Soil Quality Variables Research Articles

A tale of two theories, a chronosequence and a bioindicator of soil quality

In this Citation Classics commentary, we reflect upon a paper that we published in Soil Biology & Biochemistry in 1995 and that provided a critical assessment of the use of the microbial metabolic quotient (qCO2 or the ratio of microbial respiration to biomass) as a bioindicator of soil quality. This quotient is based on Eugene Odum's ‘Theory of Ecosystem Succession’ published in 1969 and has been widely used in soil ecology for over 30 years; a higher qCO2 value is reflective of greater energetic inefficiency of the soil microbial biomass. At the time of our study a strong demand was emerging for easily measured soil quality bioindicators and qCO2 was an obvious candidate. In our paper we drew on the plant ecological strategy theory of J. Philip Grime by highlighting that, in addition to the two major types of ecosystem identified in Odum's theory (‘disturbed’ and ‘developed’), there is a third type, ‘stressed’ that is characterized by persistently harsh conditions (e.g., nutrient poor, cold, dry). We measured qCO2 for soils collected from along the Franz Josef Glacier chronosequence in New Zealand that spans 120,000 years and which includes all three types of ecosystems, going from disturbed to developed to stressed. We found that qCO2 was least for the developed stage and was similarly high for the disturbed and stressed stages; it was not possible to discriminate between early successional stages characterized by high disturbance and high quality resource inputs from late successional stages characterized by substantial nutrient limitation and poor quality resource inputs. We further reanalyzed data from several publications from which qCO2 could be calculated and these reinforced our empirical findings. Upon reflecting on our earlier work, we conclude that highly contrasting types of ecosystems that vary in their disturbance regime and stress cannot be arranged to any satisfaction along a unidimensional axis, and that no simple, unidimensional bioindicator (including qCO2) is capable of adequately summarizing variation of soil quality among ecosystems. However, we also emphasize that despite its limitations as a bioindicator of soil quality, the qCO2 concept has proven to be highly useful for advancing conceptual understanding of the functioning of the soil microbial community and its contribution to ecosystem processes.

Evaluation of Soil Quality in Relation to Landuse Effect in Akamkpa, Cross River State – Nigeria

Soil quality variation in the tropical rainforest zone of Akamkpa upon conversion from the natural vegetation to other landuse types (natural forest, reforested lands, cultivated upland soils, swamps, soils around quarry sites, built-up areas and fallow lands) was evaluated with a view to ascertain the changes in physical, chemical and biological characteristics of the soils and determine to what extent these changes affects soil quality degradation rates and vulnerability potential. Surface soil samples were collected from four points in each landuse type at the depth of 0-15cm and mixed to obtain a composite sample for routine laboratory analysis of selected soil quality parameters. The soils were generally sandy loam to clay loam on the surface and lateritic clay at the subsurface. Bulk density varied from 1.12-1.48mgcm3, soil porosity was higher in cultivated soil (78.83%) and lower in the swamps (25.22%) water holding capacity was highest in swamps (72.9%) and lowest in the built-up areas (33.6%). Aggregate stability index was lower in the cultivated soils (0.44) and higher in the natural forest (0.69). pH value varied from 4.2-6.0, organic carbon levels were higher in the natural forest (9.84gkg) and lowest in built-up areas (4.16gkg-1). Total nitrogen varied from 0.42-0.72gkg, the value was lowest in built-up areas and highest in the natural forest soils. C:N ratio varied from 8.63-13.12. these values were lowest in cultivated soils than natural forest and reforested soils. Available P was highest in fallow lands and lowest in built-up areas. Exchangeable bases show variability across landuse types with calclium, potassium, ECEC higher in natural forest soils. Al3+, SAR, Fe, Mn, Cu and S higher were in soils around quarry mines than any other landuse type. Reforested lands, cultivated uplands and fallow lands showed a slight variability in the selected chemical parameters. The biological properties were highly correlated with soil quality status in response to landuse change types. Total microbial biomass was higher in reforested lands and lowest in built-up areas, while active microbial biomas was higher in fallow lands. Higher rates of qCO2:T for the cultivated soils, qCO2:A rates was higher for fallow lands. Resuts revealed that built-up areas and soils around quarry mines has a significantly ower SDR/VP than any other landuse type. Percentage soil quality rating was higher in the fallow land (88.0%), forested lands and reforested lands (83.3%), cultivated uplands (66.0%) swamps (56%), soils around quarry mines (44%) and built-up areas (33%). The findings suggest that the soils under fallow are slightly capable to resist degradation. Management practices such as planting leguminous crops, increased fallow period, organic manuring, planting of fast growing vegetative species and returning crop residues to the soil as a way of building up used carbon stocks.

