Types Of Soil Management Research Articles

Inventory of Viticultural Yield and Quality Parameters in Respect of Soil Management

Abstract. The purpose of this research was to analyse the yeld and quality of eight grapevine varieties (two Romanian autochthonous varieties: ‘Fetească regală’, ‘Traminer roz’, and six world-wide varieties: ‘Rhin Riesling’, ‘Sauvignon Blanc’, ‘Muscat Ottonel’, ‘Pinot gris’, ‘Chardonnay’and ‘Italian Riesling’ cultivated in two different types of soil management (low and high intensity).

Improving the fertility of tropical acid soils: Liming versus biochar application? A long term comparison in the highlands of Madagascar

Soil acidity is a major constraint for crop production on highly weathered tropical soils characterized by high Al toxicity, low cation exchange capacity and low P availability to plants. To address these constraints, we compared the effects on crop production and soil properties of liming and adding biochar. Experiments were conducted under field conditions in an acidic soil in the Madagascar highlands using a two year rotation of maize intercropped with beans followed by rainfed upland rice over a period of six years. Five different levels of amendment were compared: 10 and 50tha−1 of eucalyptus charcoal residues (referred to as biochar), 1 and 3tha−1 of dolomite and a control (no amendment). They were combined with two types of soil management (conventional tillage and no tillage) and two fertilization levels. Soil characteristics were measured once after five years. Both biochar and dolomite amendment significantly improved yields of the maize and beans due to an increase in soil pH and a decrease in exchangeable aluminium. However, no significant effect was observed on the yield of upland rice. The incorporation of 50tha−1 of biochar was necessary to match the results obtained with 3tha−1 of dolomite. Amendment with dolomite was a more practical and cost-efficient option than amendment with biochar in our conditions. Long term trials are now needed to evaluate other types of biochar.

English

The Quirinopolis microregion (QMR) is located in the Southwestern Goias State, and represents the recent expansions of sugar cane crops in the state. The maintenance of the agricultural and forest ecosystem productivity depends largely on the organic matter transformation process and therefore on the microbial biomass. The goal of this study was to evaluate the effects of the different management methods used in sugar cane cultivation on soil microbiological parameters and on indices derived from dystroferric (DfRO) and dystrophic (DRO) red oxisols in the region of Quirinopolis, Goias. Eight sampling sites were selected in this study within areas occupied by DfRO and DRO, and two reference sites with semidecidual forest vegetation. The microbial biomass of the soil planted with sugar cane responded to changes caused by the two different soil management types (fertilized and not fertilized), so it may be considered a potential soil quality bioindicator. The soil profiles subject to crop succession before planting sugar cane favored the maintenance of the soil microorganism community in regards to other managements. DfRO profiles previously planted with soybean showed the best physical and chemical condition for a dynamic biomass balance. Profiles with vinasse showed no improvement in the development of soil microorganisms nor better physical and chemical conditions. Key words: Soil quality, bioindicators, organic C, fertilization, soybean crop, vinasse.

Geochemical characterization of elements in Vitis vinifera cv. Negroamaro grape berries grown under different soil managements.

The present geochemical study concerns the impact of viticultural practices in the chemical composition of the grape cultivar "Negroamaro" in Apulia, a southern Italian region renowned for its quality wine. Three types of soil management (SM), two cover cropping with different mixtures, and a soil tillage were considered. For each SM, the vines were irrigated according to two irrigation levels. Chemical composition of soil and of berries of Vitis vinifera cultivar "Negroamaro" were analyzed by X-ray fluorescence, inductively coupled plasma-mass spectrometry and multivariate statistics (linear discrimination analysis). In detail, we investigated major and trace elements behavior in the soil according to irrigation levels, the related index of bioaccumulation (BA) and the relationship between trace element concentration and soil management in "Negroamaro" grapes. The results indicate that soil management affects the mobility of major and trace elements. A specific assimilation of these elements in grapes from vines grown under different soil management was confirmed by BA. Multivariate statistics allowed to associate the vines to the type of soil management. This geochemical characterization of elements could be useful to develop fingerprints of vines of the cultivar "Negroamaro" according to soil management and geographical origin.

