Knowing the land: soil and land resource evaluation and indigenous knowledge

Abstract. Scientific land and soil resource surveys have had only limited impacts locally on development and extension practice in the tropics. They are thought to have little relevance for subsistence farmers. Their failure to accommodate local social and cultural priorities is a factor. Soil scientists have, until recently, given little attention to others' understanding of soil or 'ethnopedology'. The incorporation of indigenous soil and land resource knowledge has recently been advocated to improve their relevance. But a common error is uncritically to impose a western scientific model, which may distort understanding. The ill-informed, decontextualised knowledge that results may even promote negative interventions. This paper criticises the narrow idea of 'indigenous technical knowledge', citing evidence from Papua New Guinea, Bangladesh and Indonesia. While we find farmers consistently use some of the same information as scientists to assess soils, their definitions of soils and land types are often at odds. Scientists identify classes by a range of technically assessed properties, whereas farmers may not. Their more holistic approach also accounts in part for the disjunction, frequently incorporating exotic social and cultural aspects. The wider use of indigenous soil notions in agrotechnology transfer may be limited too by some of their intrinsic characteristics, inclined to be location specific, and culturally relative.     

An evaluation of Colwell‐P as a measure of plant‐available phosphorus in soils of volcanic and non‐volcanic origins in the highlands of Papua New Guinea

Various soil test methods including Olsen, Colwell, Bray and Truog have been used to assess the levels of plant‐available P (PAP) in soils situated in the highlands of Papua New Guinea (PNG). Up until now, though, there has been no guarantee that these tests provide valid assessments of PAP in these somewhat atypical organic matter‐rich tropical soils. Furthermore, the critical soil‐P concentrations associated with the tests have been based on studies conducted elsewhere in sub‐tropical and temperate latitudes and as such may or may not be valid for soils or cropping situations in PNG. Soil (Colwell)‐P and leaf‐P data collected during a recent survey of sweet potato gardens in the highlands of PNG were therefore used to determine if useful relationships existed between these variables for different groups of soils, and if they do, to use these relationships to evaluate critical soil Colwell‐P concentrations corresponding to a known critical concentration of P in sweet potato index leaf tissue. Separate, highly significant linear relationships were obtained between leaf‐P and Colwell‐P for soils of volcanic and non‐volcanic origins. Based on these relationships, the critical Colwell‐P concentration for volcanic soils was found to be four times greater than that for non‐volcanic soils, presumably because much of the P extracted from the former soils with alkaline sodium bicarbonate had been chemically ‘fixed’ via sorption and precipitation reactions with sesquioxides and rendered unavailable to plants at ambient soil pH. These critical Colwell‐P concentrations if adopted as benchmark values for the soil groups in question should ensure that the results of future soil fertility surveys involving Colwell‐P assessments are correctly interpreted.     

Relationships between important soil variables in moderately acidic soils (pH ≥5.5) in the highlands of Papua New Guinea and management implications for subsistence farmers

The fertility of farmed soils in parts of the Papua New Guinea (PNG) highlands reputedly has been declining for some time owing to population pressure. To assess the extent of the problem, a survey of sweet potato gardens was conducted across four of the highlands provinces and information on soil variables was obtained for gardens on soils of volcanic and non-volcanic origins. In the absence of fertilizer application, soil fertility in the humid tropics is largely a function of soil cation exchange capacity (CEC), and soils of low CEC had previously been reported in this region. In the present study, relationships between effective CEC (ECEC) and other soil properties in moderately acidic soils (pH 5.5–6.3) were investigated to see if there was scope for improving soil cation retention characteristics through management of key soil variables. For volcanic soils of varying allophane content, ECEC was, unexpectedly, negatively correlated with soil C and soil C/N, most probably because of the formation of humus–allophane complexes which had facilitated organic matter accumulation whilst dramatically reducing the free negative charges on the material. Given the latter outcome, the indigenous practice of heaping compost in the centre of soil mounds appeared to be one of the best strategies for circumventing the problem of low CEC, as nutrients in the compost are held in an environment virtually independent of the surrounding soil mineralogy. Although the positive correlation between soil pH and soil ECEC was weak for volcanic soils, it was concluded that liming might nevertheless be an effective means of enhancing the nutrient retention characteristics of these soils provided the practicalities and costs were not prohibitive.     

