Soil Quality Variables Research Articles

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.

Spatio-temporal Soil Quality Assessment under Crop Rotation Irrigated with Treated Urban Wastewater using Fuzzy Modelling

Abstract Quantifying soil quality is important for assessing soil management practices effects on spatial and temporal variability of soil quality at the field scale. We studied the possibility of defining a simple and practical fuzzy soil quality index based on biological, chemical and physical indicators for assessing quality variations of soil irrigated with well water and treated urban wastewater during two experimental years. In this study 6 properties considered as minimum data set were selected out of 18 soil properties as total data set using the principal component analysis. Treated urban wastewater use had greater impact on biological and chemical quality. The results showed that the studied minimum data set could be a suitable representative of total data set. Significant correlation between the fuzzy soil quality index and crop yield (R2= 0.72) indicated the index had high biological significance for studied area. Fuzzy soil quality index approach (R2= 0.99) could be effectively utilized as a tool leading to better understanding soil quality changes. This is a first trial of creation of a universal index of soil quality undertaken.

Spatial variation of soil quality and pollution assessment of heavy metals in cultivated soils of Henan Province, China

Eight chemical and physical characteristics and seven biological properties of the soils from five cultivated areas in the Henan Province were quantified. Concentrations of Cu, Cr, Zn and Mn were determined using the flame atomic absorption spectrometry. In addition available phosphorus, chloride, soluble salt and pH were measured. The activities of enzymes were determined by a literature method. The results showed that the concentrations of Mn, Zn and Cr had close relationships with that of available phosphorus, and their concentrations increased with the prolonged application of organic and mineral fertilisers and pesticides-fungicides. The activities of cellulase have a relationship to the concentrations of Zn and Mn at 0.95 levels respectively, Zn and Mn stimulate many enzyme activities. The relationship between protease and available phosphorus was nearly distinctive at 0.95 levels, relating with the use of nitrogen fertiliser in the farmlands. Local organic manures and urea fertilisers did not change the soil characteristics to a great extent. However, the soils showed moderate and moderate-to-strong contamination by Mn and Zn in the study areas. Wastewater and groundwater irrigation, pesticides-fungicides, and fertiliser may be responsible for the elevated concentrations of Zn and Mn in the soil samples.

토양측정망 운영목적에 따른 토양측정망 지점 선정 방안 연구

This study developed the classification of National Soil Quality Monitoring Network (NSQM) and its site selection criteria to meet the recently established purposes of the NSQM. The NSQM were suggested by this study to classify into the sixpurposes site groups from the current classification of land uses. The six purposes site groups were 1) intensive observation sites, 2) contaminant loading sites, 3) human activity sites, 4) background sites, 5) river soil sites, and 6) sites near the groundwater quality monitoring wells. Furthermore, this study developed the site selection criteria of NSQM utilizing the accumulated NSQM data, road traffic data, chemical emission data, census, soil information, and the literature related to soil quality variation due to contaminant loads. For selecting suitable sites for NSQM, this study used road traffic, chemical emission, the distance from the contaminant sources, and population information as specific criteria. The suggested site classification and criteria were appled for the current 100 NSQM sites for evaluation. Forty sites were met to the criteria suggested by this study, but sixty sites were not met to the criteria. However, some of the sixty sites also included the obscure sites that their addresses were not apparent to find them.

The Productivity Impacts of Formal and Informal Land Rights: Evidence from Madagascar

This paper studies the relationship between land rights and agricultural productivity. Whereas previous studies used proxies for soil quality and instrumental variables to control for the endogeneity of land titles, the data used here include precise soil quality measurements, which in principle allow controlling for the unobserved heterogeneity between plots. Empirical results suggest that formal land rights (i.e., land titles) have no impact on productivity, but that informal land rights (i.e., landowners' subjective perceptions of what they can and cannot do with their plots) have heterogeneous impacts on productivity.

