Tsugiyuki Masunaga

Soil degradation during the period 1967–1995 in Bangladesh: II. Selected chemical characters

Abstract Changes in soil pH, exchangeable acidity, contents of exchangeable bases (Na, K, Ca, and Mg) and available phosphorus within the top 100 cm layers during the period 1967–1995 were evaluated in this study. Over the 27 y period, mean soil pH decreased slightly (0.07 to 0.49 unit) in all the physiographic units. Exchangeable acidity increased slightly (< 1 kmol ha-1) in Ganges Floodplain (GF), Brahmaputra Floodplain (BF), and Meghna River and Estuarine Floodplain (MF), moderately (4.5–13.7 kmol ha-1) in Old Himalayan Piedmont Plain (OHP), Northern and Eastern Piedmont Plain (NEP), and Chittagong Coastal Plain (CCP), and sharply (25.6–60.2 kmol ha-1 ) in the other units except in Tista Floodplain (TF) where a decrease of 1.8 kmol ha-1 was observed. Exchangeable Na showed a positive change in OHP, GF, Madhupur Tract (MT), MF, and CCP but a negative change in the other units. All the physiographic units showed a decline in the contents of exchangeable K, Ca, and Mg except for OHP and MT which exhibited...

The efficiency of a multi-soil-layering system on domestic wastewater treatment during the ninth and tenth years of operation

Abstract A multi-soil-layering (MSL) wastewater treatment system has been operating at Matsue City, Japan, since July 1990. This study investigates the efficiency of the MSL treatment system during the ninth and tenth years of operation. The MSL system consists of soil mixed with forest floor litter, pelletized jute and iron particles in the ratio of 60:10:15:15 by weight, respectively. The soil mixture is arranged within a 1.75×2.5×1.2 m 3 durable plastic box as blocks thus forming an alternating brick layer-like pattern with zeolite inter-layers. Household wastewater was pre-treated using the traditional Japanese septic tank system (Tandoku Johkasou) with integral aeration facility, before being gravitationally discharged continuously into the MSL system. The flow rate of pre-treated wastewater into the MSL system varied from 1.2 to 113.4 l h −1 as a function of household water consumption. The results indicate that during the period of investigation, the MSL system was still effective at removing biochemical oxygen demand (BOD 5 ) and total phosphorus (TP). The removal rates of BOD 5 and TP were up to 91.0±4.5 and 89.0±4.4%, respectively, in the ninth year and 95.2±3.8 and 82.9±11.9%, respectively, in the tenth year of operation. Total nitrogen (TN) removal was significantly dependent on aeration of the MSL system, quality of pre-treated wastewater and temperature. Although the continuous aeration of the MSL system for 24 h d −1 , which was equivalent to 2.8×10 4 l m −3 d −1 , was effective in facilitating the removal of BOD 5 and TP, it was inappropriate for TN removal. However, after aeration was stopped, TN removal improved considerably, increasing to 89%.

Mineral composition of leaves and bark in aluminum accumulators in a tropical rain forest in Indonesia

Abstract Mineral composition including AI, Ca, Mg, P, S, and Si and relationships between Al and other elements such as Ca, Mg, P, S, and Si in leaves and bark of trees in a tropical rain forest in West Sumatra were studied. Sixty five tree species and 12 unidentified trees were referred to as AI accumulators based on Chenery\ss definition (more than 1 g kg-1 Al in leaves). For most of the Al accumulators, Al concentration in leaves was higher than in bark. However, some members of Euphorbiaceae, Melastomataceae, and Ulmaceae families showed a reverse trend. Most of the non-accumulators also showed a higher Al concentration in bark than in leaves. These results indicated that there was a difference in the mechanism of Al accumulation in tree bodies. Some of the Al accumulators showed an extremely high Al concentration (more than 10 g kg-1) not only in the mature leaves, but also in the new leaves. Analysis of the relationships between the concentration of Al and the other 5 elements in leaves, revealed t...

Soil Degradation during the Period 1967-1995 in Bangladesh : I. Carbon and Nitrogen

Long-term changes in carbon and nitrogen storage in the top 100 em layers of soils from different physiographic units in Bangladesh were evaluated using 460 soil samples from 43 profiles collected in 1967 and 1994/95. The study area consisted of ten physiographic units, viz.: Old Himalayan Piedmont Plain (OHP), Tista Floodplain (TF), Barind Tract (BT), Ganges Floodplain (GF), Madhupur Tract (MT), Brahmaputra Floodplain (BF), Meghna River and Estuarine Floodplain (MF), Surma-Kushiyara Floodplain (SKF), Northern and Eastern Piedmont Plain (NEP), and Chittagong Coastal Plain (CCP). During the period 1967–1995, mean values of soil carbon and nitrogen declined by 16.2 t C ha-1 and 1.38 t N ha-1 in Bangladesh. The total carbon and nitrogen budgets showed a fall of 42.8 × 106 t C and 3.36 × 106 t N within the 27 y period in Bangladesh. All the physiographic units showed a decline in carbon and nitrogen contents except for BT which showed an increase of 3.76 t C ha-1 and 0.77 t N ha-1 for these elements....