Demonstrating decline of an iconic species under sustained indigenous harvest – The pig-nosed turtle (Carettochelys insculpta) in Papua New Guinea

Papua New Guinea has astonishing biological and cultural diversity which, coupled with a strong community reliance on the land and its biota for subsistence, add complexity to monitoring and conservation and in particular, the demonstration of declines in wildlife populations. Many species of concern are long-lived which provides additional challenges for conservation. We provide, for the first time, concrete evidence of a substantive decline in populations of the pig-nosed turtle (Carettochelys insculpta); an important source of protein for local communities. Our study combined matched village and market surveys separated by 30 years, trends in nesting female size, and assessment of levels and efficacy of harvest, each of which was an essential ingredient to making a definitive assessment of population trends. Opportunities for an effective response by local communities to these declines needs to consider both conservation and fisheries perspectives because local communities consider the turtle a food resource, whereas the broader global community views it as a high priority for conservation. Our study in the Kikori region is representative of harvest regimes in most rivers within the range of the species in Papua New Guinea, and provides lessons for conservation of many other wildlife species subject to harvest.     

Influence of water level,hunting pressure and habitat type on crocodile abundance in the fly river drainage,Papua New Guinea

Between October 1978 and July 1980, day and night crocodile surveys were conducted at low, normal and high water levels over 2703 km of river and lakeshore in the Western and Southern Highlands provinces of Papua New Guinea. The 1353 crocodiles seen ranged between 0·18 and 2·23 animals per km.Night counts recorded 12·9 times as many crocodiles as day counts over the same area. This may indicate more nocturnal activity than occurs in other crocodilians. Unhunted areas had a greater proportion of large crocodiles than did hunted regions. As the water level rose, the ‘visible juveniles’ category decreased as a result of migration into newly flooded adjacent swamplands. The upstream range of New Guinea crocodiles on the Strickland River extended only to the Burnett River junction.There was an increase in flight distance with increasing body size and this rate of increase was over twice as large for hunted populations as for unhunted ones.     

基于信息熵原理的土壤pH影响因素空间相关性分析

土壤酸碱度是土壤重要的基本性质之一,它受特定的生物气候条件、地形、母质来源以及人为活动的影响.本文选取发育于不同母质和不同地形部位,且土地利用方式多样的丘陵区土壤,进行高密度土壤剖面样品的采集,分析获取表层和底层土壤pH数据.基于信息熵原理对土壤pH与母质、地形和土地利用方式之间的空间相关性进行定量分析,结果表明表层土壤pH主要受土地利用方式的控制,耕作土壤pH值明显小于自然土壤;而底层土壤pH主要受母质的影响,不同母质上发育的土壤pH值从高到低依次排列为紫红色砂页岩风化物、下蜀黄土和砂岩风化物.本文的研究特色是应用联合信息熵算法,在定性变量和定量变量之间进行定量的空间相关性分析,这点克服了以前定性变量和定量变量之间相关关系研究的不足.     

Losing ground? soil loss and erosion in the highlands of papua new guinea

First impressions suggest that the risk of soil loss through fluvial erosion from land under cultivation is considerable in the Southern Highlands Province of Papua New Guinea. the climate is very wet all year round, The terrain precipitous, and people regularly farm on steep slopes. the Wola-speaking people, who occupy a series of valleys in the centre of the province, and who practice a semi-shifting form of cultivation, are nonetheless off-hand about soil conservation and declare that erosion is not a serious problem. This paper assesses the status of their assertions by calculating potential soil loss rates. It applies the universal soil loss equation to data on rainfall erosivity, soil erodibility, slope length and steepness, vegetation cover and conservation measures, to compute likely runoff losses. the calculations suggest that, The steep slopes cultivated and wet climate notwithstanding, The local population's assessment of the dangers of erosion is realistic and not reckless. Although rainfall is high, it is rarely of an intensity sufficient to threaten serious soil erosion losses. the physical properties of the soils, which feature volcanic ash components and high organic matter levels, are such that they are particularly resistant to erosion. the staple crop of the region, sweet potato (Ipomoea batatas), also gives particularly good ground cover and protection when established, effectively shielding the soil from erosive rainfall.     

