Seventy Years’“Micropedology”1938-2008:The Past and Future

Although the first microscopic observations on soils date already from the beginning of the twentieth century, the publication of Kubiena＇s book ＂Micropedology＂ in 1937 is considered as the beginning of this new scientific discipline. This first system for micromorphological descriptions of soils is considered as morphoanalytical, analysing the fabric according to pure morphological criteria. In a second period Kuniena used a morphogenetic approach, directly relating the global observed fabric to genetic soil horizons. This system, mainly limited to European soils, was in general use till the early nineteen-seventies. End of the nineteen-fifties non- genetic soil classification systems were developed （e.g. USDA）. This trend prompted R. Brewer to publish in 1964 a new morphoanalytical system for fabric analysis, used till the end of last century. Because of some inconsistencies in this approach, a working group of the ISSS published in 1985 a new set of morphoanalytical concepts and associated terminology （Bullock et al.）, in 2003 adapted and extended by Stoops. Several morphosynthetic systems, expressing a complete soil microfabric in a single （compound） term have been proposed, but none was really successful. In 1967 Kubiena introduced the term ＂micromorphometry＂ to name a new branch of micromorphology quantifying the soil fabric, mainly evaluating changes in porosity and structure resulting from soil management. The necessity of dearly defined concepts and terms for fabric analysis of soils and regoliths, even as a need for standardisation of quantitative methods, are discussed in the conclusions.

Long-Term Impact of Soil Management on Microbial Biomass C, N and P in Rice-Based Cropping System

A 12-year field experiment was conducted to investigate the effect of different tillage methods and fertil- ization systems on microbial biomass C, N and P of a gray fluvo-aguic soil in rice-based cropping system. Five fertilization treatments were designed under conventional tillage (CT) or no tillage (NT) system: no fertilizer (CK); chemical fertilizer only (CF); combining chemical fertilizer with pig manure (PM); combining chemical fertilizer with crop straw (CS) and fallow (F). The results showed that biomass C, N and P were enriched in the surface layer of no-tilled soil, whereas they distributed relatively evenly in the tilled soil, which might result from enrichment of crop residue, organic manure and mineral fertilizer, and surficial development of root systems under NT. Under the cultivation system, NT had slightly greater biomass C, N and P at 0～5 cm depth, significantly less biomass C, N and P at 5～15 cm depth, less microbial biomass C, N and equivalent biomass P at 15 ～30 cm depth as compared to CT, indicating that tillage was beneficial for the multiplica tion of organisms in the plowed layer of soil. Under the fallow system, biomass C, N and P in the surface layer were significantly greater for NT than CT while their differences between the two tillage methods were negligible in the deeper layers. In the surface layer, biomass C, N and P in the soils amended with organic manure combined with mineral fertilizers were significantly greater than those of the treatments only with mineral fertilizers and the control. Soils without fertilizer had the least biomass nutrient contents among the five fertilization treatments. Obviously, the long-term application of organic manure could maintain the higher activity of microorganisms in soils. The amounts of biomass C, N and P in the fallowed soils varied with the tillage methods; they were much greater under NT than under CT, especially in the surface layer, suggesting that the frequent plowing could decrease the content of organic matter in the surface layer of the fallowed soil.

Community Soil Resources Management for Sub-Saharan West Africa： Case Study of the Gourma Region in Burkina Faso

A study on community soil fertility management concepts and practices was conducted through rapid and participatory method of research in 15 villages of the Gourma region in Eastern part of Burkina Faso. These investigations aimed at determining farmers＇ knowledge on soil resources： local soil taxonomy and indicators of soil degradation, soil fertility management practices, and capacity for adoption of new technologies in soil fertility management. The results of the study showed that the main parameter for soil classification for all the investigated villages was soil texture composition; soil degradation was evaluated according to crops yield decrease and the development Striga sp. in 100% of the investigated villages; the use of organic manure and long term fellow were the main practices for soil fertility management; concerning the villages where modem technologies of soil fertility management were introduced, the lack of tools and capacity building were the main limiting factors of the adoption of these improved practices at small scale farmers＇ level. Even if discordance between scientific and local soil taxonomy were revealed by our investigations; significant similarities between indigenous and scientific indices of soil degradation were noticed. With regard to the actual magnitude of soil degradation; the local techniques of soil fertility management need to be improved and accessible to a big number of farmers.

Diagnosis of Soil Nutrient Constraints in Small-Scale Groundnut （Arachis hyopaea L,） Production Systems of Western Kenya Using Infrared Spectroscopy

Wise decision-making on resource allocation and intervention targeting for soil management cannot rely solely on trial and error methods and field observations used by small-scale farmers： cost-effective soil fertility survey methods are needed. This study aimed to test the applicability of infrared spectroscopy （IR） as a diagnostic screening tool for making soil fertility recommendations in small-scale production systems. Soil fertility survey of 150 small-scale groundnut farms in western Kenya was conducted using a spatially stratified random sampling strategy. Soil properties examined were pH in water （pHw）, total carbon （C）, total nitrogen （N）, extractable phosphorus （P）, exchangeable potassium （K）, calcium （Ca）, magnesium （Mg） and texture. These properties were calibrated to mid-infrared （MIR） diffuse reflectance using partial least square regression （PLSR）. Cross-validated coefficient of determination （r2） values obtained from calibration models were 〉 0.80 for all properties, except P and K with 0.66 and 0.50 respectively. Soil nutritional deficiencies were evaluated using critical nutrient limits based on IR predictions and composite soil fertility indices （SFIs） developed from the soil properties using principal component analysis. The SFIs were calibrated to MIR soil spectral reflectance with cross-validated r： values 〉 0.80. The survey showed that 56% of the groundnut farms had severe soil nutrient constraints for production, especially exchangeable Ca, available P and organic matter. IR can provide a robust tool for farm soil fertility assessment and recommendation systems when backed up by conventional reference analyses. However, further work is required to test direct calibration of crop responses to spectral indicators and to improve prediction of extractable P and K tests.