Non-cultivated Soils Research Articles

Sources, atmospheric transport and deposition mechanism of organochlorine pesticides in soils of the Tibetan Plateau

Because of mountain cold-trapping, the soil in the Tibetan Plateau may be an important global sink of organochlorine pesticides (OCPs). However, there are limited data on OCPs in the soils of the Tibetan Plateau. In addition, the atmospheric transport and deposition mechanisms of OCPs also need to be further studied. In this study, the sampling area covered most regions of the Tibetan Plateau. The detection frequencies of ΣChlordane (sum of trans-chlordane, cis-chlordane and oxychlordane), HCB, ΣNonachlor (sum of trans- and cis-nonachlor), DDTs, ΣEndo (sum of endosulfan-I, endosulfan-II and endosulfate), aldrin, HCHs, ΣHeptachlor (sum of heptachlor and heptachlor epoxide), mirex and dieldrin were 100%, 98.3%, 96.6%, 94.8%, 89.7%, 87.9%, 62.1%, 55.2%, 32.8% and 6.9%, respectively. DDTs (with arithmetic mean values of 1050ngkg−1 dw) and HCHs (393ngkg−1) were the principal OCPs in cultivated soils, whereas ΣEndo (192ngkg−1) and ΣChlordane (152ngkg−1) were the principal OCPs in non-cultivated soils. Local use of DDTs, dicofol and HCHs may be an important source of OCP accumulation in the soil of the Tibetan Plateau. Aldrin and endosulfan are considered to be good indicators for studying atmospheric transport and deposition of OCPs from South Asia and Southeast Asia. Two zones with high OCP levels were found in the southeast and northwest of the Tibetan Plateau. The zones have dissimilar pollution sources of OCPs and are influenced by different factors that affect their precipitation scavenging efficiency. The amount of precipitation was the dominant factor in the southeast, whereas large differences in temperature and wind speed were the dominant factors in the northwest.

Rapid Quantification of Soilborne Pathogen Communities in Wheat-Based Long-Term Field Experiments.

Rainfed experiments operated continuously for up to 84 years in semiarid eastern Oregon are among the oldest agronomic trials in North America. Disease incidence and severity had been quantified visually but quantification of inoculum density had not been attempted. Natural inoculum of 17 fungal and nematode pathogens were quantified for each of 2 years on eight trials using DNA extracts from soil. Crop type, tillage, rotation, soil fertility, year, and their interactions had large effects on the pathogens. Fusarium culmorum and Pratylenchus thornei were more dominant than F. pseudograminearum and P. neglectus where spring crops were grown, and the opposite species dominances occurred where winter wheat was the only crop. Bipolaris sorokiniana and Phoma pinodella were restricted to the presence of spring cereals and pulse crops, respectively. Helgardia spp. occurred in winter wheat-fallow rotations but not in annual winter wheat. Gaeumannomyces graminis var. tritici was more prevalent in cultivated than noncultivated soils and the opposite generally occurred for Rhizoctonia solani AG-8. Densities of Pythium spp. clade F were high but were also influenced by treatments. Significant treatment effects and interactions were more prevalent in two long-standing (>50-year) annually cropped experiments (29%) than two long-standing 2-year wheat-fallow rotations (14%). Associations among pathogens occurred mostly in an 84-year-old annual cereals experiment. This survey provided guidance for research on dynamics of root-infecting pathogens of rainfed field crops and identified two pathogens (Drechslera tritici-repentis and P. pinodella) not previously identified at the location.

Bacterial Diversity and Community Structure in Korean Ginseng Field Soil Are Shifted by Cultivation Time.

