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Several ethnopedological studies highlight the plurality of soil knowledge and the complexity of soil knowledge systems. These knowledge systems are specific to social groups or communities and the dialogue between them is not easy. Local soil knowledge is often misrepresented and reduced when correspondences with soil sciences categories are established without due care. This paper results from two field studies in an upland village of Southern Philippines. The sociocultural richness and the high diversity of farming systems characterizing this local context have highlighted the importance of accounting for the diversity of soil knowledge related to local issues and sustainability. Looking for a dialogue among the plurality of perceptions, knowledge system, and typologies regarding soils implies that attention be given to knowledge construction processes. In order to facilitate an egalitarian dialogue it is also essential to explore relations between soil knowledge, farming systems, and sociocultural context. Discussion with farmers about their soils has cast doubt on the practical relevance of soil science knowledge in a context of non-industrial and non-chemical agriculture and revealed the dynamic dimension of farmers’ soil knowledge construction and the practical relevance of contextualized knowledge. In this paper, we propose methodological and epistemological thoughts to help establish a common language between scientists and farmers. We also propose to use the soil groups emerging from field characterization as a practical tool to dialogue with farmers in the field, to build a common understanding of soil heterogeneity. We consider this approach as a critical step to initiate collaborative soil studies from a practical and endogenous perspective., SCOPUS: ar.j, info:eu-repo/semantics/published

Summary The degree of phosphorus saturation (DPS) represents the ratio of sorbed phosphorus (P) to the P sorption capacity (PSC) of soils. In some countries, DPS is used to evaluate the risk of P loss and surface water eutrophication. This study investigated DPS measurement and prediction in neutral loamy soils from Wallonia, Belgium. A total of 57 agricultural topsoil samples subject to diverse P management were evaluated. No satisfactory relationship could be found between PSC determined by a one-point short-term isotherm in the laboratory and the sum of aluminium and iron extracted by oxalate (Alox + Feox). The equation PSC = a Alox + b pHw appeared to be more appropriate for estimating PSC in the soils studied. These soils had a near-neutral pH, and P fixation processes linked to the presence of calcium ions or carbonates were important. Comparisons of DPS with soil-test P and water-extracted P suggested that DPS could be a useful agronomic and/or environmental indicator. Our results also showed that DPS values between 20 and 30% corresponded to the agronomic optimum of soil P content. Consequently, DPS may be used as an indicator of P status in neutral soils, provided that the PSC assessment is adapted to the local soil characteristics. Resume Le degre de saturation en phosphore dans les sols agricoles limoneux avec un pH proche de la neutralite. Le degre de saturation en phosphore (DPS) est un indicateur des risques de perte en phosphore (P) vers l'environnement utilise dans de nombreux pays qui exprime la part de la capacite de sorption du P (PSC) reellement occupee par cet element. L'objectif de cette etude est d'evaluer la faisabilite de l'utilisation du DPS pour les sols limoneux wallons presentant un pH proche de la neutralite. L'etude de 57 echantillons de surface de sols agricoles soumis a des modes de gestion contrastes n'a pas permis d'etablir une bonne relation entre la PSC mesuree en laboratoire et la somme des teneurs en Al et Fe extraites a l'oxalate (Alox et Feox). L'utilisation d'une equation du type PSC = a Alox + b pHw semble plus appropriee dans les sols dont le pH est proche de la neutralite et ou les carbonates de calcium interviennent dans la fixation du P. De plus, une comparaison du DPS avec les indicateurs agronomiques et environnementaux, P disponible et P extrait a l'eau, montre que DPS est compatible au systeme d'evaluation de la fertilite utilise actuellement. Un DPS entre 20 et 30% correspond a une bonne fertilite du sol. Ainsi, le DPS peut etre utilise comme indicateur dans les sols neutres, a condition de prealablement adapter son calcul aux caracteristiques du sol.