Soil carbon fractions influenced by temperature sensitivity and land use management

Globally about 23 % of the dry lands are affected by soil degradation due to lack of soil organic carbon (SOC). Increasing temperature and artificial stress of various management practices including tillage accelerate soil aggregate breakdown and increase the loss of soil organic carbon to the atmosphere. This study was conducted for comparing SOC fraction in different land use and soil management types in arid soils of Rajasthan and to study the effects of temperature fluctuation on soil organic carbon fraction dynamics. In the experiment two temperature regimes were maintained; ambient and elevated (ambient + 40 °C). All the soil organic carbon fractions were analyzed and it was revealed that soil organic carbon fractions were more under trees (0.33 %) compared to grass (0.23 %) land use system. The mean soil microbial biomass carbon (SMBC) and dehydrogenase activity under trees were 13.9 µg C/g soil, 3.2 pkat/g and under grasses were 10.8 µg C/g soil, 2.0 pkat/g respectively. The SOC content under temperature fluctuated samples were about 18 % higher than the control samples. Overall increasing temperature to about 45 °C reduced the SMBC to an extent of 19 % compared to room temperature and the dehydrogenase activity was about 9 % lower than room temperature.

Índice para a avaliação do risco de contaminação da água por pesticidas: desenvolvimento e validação

Since surface and ground water are strategic and vulnerable environmental compartments, their contamination by pesticides can cause significant damage to man and ecosystems. The objective of the present paper was to develop a simple and robust index to estimate the risk of water contamination by pesticides, in different agronomic and environmental settings, and to validate it at the field level. The risk of contamination (R) was defined as the product of the environmental vulnerability of the site (V) and the contamination potential of the pesticides (Pc). The vulnerability is calculated using the clay content of the soil, the distance to the nearest stream, and the type of soil management. The contamination potential is the product of the pesticide mobility, persistence, and toxicity to man and fish. A validation experiment was carried out in a soybean field in the Distrito Federal, Brazil. In that study, the glyphosate concentration on the runoff of the slope was compared with the behavior predicted by the index. Furthermore, the glyphosate concentrations in the river downstreamr were compared with the risk calculated by the index. In both cases, the ARCA index correctly predicted the values and trends obtained in the field study. However, considering the limited scope of the experiment, it is recommended that further studies be performed to better assess model validity

Runoff and sediment yield of tilled and spontaneous grass-covered olive groves grown on sloping land

Soil erosion in olive groves is a widespread phenomenon in the Mediterranean Basin. Many studies have investigated the effects of tillage and herbaceous ground cover (spontaneous or seeded) in their effectiveness to reduce soil erosion in a wide range of Mediterranean sites under different pedoclimatic and topographic conditions. The present study was performed in Ferrandina, southern Italy: a small drip-type rainfall simulator was used on square microplots (0.25 × 0.25 m) to evaluate the propensity to erosion of a steep rain-fed olive grove (mean slope ~10%) with a sandy loam soil by measuring runoff and sediment load under extreme rain events. Two types of soil management were compared: (1) spontaneous grasses as ground cover (GC) providing a maximum ground cover close to 100%; and (2) tillage (T). In the tillage treatment, a further distinction was made between runoff and sediment produced 1 day (T1) and 10 days (T2) after tillage in order to assess the temporal evolution of tillage effects. The results show that GC reduced surface runoff to approximately one-third and soil losses to zero compared with T1. T2 microplots, tested 10 days after tillage, produced only one-tenth the sediment compared with T1 microplots that were subjected to rainfall simulations 1 day after tillage. Total runoff between the two tilled microplots was similar, although runoff on T1 microplots increased steadily over time whereas runoff on T2 microplots remained stable over the duration of simulations. Such findings may be useful to direct and strengthen the policy towards measures to prevent further soil degradation, as clearly requested by the European Union via the cross-compliance concept. A further economic recognition to the olive growers for the achievable environmental benefits could convince them to a shift towards alternative soil management strategies.

