The quantity of nitrate leached over winter depends mainly on the quantity present in soil in late autumn. The proposed definition of sandy soil have been widened to include sandy loam at 40-80 cm depth. N leaching rates were significantly lower in December and January while FYM caused consistently less N leaching. This data is shown in Figures 1-7. Solutes are leached out of sandy soils faster than heavy soils.
Deep silts are the most retentive of all.
The main reason for this is that the total quantity of water which a sandy soil can hold is small. Therefore, it takes relatively little input of water for above over winter to push all the water that was present in autumn down to below rooting depth. The main reason any nitrate remains behind after winter is due to diffusion, and incomplete displacement of soil water by incoming water. This is particularly noticeable on structured soils. With certain clay soils most water movement is via cracks, and nitrate inside peds may diffuse out rather slowly.