Influence of wheat tillage practices on shallow groundwater recharge

ABSTRACT:

A three-year study (1994 to 1996) using four-ha watersheds was done to determine the impact of no-till, moldboard, and sweeps tillage practices on recharge to a shallow unconfined groundwater system. A native grass watershed was used for control. Each watershed was equipped with three groundwater wells, which allowed monthly monitoring of water levels. Two methods of quantifying recharge from fluctuating water table levels (deep percolation) were used: an averaged index and active monthly recharge. Results show native grass with the highest index (0.7) followed by moldboard (0.6), sweeps (0.2), and no-till (.06). Recharge rates under the native grass watershed are larger than the tilled watersheds for years with average and above average rainfall. However, during a year with below average rainfall, no active recharge was found. The watersheds with different tillage practices had lesser recharge amounts with mold-board ranging from 10.4 to 20.8 cm, no-till ranging from 3.8 to 11.7 cm, and sweeps ranging from 2.0 to 10.9 cm. This recharge is attributed to fallow practice during summer and low evapotranspiration during the fall and early winter.