To assess the effects of timing and frequency of weed harrowing on weed abundance and crop yield, different pre- and post-emergence weed harrowing sequences were applied to spring cereals and peas in field experiments performed during 2003 and 2004 in Sweden. Post-emergence harrowing was performed at crop growth stages 2–3 and 5–6 true leaves respectively. The best weed control was obtained by a combination of pre- and post-emergence harrowing, but these treatments also caused yield losses of 12–14% in spring cereals, while no yield losses were observed in peas.
The three types of pf plate boundaries are spreading zones, transform faults and subduction zones. Most earthquakes occur along the boundaries of plate tectonics due to the effects of the earth's mantle layer that acts as a recycling agent and recycles 99% of the earth's surface layers from above.
Various tectonic forces and process act son these slabs and rocks from above and hence through the activities of erosion and denudation of the rocky masses these plates collide with each other as the earth is it's self not static its dynamic and moves continuously on a regular basis and hence changes take place on the surface of earth.
Thus it can be seen that the earthquakes and volcanic events occur at the plate boundaries and hence produce or are responsible for the various activities.
Im not really good with essays,but i can give you an idea.
I think the best way to learn things is to find an interest in it and continue doing some research on it until you have a good understanding of it.Thing like a new sport or experiment