A profile comprising a limestone substrate overlain by a clay-rich interval, which represents a common sequence, was studied with the objective of determining the relationship between substrate and cover. The profile was characterized by various types of mineralogical and chemical analyses, and by a micromorphological study. The mineralogical and chemical data demonstrate that the cover is unrelated to the parent rock, including all horizons below the loess-derived Ap horizon. Thin section observations show that the basal C3 horizon is largely composed of illuvial clay, deposited around claystone fragments, resulting in a fabric that, together with profile position, relates the interval to so-called beta horizons. In higher parts, up to a level recognized as a lithological discontinuity based on mineralogical composition, the profile largely consists of fragments of clay coatings and disintegrated claystone fragments, with an overall upward increase in degree of pedoturbation. The source of the clay is assumed to be Cenozoic deposits that are known to occur in the region. The main conclusion of this study is that clay intervals overlying limestone can have a complex mode of development, to be studied by a combination of methods, and with implications for the valorization of existing soil maps.

In the complex soilscape of Rwanda, failure to tailor soil fertility management technologies to specific soil types is the major constraint to their adoption. A study was undertaken to understand how scientists can introduce new soil-related technologies as part of the already functioning farmers’ soil knowledge (FSK) system and achieve soil-specific fertility management interventions. Farmer participatory research and biophysical diagnostic methods were used in Akavuguto watershed, southern Rwanda. Results from this study show that the FSK system is not only rational but also practical and consistent with the technical soil knowledge and has the potential of being user-friendly for local fertility experts, agronomists and extensionists compared to the international soil classification systems. The farmers’ rationality is demonstrated by a clear agreement between farmers’ cognitive soil knowledge and farmers’ soil-related practices. The farmers’ practices follow a clear coping strategy in a poor and complex biophysical environment. In the Akavuguto watershed case study, the mountains, with their Urubuye (Entisols), are limited by the slope gradient and stoniness; they are planted with trees. The upper hills, with their Urusenyi (Entisols) and Inombe (Ultisols), do not have major edaphic limitations; they are used for growing beans and sorghum, crops that are demanding but key in farmers’ food security strategy. The back slopes, with their Umuyugu/Mugugu (Oxisols), are limited by poor fertility status; they are used for growing cassava and sweet potato which are acid tolerant and less demanding. The valley bottoms, with their Nyiramugengeri (Histosols) and Ibumba (Ultisols), are limited by very strong acidity; they are used for growing sweet potatoes. It was concluded that understanding the biophysical environment in terms of land units and associated farmers’ soil types constitutes an appropriate entry point to achieve soil-specific and replicable fertility management technologies

Application of phosphorus (P) fertilizers to agricultural soils should be based on sound knowledge about soil P reserves, availability and lability to optimize conditions for plant uptake while limiting P transport to surface waters. This study investigated relationships between parent material (PM), land use and P fractions in agricultural soils at a regional scale. Surface and deep (100–120 cm) soil samples were collected from 120 agricultural sites (240 total samples) and analysed for three P forms (inorganic, organic and available) as well as for additional key properties. Land uses within the study area were continuous cropland, permanent pasture and temporary grassland. The area covered the 12 most common parent types in Wallonia. Mean total P contents were 904 and 401 mg/kg in surface and deep samples, respectively, with a 33% coefficient of variation for both horizons. The organic P fraction represented, on average, 30% of total P, while available P corresponded to 9% of total P. The influence of PM was apparent in both the surface and deep soil samples, while land use influenced only surface properties. The pattern in total P content relative to land use was pasture ≥ cropland ≥ temporary grassland. Correlation analyses highlighted significant relationships between edaphic parameters viz Alox, Feox, CEC, TOC, pH and P content, the main soil parameter being Alox which determines P sorption capacity. An enrichment factor was used to distinguish between geogenic sources and human activities in terms of topsoil P content.