Assessment of the quality of the Harran Plain soils under long-term cultivation.

Soil quality refers to the ability of soils to perform their functions well. The soils of the Harran Plain, Turkey, have been put into intensive crop production with the introduction of an irrigation scheme and become increasingly degraded due to unsustainable management and cropping systems that resulted in the loss of production potential. The goal of this study was to quantify the quality of common soil series in the Plain using soil quality indexes (SQI) and to compare SQIs of two long-term crop rotations, cotton and wheat-corn cultivation, and different soil types. Over 400 samples were collected at a 0- to 30-cm depth and analyzed for 31 soil variables. The best representative soil quality variables forming a minimum data set (MDS) were selected using principal component analysis (PCA), and soil quality scores were obtained using both linear and non-linear scoring functions. The MDS included three physical (hydraulic conductivity, bulk density, and plant available water content), two biological (soil organic matter and catalase enzyme activity), and nine chemical soil quality indicators (CEC, pH, plant available Cu and Fe, exchangeable Na and K, soluble Ca, Mg, and Na). Because of the low level of SOM, soil qualities were overall low with indexes obtained using two scoring functions ranging from 38.0/100 to 48.7/100. Correlations between SQI obtained using two approaches (linear vs. non-linear; r>0.61) and using two data sets (all data vs. MDS; r>0.79) were high. Non-linear scoring functions were more sensitive to management impacts. ANOVA models testing the individual impacts of soil types and crop management on soil quality were statistically different (p<0.01), but the models including interactions were not. Overall, the fields under cotton cultivation were generally associated with higher clay contents and had the lowest SQIs as a result of intensive cultivation.

Long-term agricultural activity affects anthropogenic soil on the Chinese Loess Plateau

Anthropogenic activities largely influence the soil quality of agricultural fields and the composition of soil. Samples of typical anthropogenic Loutu soil in the Guanzhong area of the Loess Plateau, Shaanxi Province, China were collected and measured for soil compaction, bulk density, total organic carbon (TOC), active organic carbon (AOC), and soil enzyme activities to investigate spatial variations in soil quality. The results indicate that soil compaction and bulk density increased with increasing distance from the farm village, whereas soil TOC, AOC, and soil enzyme activities firstly increased and subsequently decreased with increasing distance from the farm village. All of the tested parameters presented clear concentric distribution. Vertically, soil compaction and bulk density in the topsoil were lower than those in the subsoil, but all other tested parameters in the topsoil were significantly higher than those in the subsoil. In addition, there was a significant positive correlation between organic carbon content and enzyme activities, confirming that the spatial distribution of Loutu soil characteristics has been affected by long-term anthropogenic activities to some extent. The results of this study imply that the use of farmyard manure and appropriate deep plowing are important and effective ways to maintain and improve soil quality.

