On-line Sensor Pendulum-Meter for Determination of Plant Mass

A vehicle-based mechanical sensor (pendulum-meter) was developed to measure the plant mass of crops. For testing under defined conditions, a dynamometer with pendulum-meter, sensory and electronic equipment was developed. The ability and accuracy of the sensor for measuring plant mass in different crops (winter wheat, winter rye, grass, rice) and different growth stages are discussed in this paper. Parameter trials were done for optimising pendulum parameters. The correlations between plant mass and pendulum angle measurements were good (r ² < 0.89) for all pendulum parameters, with no significant differences between suitable parameters. The speed of the pendulum-meter causes a linear increase of the measured pendulum angle. The pendulum-meter is of simple construction.     

Variable-rate fungicide spraying in cereals using a plant cover sensor

Real-time technology was developed and tested to variably apply fungicides on the plant surface of cereals. An important step towards variable-rate fungicide application in real time is the development and operation of online sensors for measuring plant parameters. The sensor signal of the CROP-Meter (real-time sensor to measure crop biomass density) is correlated with the Leaf Area Index, a measurement characterising the plant surface. Geostatistical analysis of the sensor values in the experimental fields showed that the autocorrelation distance was greater than 25 m, which was wider than the spray boom of the sensor-controlled field sprayer. Control of individual sections of the spray boom was therefore not necessary in the 5-year experiments. In the eleven field trials, average fungicide savings of 22% were achieved. Field scale strip trials were conducted with the sensor-operated field sprayer to analyse the yield response of the crop. Higher, lower, as well as similar yield levels were obtained in the variable-rate plots by comparison with the uniform plots.     

Strategy of statistical model selection for precision farming on-farm experiments

Nitrogen (N) fertilization implies two important issues: N enhances grain yields and quality, but applied in excess, nitrous oxide emissions and nitrate leaching may be induced. To reduce environmental impacts, spatial N variability in agricultural fields can be adapted using crop sensors. In on-farm experiments, sensor-based variable rate N application is compared to uniform N application, which is common agricultural practice. On-farm experiments (OFE) provide special considerations as opposed to on-station trials. In OFE, the experimental units in farmer-managed fields are considerably larger, which raises the question if soil heterogeneity may be fully controlled by the experimental design (random treatment allocation and blocking). Grain yield monitoring systems are used increasingly in OFE and provide spatially correlated data. As a consequence, classical analysis of variance is not a valid option. An alternative four-step strategy of statistical model selection is presented, generalizing the assumptions of classical analysis of variance within the framework of linear mixed models. Soil heterogeneity is preliminary identified in step 1 and finalized in step 2 using covariate combinations (analysis of covariance). Yield data correlations are handled in step 3 using geo-statistical models. The last step estimates treatment effects and derives the statistical inference. Analyses of three OFE revealed that different covariate combinations and geo-statistical models were needed for each trial, which involves higher analytical efforts than for on-station trials. These efforts can be minimized by following the steps provided in this study to find a best model approximation. Nevertheless, model selection in precision farming OFE will always accompany some uncertainty.     

Measuring Mass Flow by Bounce Plate for Yield Mapping of Potatoes

There are reports about measuring mass flow in potato harvesters by X-ray with two wave lengths sources, by load cells in conveyors and by optical surveying with image analysis. In mechanics, an impulse is defined as the integral of force over time. If one succeeds in producing a constant velocity difference in the mass flow of potatoes, then there exists a directly proportional correlation between the integral force and the mass flow. A constant speed difference can be produced when the potatoes hit a plate on which the potatoes bounce almost vertically in the discharge trajectory of a conveyor belt. Under laboratory conditions, a rubber coated plate with a force measuring instrument was placed in different positions in the discharge trajectory of a conveyor belt running at 3 different speeds. For simulation of mass flow in steps of about 1 kg up to 40 kg, different masses of potatoes were placed on the conveyor belt. For additional simulation of vibrations in a potato harvester, the measurement device was moved horizontally, at five different frequencies and four amplitudes. The results showed a clear linear relationship between mass flow and force. For many parameter combinations, the quality of fit was more than 0.99 and, in some cases, standard error was less than 0.083 kg s^–1. The results indicated that a bounce plate provides a basis for measurement in potato harvesters for yield mapping.     

