Effects Of Different Management Practices Research Articles

Parameterization of a crop growth and development simulation model at sub-model components level. An example for winter wheat ( Triticum aestivum L.)

Dynamic simulation models are frequently used for assessing agronomic and environmental effects of different management practices, under various pedo-climatic conditions. CropSyst is a suitable cropping systems simulation model for such applications. However, available CropSyst crop parameters for winter wheat, one of the most important cereals in the world, are limited. In this work we show that it is possible to parameterize separate sub-model components by using existing experimental data and literature. The experiments, carried out in northern Italy between 1986 and 2001, quantified the dynamics of aboveground biomass (AGB), plant nitrogen (N) concentration (PNC) and N uptake (UPTK) by means of periodical measurements. The relative root mean square error (calculated by dividing the root mean square error by the average of observations) obtained after model calibration and validation on an independent data set was, respectively, in the range 9–30% and 17–32% for AGB, 10% and 6–40% for PNC, 8–28% and 9–24% for UPTK. AGB was frequently underestimated. Despite the limited accuracy of simulations, we argue that calibrated crop parameters are adequate for scenario analysis as most differences between years and fertilization levels were reproduced by the model and final AGB and cumulative UPTK were also correctly simulated.

Effects of different management practices on soil conservation and soil water in a rainfed olive orchard

A field experiment was conducted in an olive orchard of impoverished sandy soil to evaluate the efficacy of different management systems involving the use of plant covers, with respect to the tillage systems generally used in semiarid, continental environments. The results obtained were used to establish the most appropriate herbaceous cover in terms of reduced competition for water and erosion control, and to assess the efficacy of different strategies aimed at increasing soil N and OM contents. Experimental plots were subjected to the following treatments: (1) non-tillage plus a natural vegetation cover; (2) non-tillage plus a subterranean clover (and natural vegetation) cover; (3) tillage plus a vetch cover; (4) non-tillage and weeds control by herbicides; and (5) tillage, leaving the soil free of weeds all year-round. Water contents were determined for soil samples collected at depths of 0–20, 20–40 and 40–60 cm in the plots subjected to the different management systems to identify the effects of rainfall and management on soil water balance in periods of normal, high or low rainfall. The impact of the different management systems on chemical (OM, N, K, P 2O 5, anions) and biochemical (ATP, CO 2/ATP, urease, phosphatase) fertility was also examined. During years of normal or high rainfall, these covers showed no significant, or scarce, competition with the tree. The management strategy used favored the presence and abundance of spontaneous legumes in the covers including natural vegetation. Soil C and N contents were higher in the plant cover systems. Effects on biochemical soil fertility are starting to emerge, with clear indications of microbial regeneration. This was of greatest intensity in plots with substantial proportions of legumes in the covers. The control of soil erosion achieved by covers comprised of herbaceous species was especially satisfactory.

Simulation of nitrate leaching using a modelling system with automatic parameterization routines

Abstract. For an efficient abatement of diffuse N pollution from arable land, it is important to have practical and reliable tools that can quantify the effect of different management practices on leaching, and also analyse the effect of alternative management scenarios aimed at reducing leaching. We present here an application of soilndb, a management‐oriented model for quantifying nitrate leaching from arable land. Simulations with soilndb were compared with measurements of pipe‐drain discharge of nitrate taken in a 14‐year field experiment on a sandy loam soil in south‐west Sweden. Following adjustment of parameters connected to litter and faeces decomposition and mineralization, the model gave satisfactory predictions of nitrate leaching for all 10 treatments. The temporal pattern was generally well captured by the model, as was confirmed by high model efficiency values (average = 0.59). This application also supports the model's ability to simulate the long‐term influence of different crops and catch crops as well as different manure strategies on leaching. However, further studies should be done to evaluate the model under additional agro‐environmental conditions (e.g. soils, climates, and crops).