Traditional molecular methods have been used to examine bacterial communities in ginseng-cultivated soil samples in a time-dependent manner. Despite these efforts, our understanding of the bacterial community is still inadequate. Therefore, in this study, a high-throughput sequencing approach was employed to investigate bacterial diversity in various ginseng field soil samples over cultivation times of 2, 4, and 6 years in the first and second rounds of cultivation. We used non-cultivated soil samples to perform a comparative study. Moreover, this study assessed changes in the bacterial community associated with soil depth and the health state of the ginseng. Bacterial richness decreased through years of cultivation. This study detected differences in relative abundance of bacterial populations between the first and second rounds of cultivation, years of cultivation, and health states of ginseng. These bacterial populations were mainly distributed in the classes Acidobacteria, Alphaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, and Sphingobacteria. In addition, we found that pH, available phosphorus, and exchangeable Ca+ seemed to have high correlations with bacterial class in ginseng cultivated soil.

Air-drying and long-term storage effects on β-glucosidase, acid phosphatase and arylsulfatase activities in a tropical Savannah Oxisol

Air-drying soil samples causes a rapid cessation of microbial activity and is a useful means of storing soil samples and standardizing experiments as moisture levels can be accurately controlled. In contrast to temperate soils, there is little information regarding the advantages and disadvantages of using field-moist or air-dried soil samples in the assessment of enzyme activities in tropical soils. The aim of this study was to evaluate the effects of air-drying and a two-year storage period on β-glucosidase, acid phosphatase and arylsulfatase activities in soil samples from cultivated and non-cultivated clayey Oxisols from the Cerrado region. Cultivated soil samples (0–10cm depth) were collected from 24 treatments in three long-term experiments and analyzed to determine their enzyme activities and soil organic carbon (SOC). These treatments presented a large range of extractable Mehlich-P values and cumulative corn and soybean yields. Non-cultivated soil samples from four nearby areas with native Cerrado vegetation were also included in the study. In the laboratory, soil samples were divided into two groups. In the first group, soil samples were separated, stored at 7°C at field moisture levels and sieved through a 4mm sieve. The analyses were performed within 1 week after sampling. In the second group, soil samples were air-dried at room temperature for two weeks, sieved through a 2mm sieve and stored for 2 years at room temperature. Average reductions of 26%, 53% and 72%, were observed in the activities of β-glucosidase, arylsulfatase and acid phosphatase in the air-dried long-term stored samples, in both cultivated and non-cultivated Cerrado clayey Oxisols. Air-drying and long-term storage hardly changed the ranking of treatments for β-glucosidase, arylsulfatase and acid phosphatase. However, a reduction in the capacity to detect changes among treatments was observed for acid phosphatase, which prevents the recommendation of air-drying prior to its analyses. As long as the effects of air-drying upon soil enzymes activities are well established, this pretreatment can be used for β-glucosidase and arylsulfatase analyses in the Cerrado clayey Oxisols.

Analysis of phthalate esters in soils near an electronics manufacturing facility and from a non-industrialized area by gas purge microsyringe extraction and gas chromatography

Here, a novel technique is described for the extraction and quantitative determination of six phthalate esters (PAEs) from soils by gas purge microsyringe extraction and gas chromatography. Recovery of PAEs ranged from 81.4% to 120.3%, and the relative standard deviation (n=6) ranged from 5.3% to 10.5%. Soil samples were collected from roadsides, farmlands, residential areas, and non-cultivated areas in a non-industrialized region, and from the same land-use types within 1km of an electronics manufacturing facility (n=142). Total PAEs varied from 2.21 to 157.62mgkg−1 in non-industrialized areas and from 8.63 to 171.64mgkg−1 in the electronics manufacturing area. PAE concentrations in the non-industrialized area were highest in farmland, followed (in decreasing order) by roadsides, residential areas, and non-cultivated soil. In the electronics manufacturing area, PAE concentrations were highest in roadside soils, followed by residential areas, farmland, and non-cultivated soils. Concentrations of dimethyl phthalate (DMP), diethyl phthalate (DEP), and di-n-butyl phthalate (DnBP) differed significantly (P<0.01) between the industrial and non-industrialized areas. Principal component analysis indicated that the strongest explanatory factor was related to DMP and DnBP in non-industrialized soils and to butyl benzyl phthalate (BBP) and DMP in soils near the electronics manufacturing facility. Congener-specific analysis confirmed that diethylhexyl phthalate (DEHP) was a predictive indication both in the non-industrialized area (r2=0.944, P<0.01) and the industrialized area (r2=0.860, P<0.01). The higher PAE contents in soils near the electronics manufacturing facility are of concern, considering the large quantities of electronic wastes generated with ongoing industrialization.