Origin of the name “Ando soils”

The name “Ando soils” was introduced in 1947 during reconnaissance soil surveys in Japan by American soil scientists. The name identified a great soil group of the intrazonal order in the then current U.S. system. The group consists of soils that had rather thick, dark A1 horizons, were derived from volcanic ash and were acid in reaction. The great soil group was later recognized in places as far apart as Alaska, France and New Guinea. Although the original name is being phased out at the present time, it has been the source of two other names that are in current use, viz., Andepts and Andosols.     

BOOK REVIEW

Book reviewed in this articles:
Review of Soil Research and Management in Papua New Guinea . Special issue of Papua New Guinea Journal of Agriculture, Forestry and Fisheries, 1998.     

SOIL TEXTURE PATTERNS IN THE ALLUVIUM OF THE LOWER INDUS PLAINS

Soil texture was mapped in the immature alluvial soils of the Lower Indus plain. A disadvantage of soil texture as a mapping criterion in such soils is the great complexity of their textural patterns. The geomorphological background of the Lower Indus plains is examined, and a classification of texture and textural profiles is defined. The mapping unit proposed, the‘textural association', comprises a certain range of textural profiles within a given landform, related to each other by the modes of deposition which established that landform. It seems likely that the textural association could, in more detailed surveys, form the basis of a soil series classification.     

应用危险确认模型评估土地管理的可持续发展

New Zealand is highly dependent on its soil resource for continued agricultural production.To avoid depleting this resource,there is a need to identify soils and associated land management practices where there is a risk of soil degradation.Environmental integraity and ecosystem services also need to be maintoained.Accordingly,to ensure sustainable production,The on -and off-site environmental impacts of aldn management need to be identified and managed.We developed a structural vulnerability index for New Zealand soils.This index ranks solis according to their inherent susceptibility to physical degradation when used for agricultural (pasture,forestry and cropping) Purposes.We also developed a rule-based model to assess soil sompaction vulnerability by characterising the combined effects of resistance and resilience,Other soil attributes have been approatised using seven chemical,physical and biological indicators of soil quality.These indicators have been applied in a nation -wide project involving data collection from over 500 sites for a range of land uses.These soil quality data can be interpreted via the World Wide Web -through the in teractive decisionsupport tool SINDI,The land-use impact model is a framework to assess agricultural land management and environmental sustainability,and may be applied to land units at any scale.Using land resource data and information the model explicitly identifies hazards to land productivity and environmental integrity,It utilises qualitative expert and local knowledge and quantitative model-based evaluations to assess the potential environmental impacts of land-management pratices.The model is linked to a geographic information system(GIS),allowing model outputs.such at the environmental impacts of site-specific best management practices,to be identified in a spatially explicit manner,The model has been tested in New Zealand in an area of pastoral land use.Advantages of this risk identification model include:utilising current knowledege of the causes and effects of land-management practices on soil degradation;linking land management practice to both on-and off-site environmental consequences;identifying important gaps in local knowledge,and providing spatially explicit information on the environmental impact of land-management practices.     

Soils at risk of accelerated erosion in England and Wales

Abstract. The 296 soil associations of the National Soil Map of England and Wales are placed into five categories of erosion risk. These are based on land use, landform and soil properties and take into account the extent of erosion in the uplands, and its frequency, extent and rates in the lowlands. Erosion of arable land is by water or wind, but in the uplands frost action and disturbance by sheep are also important. A large proportion of arable England (36%) is at moderate to very high risk of erosion, including much of the better drained and more easily worked land, especially sandy soils. In the uplands thin soils or deep peats are most at risk. If land use changes, because of increasing intensification of agriculture or in response to climatic changes, many soil associations will become more at risk of erosion.     