Moose directly slow plant regeneration but have limited indirect effects on soil stoichiometry and litter decomposition rates in disturbed maritime boreal forests

Summary Foraging decisions by herbivores are modulated by physiological demands for nutrients and these decisions can influence the biomass, abundance and dynamics of plant species with consequences on key ecosystem processes, such as nutrient cycling and decomposition. Some studies have found that large browser populations can reduce the abundance of nutrient‐rich preferred species, promoting the dominance of nutrient‐poor non‐preferred species. This can have indirect effects on soil nutrient concentrations, soil microbe community composition and above‐ground invertebrates and birds that depend on nutrient‐rich plant species. However, very little research has compared the impact of biotic and abiotic features on nutrient cycling and decomposition in areas of high moose density. We performed a field study to test the generality of moose effects on forest ecosystems observed in iconic study systems such as Isle Royale. Specifically, we used 10 paired moose exclosure and control plots to test the effects of moose on plant community characteristics, litter fall quantity, soil properties and litter decomposition rates in regenerating disturbed forests in Newfoundland, Canada. We found evidence that moose reduce plant height and plant litter biomass, thereby affecting the quantity of carbon, nitrogen and phosphorus available in litter fall with potential indirect effects on soil pH and soil depth. However, we found no evidence that the direct effects of moose lead to indirect effects on soil quality, soil moisture and litter decomposition rates. Disturbance regime and site explained a large portion of the variance in plant community characteristics, litter fall quantity, soil properties and litter decomposition. Our results suggest that while introduced moose in Newfoundland have measurable direct influence on plant regeneration and litter fall biomass, other factors such as disturbance history and climate may be more important predictors of landscape‐scale variation in soil quality and litter decomposition rates. Our study suggests a need for further development of theory to predict the relative contribution of biotic vs. abiotic effects on nutrient cycling in forest ecosystems. A lay summary is available for this article.

Study on Determination of Categories of Soil Quality Variable Concentrations in Brackish water Ponds of Java Island, Indonesia

Soil quality plays pivotal role in increasing productivity and brackish water ponds successfulness, including ponds of Java Island, Indonesia. However, the availability of data on concentration categories for soil quality variables for ponds soils in Java Island, which is volcanic-dominated soils and the largest area for ponds in Indonesia, is still scarce. This study was aimed to categories soil quality variable concentrations as an initial point in interpreting pond soils quality of Java Island. Soil samples were collected from two different soil depths of 923 sampling points representing 13 regencies/cities of West Java, Central Java, and East Java Provinces. Twenty soil quality variables were measured based on in-situ and ex-situ measurements. The t-Student and U-Mann Whitney tests were applied to analyses the differences in soils quality at each soil depth which were firstly analyzed using z-score to eliminate outlier data. The data were firstly rearranged from the smallest to the largest data prior to measuring data deciles; the deciles, as considered as the basic measurement, were used for categorizing each soil quality variable. The results of this study indicated that the pH and nutrients are higher at pond top soils, 0-0.2 m compared to that observed on the depth of 0.2-0.5 m. Concentration of soil quality variables such as SKCl, SP, SPOS, TPA, TAA, TSA, and pyrite relatively similar between the two depths. Data of each soil quality variable were categorized into very low, low, moderate, high, and very high to facilitate a comparison to other data of ponds soil qualities. The results of this study are not recommended for assessing the relationship between ponds soil quality and ponds productivity; yet are usefull in measuring which variable of ponds soil quality is categorized as very low, low, moderate, high or very high; and also useful in making decision on pond soils quality management in Java Island.

Comparison of two cold test procedures for seed vigour evaluation of maize inbred lines

Cold test (CT) is a valuable method of assessing maize seed vigour. Although widely used CT is not standardized because of variations in CT procedures. The objective of this study was to evaluate seed vigour of 15 maize inbred lines developed at the Maize Research Institute Zemun Polje, using two different substrates (soil and sand) in a severe CT (7.5°C for 10 days followed by 7 days at 20/30 °C). Statistical analysis showed that inbred lines differ significantly in seed vigour, and no difference between two applied substrates in CT. Coefficients of variation were lower in CT with sand (6.05 %), compared to the CT with soil (6.74%) due to variation in soil quality and presence of soil-borne pathogens. Both CT procedures were highly correlated with field emergence. Results of this research indicate that CT with sand is appropriate for testing maize seed vigour, with the potential for standardization.