Case report: Porcine circovirus type 2 infection in an European wild boar (Sus scrofa) in the state of Brandenburg, Germany

This case represents the first case of Porcine Circovirus Type 2 (PCV-2)--infection in a free living European wild boar associated with morphological lesions, which are regarded as characteristic for Postweaning Multisystemic Wasting Syndrome (PMWS) in domestic pigs. The animal, an approximately 10 month old male, was found dead in a rural area within the state of Brandenburg, Germany. The closest commercial pig farm is located in 3 km distance from the spot where the carcass was found. At necropsy, the animal was found to be in a runted condition. Morphological investigation revealed two lesion complexes. Firstly, lymphatic depletion was present in different organs. Mainly the white pulp of the spleen was affected, where lymph follicles and periarteriolar lymphatic sheaths were nearly completely depleted of lymphoid cells. The former lymphatic areas could only be identified by the presence of histiocytic cells. Secondly, there were widely distributed lesions indicative of a bacterial septicemia i.e. purulent-necrotizing lymphadenitis, pulpous hyperplasia of the spleen, miliary lytic liver necroses and foci of fibrinous pneumonia. Within the lesions, bacterial colonies were found (short Gram-negative rods). Bacteriology revealed a septicemic Salmonella choleraesuis var. Kunzendorf--infection. Virologically, the animal was tested with negative results for Classical Swine Fever Virus and PRRSV. The unusual depletion of the lymphatic tissue mainly in the spleen led to the suspicion of a PCV-2 infection. Typical circoviral particles were found by negative-contrast electron microscopy in samples from spleen and lymph nodes. Using a commercial antiserum against Porcine Circovirus, positive staining was found by fluorescence microscopy in tonsils, spleen and lymph nodes. Finally, the virus was identified to be PCV-2 by species-specific PCR. The presented case rises the questions if PCV-2 is endemic in the European wild boar population at least in certain areas, if it is of pathogenetic importance for wild boars and if the virus present in wild boars is identical to that present in domestic pigs with PMWS.     

Comparison of wetness sensors and the development of a new sensor for apple scab prognosis

Journal of Plant Diseases and Protection - Apple scab prediction is based on the model of Mills which describes the risk of Venturia inaequalis infection using leaf wetness duration and air...     

Approaches to calculating P balance at the field‐scale in Europe

Policies for mitigating phosphorus (P) loss from agriculture are being developed in a number of European countries and calculation of P balance at farm‐gate or field‐scale is likely to be a part of such policies. The aim of the paper was to study P balance at the field‐scale in 18 countries that participated in the European Union's (EU) European Co‐operation in the Field of Scientific and Technical Research (COST) action on “Quantifying the Agricultural Contribution to Eutrophication (COST 832)”. A questionnaire related to P balance at the field‐scale was sent to representatives in the 18 countries and all replied. The field as a unit is defined differently in the various European agricultural systems. The identification of the inputs and outputs differ among the countries. For example, P losses may or may not be taken into account in balances. Phosphorus balance at the field‐scale is used in all countries in the context of soil analysis and P recommendations for crops and advisory and research purposes, while only a few countries use it for policy purposes (agri‐environmental). There is wide variation in P balances between countries in relation to soil fertility and vulnerability of water to eutrophication from nutrients from agricultural sources. In several eastern European countries, Hungary for example, fertilizer P use has dropped to about one tenth of the levels used in the 1980's. Many of these countries now have a negative P balance. In western European countries, by contrast, although fertilizer P use has decreased in recent years, the average input is higher than the average off take, and soil test phosphorus (STP) values remains high and continue to increase in some areas. Twelve different soil extractants for STP are used in Europe, and their interpretation can hinder direct comparisons. Calculating P balance at the field‐scale involves approximations in estimating inputs and outputs and spatial variations in fertility in individual fields. Accuracy of data and standardization of methods for calculating balances with inputs and outputs will be a challenge for the future development of a sustainable agriculture in Europe.     

Experiments in biological engineering to induce puberty in young female swine. 4: Ovulation period after puberty in animals aged about 200 days, using different combinations of gonadotropic hormones

44 prepuberal gilts were treated with gonadotropic combinations and investigated for ovarian dynamics. 400 PMS + 200 HCG (Suigonan-Vemie) induced ovulations at the 4th day p.i., 100 FSH + 100 HCG resp. 200 FSH + 200 HCG at the 6th day p.i. At the 8,-11th day p.i. the PMS/HCG-treated animals showed corp. lut, in 100, the FSH/HCG-treated in 50 resp. 87% of the cases. A second injection of 250 HCG 3 days after 200 FSH + 200 HCG increased the number of animals which had ovulated. Zystic ovaries (larger than or equal to 11 mm) developed in all groups. Declaration of gonadotropins in "international units".     

Variable Rate Nitrogen Fertilisation of Winter Wheat Based on a Crop Density Sensor

Site-specific nitrogen fertilisation is important in precision agriculture. Based on positive results from a mechanical sensor (pendulum-meter) for the indirect measurement of existing plant mass in cereals, late nitrogen fertilisation in a farm scale strip trial was tested in the growing seasons of the year 2000 in one field and 2001 in two fields. The pendulum-meter was mounted at the front of a tractor. For site-specific fertilising, a tractor-mounted spreader which included an on-board computer was modified. The fertiliser rate was varied according to plant growth. In parts of the plots with low plant mass, the application rate was reduced and in parts with high mass increased. The result of site-specific fertilising was that, for the three fields calcium–ammonium–nitrate (CAN) could be saved in the range of 10–12% without reducing yields. The grain quality was not significantly influenced by low or high fertiliser rates.