KMnO4 determination of active carbon for laboratory routines: three long-term field experiments in Austria

Recent studies show that a labile soil carbon (C) fraction determined with potassium permanganate (KMnO4) reflects the type of soil management. The present study combines the method for determining the active C (AC) pool with an alternative titration of the 0.02 m KMnO4 solution with sodium oxalate (Na2C2O4) for routine laboratory analyses. Three long-term field experiments investigated: (i) different cropping systems and 14C-labelled organic amendments, (ii) three different tillage systems, and (iii) the application of four different kinds of compost. The results showed the depletion of AC in the permanent bare-fallow system of the 14C-labelled field experiment. When calculating the ratio AC/total organic C (TOC), the depletion of the AC/TOC curve reflected a priming effect, in accord with previous work. We obtained significant positive correlations of AC with TOC, total nitrogen (Nt), humic acid-C and remaining 14C-labelled material. The AC in the tillage systems experiment was significantly (P < 0.05) different between all three tillage treatments at 0–10 cm depth, and the ratio AC/TOC also revealed a significant difference between minimum and conventional tillage treatments at 10–20 cm. For the compost field experiment, significant differences occurred between plots fertilised solely with N and plots receiving organic amendments. The AC/TOC ratio of the sewage sludge amendment was significantly lower than in all other systems. Correlations of AC with TOC for all samples of the different long-term field experiments revealed different behaviours in different soil types. The correlations of AC with Nt showed higher coefficients than with TOC. The applied methodology has a potential for sensitive and reliable detections of differences in soil organic matter characteristics.

Celkový obsah uhlíku a kvalita humusových látek u vybraných subtypů kambizemí

Cambisols cover an estimated 45% of agricultural soils in the Czech Republic. We aimed our work at stabile forms of organic carbon and humic substances quality in Cambisols under different types of soil management (grassland and arable soil). Object of our study were the following subtypes of Cambisols: Eutric Cambisol (locality Vatín – arable soil), Eutric Cambisol (locality Vatín – grassland), Haplic Cambisol (locality Náměšť n/Oslavou – arable soil), Leptic Cambisol (locality Ocmanice – grassland), Haplic Cambisol (locality Nové Město na Moravě – arable soil), Haplic Cambisol (locality Přemyslov – Tři Kameny – grassland), Arenic Cambisol (locality Pocoucov – arable soil), Dystric Cambisol (locality Sněžné – arable soil), Dystric Cambisol (locality Velká Skrovnice – arable soil), Dystric Cambisol (locality Vojnův Městec – arable soil). Non-destructive spectroscopic methods such as UV-VIS spectroscopy, synchronous fluorescence spectroscopy (SFS) and 13C NMR spectroscopy for humic substances (HS) quality assessment were used. Total organic carbon (TOC) content was determined by oxidimetric titration. Fractionation of HS was made by short fractionation method. Isolation of pure humic ­acids (HA) preparation was made according to the standard IHSS method.Results showed that TOC and humus content varied from 2.70 % (grassland) to 1.3 % (arable soil). Ave­ra­ge HS sum was 8.4 mg / kg in grassland and 6.4 mg / kg in arable soil. Average HA sum was 3.6 mg / kg in grassland and 3 mg / kg in arable soil. Fulvic acids (FA) content was 4.7 mg / kg in grassland and 3.7 mg / kg in arable soil. HS quality was low and very similar for all studied samples. HA/FA ratio low (< 1). HS absorbance in UV-VIS spectral range was low and similar in all studied samples. Higher absorption in this spectral range was closely connected with higher HS content. Also in 2D-synchronous fluorescence scan spectra similar shape of spectral lines was detected. Relative fluorescence intensity strongly depended on HA and FA content. Five main fluorescence peaks for HA and FA presence at λex./ λem.: 468/488, 482/502, 450/470, 376/396, 340/360 at constant difference of ∆λ=20 nm were measured. 13C NMR spectra of HA isolated from Eutric Cambisol showed low aromaticity degree and high content of aliphatic moieties. HA were young (= less aromatic compounds in HA molecule) and no differences in HA structure were detected to compare arable soil and grassland.