MICROWAVE REMOTE SENSING IN SOIL QUALITY ASSESSMENT

Abstract. Information of spatial and temporal variations of soil quality (soil properties) is required for various purposes of sustainable agriculture development and management. Traditionally, soil quality characterization is done by in situ point soil sampling and subsequent laboratory analysis. Such methodology has limitation for assessing the spatial variability of soil quality. Various researchers in recent past showed the potential utility of hyperspectral remote sensing technique for spatial estimation of soil properties. However, limited research studies have been carried out showing the potential of microwave remote sensing data for spatial estimation of various soil properties except soil moisture. This paper reviews the status of microwave remote sensing techniques (active and passive) for spatial assessment of soil quality parameters such as soil salinity, soil erosion, soil physical properties (soil texture &amp;amp; hydraulic properties; drainage condition); and soil surface roughness. Past and recent research studies showed that both active and passive microwave remote sensing techniques have great potentials for assessment of these soil qualities (soil properties). However, more research studies on use of multi-frequency and full polarimetric microwave remote sensing data and modelling of interaction of multi-frequency and full polarimetric microwave remote sensing data with soil are very much needed for operational use of satellite microwave remote sensing data in soil quality assessment.

Factors affecting vegetation and soil recovery in the Mediterranean woodland of the Canary Islands (Spain)

We investigated whether human-induced soil degradation may hinder the regeneration of a semiarid Mediterranean-type ecosystem with high biodiversity and conservation interest on the Canary Islands. To further this aim, the replacement of plant species and life-forms and the variation in soil quality were studied during the process of succession in old fields abandoned at different times and in relicts of the original thermophilous woodland by means of multivariate techniques of ordination (RDA, DCA, CCA) and clustering (k-means + IndVal). The studied ecosystem showed a limited capacity for recovery, which appears to be lower than in other similar semiarid Mediterranean ecosystems. Soil parent material exerted a considerable influence on plant reestablishment, and this process was more efficient with pumice-type rocks. Human activities have given rise to a loss of soil organic matter and an enrichment of certain nutrients, which revert to their normal levels once disturbance ceases. However, the erosion resulting from ploughing, farming and subsequent land abandonment has resulted in irreversible degradation of the soil water regime, thus severely limiting the restoration of the original ecosystem. We concluded that aridification due to soil degradation may, in certain cases, prevent the complete regeneration of thermophilous woodlands of the Canary Islands, and it must be taken into account when performing restoration activities. Pumice mulch can be useful for restoration, as it provides a suitable substrate in key stages of the plant recolonisation process.

Spatial variability of soil quality and asparagus spear yield in an area of plastic- greenhouse cultivation on Chongming Island, China

This study was undertaken to determine the spatial variability of pH, organic matter, soil salinity and spear yield of asparagus (Asparagus officinalis L.) in an area of plastic-greenhouse cultivation on Chongming Island, an alluvial island in the Yangtze River Delta and forming part of Shanghai City. Classical statistic and geostatistic analysis were applied. Results showed that, different soil properties were found to have different spatial heterogeneities as a result of agricultural practices and fertilization. Spatial dependences of the electrical conductivities of 1:5 soil: water extracts (EC), organic matter (OM), exchangeable sodium percentage (ESP) and total soluble salt (TSS) were moderate, while pH was high. Soil EC varied from 0.27 to 2.10 mS cm-1, pH from 6.59 to 8.28, OM from 0.3 to 3.4%, ESP from 2.4 to 16.7 and TSS from 0.07 to 1.11%. In this study, Ca2+, Mg2+ and K+ were the predominant soil cations, while the anions were Cl-, NO3-, SO42- and HCO3-. In addition, the in situ electrical conductivity of greenhouse soil had a significantly positive correlation (R2 = 0.97) with soil EC. Meanwhile, different fertilization management practices had significant effects on asparagus spear yield (P < 0.05). Key words: Greenhouse cultivation, soil quality, asparagus, spatial variability, geostatistic.

