Effects of Eighteen Years of No-Tillage and Cover Crops on Soil Properties and Function in California’s San Joaquin Valley.

Eighteen years’ effects of no-tillage and cover crops on soil properties and function in California’s San Joaquin Valley No-tillage seeding coupled with winter cover crops are infrequently used in annual cropping systems in California. From 1999 – 2017, we have evaluated the effects of these practices on a variety of soil properties including water infiltration, aggregation, carbon and nitrogen contents, bulk density, and productivity. During this period, an average of 4257 kg ha-1 of annual cover crop biomass was produced with winter rainfall and supplemental irrigation in only three years. Infiltration rate, aggregation, and soil carbon and nitrogen contents were generally increased by cover crop and to a lesser extent reduced tillage at the most recent sampling times during the 2016 – 2017 period. Findings from a later summer 2017 sampling will also be provided.