All are inter-related as they influence soil temperature and thereby early season crop growth. Any factor which results in low soil temperature during germination and establishment can result in slow crop development and a reduction in crop yield potential. Surface residue breaks the direct impact of the rain drop and therefore lessens the potential for soil particles to be dislodged. Surface residue slows the runoff of water and increases infiltration which results in less erosion. Rough surface preparation leaves the soil in larger aggregate which are less easily moved with runoff.
Rough preparation results in an irregular surface which slows runoff and promotes infiltration.
Reduced tillage systems leave the total soil profile in better physical structure, thereby promoting greater infiltration and less runoff and erosion. By definition, the Economic Goal or Critical Level assumes that soil fertility will be limiting to yield at a frequency of 1 to 4 out of 10 years. It is not economically advantageous to sustain soil fertility at levels which are never limiting since other factors such as inadequate soil moisture during pollination, crop disease, insect infestation, etc.