Comparative Effects of Vetiver Grass (Chrysopogon zizanioides) Strips, Vetiver Mulch and Veticompost on Soil Quality and Erodibility of a Sloping Land

This study investigates the influence of vetiver grass strips (VGS), vetiver mulch (VGM) and composted vetiver prunes (veticompost) on soil quality of an eroded land in the Institute of Agricultural Research and Training, Ibadan (70 22 ’ N; 3 0 50 ’ E), Nigeria. The treatments were 3-m wide VGS established at 10-m inter-row spacing, VGM imposed at 5 Mg ha-1 , veticompost applied at 5 Mg ha -1 and a control (no-vetiver grass). All quality indicators including physical, chemical and biological indices and soil erodibility (K) factors were determined between 2008 and 2011. Results show that soil organic matter (SOM) and associated nutrients play a major role in soil quality variation. VGM had the highest impact on soil quality (76.5%) but not significantly different (P veticompost > VGS > control. Significant and positive relationship (r = 0.92*) exist between soil quality ratings and maize yield, with 70% of grain yield variability accounted to the soil quality. K factor ranged from 0.013 to 0.030 Mg h MJ-1 mm -1 with the VGM and control plots having the least and highest K factors, respectively. Although the soil quality under veticompost is lower than vetiver mulch but the SOM and associated nutrients under veticompost enhanced better soil productivity, and thus accounted for higher crop yields than other treatments.

Impacts of agricultural land management on soil quality after 24 years: a case study in Zhangjiagang County, China

Agricultural soil quality is drastically affected in modern societies by human activities. This paper evaluates the anthropogenic influence on agricultural soil quality variation in Zhangjiagang County, China from 1980 to 2004 based on indicator selection and standard scoring function (SSF). The results indicated that after 24 years of anthropogenic influence, soil organic matter (SOM), total nitrogen (TN), cation exchange capacity (CEC) and available phosphorus (av-P) increased significantly and total phosphorus (TP) and available potassium (av-K) decreased slightly. Soil pH increased slightly for Cambosols and decreased significantly for Anthrosols. According to analysis of an integrated soil quality index (SQI), both Cambosol and Anthrosol soil quality have improved. For Cambosols, class II and III soil increased by 4.4% and 5.7%, respectively; class IV soil decreased by 10.1%. For Anthrosols, Class II soil increased in area by 74.6%; class III soil decreased to 8.1%. ΔSQI showed the same variation trend for Cambosols and Anthrosols. Among the total selected indicators, SOM was the main driving factor and pH was the limiting factor of soil quality base on path analysis. Current anthropogenic influence on soil quality variation was double-edged, stakeholders must pay close attention to this tendency and closely monitor not only agricultural production yields but also crop safety, long-term soil quality and environmental quality indicators, and timely direct agricultural and economic activities to achieve the best economic performance while protecting natural resources.

Hydrology is reflected in the functioning and community composition of methanotrophs in the littoral wetland of a boreal lake

In lake ecosystems a major proportion of methane (CH(4) ) emissions originate from the littoral zone, which can have a great spatial variability in hydrology, soil quality and vegetation. Hitherto, spatial heterogeneity and the effects it has on functioning and diversity of methanotrophs in littoral wetlands have been poorly understood. A diagnostic microarray based on the particulate methane monooxygenase gene coupled with geostatistics was used to analyse spatial patterns of methanotrophs in the littoral wetland of a eutrophic boreal lake (Lake Kevätön, Eastern Finland). The wetland had a hydrology gradient with a mean water table varying from -8 to -25 cm. The wettest area, comprising the highest CH(4) oxidation, had the highest abundance and species richness of methanotrophs. A high water table favoured the occurrence of type Ib methanotrophs, whereas types Ia and II were found under all moisture conditions. Thus the spatial heterogeneity in functioning and diversity of methanotrophs in littoral wetlands is highly dependent on the water table, which in turn varies spatially in relation to the geomorphology of the wetland. We suggest that changes in water levels resulting from regulation of lakes and/or global change will affect the abundance, activity and diversity of methanotrophs, and consequently CH(4) emissions from such systems.

