An agronomic practice in CA for annual crops, and is defined as a way to farm without disturbing the soil through tillage. NT must leave at least 30% of area covered by plant residues right after crop establishment, and crops are sown using machinery which is able to place seeds through plant residues from previous crops. The agronomic practice that best characterizes CA for annual crops is NT, which has the highest degree of soil conservation in annual crops, since the mechanical tillage of the ground is completely suppressed. Also, in arid climates it enhance water retention in soils through decreasing evaporation losses from the soil surface which is usually enhanced by tillage involving soil invert.