The crocodile project in Papua New Guinea

Crocodilians throughout the world are under very heavy pressure from habitat destruction, human displacement and deliberate hunting for skins. In Papua New Guinea crocodiles of two species are still relatively plentiful and play an important part in the economy of many remote settlements. An attempt is being made by the national government to implement a policy intended to bring about the harvesting of wild crocodiles on a sustained yield basis and provide an economic incentive for conserving wild stocks in their natural habitat. Low human population density and the existence of vast swamplands make this a possibility. In recognition of the policy and the exceptional circumstances, Papua New Guinea has been exempted from trade restrictions imposed by a number of countries under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).     

Soil mapping for land‐use planning in a karst area of N Thailand with due consideration of local knowledge

For the development of sustainable land‐management systems in the highlands of N Thailand, detailed knowledge about soil distribution and soil properties is a prerequisite. Yet to date, there are hardly any detailed soil maps available on a watershed scale. In this study, soil maps on watershed level were evaluated with regard to their suitability for agricultural land‐use planning. In addition to common scientific methods (as underlying the WRB classification), participatory methods were used to exploit local knowledge about soils and to document it in a “Local Soil Map”. Where the WRB classification identified eight soil units, the farmers distinguished only five on the basis of soil color and “hardness”. The “Local Soil Map” shows little resemblance with the detailed, patchy pattern of the WRB‐based soil map. On the contrary, the “Local Soil Map” is fairly similar to the petrographic map suggesting that soil color is directly related to parent material. The farmers' perception about soil fertility and soil suitability for cropping could be confirmed by analytical data. We conclude that integrating local soil knowledge, petrographic information, and knowledge of local cropping practices allows for a rapid compilation of information for land‐evaluation purposes at watershed level. It is the most efficient way to build a base for regional land‐use planning.     

利用人工神经网络以及相关地形属性绘制数字土壤地图

Detailed soil surveys involve costly and time-consuming work and require expert knowledge. Since soil surveys provide information to meet a wide range of needs, new methods are necessary to map soils quickly and accurately. In this study, multilayer perceptron artificial neural networks (ANNs) were developed to map soil units using digital elevation model (DEM) attributes. Several optimal ANNs were produced based on a number of input data and hidden units. The approach used test and validation areas to calculate the accuracy of interpolated and extrapolated data. The results showed that the system and level of soil classification employed had a direct effect on the accuracy of the results. At the lowest level, smaller errors were observed with the World Reference Base (WRB) classification criteria than the Soil Taxonomy (ST) system, but more soil classes could be predicted when using ST (7 soils in the case of ST vs. 5 with WRB). Training errors were below 11% for all the ANN models applied, while the test error (interpolation error) and validation error (extrapolation error) were as high as 50% and 70%, respectively. As expected, soil prediction using a higher level of classification presented a better overall level of accuracy. To obtain better predictions, in addition to DEM attributes, data related to landforms and/or lithology as soil-forming factors, should be used as ANN input data.     

Landform classification and soil distribution in hummocky terrain, Saskatchewan, Canada

This study presents a classification of distinct, three-dimensional landform elements and examines the relationship between these landform elements and selected soil morphological properties of Udic Boroll soils in southern Saskatchewan, Canada. The classification is based on defined ranges of three criteria derived from topographic data: gradient, profile (downslope) curvature, and plan (across-slope) curvature. Seven landform elements are recognized: convergent shoulders, divergent shoulders, convergent backslopes, divergent backslopes, convergent footslopes, divergent footslopes, and level elements. All of the elements are easily identified in the field.

The thicknesses of A horizons and depths to calcium carbonate of the soils were consistently greater in convergent versus divergent elements in the same profile group (e.g. shoulders), and showed an overall increase in the sequence shoulders相似文献