Sustainable agricultural practices for Mediterranean olive grove. Effect of soil management on soil properties .

The olive is one of the most important crops grown in the Mediterranean region, both in terms of total surface area and its socioeconomic and environmental impact. In the present work, the main soil parameters of olive groves under different management systems are compared to an uncultivated area. Soil samples were collected and analysed from native vegetation (NV) and olive groves under three different soil management systems: conventional tillage (T), no-tillage bare soil (NT) and cover crop (CC). The groves (T, NT, and CC) increased the calcium carbonate content in the uppermost part of the soil profile with respect to NV. The lowest calcium carbonate concentrations were recorded in the top few centimetres of NV soil, with concentrations increasing with depth, while in the cultivated soils, no depth-related variations were found. The results showed an accumulation of soil organic carbon (SOC) in the shallowest soil layer resulting in a high stratification value in the NV; however, this diminished in the cultivated soil and particularly in the tilled plots. The plots under these types of soil management also presented the lowest SOC, nitrogen, potassium and C/N values. CC was the soil management system that showed the best soil properties. Our results indicate that using cover crops and eliminating tillage practices significantly improve soil quality in Mediterranean olive groves.

The influence of land use systems on soil and surface litter fauna in the western region of Santa Catarina

The aim of this study was to evaluate the abundance of soil and surface litter fauna in the western region of Santa Catarina state, southern Brazil, in the following land use systems (LUS): no-tillage crops (NT), integrated crop-livestock (ICL), pasture (PA), Eucalyptus plantation (EP) and native forest fragments (NF). Sampling was done in three counties in the western region of Santa Catarina: Xanxerê, Chapecó and São Miguel do Oeste, in two seasons (winter and summer). The evaluation of soil/litter fauna in each LUS was performed by installing nine "pitfall traps" per sampling grid (3 x 3). The counties are true replicas. The soil for the chemical attributes was collected at the same sampling points for soil fauna. Altogether, 17 taxa were identified in the five LUS. The presence of groups of fauna was influenced by the type of soil management used. The LUS NF and EP provide better soil conditions for the development of a higher diversity of soil fauna groups compared to other LUS, which showed varying degrees of human intervention, regardless of the sampling season (winter or summer). However, annual crop systems NT and ICL groups showed greater richness and total abundance when compared to the perennial systems (EP and PA). Principal component analysis is an important tool in the study of biological indicators of sustainability because it allows use of soil attributes (chemical and physical) as explanatory environmental variables, which helps in the interpretation of ecological data.

Produtividade do milho em condições de diferentes manejos do solo e de doses de nitrogênio

Pesquisas têm sido desenvolvidas buscando identificar a melhor dose de N para o milho nos mais diferenciados sistemas de manejo do solo. Contudo, não há ainda concordância quanto aos resultados, pois a dinâmica desse nutriente é influenciada pelo manejo do solo e pelas coberturas vegetais. O objetivo deste trabalho foi avaliar a produção de matéria seca e acúmulo de nutrientes em coberturas vegetais e produtividade do milho em sucessão, submetidos a diferentes manejos do solo e de doses de N. Os experimentos foram conduzidos no município de Selvíria, MS, durante os anos agrícolas 2009/2010 e 2010/2011, sob Latossolo Vermelho distrófico típico argiloso. Foram estabelecidos 36 tratamentos com quatro repetições, em blocos casualizados, resultantes da combinação de coberturas vegetais (milheto, Crotalaria juncea e milheto + Crotalaria juncea), manejo do solo (preparo com escarificador + grade "leve", grade "pesada" + grade "leve" e sistema plantio direto) e doses de N em cobertura (0, 60, 90 e 120 kg ha-1 - ureia como fonte). O híbrido de milho utilizado foi o DKB 350 YG® e o N, aplicado no estádio V5 (quinta folha expandida). Ocorreu incremento linear do índice de clorofila foliar, teor de N foliar, comprimento e diâmetro de espiga, massa de 1.000 grãos e produtividade, com o aumento nas doses de N em cobertura. A utilização de crotalária e de milheto + crotalária como antecessoras, associada à aplicação de 120 kg ha-1 de N em cobertura, proporcionou maior produtividade do milho após dois anos agrícolas.