Land Use Change and Policy in Iowa’s Loess Hills

&lt;p class="sar-body"&gt;&lt;span lang="EN-US"&gt;Land use changes have important implications on ecosystems and society. Detailed identification of the nature of land use changes in any local region is critical for policy design. In this paper, we quantify land use change in Iowa’s Loess Hills ecoregion, which contains much of the state’s remaining prairie grasslands. We employ two distinct panel datasets, the National Resource Inventory data and multi-year Cropland Data Layers, that allow us to characterize spatially-explicit land use change in the region over the period 1982-2010. We analyze land use trends, land use transitions and crop rotations within the ecoregion, and contrast these with county and state-level changes. To better comprehend the underlying land use changes, we evaluate our land use characterizing metrics conditional on soil quality variables such as slope and erodibility. We also consider the role of contemporary agricultural policy and commodity markets to seek explanations for land use changes during the period of our study. Although crop production has expanded on the Loess Hills landform since 2005, much of the expansion in corn acres has been from reduced soybean acreage. We find that out of the total 258 km&lt;sup&gt;2&lt;/sup&gt; increase in corn acreage during 2005-’10, about 100 km&lt;sup&gt;2&lt;/sup&gt; transitioned from soybeans. Data also indicate intensifying monoculture with higher percentage of corn plantings for two to four consecutive years during 2000-’10. In addition, crop production is found to have moved away from more heavily sloped land. Cropping does not appear to have increased on lands with higher crop productivity.&lt;/span&gt;&lt;/p&gt;

Assessment of soil quality of coastal shrimp culture pond at Chakaria, Cox’s Bazar

The present study was carried out to find the status of different soil quality variables of coastal shrimp culture pond at different tidal marks of Chakaria, Cox’Bazar during the period from August 2012 to July 2013. The values of different soil quality variables such as sand, silt, clay, pH, organic matter, NO2-N, PO4-P, exchangeable K+, Soil compactness, bulk density, particle density, porosity and Field water capacity fluctuated between 2.04-43.88%, 30.80-55.36%, 23.98-49.94%, 5.9-8.9, 1.62-9.95%, 4.01-9.92 ?g/Kg, 1.14-3.50 ?g/Kg, 0.82-1.74 meq/100g, 14.00-31.5 cm, 0.80-1.21 gcm-3, 2.11-2.74 gcm-3, 52.7-65.97% and 44.27-78.18% respectively. Significant differences (p&lt;0.05) in the values of sand, silt, clay, bulk density, porosity, NO2-N and field water capacity of soil of the culture ponds at tide marks were observed. Strong correlations between soil bulk density vs sand (0.863), field water capacity vs clay (0.845), field water capacity vs silt (0.797), exchangeable K+ vs PO4-P (0.787), porosity vs field water capacity (0.769) and porosity vs clay (0.705) were found at 0.01% level of significance.J. Asiat. Soc. Bangladesh, Sci. 42(1): 21-27, June 2016

THE USE OF PATH ANALYSIS IN THE DETERMINATION OF ENVIRONMENTAL FACTOR EFFECTS ON THE TOTAL PRODUCTION OF AQUACULTURE PONDS IN PASURUAN, EAST JAVA PROVINCE

Environmental factors in the form of soil and water quality are the important factors of aquaculture pond productivity, including total production (tiger shrimps, Penaeus monodon, and milkfish, Chanos chanos) in Pasuruan, East Java Province. The objective of this study was to analyze the direct or indirect effects of soil and water quality on the total production of ponds in Pasuruan using a path analysis application. Data were collected in the pond areas around Pasuruan Regency including Nguling, Lekok, Rejoso, Keraton, and Bangil Sub-Districts as well as Pasuruan City. Soil quality was determined as a free variable and exogen; water quality as mediate variable, suspended, and endogen; as well as milkfish production as suspended variable and endogen. Environmental characteristics were illustrated using descriptive statistics, while environment factor effects on total production were analyzed using path analysis. The results of path analysis show that from the 12 analyzed soil quality variables, only two variables were affected in the total production of pond (tiger shrimps and milkfish) namely: contents of soil organic carbon and soil phosphate. While based on 11 water quality variables, two variables (water salinity and water iron) were affected the total production of ponds in Pasuruan Regency. The direct effects of soil organic carbon and phosphate on the total production were 0.314 and -0.600, respectively. Water salinity and water iron gave direct effects on total production amounting to -0.678 and 0.358 respectively. It is also found that two soil variables which were affected in the total production, did not indicate the effect towards water quality in ponds. Further implication of this research is put more attention for these variables into pond’s management in order to gain more production. Technical application could be appropriate for pond preparation and frequently water changing during grow out.