Microbial diversity along a transect of agronomic zones

The diversity of microbial communities constitutes a critical component of good soil-management practices. To characterize the effects of different management practices, molecular indicators such as phospholipid fatty acid (PLFA), denaturing gradient gel electrophoresis (DGGE) and composition of ammonia-oxidizing bacteria were used to analyze bacterial community structure and diversity from four eastern Washington State soils. Samples from four sites were collected representing a transect of high-precipitation to low-precipitation areas that covered different agronomic zones with different management and cropping practices. Biomass amounts estimated from extractable PLFA were significantly higher in the no-till (NT) soil than in the conventional-till (CT) soil. Similarities among the different 16S rDNA DGGE band profiles were analyzed quantitatively using correspondence analysis and this confirmed that the CT soil was the most dissimilar soil. DGGE analysis of 16S rDNA ammonia-oxidizing bacteria from the four soils revealed two identical bands, indicating little effect of agronomic practices and precipitation on these species. A second set of primers, specific for amoA (ammonia monooxygenase) genes, was used to examine ammonia oxidizers in the samples. Six banding patterns (clusters) from amplified rDNA restriction analysis of 16S rDNA fragments were observed after restriction analysis with HinfI. Sequencing of these clones revealed the presence of only Nitrosospira-like sequences. Analysis of the sequences showed that ammonia oxidizers from the NT soil were more diverse compared to those from the CT and conservation reserve program soils. Our data showed that management and agronomic practices had more impact on bacterial community structure than annual precipitation.

Microbial diversity along a transect of agronomic zones

The diversity of microbial communities constitutes a critical component of good soil-management practices. To characterize the effects of different management practices, molecular indicators such as phospholipid fatty acid (PLFA), denaturing gradient gel electrophoresis (DGGE) and composition of ammonia-oxidizing bacteria were used to analyze bacterial community structure and diversity from four eastern Washington State soils. Samples from four sites were collected representing a transect of high-precipitation to low-precipitation areas that covered different agronomic zones with different management and cropping practices. Biomass amounts estimated from extractable PLFA were significantly higher in the no-till (NT) soil than in the conventional-till (CT) soil. Similarities among the different 16S rDNA DGGE band profiles were analyzed quantitatively using correspondence analysis and this confirmed that the CT soil was the most dissimilar soil. DGGE analysis of 16S rDNA ammonia-oxidizing bacteria from the four soils revealed two identical bands, indicating little effect of agronomic practices and precipitation on these species. A second set of primers, specific for amoA (ammonia monooxygenase) genes, was used to examine ammonia oxidizers in the samples. Six banding patterns (clusters) from amplified rDNA restriction analysis of 16S rDNA fragments were observed after restriction analysis with HinfI. Sequencing of these clones revealed the presence of only Nitrosospira-like sequences. Analysis of the sequences showed that ammonia oxidizers from the NT soil were more diverse compared to those from the CT and conservation reserve program soils. Our data showed that management and agronomic practices had more impact on bacterial community structure than annual precipitation.

On-farm assessment of management practices on the productivity of rice (Oryza sativa)-wheat (Tcum aestivum) system

On-farm trials were conducted from 1990-91 to 1992-93 to study the effect of different management practices on the productivity of rice (Oryza sativa L.)-wheat (Triticum aestivum L. emend. Fiori & Paol.) system. Productivity of rice and wheat as individual crops and total productivity of rice-wheat system could be incresased by 24.76,20.68 and 22.74% respectively over farmers practice by adoptlng integrated approach of recommended NPK + chemical weed control + need-based plant-protection measures. Among different management practices, chemical weed control showed highest contribution of 0.37 tonneha to rice yield, whereas application of balanced fertilizer (NPK) made greater contribution of 0.35 tonneha to wheat yield. Similarly, contribution of recommended NPK was higher (0.52 tonnelha), followed by chemical weed control (0.48 tonnelha) to the total productivity of rice-wheat system.

Conservation of organic carbon in relation to crop productivity, yield stability and soil fertility under rice (Oryza sativa) wheat (lkiticum aestivum) cropping system

A field experiment was conducted for 6 years at Kanpur, Uttar Pradesh, and 7 years at R.S. Pura, Jammu and Kashmir, to study the effect of different management practices on soil organic carbon conservation on crop productivity and soil fertility in rice (0ly.a sativa L.) wheat (Triticum aestivum L. emend. Fiori Paol.) cropping system. Higher system productivity of 9.30 tonneslha was recorded when 20 kg N/ha was applied in addition to recommended dose of N at Kanpur, while application of recommended dose of N along with 5 tonnes FYM/ ha in rainy season (kharif) gave greater system productivity of 8.49 tonneslha at R.S. Pura. The different management practices of soil organic carbon conservation not only increased the organic carbon in the soil but also improved the soil fertility under nce wheat system at both the locations.