Coberturas vegetais, manejo do solo, doses de nitrogênio e seus efeitos na nutrição mineral e nos atributos agronômicos do milho

Pesquisas são desenvolvidas buscando identificar a melhor dose de N para o milho nos mais diferenciados sistemas de manejo do solo. O objetivo deste trabalho foi avaliar a influência de coberturas vegetais, os sistemas de manejo do solo e as doses de N em cobertura sobre a produção de matéria seca, nutrição mineral, quebramento e altura de planta e inserção de espiga do milho. Os experimentos foram conduzidos no município de Selvíria, MS, durante os anos agrícolas 2009/2010 e 2010/2011, em Latossolo Vermelho distrófico típico argiloso (20º 20' S e 51º 24' W, com altitude de 340 m). Foram estabelecidos 36 tratamentos com quatro repetições, em blocos casualizados, resultantes da combinação entre coberturas vegetais (milheto, Crotalaria juncea e milheto + Crotalaria juncea), manejo do solo (preparo com escarificador + grade "leve", grade "pesada" + grade "leve" e sistema plantio direto) e doses de N em cobertura (0, 60, 90 e 120 kg ha-1 - utilizando-se ureia como fonte). O híbrido de milho utilizado foi o DKB 350 YG® e o N, aplicado no estádio V5 (quinta folha expandida). O cultivo de crotalária e de milheto + crotalária, como antecessoras, resultou em maior massa de matéria seca da parte aérea, teor de P foliar e quantidade de N, P e K acumulada. O sistema plantio direto proporcionou maior população inicial e final de plantas e matéria seca de parte aérea e menor altura de planta e de espiga. A aplicação de 120 kg ha-1 de N em cobertura proporcionou maior teor de P foliar, teores de N e de P na planta inteira, matéria seca de parte aérea, quantidade de N, P e K acumulada, altura de planta e de inserção de espiga do milho.

Cultivares de arroz de terras altas afetadas pelo manejo do solo

The identification of cultivars more adapted for each type of soil management could increase the yield of upland rice. Therefore, this study aimed to evaluate rice genotypes in two systems of soil management, conventional tillage with moldbard plow (CT) and no-tillage system (NTS) under Cerrado conditions. The work was carried out in two places of the Ipameri municipality, in Goiás State, during 2008/2009 season. A randomized block design in a factorial scheme 2 x 5 with five replications was used. The first factor was composed of soil management (CT and NTS) and the second one was rice genotypes (BRS Sertaneja, BRS Primavera, BRS MG Curinga, Caiapó and BRS Bonança). The cultivars BRS Sertaneja, BRS MG Curinga, Caiapó e BRS Bonança had higher grain yield under CT compared to NTS. BRS Primavera had similar yield in both soil managements. The cultivar BRS Primavera was the most productive under NTS, and under CT cultivars had similar development. Upland rice grain yield was higher at UEG-Ipameri than at Santa Brígida Farm.

Soil micromorphological evidence from Iron Age land use at Tornby and Mörtlösa in Linköping, Sweden

The area of Linköping, Sweden, has a land use history of several millennia. In the last two decades, many archaeological investigations of different types have been conducted here. They range from trial trenching to full scale excavations of large areas and are connected to the expansion of the city.The Early Iron Age landscape of the area was formed by animal husbandry and the requirements of the domesticated animals. Earlier research has revealed an intensification and specialization within animal husbandry in the region, occurring around the Birth of Christ, when farms seemed particularly to specialize towards milk production. However, this transition and its local variations is still poorly investigated. Arable farming is assumed to have been characterized by small intensively used and improved cultivated areas close to the settlements, but there are many questions still to be answered about the specific soil management types and crops. There is a need to further investigate the land use history of the area from the Early Iron Age (2440–2010 BP) until Medieval times (AD 1030–1536).As part of the archaeological excavations carried out by the Swedish National Heritage Board in 2007, six samples from three localities, all in the Linköping municipality, were chosen for soil micromorphological analysis. At the locality of Tornby I, traces were found of anthropogenic activities including some kind of building activities, prior to a period with extensive cultivation activities nearby, presumably when the settlement was established in the Pre-Roman Iron Age (ca. 200 BC). It was followed by a period with soil management on the locality, interpreted as a kind of garden cultivation. The locality of Tornby II, was presumably used a pasture in an early period and as a cultivation field with soil improvement in a later period. At the locality of Mörtlösa, dated to the Roman Iron Age (2010–1680 BP) and the Migration Period (BC/AD – 550 AD), traces from two different contemporary activity areas could be differentiated within few meters of a profile: a cultivated field which has been improved with different kinds of manure through time, and presumably a pathway for animals.