The Productivity Impacts of Formal and Informal Land Rights

There is an important literature on the causal relationship flowing from the quality of institutions to economic performance. This paper studies this relationship at the micro level by looking at the productivity impacts of land rights. Whereas previous studies used proxies for soil quality and instrumental variables to control for the endogeneity of land titles, the data used here include soil quality measurements, which allow controlling for the unobserved heterogeneity between plots. Results suggest that formal rights (i.e., land titles) have no impact but informal rights (i.e., landowners’ perceptions of what they can do with their plots) have heterogeneous impacts on productivity. Alternative specifications are also estimated so as to (i) separate the reduced-form causal impacts of land rights from the mechanisms through which land rights affect productivity; and (ii) assess the limits to the internal and external validity of the empirical results.

THE FINANCIAL RETURN OF CEREAL FARMING FOR SMALLHOLDER FARMERS IN THE CENTRAL HIGHLANDS OF ETHIOPIA

SUMMARYA study was conducted in Suba area, central highlands of Ethiopia, to assess the net return, land and labour productivity, and the return to scale of cereal farming practice. Seventy-five farmers belonging to three local wealth classes (poor, medium and rich) were randomly selected and interviewed about inputs and outputs related to cereal farming for the production year 2007/2008. Farm soil properties were investigated to check the variability in soil quality among the wealth classes. Benefit:cost ratio (BCR), net returns and annual profit were used to indicate the worthiness of the cereal farming activity. The return to scale was estimated by using the Cobb–Douglas production function. The results show that cereal farming is a rewarding practice, with the rich households gaining more profit than the poor. Farm size was the most important variable that affects the net return. There is an increasing return to scale. However, it is unlikely that farmers will have more land than they own at present because of the land shortage problem in the country caused by the increasing human population. Thus, attention should be given to minimizing the costs of production through proper regulation of domestic fertilizer costs and increasing labour productivity especially for the poor and medium households. The use of manure and compost as an additional fertilizer should also be promoted.

Spatial distribution and content of soil organic matter in an agricultural field in eastern Canada, as estimated from geostatistical tools

AbstractSoil erosion induces soil redistribution within the landscape and thus contributes to the spatial variability of soil quality. This study complements a previous experimentation initiated by the authors focusing on soil redistribution as a result of soil erosion, as indicated by caesium‐137 (137Cs) measurements, in a small agricultural field in Canada.The spatial variability of soil organic matter (SOM) was characterized using geostatistics, which consider the randomized and structured nature of spatial variables and the spatial distribution of the samples. The spatial correlation of SOM (in percentages) patterns in the topsoil was established taking into account the spatial structure present in the data. A significant autocorrelation and reliable variograms were found with a R2 ≥ 0·9, thus demonstrating a strong spatial dependence.Ordinary Kriging (OK) interpolation provided the best cross validation (r2 = 0·35). OK and inverse distance weighting power two (IDW2) interpolation approaches produced similar estimates of the total SOM content of the topsoil (0–20 cm) of the experimental field, i.e. 211 and 213 tonnes, respectively. However, the two approaches produced differences in the spatial distribution patterns and the relative magnitude of some SOM content classes.The spatialization of SOM and soil redistribution variability – as evidenced by 137Cs measurements – is a first step towards the assessment of the impact of soil erosion on SOM losses to recommend conservation measures. Copyright © 2009 John Wiley &amp; Sons, Ltd.