Effects of different management practices on preweaning and early postweaning growth of Alpine kids

Two sets of 40 dairy goat Alpine kids (3–9 days of age) were used to determine effects of group versus individual pens, preweaning access to forage and different milk feeding restriction regimens on preweaning and early postweaning growth. Treatments in the first experiment were: C1: individual pens; C2: two kids per pen; P: group pen; and PF: P plus free access to alfalfa hay. Treatment did not affect ADG gain in the 8-week preweaning phase (167, 173, 167 and 168 g per day; S.E.=4.5) or in week 1–12 (137, 134, 149 and 128 g per day for C1, C2, P and PF, respectively; S.E.=6.7). Treatments in the second experiment were: AL: ad libitum milk intake with two meals in week 3–8, then 50% of intake on the preceding few days with one meal in week 9–10; R-1X and R-2X: 75% of intake on the last few days of week 2 with one or two meals, respectively, in week 3–8, then, 50% intake with one meal in week 9–10; and R-2X-1X: 75% intake with two meals in week 3–6, then 37.5% intake with one meal in week 7–10. Milk DM intake in week 1–10 was greatest ( P<0.05) among treatments for AL (174, 115, 128 and 113 g per day for AL, R-2X, R-1X and R-2X-1X, respectively). Starter diet DM intake (g per day) was 51, 78, 72 and 143 in week 7–8 (S.E.=16); 138, 194, 165 and 249 in week 9–10 (S.E.=15); 343, 396, 388 and 417 in week 11–12 (S.E.=47); and 508, 530, 489 and 539 in week 13–14 (S.E.=38) for AL, R-2X, R-1X and R-2X-1X, respectively. ADG (g per day) was 139, 120, 119 and 131 in week 1–10 (S.E.=7) and 105, 109, 123 and 117 in week 11–14 (S.E.=16) for AL, R-2X, R-1X and R-2X-1X, respectively. In conclusion, although group pens and forage access may not enhance ADG of artificially reared dairy goat kids by promoting early dry feed consumption restricted feeding regimens can yield preweaning and early postweaning ADG comparable to ad libitum milk intake. Also, feeding milk in restricted amounts once daily appears feasible, and a second reduction in milk intake in the latter part of the suckling phase may further stimulate dry feed intake.

Effect of different management practices on water quality of intensive tilapia culture systems in Israel

Commercial intensive aquaculture systems werebuilt and are managed in a somewhat differentway in each farm. To evaluate the effects ofseveral management procedures on water qualityin intensive fish ponds, data from severallocations, times and culture conditions indifferent farms were collected and are hereinanalyzed through multivariate statistics. Water quality in the intensive ponds depends onthe water entering, the biological processeswithin, and the water leaving the ponds. Areservoir used as source and sink water supplied theintensive ponds with higher organic loadingthan clear source waters, and its phytoplanktoncontent affected nitrogen cycling within theintensive ponds. The systems with a reservoirhad better water quality in the intensive pondsthan those with only clean source water. Within the ponds (1) compared to paddle-wheelaeration, aeration by pure oxygen increasedoxygen concentration, improved nitrificationand promoted decomposition that reduced organicloading. (2) In concrete ponds accumulation oforganic matter and development of anerobicconditions on the pond bottom was higher thanin the slippery plastic-covered ponds. (3) Allintensive ponds provided good growthconditions, tilapia biomass having relativelysmall influence on water quality. Only inpaddle-wheel aerated ponds did increased tilapiabiomass increased inorganic nitrogen compoundsand soluble phosphorus through excretion, andreduce organic nitrogen through a moreefficient removal of food particles. Water leaving the ponds removes matteraffecting water quality within the pond. (1)Draining sediments accumulated on the bottomavoided development of anaerobic conditionswhere denitrification and phosphorus liberationcan occur. (2) Water exchange removed particleswith nitrifying bacteria and algae that absorbnutrients. A high water exchange rate may havea negative effect from the water quality pointof view and from the extra costs incurred inenergy and feeds washed out. The processes described occur simultaneouslythroughout the culture period and shape waterquality dynamics in the ponds. This researchcontributed to the understanding of howmanagement procedures affect the differentphases of water quality dynamics in real-scaletilapia commercial intensive systems.