Ecological Engineering for Sustainable Food Production and the Restoration of Degraded Watersheds in Tropics of Low pH Soils: Focus on West Africa

Since upland rice under shifting cultivation is common, the mean paddy yield in sub-Sahara Africa (SSA), especially West Africa, has been stagnated at 1.3–1.7 t ha−1 during the past 30 years of 1970–2000. There exist numerous small inland valley swamps (IVS), of which 10 million ha is capable of being turned into small scale irrigated rice fields, i.e., sawah* by simple and low cost ecological engineering technology with farmers self-support efforts. The fertility of lowland soils in West Africa was the lowest, particularly available phosphorous status was extremely poor and low pH as well as low exchangeable bases among the three tropics of Asia, Africa and Latin America. However, because of multi-functional mechanisms of soil and water conservation and replenishment of nutrients, sustainable productivity of 1 ha of lowland sawah system can be equivalent more than 10 ha of upland fields. Geological fertilization, nitrogen fixation, neutralization of pH and increase phosphorous availability are the important functions of the sawah system. Sustainable development of sawah systems in IVSs can contribute to increase food production and to restore the degraded watersheds of SSA. *Sawah: The term sawah refers to leveled rice field surrounded by bund with inlet and outlet connecting irrigation and drainage. The term originates from Malayo-Indonesian. The English term, Paddy or Paddi, also originates from the Malayo-Indonesian term, Padi, which means rice plant. The term, Paddy, refers to rice grain with husk in West Africa of SSA. Most of the paddy fields in the Asian countries correspond to the definition of the term sawah. Paddy field is almost equivalent to sawah for Asian scientists. However, the term paddy fields refers to just a rice field including upland rice field in West Africa of SSA. Therefore in order to avoid confusion between the terms rice plant, paddy, and the improved man-made rice growth environment through ecological engineering, the authors propose to use the term sawah.

Sulfur and zinc levels as limiting factors to rice production in West Africa lowlands.

Abstract A total of 172 soil samples from 85 locations within river flood plains and 201 samples from 78 locations within inland valley swamps were collected and analyzed to determine their sulfur (sulfate-S) and micronutrients (Zn, Fe, Mn, Cu, Ni) supplying capacities. The soils were observed to be very deficient in both sulfate-S and available Zn. Mean topsoil (0–15) cm sulfate-S levels were 3.41 mg kg−1 for river flood plains and 4.88 mg kg−1 for inland valley swamps . Even though mean topsoil available Zn levels were 1.23 and 1.56 mg kg−1 for river flood plains and inland valley swamps, respectively, over 66% of West Africa lowlands had available Zn below the critical soil level of 0.83 mg kg−1 necessary for rice cultivation. Observed levels of topsoil mean available Fe (163 and 220), Mn (66.6 and 57.6), Cu (3.38 and 2.49), and Ni (1.68 and 1.36) mg kg−1 for river flood plains and inland valley swamps, respectively, were moderate across the sub-region. However, isolated areas within both lowlands showed very high levels of available Fe, more especially within the inland valley swamps. A correlation analysis with some selected nutrient parameters showed that topsoil sulfate-S correlated positively and significantly with total C (r=0.690), available P (r=0.939), eCEC (r=0.867) and Clay (r=0.859) for river flood plains but only with total C (r=0.874), available P (r=0.873) and eCEC (r=0.612) for inland valley swamps. Available Zn showed a similar relationship with total C (r=0.867 and 0.800) and available P (r=0.690 and 0.850) but a negative correlation with eCEC (r=−0.675 and −0.544) for both river flood plains and inland valley swamps, respectively. Available Ni showed a similar relation to Zn. Available Mn significantly correlated positively with total C and available P but showed a negative correlation with pH for both lowland types. Nutrient availability and distribution were more influenced by agro-ecology within the inland valley swamps than the river flood plains.

Soils of Flood Plains of West Africa : General Fertility Status

Abstract As a part of efforts to effectively utilize the wetlands of the West Africa sub-region for the production of rice and other crops, in order to alleviate the persistent food shortage while also protecting and conserving the environment for sustainability, the general fertility status of flood plain soils were assessed. The whole sub-region was found to be deficient in available phosphorus. Available P (Bray No.2) was deficient for both the humid Equatorial forest (EF) and sub-humid Guinea savanna (GS), as well as the drier northern sector of Sudan savanna (SuS) and Sahel savanna (SaS) zones. Mean available P levels in the topsoil (0-15 cm) were 9.84, 8.01, 7.25, and 7.31 mg kg-1 for the EF, GS, SuS, and SaS zones respectively. Effective cation exchange capacity (eCEC) and levels of exchangeable K, Ca, and Mg were higher for the SaS and SUS than for the GS and EF zones. The level of exchangeable K was, however, very low within the EF zone. The soils were slightly acidic to neutral but with isolated...