Effects of cultivation on chemical and biochemical properties of dryland soils from southern Tunisia

The progressive degradation of cultivated drylands has been mainly ascribed to adoption of intensive soil use, namely repeated soil cultivation with external inputs and disturbances. Consequently, soil managements in equilibrium with environmental and social constrains are required to conserve and improve the soil fertility. We evaluated the impact of soil cultivation and management on chemical and biochemical properties of dryland soils from the Tunisian Jeffara Plain. This study considered three sites (Chenini Nahel, Matmata Nouvelle, and Menzel Habib), with both non-cultivated and cultivated soils. These latter were subjected to different soil management: organic fertilization and irrigation by submersion, chemical fertilization and drip irrigation, no fertilization and sporadic watering. The results showed that the addition of organic matter as compost or manure combined with irrigation may favor pH reduction, with consequently higher enzymatic activity and organic matter storage. The latter occurred because of the encapsulation of organic particles into collars made of re-precipitated gypsum and calcite. In cases where chemical fertilization and drip irrigation were applied, the organic matter stabilization occurred only at the surface; at depth we observed a reduction of organics due to microbially-mediated mineralization processes. When neither organic amendment nor water was supplied, no substantial difference occurred between cultivated and non-cultivated soils. We concluded that, in drylands, agricultural managements providing the use of water and organic amendments is the way to increase soil organic matter storage and improve physical, chemical and biological properties so to enhance the soil fertility.

The influence of soil properties on denitrifying bacterial communities and denitrification potential in no-till production farms under contrasting management in the Argentinean Pampas

The aim of this work was to investigate the response of the structure, abundance and potential activity of denitrifiers to contrasting agricultural management in no-till production fields, across a regional scale within the highly productive Argentine northern Pampas. Treatment categories were grouped according to the sustainability of the soil management, in terms of crop rotation, fertilization, agrochemicals use and pest control, as good no-till agricultural practices (GAP) and poor no-till agricultural practices (PAP). Non-cultivated soils in each geographic location were also evaluated as reference groups.Mixed models, with sites treated as random factors, indicated that the potential denitrification activity and the size of the nirS community differed significantly between non-cultivated and PAP soils. Soil properties were separated into dynamic and inherent according to their variance components. The former had the largest part of their variances explained by agricultural management, while the latter were more affected by edaphic–climatic differences between sites. Both inherent and dynamic properties could explain the changes in potential denitrification activity, whereas changes in the abundance of denitrifiers were only related to inherent soil properties. Results from principal components analysis suggested site-specific response of most dynamic soil properties. Among the latter, only aggregate stability indices were strongly associated with potential denitrification activity after removing the geographical effect.

Description of spatial patterns of radionuclide deposition by lognormal distribution and hot spots

Spatial distributions of activity density (kBq/m2) and activity concentration (Bq/kg) are studied on sites with non-cultivated soils. Fitting datasets with lognormal, Weibull and normal distributions with sampling size n ≥ 60 showed that radionuclide deposition (90Sr, 137Cs, 238Pu, 239+240Pu, 241Am) due to Chernobyl fallout no more than in 10% of cases are described by Weibull distribution, and in the rest of the cases – by lognormal distribution. However asymptotics of “righthand tail” of empirical (sample) distribution quite often differs from the right-hand tail asymptotics of lognormal distribution. Thereby lognormal distribution is only an approximate statistical model of radionuclides' spatial pattern.Estimates of site surface area with “hot spots” are considered. Also distributions of 137Cs and 134Cs activity concentration on the territory contaminated by Fukushima fallout are reviewed. Characteristics of activity concentration for Fukushima and Chernobyl fallouts are collated. The results obtained make it possible to suggest that in both cases spatial contaminations of soil are described by approximately the same statistical models.

