land surface was measured using a spectroradiometer which had a sensor in visible and near infrared wavelength (Wavelength range : 350-1050nm). For an application to satellite imagery of optical sensors, four spectral bands were selected to be analyzed. The estimation method of soil moisture content by applying pattern decomposition has already been reported. In this investigation, we found that the soil spectral reflectance curve was steep when the soil moisture content is high, and becomes flat when the soil moisture content is low. Thus, in the pattern decomposition method, the flat model pattern is defined as the spectral reflectance pattern that corresponds to completely dried soil. The pattern decomposition coefficient for the flat model pattern was calculated from the pattern decomposition method using flat model pattern. The result of application of the suggested method to soil reflectance pattern from field survey showed a negative correlation (r^2=0.72) between soil water content and the pattern decomposition coefficient for the flat model pattern. This high correlation was shown throughout all the soil types in this study. The result of vegetation survey showed that there was a difference of soil water content between the two survey plots where low vegetation cover ratios were recorded. The reason for this result was assumed to be the effect of soil moisture deficiency or overgrazing.

ポット植えしたカシス`ラジアント'を,かん水量を制限した乾燥土壌で栽培した。その結果,十分にかん水した場合と比較して果実が小型化し,滴定酸度は上昇し,ビタミンC含量は増加傾向を示した。屈折計示度および抗酸化能(H-ORAC)は変化しなかった。また,カシス`ネービス'を,株の周辺に光反射シートを敷設して栽培した。この際,かん水は十分量を与えた。その結果,無処理の場合と比較して屈折計示度および滴定酸度は変化しなかったが,ビタミンC含量が増加し,抗酸化能は上昇傾向を示した。以上のことから,土壌乾燥処理や光反射シートの利用によってカシス果実の栄養および機能性を向上させ得ることが示された。, Potted plants of the blackcurrant cultivar `Radiant' were subjected to soil drying with limited irrigation. The treatment decreased fruit size, increased titratable acidity, and tended to increase vitamin C content in fruits, as compared with sufficiently irrigated plants. There was no difference in soluble solid content and antioxidant capacity (evaluated using the hydrophilic-oxygen radical absorbance capacity (H-ORAC) method) between the treated and control plants. Potted plants of the blackcurrant cultivar `Nevis' were subjected to mulching culture by using a light-reflecting sheet. In this experiment, both treated and control plants were sufficiently watered. The soluble solid content and titratable acidity of the treated fruits were similar to those of the control fruits, while vitamin C content of the treated fruits was higher and antioxidant capacity of the treated fruits tended to increase as compared with the control fruits. These results indicate that soil drying and a light-reflecting sheet are capable of increasing the nutritional quality and functional components of blackcurrant fruits.

本報では土壌動物相の多様性を利用した畑地の環境評価の一助として施設栽培環境下の中型土壌動物の多様性について調査を行い,土壌の水分環境の違いと中型土壌動物相との関連性について考察した。その結果多様度指数においてはSimpsonの多様度指数(1/λ),Fisherの多様度指数(α+1)とも点滴灌漑の節水区が最も高く,次いで点滴灌漑の中間区,多孔管灌漑区,点滴灌漑の標準区の順となった。多孔管灌漑区では点滴灌漑の各区に比べて団粒が少なく,中型土壌動物の住処となる土壌間隙が少なかったためと推察された。各試験区の観測回ごとのSimpsonの多様度指数とFisherの多様度指数の関係から,点滴灌漑区ではFishierの多様度指数の変動よりSimpsonの多様度指数の変動が大きいことがわかった。中型土壌動物の個体数が最も多かった点滴灌漑の標準区と最も少なかった多孔管灌漑区とではSimpsonの多様度指数とFisherの多様度指数の差が小さくなった。多孔管灌漑区と点滴灌漑の標準区の体積含水率が比較的安定していたことから,土壌の体積含水率の安定は土壌動物相の多様度の安定に寄与するが,個体数や種数の多少とは必ずしも関係がないと考えられた。, Relationships in diversity of soil meso-fauna and soil moisture conditions were investigated in some types of drip irrigation plots and tube irrigation plot in green house. Water content and soil, animal population, number of genera, diversity index of Simpson (1/λ) and that of Fisher (α+1) were measured. The results showed that both standard irrigated plot in drip irrigation and underground water irrigation plot showed stable conditions of diversity indices, and moisture conditions were stable. But populations and number of genera in the standard irrigated plot were much larger than in the under ground one. Low and Less irrigated plots showed unstable conditions of diversity indices and soil moisture. Therefore, we concluded that stable soil moisture condition is useful for balancing soil animal's diversity, but not for the population and number of genera.