Physical and Cultural Weed Control Working Group of - European ...

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9 th EWRS Workshop on Physical and Cultural Weed Control 12 Samsun, Turkey, 28 – 30 March 2011 From key research concepts in post-emergence weed harrowing to an automatic adjustment of the intensity Victor Rueda-Ayala Martin Weis Roland Gerhards Department of Weed Science (360b), University of Hohenheim, 70599 Stuttgart, Germany, Victor.Rueda.Ayala@uni-hohenheim.de, Tel.: 0711 - 459-23444, Fax.: 0711 - 459-22408 It is well known that crop yield and quality are negatively influenced by weeds, therefore weed control is a crucial element in farm management. In Ecological farming, weeds can be suppressed through interactions between preventive and mechanical weed control methods, however, conventional farming may also get advantage of those measures. Mechanical weed control mainly refers to cultivating tillage, meaning that both crop and weeds are cultivated, thus resulting in a trade-off between weed control and crop injury. Post-emergence weed harrowing is a cultivation method frequently used to control annual weeds in growing cereals and legumes. The primary control mechanism is burial of weed seedlings with soil, but larger weeds may require to be uprooted to be killed. A main challenge in weed harrowing is to find the right crop growth stage and the optimal intensity to obtain the highest control effect and the least crop damage. Research in weed harrowing has been focused on key concepts to successful weed control: selectivity, crop tolerance, competitive ability of weeds, and potential to yield gains. We carried out field experiments in winter and summer cereals from 2007 to 2010 to gather information about selectivity, crop tolerance and crop yield gains, with the aim of developing algorithms for site– specific weed harrowing. Different crop growth stages and harrowing intensity levels were tested in previous experiments. Variability of the soil and weeds was measured with different sensors mounted on a field vehicle. Bi–spectral cameras were used to determine the total leaf coverage (crop and weeds); also recognition of the weed composition was achieved. A sensor measuring the power transmission was used to calculate the soil resistance to the forward movement of the harrow. The vehicle was connected to a RTK-DGPS for positioning, which allowed creating weed distribution, crop–weed coverage and soil resistance maps. Our results showed high variability in total leaf coverage and soil resistance within the fields, meaning that permanent intensity adjustment is needed to avoid crop damages. A linguistic fuzzy model was developed to adjust the harrowing intensity; it was based on analog input of continuous percentage (0–100%) values of resistance, leaf coverage, and weed density. Intensity levels which achieved at least 80% weed control and caused no yield loss were used as the best possible settings for automation. Application maps were elaborated and the intensity settings were tested in an experiment for off-line harrowing application to validate and improve the algorithm. The prototype of the automatic harrow will be presented in the workshop through some photos and a video.
9 th EWRS Workshop on Physical and Cultural Weed Control 13 Samsun, Turkey, 28 – 30 March 2011 Pro's and con's of reduced tillage in maize with respect to weeds R.Y. van der Weide 1 , H.F. Huiting 1 , P.O. Bleeker 1 and M.M. Riemens 2 1 Wageningen UR, Applied Plant Research (PPO), P.O. Box 430, NL-8200 AK, Lelystad Email: rommie.vanderweide@wur.nl 2 Wageningen UR, Plant Research International (PRI), P.O. Box 616, Nl-6700 AK, Wageningen Herbicides cause problems with respect to the quality of surface and groundwater. European and national regulations demand a reduction of this impact. To achieve this, innovations are required that result into a herbicide and crop protection product emission reduction in general, together with cost reduction. In recent years both worldwide and in the Netherlands there has been increasing agricultural interest in reduction of the intensity of soil cultivation. The reason for this increase is twofold. First, no or less soil tillage benefits the producer in terms of less energy and labor input as well as lower mechanization costs. Secondly, the increased awareness of society to climate change and soil and water quality demands agriculture to improve current systems. In the past, exploratory research has shown that weed control was the main bottle neck for the introduction of reduced or no till systems and making those systems not economically feasible. However, recent technological developments and innovations have brought new agricultural systems in with considerably reduced energy use and costs. Some of these systems even suppress weed growth and have reduced the dependence of herbicides. Especially in North and South America and Australia many different cultivation systems and techniques are used, and the development of innovations to tackle specific problems is ongoing. This has led to many different forms of minimum tillage. With increasing reduction of soil cultivation, we discriminate: non inversion tillage (no ploughing but cultivation in various ways, often in combination with a powered tool (harrow or cultivator); permanent ridge tillage (the ridges are built once; only the top is removed and ridged back); strip tillage, where only a strip of soil is cultivated; no till, direct sowing in preferably a green manure crop. In Western Europe and the Netherlands, the development of these production systems are lagging behind, although mainly in England, Germany, France and Switzerland, the areas which are not ploughed are now substantial. The objective of our research is to investigate the usability of ridge till /no till systems as recently developed in the US and Canada for Dutch conditions. In 2009, a multi-year experiment in maize (after grassland on a marine loam soil) started including: 5 tillage systems (no till, ridge till, strip till, non inversion tillage and ploughing); 5 green manure crops (organic cultivators and weed suppressors); 2 weed control systems (mainly mechanical or chemical weed control). The results of the first year will be presented and indicate: Several reduced tillage systems resulted in good yields, in case cover crop control and weed control were good. No till yields remained slightly behind the first two years; The green manure crops rye and rape had a better performance compared to no green manure, grass/clover or hairy vetch cover, improving weed suppression and manageability;
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