Bacterial Indicator of Agricultural Management for Soil under No-Till Crop Production

The rise in the world demand for food poses a challenge to our ability to sustain soil fertility and sustainability. The increasing use of no-till agriculture, adopted in many areas of the world as an alternative to conventional farming, may contribute to reduce the erosion of soils and the increase in the soil carbon pool. However, the advantages of no-till agriculture are jeopardized when its use is linked to the expansion of crop monoculture. The aim of this study was to survey bacterial communities to find indicators of soil quality related to contrasting agriculture management in soils under no-till farming. Four sites in production agriculture, with different soil properties, situated across a west-east transect in the most productive region in the Argentinean pampas, were taken as the basis for replication. Working definitions of Good no-till Agricultural Practices (GAP) and Poor no-till Agricultural Practices (PAP) were adopted for two distinct scenarios in terms of crop rotation, fertilization, agrochemicals use and pest control. Non-cultivated soils nearby the agricultural sites were taken as additional control treatments. Tag-encoded pyrosequencing was used to deeply sample the 16S rRNA gene from bacteria residing in soils corresponding to the three treatments at the four locations. Although bacterial communities as a whole appeared to be structured chiefly by a marked biogeographic provincialism, the distribution of a few taxa was shaped as well by environmental conditions related to agricultural management practices. A statistically supported approach was used to define candidates for management-indicator organisms, subsequently validated using quantitative PCR. We suggest that the ratio between the normalized abundance of a selected group of bacteria within the GP1 group of the phylum Acidobacteria and the genus Rubellimicrobium of the Alphaproteobacteria may serve as a potential management-indicator to discriminate between sustainable vs. non-sustainable agricultural practices in the Pampa region.

High levels of diversity in Fusarium oxysporum from non-cultivated ecosystems in Australia

The Fusarium oxysporum species complex (FOSC) is a ubiquitous ascomycetous group that includes both pathogenic and non-pathogenic strains, the former being responsible for disease in over 100 cultivated plant species. Previous phylogenetic studies have uncovered at least four major clades within the FOSC, with Clade 1 hypothesised as being ancestral. However, the origin of these clades and pathogenic strains is poorly understood. Due to an emphasis on agricultural isolates in previous studies, the underlying diversity of this species complex in non-cultivated soils is largely unknown. To address this imbalance an extensive survey of isolates associated with native vegetation geographically isolated from cultivation throughout the Australian continent was conducted. A multi-gene phylogenetic analysis of the translation elongation factor (EF-1α) and the mitochondrial small subunit (mtSSU) rDNA loci did not recover any novel clades. However, the Australian isolates had high levels of intra-Clade diversity based on EF-1α sequence type (ST) comparison with a global dataset. The ST diversity was not equally distributed across the four clades, with the majority of novel STs recovered from Clade 1. Implications on the origin of the FOSC are discussed.

Evaluation of soil quality on the basis of chemical and microbial health for potential use in agriculture

The present study is a comparison of chemical and microbial status of wheat cultivated and noncultivated soil from different localities. Soil samples were collected randomly and tested for soluble salts, pH, electrical conductivity, sodium adsorption ratio and microbial population. Soil samples pH, mostly lied in range between 7.29-7.94 [H + ]. The electrical conductivity (EC) of all soil samples except selected wheat agriculture land, lies within the standard range, that is, <4 ds/l which shows that soluble salts are present in the soils. The specific absorption rate (SAR) value varies greatly in wheat agricultural land due to more adsorption of sodium by roots in rhizosphere. Agricultural land soil samples showed high level of salinity and toxicity as compare to other test samples. Cocci and rod shape bacteria were present in the all soil samples. It has been also found that all the soil samples sites have less pathogenic microbes and have less accumulated salts and toxin and can be used efficiently for other crops cultivation. Uncultivated land was suitable for wheat cultivation but wheat cultivated lands was diverging towards salinity which is quite alarming. Agricultural lands need some amendments for salinity.

