Herbicide-resistant weeds • The inferited ability of a weed to survive a rate of herbicide, which would normally result in effective control • This happens trough evolutionary process, whereby a population changes from being susceptible to being resistant- • Happens when the same herbicide has been used over a period of years • Resistance can be passed from one generation to the next Prevention of resistance Cultural control methods • Cultivation- incession tillage can bury seeds to a depth from which seedlings of most weeds are unlikely to emerge (5cm or deeper) • Crop rotation – many annual weeds are strongly associated with specific crops Prevention of resistance Herbicidal control methods • Alternative herbicides – likely to have effect on resistant populations • Mixtures and sequences – use two or more herbicides which have different modes of actions • Herbicide rotations – rotation of
Precise tillage systems for enhanced non-chemical weed management Dirk A.G. Kurstjens Kati Zoobel Sissejuhatus Artikkel on efektiivsetest umbrohutõrje kasutamisest, mis ei sisalda herbitsiide. Teemat on üldiselt vähe uuritud, kuna kiirelt arenev herbitsiidide arendamine on jätnud mulje, et järjest uuenevad kemikaalid lahendavad tuleviku umbrohtude probleemi. Siiski Euroopa liit on paljude herbitsiidide kasutamisele pannud piirangud. Uute põllumajanduslike kemikaalide arendamisele kulutatakse järjest rohkem raha ( 25 M€ 1975-1980 ja aastal 2000 on summa 200M€) Umbrohud kohanevad aja jooksul herbitsiididega ja muutuvad immuunseks umbrohutõrje vahendile (hetkel 310 umbrohu biotüüpi ja 10 glüfosaadile vastupidavat umbrohutüüpi) Keskmiselt kulub uue agrokemikaali sünteesimiseks ja müümiseks 9 aastat See kõik viitab sellel...
Today, algae are used by humans in many ways; for example, as fertilizers, soil conditioners and livestock feed.[54] Aquatic and microscopic species are cultured in clear tanks or ponds and are either harvested or used to treat effluents pumped through the ponds. Algaculture on a large scale is an important type of aquaculture in some places. Maerl is commonly used as a soil conditioner. Factors incluencing soil microflora 1. Cultural practices (Tillage):Cultural practices viz. cultivation, crop rotation, application of manures and fertilizers, liming and gypsum application, pesticide/fungicide and weedicide application have their effect on soil organism. Ploughing and tillage operations facilitate aeration in soil and exposure of soil to sunshine and thereby increase the biological activity of organisms, particularly of bacteria. Crop rotation with legume maintains the favorable
However, most of these nutrients are returned to the soil with the stover. Sunflower is low in salt tolerance but is somewhat better than fieldbean or soybean in this respect. Corn, wheat, rye and sorghum are rated medium, and sugarbeet and barley are high in salt tolerance. Good soil drainage is required for sunflower production, but this crop does not differ substantially from other field crops in flooding tolerance. V. Cultural Practices: A. Seedbed Preparation: Many different tillage systems can be used effectively for sunflower production. Conventional systems of seedbed preparation consist of moldboard plowing or chisel plowing to invert residue and several secondary field operations. Conventional systems have been shown to increase the availability and improve the distribution of potassium and nitrogen and to increase the seed zone temperatures. However, the risk of erosion and expense of the several tillage operations has led to greater interest in minimum or ridge
4.1. Greenhouse gas (GHG) balance One of the advantages for adopting biofuels is the offsetting of carbon in the production process. Biofuels are carbon neutral when their combustion doesn't release any more carbon dioxide into the atmosphere, than was sequestered by the plant through photosynthesis (Rajagopal, Zilberman, 2007). Nevertheless, there are many uncertainties around the biofuels' carbon neutrality. In the production process, biofuel require significant amounts of energy for tillage, fertilizers, pesticides, irrigation and for harvesting. Nitrogen oxide from fertilisers are known to be particularly potent greenhouse gases with 300 times more potential than CO 2 and it has a harmful effect on the stratospheric ozone (Schaerlmann, Laurence, 2008). Also, as in any other agricultural production, biofuels can cause erosion and eutrophication due to fertilizer runoffs (Rajagopal, Zilberman, 2007). According to the International Energy
diversity / AW; ref to, disease / population crash; AVP; e.g. ref to exposure to different selection pressures max 4 [4] 72. plot size; soil type; soil pH; plant cover; aspect / locality; ref to temperature linked to aspect; slope; ref to rainfall or irrigation; time period; AVP; e.g. tillage, method of cultivation, degree of compaction AVP; e.g. previous use of land max 3 [3] 73. (i) A cartilage; B synovial fluid; 2 (ii) reduces friction / stops bones rubbing together; R no friction shock absorber / cushions bone;
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