The network of interactions among soil quality variables and nematodes: short-term responses to disturbances induced by chemical and organic disinfection

Anthropogenic pressures that involve different kinds of inflows (chemical vs organic) to soils are likely to induce different responses of individual soil components as well as to affect the web of interactions between them. The aim of this paper was to explore whether chemical or organic disinfection constitute two different types of disturbance, regarding both their severity on individual soil components and the structural changes they induce on the network of interactions among soil biochemical variables and nematode functional guilds. Network analysis, a novel approach in the context of soil ecology, was used to explore these interactions. Different plots within a field cultivated conventionally with Phaseolus vulgaris for many years were disinfected either with metham sodium or with a mixture of plant-based alternatives (neem and essential oils). Control plots receiving no disinfectants were also included in our study. One month after the treatments were applied, we estimated microbial C and N, activities of asparaginase, glutaminase, urease and phosphatase, organic C and N, inorganic N and P as well as the functional diversity of nematodes. Chemical disinfection had a direct lethal effect on all nematodes, while the effect on the microbial community was less obvious, implying that at the time of sampling, microbial populations, especially bacterial ones had started to recover from disturbance. Urease and phosphatase activities were inhibited, which may partly be responsible for the reduced amounts of inorganic N and P. Organic disinfectants reduced microbial populations, mainly the fungal ones, but they did not inhibit enzyme activities. The availability of N and P increased and nematode abundance was not affected significantly. The results demonstrate the usefulness of network analysis in providing insight into the structure and robustness of the soil network and its response to disturbance. Despite the pronounced reduction in nematode numbers due to chemical disinfection, the importance of nematode guilds within the interaction network was amplified and a more compact network was formed. On the other hand, interactions within organic plots were found to be primarily dictated by soil biochemistry. Finally, the analysis showed that both types of disinfection increased the vulnerability of the interaction network and this was more pronounced in chemically treated plots.

Relationship of Soil Qualities to Maize Growth Under Increasing Phosphorus Supply in Acid Soils of Southern Cameroon

A large array of soil properties influences plant growth response to phosphorus (P) fertilizer input in acid soils. We carried out a pot experiment using three contrasted acid soils from southern Cameroon with the following main objectives: i) to assess the main soil causal factors of different maize ( Zea mays L.) growth response to applied P and ii) to statistically model soil quality variation across soil types as well as their relationships to dry matter production. The soils used are classified as Typic Kandiudox (TKO), Rhodic Kandiudult (RKU), and Typic Kandiudult (TKU). Analysis of variance, regression, and principal component analyses were used for data analysis and interpretation. Shoot dry matter yield (DMY) was significantly affected by soil type and P rate with no significant interaction. Predicted maximum attainable DMY was lowest in the TKO (26.2 g pot −1) as compared to 35.6 and 36.7 g pot −1 for the RKU and TKU, respectively. Properties that positively influenced DMY were the levels of inorganic NaHCO 3-extractable P, individual basic cations (Ca, Mg, and K), and pH. Their effects contrasted with those of exchangeable Al and C/N ratio, which significantly depressed DMY. Principal component analysis yielded similar results, identifying 4 orthogonal components, which accounted for 84.7% of the total system variance (TSV). Principal component 1 was identified as soil nutrient deficiency explaining 35.9% of TSV. This soil quality varied significantly among the studied soils, emerging as the only soil quality which significantly ( P < 0.05) correlated with maize growth. The 2nd, 3rd, and 4th components were identified as soil organic matter contents, texture, and HCl-extractable P, respectively.

An on-farm approach to quantify yield variation and to derive decision rules for site-specific weed management

Grain yield often varies within agricultural fields as a result of the variation in soil characteristics, competition from weeds, management practices and their causal interactions. To implement appropriate management decisions, yield variability needs to be explained and quantified. A new experimental design was established and tested in a field experiment to detect yield variation in relation to the variation in soil quality, the heterogeneity of weed distribution and weed control within a field. Weed seedling distribution and density, apparent soil electrical conductivity (ECa) and grain yield were recorded and mapped in a 3.5 ha winter wheat field during 2005 and 2006. A linear mixed model with an anisotropic spatial correlation structure was used to estimate the effect of soil characteristics, weed competition and herbicide treatment on crop yield. The results showed that all properties had a strong effect on grain yield. By adding herbicide costs and current grain price into the model, thresholds of weed density were derived for site-specific weed control. This experimental approach enables the variation of yield within agricultural fields to be explained, and an understanding of the effects on yield of the factors that affect it and their causal interactions to be gained. The approach can be applied to improve decision algorithms for the patch spraying of weeds.