Tradeoffs between production and perennial vegetation in dairy farming systems vary among counties in the northeastern U.S.

Dairy farms that grow more perennial vegetation as grazing pastures or conserved forages can offer many environmental benefits but may show reduced milk production relative to farms feeding higher amounts of grain and corn silage. Because yields of annual and perennial crops vary with soil type, an accurate comparison of the productive potential of these systems over county or regional scales may require taking into account spatial variation in soil quality. In this study, we present a novel approach to calculate the production from dairy systems that adjusts average crop yields to the productive potential of local soils using the National Commodity Crop Productivity Index (NCCPI). We used on-farm survey data to define confinement and grazing systems with varying amounts of perennial forage and applied our method to a sample of five counties in the northeast United States. High corn silage farm systems produced 21 to 168% more milk per hectare of farmland than grazing-based farm systems, but variation among counties was greater than variation among systems, with the best (Lancaster, PA) producing as much as 5.3 times more than the least (Orange, VT). Adjusting yields for soil productivity had smaller effects on milk production than differences in farm system or county. On average, grazing farm systems generally produced slightly more milk when yields were adjusted using the NCCPI (8%) while high corn silage systems showed a moderate decrease (13%). Compared to scenarios of all local crop production, scenarios with unlimited corn and soybean imports often more than doubled county-scale milk production. Restricting grain imports to prevent excess phosphorus resulted in a 3–15% decrease in milk production relative to unlimited imports, but still produced far more milk than in the all local production scenarios. Sensitivity analysis of the model showed that milk production in each county was very responsive to changes in perennial forage yields (especially for grazing systems), responsive to changes in average daily milk production per cow, and generally not responsive to changes in the productive lifetime of lactating cows. This study demonstrates a persistent tradeoff between perenniality and production in dairy systems, but suggests that opportunities may exist to maintain current milk production levels in the Northeast while also expanding land cover in perennial vegetation.

Soil Quality in Relation to Agricultural Production in the North China Plain

Sustainable agricultural production is of vital importance to food supply security. This study aimed to investigate crop yield response to spatial variability of soil quality at a county scale in the North China Plain (NCP) and subsequently derive key soil quality indicators. Soil samples were geo-referenced and taken in 2008 from both surface (0–20 cm) and subsurface (20–40 cm) layers in 132 fields throughout the Fengqiu County, located in the centre of the NCP, for subsequent soil properties' analyses. Annual crop yields were obtained from the same fields where soil samples were collected. Soil quality was evaluated based on a fuzzy set with 13 soil properties, and its spatial distributions were investigated by integrating geostatistical analysis and geographic information system (GIS) techniques. Soil quality indices were classified into five grades, and their spatial distributions were mapped within the county. The surface soil qualities were about one to two grades higher than the subsurface soil. The quality indices for surface and subsurface soils were positively associated with the annual crop yields, suggesting the importance of both. Soil organic matter, total nitrogen, available P, and available K contributed 50% of the combined weight to the soil quality index and were identified as key indicators of soil quality status in the area in terms of sustainability.