Five profiles located in the peri-urban market garden of Yunnan Province, China were investigated for the distribution and sequential extraction fractions (SEF) of Pb, Cd, Cu and Zn, and mobility in relation to soil properties. SEF heavy metals included acetic acid extractable (A-fraction), hydroxylamine hydrochloride extractable (B-fraction) and hydrogen peroxide and ammonium acetate extractable fractions (C + D-fraction). The results showed that: (1) Total Pb and Zn contents decreased with soil depth. The accumulation of different fractions of Pb and Zn was due to accumulation of organic carbon and Fe–Mn oxides. (2) Total Cd content increased with soil depth with the ratio of A to C horizons (RAC)

Pot experiments were conducted in the laboratory with lime applications to decrease trace elements in Chinese cabbage produced on soils contaminated by trace elements in the intensive periurban area in Chenggong County, Yunnan Province, China. Soil was an acidic loam developed from lacustrine-alluvial deposits. Results showed the following: (1) soil pH increased from 5.3 to 6.5, and acetic-acid-extractable trace-element contents and ratio of acetic-acid-extractable trace-element contents in treatments relative to those in the control (RRCT) decreased with increased rate of lime application. (2) Chinese cabbage more easily absorbed acetic-acid-extractable trace elements. Enrichment coefficients related to trace-element availability (AEC) of lead (Pb; mean: 3.3) and zinc (Zn; mean: 5.8) were stable, and the AEC of cadmium (Cd) was 1.8–2.0 with increased lime application rate. (3) Trace-element contents in Chinese cabbage decreased, and biomass of Chinese cabbage increased, with lime application rate. Trace-...

Field investigations were conducted to measure subsoil trace element content and factors influencing content in an intensive periurban market garden in Chenggong County, Yunnan Province, South-West China. The area was divided into three different geomorphological units: specifically, mountain (M), transition (T) and lacustrine (L). Mean trace element content in subsoil were determined for Pb (58.2 mg/kg), Cd (0.89 mg/kg), Cu (129.2 mg/kg), and Zn (97.0 mg/kg). Strong significant relationships between trace element content in topsoil and subsoil were observed. Both Pb and Zn were accumulated in topsoil (RTS (ratio of mean trace element in topsoil to subsoil) of Pb and Zn ≥ 1.0) and Cd and Cu in subsoil (RTS of Cd and Cu ≤ 1.0). Subsoil trace element content was related to relief, stoniness, soil color, clay content, and cation exchange capacity. Except for 7.5 YR (yellow-red) color, trace element content increased with color intensity from brown to reddish brown. Significant positive relationships were observed between Fe content and that of Pb and Cu. Trace element content in mountain unit subsoil was higher than in transition and lacustrine units (M > T > L), except for Cu (T > M > L). Mean trace element content in calcareous subsoil was higher than in sandstone and shale. Mean trace element content in clay texture subsoil was higher than in sandy and sandy loam subsoil, and higher Cu and Zn content in subsoil with few mottles. It is possible to model Pb, Cd, Cu, and Zn distribution in subsoil physico-chemical characteristics to help improve agricultural practice.

Soil fertility diagnostics rely not only upon measurement of available nutrients but also upon the ability of the soil to retain these nutrients. Near infrared (NIR) reflectance spectroscopy is a rapid and non-destructive analytical technique which allows the simultaneous estimation of standard soil characteristics and does not require the use of chemicals. Previous studies showed that NIR spectroscopy could be used in local contexts to predict soil properties. The main goal of our research was to build a methodological framework for the use of NIR spectroscopy on a more global scale. The specific goals of this study were (i) to identify the best spectral treatment and processing—LOCAL versus GLOBAL—regression methods, Nil to compare the performance of NIR to standard chemical protocols and (iii) to evaluate the ability of NIR spectroscopy to predict soil total organic carbon (TOC), total nitrogen (TN), clay content and cationic exchange capacity (CEC) for a wide range of soil conditions. We scanned 1300 samples representative of the main soil types of Wallonia under crop, grassland or forest. Various sample preparations were tested prior to NIR measurement. The most appropriate options were selected according to analysis of variance and multiple means comparisons of the spectra principal components. Fifteen pre-treatments were applied to a calibration set and the prediction accuracy was evaluated for GLOBAL and LOCAL modified partial least square (MPLS) regression models. The LOCAL MPLS calibrations showed very encouraging results for all the characteristics investigated. On average, for crop soil samples, the prediction coefficient of variation ( CVp) was close to 15% for TOC content, 7% for TN content and 10% for clay content and CEC. The comparisons of repeatability and reproducibility of both NIR and standard methods showed that NIR spectroscopy is as reliable as reference methods. Prediction accuracy and technique repeatability will allow the use of NIR spectroscopy within the framework of the soil fertility evaluation and its replacement of standard protocols. LOCAL MPLS can be applied within global datasets, such as the International global soil spectral library. However, the performance of LOCAL MPLS is linked to the number of similar spectra in the dataset and more standard measurements are needed to characterise the least widespread soils.

