An understanding of the differences in yield potential and soil characteristics between slope directions in hilly uplands fields is fundamentally important for efficient management of the fields. Although the influences of slope direction on soil organic matter have not been widely studied in arable land, there are extensive reports in native or uncultivated land covered with forest. The present study was done in hilly upland potato fields in Kamikawa district, Hokkaido, Japan to evaluate differences in yield potential and soil characteristics between slope directions. Eighty paired surface soil and potato samples were collected at flowering and harvesting stages, respectively, over a period of two years. Slope direction of each field was determined using ArcGIS software, and potato fields were categorized into two groups (north-facing and south-facing) based on slope direction. This study revealed that (1) the average soil total carbon content was significantly higher in fields with north-facing slopes (18.5 g kg^-1) compared to south-facing fields (13.9 g kg^-1), (2) cation exchange capacity was also significantly higher in north-facing compared to south-facing fields, and (3) tuber yields of Toyoshiro cultivar were relatively higher in fields with slope direction facing south than those facing north whereas Kitahime cultivar showed the opposite trend. In conclusion, depending on the cultivar, slope direction can affect potential yield by altering climate conditions (air temperature, soil temperature, day length, and diurnal variation of temperature) as well as by modifying soil characteristics.

　2022年から実施される学習指導要領の改訂では，地理歴史科の科目が「地理総合」，「地理探求」に変更となり，地図や地理情報システムの活用による国際性，主体的な思考力の養成が求められることとなった。これにあわせて，土壌に関して国内外で蓄積されてきた研究成果を基礎にした，正確な地図および用語を高校生が活用できるように，高校地理の土壌に関わる教育内容の更新が喫緊の課題である。そこで，現行の高校地理（地理Ｂ）の教科書にみられる用語および地図の問題点を整理し，教育内容の修正・更新案を提示した。具体的には，(1)チェルノーゼム，プレーリー土，パンパ土，栗色土の統一，(2)単独の土壌分類名と対応しないツンドラ土の削除，(3)「ラテライト」の削除とフェラルソル（ラトソル）への統一，(4)ポドゾル，フェラルソルの分布域の過大評価の修正，(5)テラロッサ，テラローシャを含む「粘土集積土壌」の追加，(6)間帯土壌（成帯内性土壌）として黒ボク土，沖積土の追加である。これによって，世界の土壌の分布と生業や文化との関わり，日本の主要な土壌の地理的分布とその特異性の理解促進に貢献できる。

　　The acidic surface soil of non-allophanic Andosols may affect grass growth in grassland. In the Kyushu region of Japan, non-allophanic Andosols are mainly concentrated on the Kuju Plateau in Oita Prefecture. This study aimed to investigate the effect of climatic factors on the distribution of non-allophanic surface soils, clarify the surface soil acidity of grasslands, and evaluate the effect of liming on the early growth of grasses and on the soil chemical properties. The surface soils of 17 out of 27 sites in 25 grassland fields had the ratio of sodium pyrophosphate-extractable Al to acid ammonium oxalate-extractable Al (Al_p/Al_o) ≧ 0.5 which is a non-allophanic characteristics. Moreover, 15 out of the 17 sites had a Thornthwaite’s P-E (precipitation–evapotranspiration) index ≧ 200, which indicates low temperatures and high precipitation. Ten sites of non-allophanic soil and two sites of allophanic soil were acidic with an exchangeable acidity (y₁) of ≧ 3. Pot experiments showed that liming the acidic soils to create y₁ < 3.0 improved the early growth of Italian ryegrass and significantly decreased the amount of exchangeable Al and organic bound-Al in the soil. These findings suggested that y₁ of 3, used as a target value for acidity management of grassland in Niigata Prefecture, could also be applied on the Kuju Plateau, regardless of the type of Andosol.

　　Soil information is key to determine optimum agricultural management. Especially, the understanding of inherent soil characteristics combined with appropriate soil fertility evaluation are necessary. In many countries, soil information is outdated and no reliable information exists. We focused our effort in the central highlands of Malawi, the major potato (Solanum tuberosum L.) producing area where the current yield is low. This study was conducted to classify and evaluate agricultural soils in the area. Three soil profiles were evaluated in the area. Bembeke Agricultural Experimental Station and Chimlambe village soils were classified into Oxisols while Sithawika village soil was classified into Entisols. Kaolinite dominated in Oxisols whereas in Entisols, kaolinite and illite co-dominated. In this area, topography was a major soil forming factor, influencing the supply of colluvial and alluvial materials. Total C contents as well as CEC were variable among the sites and reflected soil moisture regimes, topography, and intensity of agricultural management. The nutrient results indicated low base cation contents in Oxisols unlike the previous reports, while P contents were not low. In conclusion, two different soil orders exist in the study area with variable clay mineralogy and total C contents while nutrient imbalance was observed reflecting the interaction of inherent soil characteristics and agricultural management.