Effect of AMF application on growth, productivity and susceptibility to Verticillium wilt of olives grown under desert conditions

The effect of arbuscular mycorrhizal fungi (AMF) on olive (Olea europaea) growth and development was followed for 4 years after transplanting in irrigated commercial orchards under arid conditions. Sites I and II were irrigated with saline water (EC = 4.5 dS/m). In site I, the soil was infested with Verticillium dahliae and olive varieties ‘Picual’ (Verticillium susceptible) and ‘Barnea’ (relatively Verticillium tolerant) were tested. In site II, the soil was virgin soil (previously non-cultivated soil) and olive varieties ‘Souri’ and ‘Barnea’ were tested. Plants for all sites were inoculated in the nursery with Glomus intraradices alone or in a mixture with G. mosseae. Relative to non-inoculated trees, AMF colonization enhanced vegetative growth, expressed as tree height and trunk circumference, at all sites. At first commercial harvest, AMF-treated trees had higher fruit and oil yields than non-mycorrhitic controls. Under saline water irrigation, differences between inoculated and non-inoculated treatments were reduced in the slow-growing ‘Souri’ but remained apparent in the modern fast-growing ‘Barnea’. AMF colonization did not appear to improve tolerance of either ‘Picual’ or ‘Barnea’ to V. dahliae, and both were more susceptible than the non-inoculated controls. Thus inoculation of olive plants with AMF improves transplant growth and adaptation in arid areas during the first 3 years of growth and until the first commercial harvesting season.

Pore size distribution in soils irrigated with sodic water and wastewater

Soil porosity, especially pore size distribution, is an important controlling factor for soil infiltration, hydraulic conductivity, and water retention. This study aimed to verify the effect of secondary-treated domestic wastewater (STW) on the porosity of a sandy loam Oxisol in the city of Lins, state of São Paulo, Brazil. The two-year experiment was divided into three plots: soil cultivated with corn and sunflower and irrigated with STW, soil cultivated and irrigated with sodic groundwater, and non-irrigated and non-cultivated soil (control). At the end of the experiment, undisturbed core samples were sampled from 0 to 2.0 m (8 depths). The water retention curves were obtained by tension plates and Richard's pressure plate apparatus, and the pore size distribution inferred from the retention curves. It was found that irrigation with treated wastewater and treated groundwater led to a decrease in microporosity (V MI), defined as the pore class ranging from 0.2 to 50 μm diameter. On the other hand, a significant increase in cryptoporosity (V CRI) (&lt; 0.2 μm) was identified throughout the soil profile. The presence of Na+ in both waters confirmed the role of this ion on pore size distribution and soil moisture (higher water retention).

Root system traits of Mahonia aquifolium and its potential use in soil reinforcement in mountain horticultural practices

The structural changes of Hungarian agriculture in 1989 led to many mountain horticultural farms being abandoned. These structural changes have modified land use patterns which often resulted in decreasing slope stability in mountainous farms. Mahonia aquifolium has been cultivated in Hungary for over half a century for ornamental purposes; however its possible application in shallow slope stabilization has not been discussed. This paper presents the first results on the root morphology, and root tensile strength of M. aquifolium and determines its efficiency for soil protection in horticultural farming practice. Measurements were carried out on M. aquifolium seedlings from cultivated (C) and non-cultivated (NC) soil conditions. The C and NC specimens were measured and compared for root area ratio (RAR) and root tensile strength ( T R). These results were then compared with other species for which data was available. Results showed that M. aquifolium plants from C soil conditions had a significantly higher mean RAR with depth than M. aquifolium plants from NC soil conditions. The mean T R results showed no significant difference between M. aquifolium plants from C and NC environments. The study also showed that M. aquifolium's root structure is comparable as soil protection with the other species although a higher degree of soil reinforcement by roots was obtained with C M. aquifolium specimens. M. aquifolium roots could represent effective soil protection. Moreover the plant is well suited to the demands of small-scale horticultural farm practices under mountainous conditions.