The effects of crop rotation and fertilization on wheat productivity in the Pampean semiarid region of Argentina: 2. Nutrient balance, yield and grain quality

Wheat ( Triticum aestivum L.) in the semiarid region of Argentina has often been grown as a low-input crop. Rainfall scarcity and distribution are the main characteristics of the region. Consequently, a knowledge of the effect of different management practices is the key to sustainable crop production. The objective of this work was to study the effect of 15 years of different wheat management practices on plant nutrition, dry matter production and grain yield and quality. The treatments were: continuous wheat (WW), wheat-grazing natural grasses (WG) and wheat–legume: [vetch ( Vicia sativa L.) plus oat ( Avena sativa L.) or Triticale ( Triticum aestivum L. × Secale cereale L.)] (WL), with and without fertilizer (N + P) application. The WW and WL treatments involved annual tillage and a long fallow period (4–6 months) under stubble mulch, and WG involved annual alternate tillage and a short fallow (1 month). The experiment was started in 1975 and the data presented were obtained in 1989. Wheat yields were higher with the WW than with the WG rotation, but in both rotations fertilization was required to obtain better grain quality (protein content higher than 11 per cent). The wheat–legume rotation resulted in the highest yield, protein content, and better yield components. Fertilizer application did not increase dry matter production but improved nutrient uptake and grain quality. Yield component differences could be attributed to water availability due to different fallow length. The wheat–legume rotation seemed to be the best practice in the semiarid Pampean region.

Soil quality assessment in domesticated forests – a southern pine example

Maintenance and enhancement of soil productivity is central to the long-term success of intensive forest management. A simple technique is required for monitoring the effects of different management practices on soils as an aid in developing codes of practice that foster maintenance and enhancement of soil productivity. The objective of our work was to determine if management impacts on soil productivity could be assessed using the soil-quality concepts developed in agriculture. A soil-quality index (SQI) model, that measures the effects of management practices on five key growth-determining attributes of forest soils, namely (1) promote root growth, (2) store, supply and cycle nutrients, (3) accept, hold, and supply water, (4) promote gas exchange, and (5) promote biological activity, was developed and tested as part of a controlled study in intensively-managed pine plantations on the Lower Coastal Plain of South Carolina. Three 20-ha, 20-year-old loblolly pine plantations were harvested under wet and dry conditions to create a broad gradient in soil disturbance. Within each harvested plantation, a subset of 3-ha plots were site prepared by either bedding or mole-plowing plus bedding, then all sites were established as third-rotation pine plantations. Field data were collected spatially for soil bulk density, net N mineralization, water table depth, soil aeration, and soil moisture. Literature-based sufficiency values were determined for each property and substituted into the SQI model as surrogate indicators for the five key attributes, thus obtaining spatial SQI predictions within each harvesting and site preparation treatment. Our study results demonstrate how SQI monitoring could be used to identify the effects of management practices on soil productivity, which should aid in developing codes of practice as a component of achieving long-term sustainability in domesticated forests.

Characterization of soil organic matter from a sandy soil in relation to management practice using FT-IR spectroscopy

Previous results from differently fertilized long-term field experiments on a sandy soil suggested that the chemical composition of soil organic matter (SOM) is affected by fertilization. The objective of this paper is to confirm this finding for a site with higher soil-clay contents. Four combinations of different fertilizer treatments at long-term field experiment located at a sandy loam were selected: liquid manure (LM), liquid manure+N (LM+N), straw+N (S+N) and mineral nitrogen only (N). Soil organic matter was extracted using sodium pyrophosphate solution at pH of 10 and hot water. The extracts were analyzed using Fourier-Transform infrared spectroscopy. The results indicate that the composition of SOM from the hot water extracts did not show significant differences while the sodium pyrophosphate extracted SOM is affected by the type of fertilization. Soil samples fertilized with LM+N and S+N show the highest intensity of the carboxyl band. This can be explained by the fact that the combination of S+N fertilization with green manure leads to an enrichment of carboxyl groups in SOM. Differences between the band intensities of the treatments for the SOM samples are, however, not as distinct as for the sandy soil samples. This is possibly a result of the higher clay content and lower age of the long-term experiment at the sandy loam site. The intensity of the carboxyl band of the SOM is correlated with the cation exchange capacity of the soil samples. The composition of SOM may, in addition to the SOM content, be used for studying quantitative effects of different management practices or even land use changes on soil properties.