Soil Quality Variation under Enset based Conservation Tillage and Cereal based Conventional Tillage System in Southern Highlands of Ethiopia

With the objectives of assessing the variation of soil quality indicators; two land use types: Enset based conservation tillage system (EBCSTS) and Cereal based conventional tillage system (CBCVTS) were selected in Gedeo zone, Bule woreda, Southern Ethiopia. A total of 48 composite and undisturbed (for bulk density determination) soil samples (2 land use types_4 blocks_3 replication_2 soil depth: 0-15 cm and 15-30 cm) were collected for laboratory analysis. The result showed that soil textural fractions (sand, p<0.001; silt, p = 0.003 and clay = p = 0.001) and soil pH (p<0.001) significantly varied with land use types. Moreover, soil moisture content (p<0.001), bulk density (p = 0.016, p = 0.002), SOC (p<0.001), TN (p<0.001) and CEC (p<0.001, p = 0.001) have shown significant variation with land use types and soil depth respectively. Sand and clay were higher in EBCSTS and CBCVTS, respectively. Higher amount of sand fraction was observed under 0-15 cm on EBCSTS and 15-30 cm on CBCVTS land use types. Lower soil bulk density (g cm -3 ) and higher amount of SOC (%), TN (%), soil pH, CEC (meq/100g soil) and SMC (%) were observed at 0–15 cm soil layer under the EBCSTS. Soil bulk density (g cm -3 ), soil pH and SMC (%) increased while SOC (%), CEC (meq/100g soil) and TN (%) decreased with soil depth in both land use types. Improvement in the soil quality under EBCSTS was due to the presence of less soil disturbance coupled with higher addition of organic matter (SOM) in the soil. Thus, through implementing EBCSTS, it is possible to protect and maintain soil qualities for sustainable soil management and cropping practices in the area.

Advancing analysis of spatio-temporal variations of soil nutrients in the water level fluctuation zone of China's Three Gorges Reservoir using self-organizing map.

The ~350 km2 water level fluctuation zone (WLFZ) in the Three Gorges Reservoir (TGR) of China, situated at the intersection of terrestrial and aquatic ecosystems, experiences a great hydrological change with prolonged winter inundation. Soil samples were collected in 12 sites pre- (September 2008) and post submergence (June 2009) in the WLFZ and analyzed for soil nutrients. Self-organizing map (SOM) and statistical analysis including multi-way ANOVA, paired-T test, and stepwise least squares multiple regression were employed to determine the spatio-temporal variations of soil nutrients in relation to submergence, and their correlations with soil physical characteristics. Results showed significant spatial variability in nutrients along ~600 km long shoreline of the TGR before and after submergence. There were higher contents of organic matter, total nitrogen (TN), and nitrate (NO3-) in the lower reach and total phosphorus (TP) in the upper reach that were primarily due to the spatial variations in soil particle size composition and anthropogenic activities. Submergence enhanced soil available potassium (K), while significantly decreased soil N, possibly due to the alterations of soil particle size composition and increase in soil pH. In addition, SOM analysis determined important roles of soil pH value, bulk density, soil particle size (i.e., silt and sand) and nutrients (TP, TK, and AK) on the spatial and temporal variations in soil quality. Our results suggest that urban sewage and agricultural runoffs are primary pollutants that affect soil nutrients in the WLFZ of TGR.

Use of the Regularities of Within-Field Variability of Arable Soil Fertility in Precision Agrotechnologies

Abstract. The paper states the regularities of the within-field variation of soil fertilitywhich are important for variable rate fertilizer application under conditions of precisionagrotechnologies including the technologies which limit the agroeconomic efficiency. Asit is well known, the usual (traditional) fertilizer practice stipulates their application takinginto account average indices of soil fertility: mobile plant food elements (N, P, K etc.)content in the plow layer. At the same time, one part of the plants gets excess of mineralnutrition, and the other part – its deficiency. That results in shortage of agricultural products,their deterioration and also the pollution of the environment and the soil with the excessesof agrochemicals in overfertilized plots. In the last decades traditional technologies giveplace to high-precision agrotechnologies with differentiated fertilizer application takinginto account within-field heterogeneity of soil fertility. There are several constraints forwidespread adoption of high-precision agrotechnologies including the underestimation ofthe character of within-field variability of soil quality. Our investigations reveal eightregularities of the within-field variation of agrochemical indices, which characterize soilfertility in arable soils. These regularities would allow to more seriously estimate theefficiency of variable rate fertilizer application under conditions of precisionagrotechnologies.Key words: soil, within-field contours, variability, regularities, precision agriculture.