Soil organic matter accounting in the carbon footprint analysis of the wine chain

Concerns about global warming led to the calculation of the carbon footprint (CF) left by human activities. The agricultural sector is a significant source of greenhouse gas (GHG) emissions, though cropland soils can also act as sinks. So far, most LCA studies on agricultural products have not considered changes in soil organic matter (SOM). This paper aimed to: (1) integrate the Henin–Dupuis SOM model into the CF study and (2) outline the impacts of different vineyard soil management scenarios on the overall CF. A representative wine chain in the Maremma Rural District, Tuscany (Italy), made up of a cooperative winery and nine of its associated farms, was selected to investigate the production of a non-aged, high-quality red wine. The system boundary was established from vineyard planting to waste management after use. The functional unit (FU) chosen for this study was a 0.75-L bottle of wine, and all data refer to the year 2009. The SOM balance, based on Henin–Dupuis’ equation, was integrated and run using GaBi4 software. A sensitivity analysis was performed, and four scenarios were developed to assess the impact of vineyard soil management types with decreasing levels of organic matter inputs. SOM accounting reduced the overall CF of one wine bottle from 0.663 to 0.531 kg CO2-eq/FU. The vineyard planting sub-phase produced a loss of SOM while, in the pre-production and production sub-phases, the loss/accumulation of SOM was related to the soil management practices. On average, soil management in the production sub-phase led to a net accumulation of SOM, and the overall vineyard phase was a sink of CO2. Residue incorporation and grassing were identified as the main factors affecting changes in SOM in vineyard soils. Our results showed that incorporating SOM accounting into the wine chain’s CF analysis changed the vineyard phase from a GHG source to a modest net GHG sink. These results highlighted the need to include soil C dynamics in the CF of the agricultural product. Here, the SOM balance method proposed was sensitive to changes in management practices and was site specific. Moreover, we were also able to define a minimum data set for SOM accounting. The EU recognises soil carbon sequestration as one of the major European strategies for mitigation. However, specific measures have yet to be included in the CAP 2020. It would be desirable to include soil in the new ISO 14067—Carbon Footprint of Products.

Capacidade de uso de solo das propriedades rurais na microbacia do córrego Guará no Município de Marechal Cândido Rondon/PR

Soil is a finite resource, limited and non-renewable. The type of soil management is crucial to the sustainability of hydrological and productive potential of a watershed. This study aimed to diagnose the current state of the watershed of the Guara River, performing characterizations of the physical and environmental management tools such as use territorial environmental and land. The investigative unit was the soil in order to find the main agents of degradation, and finally recommend the best ways to watershed management, minimizing soil degradation.The land use is the most relevant for agriculture (65.9%) cultivated with soybeans, corn and wheat. The area used for pasture was (11.8%) used for dairy cattle feeding. The watershed has slopes 0-13 degrees, it reducing the risk of erosion. In the analyzed properties, the main obstacles were risk of erosion, stoniness, and flood risk. The watershed has a great capacity for agriculture, and areas not suitable for agriculture, appear suitable for grazing and forestry.