Chinese cabbage and surface soil samples (0–20 cm) from a periurban market garden in Yunnan Province (P.R. China) were collected to determine variations of cadmium (Cd) and zinc (Zn) contents in Chinese cabbage and the influence of soil factors. Mean Cd content was 0.49 mg kg−1 dry materials (DM) in Chinese cabbage, ranging between 0.23 and 1.34 mg kg−1 DM (n = 21 samples). Mean Zn content was 51.2 mg kg−1 DM, ranging from 34.9 to 157.5 mg kg−1 DM (n = 21 samples). The soil factors best predicting Chinese cabbage Cd and Zn contents were total and available Cd and Zn contents and cation exchange capacity (CEC). Soil samples and corresponding Chinese cabbage samples were divided into two groups: soils with low pH ( 6.5, n = 11). Positive correlation between CEC with pH > 6.5 and Cd and Zn contents in Chinese cabbage were observed. Available trace element contents and CEC explained 77% and 69% of variation of Cd and Zn contents in Chinese cabbage, respectively. AEC (enri...

The study was conducted in the crop production areas of Miarayon Village, along the volcanic footslope of Mt. Kalatungan, Talakag, Bukidnon, Philippines. The elevation range of the longitudinal toposequence is 1,900 to 1,300 m asl. Production areas in the intermediate part of the toposequence (Salsalan) are located at about 1,600 to 1,400 m asl and in the lower part (Mambuaw) at 1,400 to 1,300 m asl. A total of 24 plots (12 in each location) which were planted to potatoes, carrots and corn were investigated. Soils are “Andic” Cambisol in open and convex positions and “Andic” Umbrisol in concave positions and toeslopes. The soil pH values ranged from 5.0-5.9. TOC and TN content were medium to high (4.1-8.9% and 0.30-0.80% respectively) with C/N ratios from 8-15. Range values of available Ca, Mg, K and Na were 1.9-11.24, 0.16-2.14 and 0.20-1.13, 0.04-0.13 cmol + kg -1 , respectively. Top soil horizon exchangeable Al in Mambuaw was higher than in Salsalan. The differences in TN, C/N ratio and available K levels between the two locations were very highly significant, TOC was highly significant and for soil pH and available Ca and sum of bases, their disparities were significant. Available Mg and Na did not differ between the two sites. Mean potato yield in Salsalan was 8.97 tha -1 more than in Mambuaw. Mean carrot yield in Salsalan was 2.39 tha -1 lesser than in Mambuaw. Mean corn yield in Salsalan was higher than in Mambuaw by 0.29 tha -1 only. Correlations between potato yields with TOC, TN, and available Ca were highly significant while soil pH and K were significant. There was no relationship detected between potato yields and Mg and Na. There was no association detected between carrot yields with topsoil nutrient levels. Correlations were noted in corn yields with available Ca, Mg and K.

Soil conservation on the highland red soils of Southern China is essential for sustainable agroenvironmental development. The effectiveness of soil conservation treatments developed in runoff plots was investigated in farmer-managed plots on a natural catchment. This was achieved by the development and scientific evaluation of modified and novel cropping practices in a representative highland catchment in Yunnan Province, China. Wang Jia Catchment covers 40.1 hectares near Kedu, in Xundian County, northeast Yunnan (25°28' N, 102°53' E). The initial project consisted of an evaluation of the effects of modified cropping practices on maize productivity and soil properties. This programme was extended to investigate ways of increasing the productivity of maize, wheat and soybean on fragile slopes in a sustainable and environmentally-friendly way. The approach incorporates modified and novel agronomic and soil conservation measures, with the evaluation of their agricultural, environmental and socio-economic impacts using multidisciplinary approaches. This European Union funded project involved an international research team from Belgium, China, Ireland, Thailand and the U.K. Five co-ordinated work packages were implemented. Involving