Assessing soil quality under different land cover types within shifting agriculture in South Cameroon

The common agricultural practice in the humid tropical forest zone of Cameroon is shifting cultivation, which leads to a landscape mosaic system characterized by a diversity of land cover types. Our objective was to evaluate soil properties and soil quality under these land cover types and to investigate on their interrelationships. Topsoil samples (0–20cm) were collected at the same time from 8 different land cover types (bare soil with burned vegetation biomass (FR1), bare soil with unburned vegetation biomass (FR), Chromolaena odorata fallow (JC), bush ligneous fallow (JR), secondary forest (SF), primary forest (FC), Gilbertiodendron dewevrei forest (FG), and raffia and Uapacca forest (RA)) and analysed for routine laboratory determinations. A soil quality index (SQI) computed based on soil chemical properties, analysis of variance and multiple comparison tests were used to compare soils from different land cover types. Principal component analysis (PCA) was used to select the most appropriate indicators that control soil quality. Several soil properties showed high to very high coefficient of variation within the land cover types. Organic matter was significantly high under forested land cover types (FC, FG, RA) and under bare soil with burned vegetation (FR1). Soil quality differs significantly (p=0.000) from one land cover to another and shows the following ranking: SQI_FR1≫SQI_FG>SQI_RA>SQI_FR>SQI_FC>SQI_JC>SQI_FS>SQI_JR. Organic matter (OM), available P, calcium (Ca), and pHw combined, accounted for 88.5% of the variation of soil quality. The soil quality appeared to be highly influenced by ashes from burned vegetation biomass which temporally enriches soils with nutrient elements and by the organic matter supplied by forested land cover types.

Temporal variability in soil quality after organic residue application in mature oil palm plantations

Despite the dramatic changes in land-use arising from expansion of the palm oil industry, soil biodiversity in oil palm plantations has been little investigated. The present study aims to assess the effect of organic waste recycling (empty fruit bunches, EFB) on soil biodiversity in a mature plantation in Sumatra, Indonesia. A chronosequence was delineated taking into account the time between the applications of EFB and soil sampling; intervals of 1, 3, 6, 12, 18 and 24 months were compared with control plots without EFB application. Soil physical and chemical characteristics and macrofauna and nematofauna populations were analysed. The findings highlighted three distinct periods: a first disturbance period (0–6 months) showing a marked increase in pH, potassium content, base saturation and macrofauna abundance, especially ants, whereas earthworm, millipede and nematode populations were substantially reduced; a resilience period (6–18 months); and a final period (18–24 months) showing an improvement in most soil fertility parameters and a high density of earthworms, millipedes and nematodes. The impact of EFB application on soil quality changed as a function of time, and the present results explain the apparent discrepancy of some previous published results. This research is the first stage towards developing new strategies for enhancing soil biodiversity and related services for sustainable oil palm cultivation.

Changes in soil properties after a wildfire in Fragas do Eume Natural Park (Galicia, NW Spain)

The impact of a wildfire on some selected physicochemical, chemical (water retention, pH, electrical conductivity, free Fe and Al oxides, total C, extractable C), biochemical (microbial C, soil respiration, bacterial activity, β-glucosidase, urease and phosphatase activities) and microbiological properties (analysis of phospholipid fatty acids, PLFA pattern) was evaluated in Fragas do Eume Natural Park (NW Spain). Soil samples were collected three months after the wildfire from the A horizon (0–2.5 and 2.55cm) of the unburnt and burnt soil under climax vegetation (Quercus) and non-autochthonous vegetation (Eucalyptus). The results indicated that, independent of the vegetation considered, the wildfire induced short-term modifications of most soil properties analysed, more accentuated changes being those related to labile fractions of the soil organic matter (extractable C and microbial biomass C, negative effects) as well as those in pH and bacterial growth values (positive effects). The fire effect was often more noticeable in the 0–2.5cm layer than in the 2.5–5cm layer. The results of a principal component analysis performed with the matrix of the physicochemical and biochemical data showed that vegetation was the most important factor controlling the overall quality of these soils and that wildfire is also an important source of variation in soil quality. This is in agreement with the PLFA pattern, differentiating clearly the Quercus soil samples from the Eucalyptus ones and, to a lesser extent, the burnt soil samples from the corresponding unburnt ones. Medium- and long-term consequences of these microbial changes in the functioning of the plant–soil system should be investigated in order to preserve the biodiversity of the Natural Park.

