Cracks affect infiltration of furrow crop irrigation

Cracks can play a major role in water advance and infiltration in a cracking soil. Water flowing directly into subsurface cracks dominated the cumulative intake for the preirrigation at a site in the San Joaquin Valley. Differences in furrow inflow rates had little effect on cumulative infiltration for preirrigation. However, for subsequent irrigations, different furrow inflow rates significantly affected cumulative Infiltration. Crack flow was a significant factor in cumulative infiltration for the crop irrigations. Uniformity of water advance among furrows was high for the preirrigation but was less for the crop irrigations. A comparison of surge irrigation and continuous-flow furrow irrigation with furrow lengths of about 1/4 mile and 1/2 mile showed little difference in cumulative infiltration.