AEGIS/WIN: A Computer Program for the Application of Crop Simulation Models Across Geographic Areas

AbstractComputer‐based biological simulation models have been used to calculate the effects of different management practices and land‐use systems on agricultural production and to assess the impact of these practices on the environment. Using spatial visualization techniques to display simulation results can significantly improve the presentation and interpretation of these analyses. The objective of this study was to develop a computer program for the spatial application of crop models as well as the analysis and visualization of modeled results. The Agricultural and Environmental Geographic Information System for Windows (AEGIS/WIN) links the simulation system Decision Support System for Agrotechnology Transfer (DSSAT) v3 with the geographic mapping tool ArcView 2. The interface between the two systems was programmed using Avenue, an object‐oriented macro programming language. This interface handles automatic data and command transfers between the simulation system and the mapping tool and does not require any modifications of DSSAT v3. The main spatial input for AEGIS/WIN is a coverage in the form of a digital map of a farm, a region, or any other area. DSSAT is used to create model input files and to execute the various crop management scenarios for the selected coverage. The crop model outputs can be imported and joined with the original selected land‐use map in ArcView. The simulation results can be analyzed with AEGIS/WIN using simple statistics and bar charts. AEGIS/WIN's most important feature is the display of thematic maps of simulated crop yield, yield components, and other related agronomic and environmental variables. The system was applied to study the spatial yield variability of peanut (Arachis hypogaea L.) for a research farm in Georgia. AEGIS/WIN was shown to be an effective tool for the spatial application of crop simulation models and for the analysis and visualization of simulated outputs.

Riparian forest buffer system research at the coastal plain experiment station, Tifton, GA

Recent attention has focused on riparian forest buffer systems for filtering sediment, nutrients, and pesticides entering from upslope agricultural fields. Studies in a variety of physiographic areas have shown that concentrations of sediment and agrichemicals are reduced after passage through a riparian forest. The mechanisms involved are both physical and biological, including deposition, uptake by vegetation, and loss by microbiological processes such as denitrification. Current research by USDA-ARS and University of Georgia scientists at Tifton, GA is focusing on managing riparian forest buffer systems to alleviate agricultural impacts on the environment. The underlying concept for this research is that agricultural impact on streams is best protected by a riparian forest buffer system consisting of three zones. In consecutive upslope order from the stream these zones are (1) a narrow band of permanent trees (5–10 m wide) immediately adjacent to the stream channel which provides streambank stabilization, organic debris input to streams, and shading of streams, (2) a forest management zone where maximum biomass production is stressed and frees can be harvested, and (3) a grass buffer strip up to 10 m wide to provide control of coarse sediment and to spread overland flow. Several ongoing projects at Tifton, GA are focusing on using riparian forest buffer systems as filters. A forest management project is testing the effects of different management practices on surface and ground water quality. This project includes three different forest management practices: mature forest, selectively thinned forest, and clearcut. In a different study a natural wetland is being restored by planting frees. The effectiveness of this wetland on filtering nutrients from dairy wastes which are being applied upslope is being evaluated. At this same site, a pesticide study is being conducted on the side opposite to where dairy wastes are applied. An overland flow-riparian buffer system using swine lagoon waste is evaluating the effectiveness of different vegetative treatments and lengths of buffer zones on filtering of nutrients. In this study three vegetative treatments are compared: (1) 10 m grass buffer and 20 m riparian forest, (2) 20 m grass buffer and 10 m riparian forest, (3) 10 m grass buffer and 20 m of the recommended wetland species maidencane. Waste is applied at the upper end of each plot at either a high or low rate, and then allowed to flow downslope. The three zone riparian forest buffer system is being used for the Riparian Ecosystem Management Model (REMM). This model, which is currently under development at Tifton, GA, is a computer simulation model designed to reduce soil and water degradation by aiding farmers and land use managers in decision making regarding how best to utilize their riparian buffer system. Both information currently being collected in field studies and development of the REMM are innovative farm-level and forestry technologies to protect soil and water resources.

Bean fly, management practices, and biological control in Malawian subsistence agriculture

Subsistence farmers with little access to costly farm inputs such as pesticides and fertilizers must rely on natural pest regulation and cultural controls. To assess the effects of different management practices on a key pest, bean fly densities were compared among 19 farmers' field in central Malawi. The close proximity of these fields, synchrony of planting dates, and similar field sizes allowed a rigorous, empirical comparison of the relative susceptibility of different bean varieties, the effects of soil fertility, and effects of surrounding vegetation. The two most commonly used varieties differed significantly in bean fly infestation levels. Total soil nitrogen was positively correlated with the most common species of bean fly ( Ophiomyia spencerella); and soil phosphorus levels were negatively correlated with population densities of both bean fly species. Similar rates of biological control of bean flies by parasitic wasps occurred in all fields. Complementary experiments with potted plants showed a direct relationship between synthetic NPK fertilizer level and O. spencerella density. However, the effect was reversed in treatments with soluble fish protein fertilizer. In addition, straw mulching of newly sown fields, a practice not used by farmers in the study, may reduce bean fly damage.