Evolutive and regressive soil sequences for characterization of soils in laurel forest (Tenerife, Canary Islands) .

Soil degradation processes have achieved the recognition of a global environmental problem in recent years. It has been suggested by various international forums and organizations that in order to adequately establish methods to combat land degradation, it is necessary to evaluate this degradation locally and at a detailed scale. The evaluation of soil degradation of natural ecosystems at a detailed scale requires the definition of standards to which to compare this degradation. To define these standards and properly handle the processes that give rise to variations in soil quality and degradation, it is necessary to establish in some detail the pedogenic processes that have or have not taken place in a particular area and which lead to the formation of a mature soil. A mature soil should be considered as standard in these situations and, therefore, a non-degraded soil. This paper presents the possible evolutive and regressive sequences of soil, and provides some examples of using this methodology to evaluate the degradation of the same in the Monteverde of the island of Tenerife. It also presents some physical, chemical and mineralogical properties of climacic mature soils, degraded soils and low quality soils, and examines their similarities and differences in this bioclimatic environment and on different parent materials. Thus it is observed that the main processes of degradation in these areas are related to plant cover modifications that lead to the decreasing protection of the soil surface, which results in the long term, in the onset of degradation processes such as water erosion, biological degradation, loss of andic properties, compaction and sealing and crusting surface, loss of water retention capacity, illuviation, etc. Climacic soils that can be found in areas of steep lava flows are Leptosols, while gently sloping areas are Cambisols and Andosols. On pyroclastic materials there are vitric Andosols and andic Andosols according to their degree of evolution. The most characteristic regressive processes are illuviation/leaching, resulting in Luvisols, Lixisols and Alisols; and water erosion, causing the presence of secondary Leptosols.

Soil quality as influenced by land use history of orchards in humid subtropics

This study assessed how land use change from native deciduous forest to tropical fruit orchards viz. guava (Psidium guajava L. cv. Allahabad Safeda) and sapota (Manilkara achras Mill. cv. Cricket Ball) under humid subtropics of India impacts the soil physical, chemical and biological properties. This study also validated whether the existing orchard management practices are adequate to maintain sustainable soil quality in different guava and sapota orchards established along a chronosequence by comparing the changes in soil quality attributes between native forest (considering as baseline ecosystem) and orchards. The land-use-induced change caused significant reduction in soil physical properties (12.0 to 31.4%), chemical properties (8.8 to 61.5%), earthworm density (32.0 to 58.7%), earthworm biomass (43.6 to 68.0%) and soil enzyme activities (8.8 to 54.1%) beneath orchards relative to native forest. There was significant increase in bulk density (12 to 14%), available-P (104 to 296%) and DTPA-Fe content (36.3 to 81.4%) in orchard soils. The combined results of the principal component analysis and the analysis of similarity revealed that stronger influencing factor of variability in soil quality attributes was in the order of land-use change>orchard age>orchard type. The soil deterioration index (SDI) values (ranged from −35.3 to −77.8%) for orchard soils relative to FS indicated that orchard soils were in the serious state of deterioration in terms of physico-chemical and biological properties; and the extent of deterioration of soil quality increased with the increase of orchard age (r=0.57*, P<0.01). Soil organic carbon showed a significant positive correlation with earthworm populations, soil enzyme activities and pH and these soil attributes were the important factors influencing SDI values. In conclusion, the progressive deterioration of orchard soil quality over time was the outcome of poor/inadequate management of soil organic matter (SOM) in guava and sapota orchards. As a result, there is a need for modification of existing SOM management practices. The reason is that they are not as efficient enough to help prevent the deterioration of soil quality in orchards over time, after conversion from baseline ecosystem.