Soils of inland valleys of West Africa : General fertility parameters

Abstract In an effort to improve the critical food situation in West Africa, wetlands are currently receiving the necessary attention as the environment most suitable for rice production. Various scientific studies are required to effectively put these wetlands into sustainable crop production. Between 1983 and 1989 inland valleys (IVs) of West Africa were surveyed with the main objective of characterizing these soils; soil samples were therefore collected from these IVs throughout the various climatic zones. As inland valleys of West Africa have undergone intense leaching and weathering, the soil pH is generally low. Mean soil pH values (0–15 cm) are: West Africa, 5.3; Equatorial forest (EF), 5.3; Guinea savanna (GS), 5.3; Sudan savanna (SuS), 5.9; and Sahel savanna (SS), 6.0. Exchangeable cations for West Africa IVs are low; also low for IVs of EF; very low for GS IVs; and moderate for the drier zones (SuS and SS). Total carbon and nitrogen contents (12.8 g kg-1 C and 1.11 g kg-1 N) of these soils are l...

Nutritional characteristics of mineral elements in leaves of tree species in tropical rain forest, west Sumatra, Indonesia

Abstract The nutritional characteristics of mineral elements in tree species were studied in a 1 ha ecological observation plot at Mt. Gadut area near Padang, West Sumatra, Indonesia. The elemental composition of the 608 leaf samples from the plot was analyzed and was compared with the results of bark analyses (Masunaga et al. 1997: Soil Sci. Plant Nutr., 43, 405–418). The concentration ranges of various elements in leaves (in mg kg-1) were S (470–17,000), K (1,040– 34,430), Al (6–36,920), Ca (500-81,700), Mg (170-10,530), Si (250-89,980), N a (131– 861), Cu (0.8-63.7), Fe (38-851), Mn (4.8-3,574), P (357-4,350), Sr (0.1-690), and Zn (0.4-309), respectively. The concentration of the most of the elements such as S, K, AI, Mg, Si, Cu, Fe, Mn, P, and Zn was higher in leaves than in bark, especially Si and P, being more than seven times higher in leaves. However, the coefficient of variation was conversely higher in bark for most of the elements, suggesting that there are larger differences in nutritional cha...

Comprehensive assessment of the clay mineralogical composition of lowland soils in West Africa

Abstract The clay mineralogical composition of 87 topsoil (0–15 cm) samples from inland valleys (IVs) and flood plains (FPs) in seven West African countries, namely Côte d’Ivoire, Ghana, Guinea, Mali, Niger, Nigeria and Sierra Leone, was examined using X-ray diffraction analysis to gain basic information for the development of sustainable lowland agriculture in the region. The results of the present study revealed that the clay fraction (< 2 m) of these samples consisted of 68.4% of 7 Å minerals (low-activity clays such as kaolin minerals), 26.6% of 14 Å minerals (relatively high-activity clays such as smectite and vermiculite) and 5.1% of 10 Å minerals (illite or clay micas) and showed a high variability in the composition. With respect to the soil material classification based on the relative abundance of these three types of minerals, Type 7 (rich in 7 Å minerals) accounted for 42.5% of the total samples, while 39.7% of all the samples were Type 7-10 and 7-14 with a predominance of 7 Å minerals and with negligible amounts of 10 and/or 14 Å minerals, respectively. Type 14-7 accounted for 17.2% of the total samples and was only recorded in Nigeria. The other clay mineral types (i.e. Types 7-10-14, 14, 10, 10-7, 10-14 and 14-10) that were composed mainly of 10 and/or 14 Å minerals were hardly found in the West African lowland soils, whereas Types 14 and 7-10-14 were observed in a vertic soil of Southeast Ghana and in northern Ghana, respectively. In contrast, no significant differences in the clay mineralogical composition were found between the IV and FP soils. Geographical distribution of the soil types showed that the soils in the eastern part of West Africa contained more 14 Å and 10 Å minerals than those in the western part. Although the effect of agro-climatological differences was not conspicuous, soils in the Sahel and Sudan savanna zones showed a higher percentage of 14 Å clay minerals than those in the Guinea savanna and equatorial forest zones. The findings were as follows: (1) the low fertility status of the lowland soils in the region was closely associated with their poor mineralogical characteristics (i.e. predominance of 1:1 type clay minerals and a lower amount of 2:1 type clay minerals), (2) no significant differences in the mean clay mineralogical composition were observed between the IV and FP soils, indicating that the lower fertility of the IV soils mainly resulted from the lower clay content, (3) the clay mineralogy of the West African lowland soils was more strongly influenced by the nature of the parent materials than by the climatic conditions and relief.