Distribution of the stands with Urtica dioica L. along the Lužnice River floodplain on the border between Austria and Czechoslovakia and land management

The effects of different management practices (mainly mowing, grazing, nutrient enrichment) on floodplain vegetation were compared between the Austrian and Czech part of the Lužnice River floodplain using nitrophilous vegetation with Urtica dioica. The vegetation samples situated on crosswise transects (40 in total) were used for the analysis of vegetation. Correlations between the floodplain width on these transects and the proportions (expressed as percentage of the total floodplain width) of selected characteristics (Urtica dioica and Phalaris arundinacea stands and managed areas) were not statistically significant. Differences in the proportions of selected characteristics between the two parts of the floodplain were not significant either, except differences in the proportion of ‘managed areas’ and ‘species richness’ (higher species richness and proportion of managed areas are in the Austrian part of the floodplain). The different environmental variables were used in ordinations (DCA and CCA) of vegetation samples. In the DCA, four groups of samples were interpreted. In the CCA changes the moisture gradient was the most important one. The transect distance (from the first transect in Austria) and the soil moisture had the closest relationship to the species data.

Effects of different management practices on surface water quality from rice fields in south Louisiana∗

Abstract Water samples collected in the Mermentau River Basin over several years at Lousiana Department of Environmental Quality monitoring sites contained high levels of total solids and nutrients during the spring that were highly correlated to pre‐ and post‐plant discharges from rice fields. This study was developed to evaluate the potential of selected management practices (MP's) for reducing total solids, nutrients and pesticides from discharge water in order to improve the surface water quality in southwest Louisiana. Five rice plots located on the Rice Research Station in Crowley, LA represented the different MP's to be evaluated. The five water seeding MP's were: a.1‐no till; a.2‐water cultivation with 30‐day settling; a.3‐dry cultivation with clear water planting; a.4‐mudding‐in with vegetated filter, and b‐mudding‐in (control). Quality of discharged water from rice fields in the Mermentau River Basin was clearly affected by the different MP's. From the first year of data, all the MPa's were bett...

The Effect of Different Management Practices on Incidence of Diarrhea of Naturally Suckled Japanese Black Calves

The Effect of Different Management Practices on Incidence of Diarrhea of Naturally Suckled Japanese Black Calves

The effects of different management practices on the physical properties of a sandy loam soil in Southern Nigeria

The effects of different management practices on the physical properties of a sandy loam soil in Southern Nigeria were studied for two cropping seasons. The bulk densities of the top 0–10-cm soil depths were significantly reduced in plots under 13 years of Panicum maximum and Centrosema pubescens covers. Pores of equivalent cylindrical diameter > 0.05 mm were increased significantly under the two covers. Up to 33% of the saturation water content was released between tensions of 0 and 0.06 bar in the sandy loam soil of all the treatment plots. Furthermore an average of 24% of this water was released between tensions of 0.06 and 0.33 bar. Infiltration rates, measured at the end of the growing season, ranged from 240 mm h −1 under the bare fallow treatment to 1326 mm h −1 under the Centrosema cover. There was no significant difference between the tilled and no-tillage plots. Saturated hydraulic conductivities were significantly higher under the Panicum and Centrosema covers. The effect of tillage on conductivity was not appreciable. The highest weekly 5-cm depth, 1.30 p.m. soil temperature (32°C) was obtained under the bare fallow treatment and the lowest (23.5°) under the Panicum cover. Tillage had no significant effect on the soil temperature. Thirteen years of continuous Centrosema and Panicum covers had a significant effect on the physical properties of the tropical sandy loam soil. Tillage effects were not significant after 2 years of cropping.

Calcareous fens in south Sweden. Previous use, effects of management and management recommendations

A report written in the Swedish language has been abridged and rewritten for foreign readers. Each calcareous fen site is a unique feature though it is possible to generalise such fens into five types according to soil type and most frequent plant communities. Previously most fen sites were used for hay and/or grazing, which gradually decreased from the middle of the 19th century and, since the 1950s has become very unusual. The effects of different management practices are still insufficiently known, observations on species are often contradictory and hence experimental studies are needed. The future management should be adjusted to the sensitivity of each site, the fen type, the main plant communities and the purposes of the preservation.