Spatial Variability of Soil Properties, Cotton Yield, and Quality in a Production Field

Successful precision agriculture requires an understanding of spatial variability of soil properties, crop growth, and their interactions. The objectives of this study were 1) to examine the spatial variability of soil properties, cotton lint yield, and fiber quality and 2) to evaluate the spatial variability within mapping units at a production‐field scale. This research was conducted on an irrigated 49‐ha cotton field in Texas from 1998 through 2000. Samples were collected from regular 1‐ha grids, triangular, and random points. Results indicated that soil properties had stronger spatial dependence than did cotton lint yields and fiber quality. Soil properties, except nitrate (NO3 −) nitrogen (N) and Olsen phosphorus (P), were strongly spatially dependent, whereas lint yield was moderately to strongly spatially dependent. Fiber quality was moderately spatially dependent. Spatial appearance of higher yield in drier years was associated with the distribution of soil properties favoring cotton growth, including lower pH and calcium (Ca) and higher P and sand content. There were differences in the means and spatial structure parameters of the selected measurements among the three soil mapping units, suggesting the need for careful sampling design to make reasonable estimation of soil properties under a nonstationary situation. Furthermore, the spatial variability of soil properties and cotton yield were intensified under limited water supply, implying that site‐specific cotton management may be appropriate for cotton producers in the Texas high plains. Contribution of the College of Agricultural Sciences and Natural Resources at Texas Tech University Scientific J. Series Paper Number T‐4‐572.

Soil Quality Dynamics Under Successional Alfalfa Field in the Semi-arid Loess Plateau of Northwestern China

Long-term interactions between vegetation succession and soil quality in alfalfa fields were investigated in the semi-arid Loess Plateau of China. The successional ecosystem is composed of six different planting-year alfalfa fields (namely, 3–5–9–15–21–25 years). The yield, cover, and height of alfalfa increased from 194 g dry hay m−2, 55.6%, and 52.8 cm in the 3-year stage to 406 g dry hay m−2, 85.5%, and 72.5 cm in the 9-year stage, respectively. Subsequently, they tended to decrease and reached their respective minimum levels at the 25-year stage. The density of alfalfa continued to decrease but the plant species richness increased with successional age. Microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass C-to-N ratio and soil basal respiration (BR) at 0–20 cm soil depth decreased steadily from 3 years to 9 years, but increased from 15 years to 25 years. The values for metabolic quotient (qCO2) were the opposite of the above four parameters along the succession gradient. Principal component analysis of soil microbial activity and respiration data in relation to soil physical and chemical properties demonstrated the variable trend in soil quality along the gradient. Generally, soil quality worsened within the 9-year stage while alfalfa production increased, but it tended to recover in the following stages while alfalfa production decreased. Soil quality and vegetation variables differed with growing seasons and soil depths. Our experiment showed that alfalfa fields should be plowed down after alfalfa has been grown for more than 9 years when soil water and fertility conditions are favorable for the production of follow-up crops in this area.

Stimulating organic farming via publicly provided services and an auction-based subsidy

Summary Governments generally use a mix of temporary hectare payments and provision of public services to stimulate the organic crop sector. In this paper, a conceptual model is developed for determining a socially optimal hectare payment for any given level of public services. Farm heterogeneity, due to the variability of soil quality and management skills, is explicitly taken into account. Using an nth price auction mechanism, farmers indicate what their reservation subsidy is for a given level of public input provision. The results of this auction are used to determine the government’s optimal policy choices.