Packning av jordbruksmark

Compaction is a big problem in agriculture today since it has negative effects on both yield and environment. The change in the environment caused by compaction will mean decreased quality of atmosphere, surface- and ground water and soil resources. It is therefore very important to know how different agricultural practices and technical solutions of machinery affect the soil and its functions in order to be ab1e to decrease the negative effects from farming. Three field experiments were carried out during the autumn 200l. Vertical soil displacement and vertical soil stress was measured at 15, 30 and 50 cm depth in three different tractor comparisons; wheel- and tracked tractor, single and dual wheel and pulling and non pulling tractor. For the pull and the track experiments macroporosity, saturated hydraulic conductivity and bulk density were also measured. Calculations of the vertical soil stress were also made. For the single- dual wheel experiment a John Deere 4640 with single wheel and a wheel load of 2500 kg and a Steiger with dual wheels and a wheel load of 2200 kg were used. Both tractors had 60 kPa tyre inflation pressure. The John Deere was also used, together with a cultivator, for the pull experiment. These two experiments were carried out at Staby Säteri, Uppland. The experiment with a tracked vehicle was carried out at Krenkerup Gods, Lolland, Danmark with a rubber tracked tractor weighing 18,5 tons and a wheel tractor weighing 9,7 tons. The tracked tractor was balanced before comparing it to the wheeled tractor to get the weight distribution as even as possible. Vertical soil stress and vertical soil displacement right under the wheels of the single and dual wheels did not differ significantly. The soil stress was lowest between the dual wheel at 15 cm depth but ii was evenly distributed under the wheels at 50 cm depth. No significant differences were found between a non pulling and a pulling tractor regarding vertical soil stress and soil displacement. There was however a tendency that the saturated hydraulic conductivity was lowest after the pass of a pulling tractor. It is possible that a higher pull would have affected the soil more. The soil stress was higher at 15 and 30 cm depth for the wheeled compared to the tracked tractor. There were no significant differences in soil displacement, saturated hydraulic conductivity and bulk density but there was a tendency that the bulk density was higher for the tracked than for the wheeled tractor. The most important conclusions were: (1) The two tyres in a dual wheel arrangement acted as two separate wheels which makes it more relevant to talk about wheelload than axle 1oad regarding the risk for subsoil compaction. This is a very important result because the recommendation today is to avoid an axle load over 6 tons. (2) Even for a well balanced tracked tractor the maximum soil stress will be considerably higher than the theoretically calculated. In spite of these problems and a higher total weight, a tracked tractor can have a smaller impact on the soil than a wheeled tractor. (3) The model calculations correlated well with the measured values in the subsoil but not in the topsoil!. A better approximation for the ground pressure than the tyre inflation pressure is however' needed since the ground pressure of ten was as much as twice as high as the tyre inflation pressure

Can within field yield variation be explained using horizontal penetrometer resistance and electrical conductivity measurements? Results from three Swedish fields

Spatial variations in yield occur in all agricultural fields to some degree. Knowledge of the reasons for these variations, especially temporally stable yield patterns, is needed in order to improve productivity by changing production methods or inputs. This information must be provided in a simple, cost-effective way. This study investigated whether field-scale measurements of penetration resistance (PR) could identify temporally stable yield patterns without complementary measurements of other properties. The PR measurements were also compared with field-scale apparent electrical conductivity (ECa) measurements and correlations between yield and PR and yield and ECa were investigated. Measurements with a newly constructed horizontal penetrometer and a non-invasive proximal electromagnetic induction sensor were carried out in three fields in east-central Sweden. The measurements were made once in each field, apart from one field where PR was measured twice in one season. The sensor measurements were compared with crop yield measured over the course of several years. The horizontal penetrometer was able to identify low-yielding areas in one field. However, single measurements of PR or ECa were insufficient to consistently identify yield variations. Parts of the fields showed more consistent patterns, with stronger correlations between PR, ECa and yield. PR and ECa data were better at explaining yield variations in drier years, but showed diverging patterns in different fields and neither showed a much stronger correlation to yield than the other. In future studies, simultaneous measurement of soil water content is recommended and also PR measurements at a water content drier than field capacity