Relationships between rock fragment cover and soil hydrological response in a Mediterranean environment

Rock fragments are a key factor for determining erosion rates, particularly in arid and semiarid environments where vegetation cover is very low. However, the effect of rock fragments in non-cultivated bare soils is still not well understood. Currently, there is a need for quantitative information on the effects of rock fragments on hydrological soil processes, in order to improve soil erosion models. The main objective of the present research was to study the influence of rock fragment cover on run-off and interrill soil erosion under simulated rainfall in Mediterranean bare soils in south-western Spain. Thirty-six rainfall simulation experiments were carried out at an intensity of 26.8 mm h−1 over 60 min under three different classes of rock fragment cover (<50%, 50–60% and >60%). Ponding and run-off flow were delayed in soils with high rock fragment cover. In addition, sediment yield and soil erosion rates were higher in soils with a low rock fragment cover. The relationship between soil loss rate and rock fragment cover was described by an exponential function. After this first set of experiments, rock fragments were removed from sites with the highest cover (>60%) and the rainfall simulation experiments were repeated. The steady-state run-off rate and soil loss increased significantly, showing that run-off and soil erosion were partly conditioned by rock fragment cover. These results have significant implications for erosion modelling and soil conservation practices in areas with the same climate and soil characteristics.

South Dakota Soils: Their Genesis, Classification, and Management

South Dakota is an important agricultural state in the United States with annual cash receipts from agricultural products exceeding $9 billion dollars. This production is possible because of large areas of productive soils. This publication describes the general characteristics and qualities of the major soil groups recognized in South Dakota. The soil forming factors are briefly described, soil classification is introduced, and the genesis of typical Udalf and Ustoll soils are discussed. Soil management issues impacting the use of SD soils are considered. Long-term (>70 yrs) cultivation has significantly reduced surface soil organic carbon levels (>30% reduction) when compared to non-cultivated soil. Soil test phosphorus levels significantly increased in cultivated fields due to commercial P fertilization. The major long-term production problems for SD soils are conservation of soil moisture, organic matter and nitrogen losses, fertility management, and wind and water erosion control.

Soil organic carbon changes in particle-size fractions following cultivation of Black soils in China

Soil texture can be an important control on soil organic carbon (SOC) retention and dynamics. The (clay + silt)-sized SOC pool (SOC < 20 μm) in non-cultivated or grassland soils has been proposed to reach an equilibrium or maximum level named protective capacity. Proper knowledge of SOC in this size fraction in non-cultivated and cultivated Black soils is important to evaluate management-induced changes in SOC in NE China. Twenty-seven paired soil samples (non-cultivated vs. cultivated) were collected in the Black soil zone in Heilongjiang and Jilin provinces. Bulk soil was dispersed in water with an ultrasonic probe and then soil size fractions were collected using the pipette technique for SOC analyses. Soil organic carbon in bulk soil and size fractions was measured by dry combustion. Average content of SOC < 20 μm was 23.2 g C kg −1 at the 0–30 cm depth for the non-cultivated soils, accounting for 75.1% of the total SOC at the same depth. There was significant positive relationship between soil clay plus silt content and SOC < 20 μm in non-cultivated soils. Accordingly, a model of the maximum SOC < 20 μm in 0–30 cm depth of non-cultivated Black soils was developed: y = 0.36 x where y is the maximum SOC < 20 μm pool (g C kg −1) and x is the percentage of clay + silt (<20 μm) content. The average content of SOC < 20 μm was 18.7 g C kg −1 at 0–30 cm depth for cultivated soils, accounting for 81.5% of total SOC. This average value of SOC was 4.4 g C kg −1 less than the maximum value (23.1 g C kg −1) and accounted for 55.0% of the difference of SOC between non-cultivated and cultivated Black soils. Cultivation resulted in 45.0% loss of sand-sized (>20 μm) SOC concentration relative to SOC < 20 μm. This result indicates that SOC < 20 μm and sand-sized SOC both play important roles in SOC dynamics resulting from management practices. This model can be applied to calculate the actual potential to restore SOC for cultivated Black soils under conservation tillage in NE China.