Cover Crop Short-Term Effects on Soil NO3 −-N Availability, Nitrogen Nutritional Status, Yield, and Must Quality in a Calcareous Vineyard of the AOC Rioja, Spain

Cover crop use in vineyards can affect both vine vigor and must and wine quality because of the competition for soil nutrients and water. Our objective was to study the short-term effects of a cover crop on the nitrate (NO3 −)–nitrogen (N) availability throughout the grapevine vegetative cycle, the grapevine and cover crop N uptake, and the yield and must quality. By short-term effects we mean the first crop cycle after planting the cover crop. The experiment was set in 2009 on a cv. Tempranillo vineyard planted in a Oxyaquic Xerorthent soil. The soil had not been fertilized with N since 2000, and two types of soil management were studied: (1) conventional tillage (CT) and (2) barley (Hordeum vulgare L.) cover crop (B). Soil samples were taken in March (bud break), June (bloom), July (setting), and August (veraison) of 2009, and the extractable NO3 −-N was determined. At bloom and veraison, N contents in both blade and petiole were determined. At bloom the grapevine N uptake was estimated using the aerial parts (leaves, shoots, and bunches), and for the cover crop N uptake was determined. Total yield, bunch, and shoot weight as well as must anthocyanin and polyphenol contents were determined. Soil NO3 −-N availability decreased in the cover crop from June until August, with the reduction being similar to the cover crop N uptake. Also N contents in both petiole and blade decreased in the cover crop at veraison. Regarding must quality, the cover crop increased the anthocyanin content. The reduction of soil NO3 −-N availability throughout the vegetative cycle of grapevine caused a reduction in both N nutritional status and grapevine vigor, and therefore cover crops could affect must quality in the first harvest after the cover crop was sown.

Arbuscular mycorrhizal fungi associated with citrus orchards under different types of soil management, southern China

Communities of arbuscular mycorrhizal fungi (AMF) were studied in sod culture (SC), straw mulching (NM), and herbicide treated and no-tillage (NH) citrus orchards, respectively. The highest total colonization rate (39.47%) and hyphal length density (1.15 m/g soil) were found in SC, the highest spore numbers (1024 spores/100 g soil) in NM, while the lowest ones (31.50%, 0.94 m/g soil and 719 spores/100 g soil) in NH and they varied significantly among three different types of orchards. Total 18 AMF species belonging to five families, Acaulosporaceae (four species), Claroideoglomeraceae (two species), Gigasporaceae (one species), Glomeraceae (nine species) and Pacisporaceae (two species) were identified, and Glomus aggregatum and Claroideoglomus etunicatum were the dominant species in all surveyed plots. The redundancy analysis showed that AMF community structure was influenced greatly by pH, soil management, soil organic matter (C<sub>ox</sub>) and available phosphorus (P<sub>Olsen</sub>). In SC orchards, species richness and Shannon-Wiener index of AMF were notably higher than in other treated orchards. So, it is reasonable to select SC as the best practice in citrus orchard in order to enhance AMF benefits.  

Indicadores de qualidade dos solos na microbacia do Ribeirão Extrema, Distrito Federal: parte II

O uso agrícola cada vez mais intensivo dos solos do Distrito Federal pode comprometer a qualidade destes e desencadear problemas ambientais na região. Diante de tal fato, o objetivo deste trabalho foi o estudo de indicadores de qualidade dos solos (QS) em áreas sob plantio direto (PD), com manejos diversificados (rotação milho-soja e sucessão feijão-sorgo) na microbacia do Ribeirão Extrema, Distrito Federal. Densidade do solo (Ds), grau de floculação (GF), teor de matéria orgânica (MO), capacidade de troca catiônica (CTC), respiração basal (Rmic) e carbono da biomassa microbiana (Cmic) constituíram os atributos de QS avaliados. Para execução das análises estatísticas utilizou-se o software estatístico Statistics Analysis System (SAS) e foi realizada a análise de variância (ANOVA), seguida de teste de comparação de médias pelo método de Tukey. Verificou-se que parte dos indicadores de QS avaliados foi influenciada pelos diferentes tipos de manejo estudados (Ds, MO e Cmic), enquanto outros não se mostraram sensíveis aos mesmos (GF, CTC e Rmic). Foi constatada correlação positiva entre MO e CTC dos solos, em ambos os manejos investigados, o que destaca a importância do sistema de plantio direto na melhoria dos atributos químicos dos solos.