Platsspecifik snabbestämning av skördebegränsande fysikaliska markegenskaper

Projektets målsättning 1. Utveckla ett redskap som samtidigt gör NIR- och penetrationsmätningar on-line på olika djup i markprofilen, och att utvärdera dess potential att mäta textur, mullhalt, penetrationsmotstånd samt vattenhalt, vattenretention och ev. uttorkning 2. Relatera resultaten från snabbmätningarna och de traditionella mätningarna till variationsmönster i skörd 3. Utreda eventuella orsakssamband mellan: – mätta markegenskaper – rotdjup/vattenförhållanden – skördemönster. Allmänt kan sägas att sambanden mellan skörd och markfysikaliska parametrar var starkast vid låga skördenivåer, d.v.s. när de markfysikaliska parametrarna kan antas varit begränsande för skörden. Mätningarna visar att on-linemätning med en horisontell penetrometer är en intressant metod för att förklara skördevariationer på fältnivå, främst för att identifiera områden där markstrukturen kan vara skördebegränsande. Dock behöver detta studeras ytterligare

Förbättrad vattenbalansberäkning genom inkludering av jordbruksbevattning

Ett förändrat klimat gör att konkurrensen om vattnet ökar. Detta är särskilt uttalat i delar av landet som till exempel sydöstra Sverige. Mer konkurrens om vattnet ger ett ökat behov av kunskap om vattentillgångar och vattenbehov för att kunna planera vattenanvändningen och matcha tillgångar och behov så bra som möjligt. Kunskap om mängden vatten som används för bevattning av jordbruksgrödor är en del i det underlag som behövs för att få en bättre beskrivning av Sveriges vattenbalans. Inom detta projekt har bevattningsmodulen i den hydrologiska modellen HYPE anpassats till svenska förhållanden. Arbetet har bedrivits stegvis och det första steget var att beskriva allmänna bevattningsstrategier i Sverige. Utifrån denna beskrivning och tillgänglig bevattningsstatistik har sedan antaganden för den hydrologiska beräkningsmodellen gjorts. Sedan har specifika data för ett pilotområde i Skåne (Vramsån) inhämtats, för att kunna utvärdera modellen för detta område. Verifieringen av modellresultatet visar att bevattningens intensitet och frekvens för olika grödor i stora drag stämmer, att den totala bevattningsmängden är i rätt storleksordning och att flödes-beräkningarna förbättras avseende lågflöden när bevattning ingår i beräkningarna. Det finns möjligheteter till fortsatt utveckling så att modellen kan användas både för att beräkna bevattningsuttagets dagliga påverkan i vattenbalansberäkningen för hela landet och för att förbättra den officiella statistiken för bevattningsuttag

The experience of healthcare staff of incident reporting with respect to venous blood specimen collection practices’

Venous blood specimen collection is an important practical task that results in an analysis response that often leads to a clinical decision. Errors due to inaccurate venous blood specimen collection are frequently reported and can jeopardize patient safety because inaccurate specimens may result in a delayed or incorrect diagnosis and treatment. However, few healthcare personnel have written an error report regarding venous blood specimen collection practices. The aim of this study is to describe the experiences of healthcare personnel with incident reporting of venous blood specimen collection practices in primary health care. Our study is based on 30 individual interviews with healthcare personnel from 10 primary health care centres. Data were analysed using qualitative content analyses. Personnel experiences of incident reporting were summarized in three categories; Uncertainties in the planning and organization, High workload and low priority and, A need for support and guidance. More specifically, barriers hinder personnel in reporting mistakes. An interpretation based on the results is that surrounding circumstances within the organization influence whether personnel report mistakes or not. The result indicates a need for parallel systems, to identify and report errors or near-misses to prevent mistakes. Processed incidents should be returned promptly to the personnel to use as a learning experience. Having a valid questionnaire and a key person to write an incident report, might reduce the burden on the health care staff and increase the numbers of incident reports and patient safety