Ecological distribution and characterization of four collections of Bacillus thuringiensis strains

Four collections comprising 507 strains of Bacillus thuringiensis have been analysed in this study. A different ecological origin characterizes each collection. Collection No. 1 was established from soil, dust, and grain samples from Spanish agricultural and non-cultivated soil, silos, and mills. Collection No. 2 is the result of a screening in olive-crop related environments in Spain. Collection No. 3 is made up of strains isolated from potato-growing areas in Bolivia. Collection No. 4 has been generated for this study and includes strains collected from diverse types of samples belonging to several habitats from Spain and Mexico. Crystal morphologies and cry1A and cry2 gene content were assessed for all isolates from each collection. In the 507 strains, the most common crystal morphology was bipyramidal crystals. Frequencies of cry1A and cry2 genes were 61.5% and 59.2%, respectively, and there was a strong correlation between the occurrence of cry1A and cry2 genes.

Comparison of soil properties between continuously cultivated and adjacent uncultivated soils in rice-based systems

To assess cultivation-induced changes followed during the Green Revolution on continuous rice–rice and rice–wheat cropping, fence-line comparisons between cultivated and adjacent noncultivated soils were made to (a) quantify changes in selected soil chemical and biological properties at two moisture conditions, (b) determine the N, P, and K uptake of rice and wheat as affected by changes in soil properties, and (c) determine the relationship between N, P, and K uptake and soil properties. Two parallel experiments were conducted: laboratory incubation and a greenhouse experiment with soils collected from seven rice–wheat and two rice–rice soils. As an average, NH4OAc-extractable K, water soluble organic carbon, and hot water soluble organic carbon were all lower by 48%, total carbon by 35%, total nitrogen by 33%, and microbial biomass carbon by 38% in the cultivated soils, whereas no significant change was observed in the enzyme activities. Changes were mostly associated with the existing fertilizer practices and moisture status of the soil during cultivation. In general, fertilizers were not sufficient to replenish crop removal. Soil type also influenced cultivation changes especially soil carbon parameters. Lighter soil texture had higher decomposable organic C and total C declined than heavy soils. Soils with higher declined in both decomposable organic C and total C had higher reduction in functional diversity of culturable microorganisms. The declining C pools caused lower N uptake and there was a clear association between organic matter parameters and N uptake. Olsen P was correlated with P uptake and extractable K with K uptake. As expected, crop biomass correlated with N, P, and K uptake of plants. Comparison of cultivated and its corresponding uncultivated soil provides possibility to determine management effect on soil status.

Nitrogen conversion and nitrous oxide hot spots in energy crop cultivation

Since 1999, nitrous oxide (N&lt;sub&gt;2&lt;/sub&gt;O) soil emissions from sites cultivated with energy plants have been measured by gas chromatography and gas flux chambers in experimental fields. The main aim of this study was the nitrogen conversion factor and its variability for sandy soils under climatic conditions of Central Europe. Annual plants (hemp, rape, rye, sorghum, triticale) and perennial plants (grass, perennial rye, poplar, willow) were fertilised with three different levels of nitrogen (150 kg N/ha/year, 75 kg N/ha/year, and none). The annual nitrogen conversion factors were derived from the annual mean differences between the fertilised sites and non-fertilised control sites. The mean nitrogen conversion factor for the non-cultivated soils was lower (perennial crops: 0.4%) than that for the regularly cultivated soils (annual crops: 0.9%). Few times, enhanced N&lt;sub&gt;2&lt;/sub&gt;O emission spots with maxima above 1000 &amp;mu;&lt;sub&gt;2&lt;/sub&gt;O/m&lt;sup&gt;2&lt;/sup&gt;/h, lasting for several weeks, were observed in the course of measurements. The influence of these local peak emissions on the nitrogen conversion factor is discussed.