Impact of Agricultural Management Practices on Sediment and Nutrient Losses to Runoff.
Zahangir Kabir, Aaron Ristow, and William Horwath. Univ of CA, Davis, Dept of LAWR, Davis, CA 95616
of Agricultural Management Practices on Sediment and Nutrient Losses to Runoff
Z. Kabir, Aaron Ristow and W. Horwath
The experiment was
conducted in the research plots and growers' fields in different agricultural management
practices. Farming practices that preserve or enhance soil cover entering the
rainy season appear to be effective at reducing cumulative runoff and, hence, nonpoint source pollutions (NPSP) load. In general,
research plots and grower fields demonstrate challenges to agricultural runoff
monitoring. Adherence to strict conservation tillage (CT) practices can
immediately reduce fuel costs, but the potential benefits to water quality may
take years to realize. In the short term, growers may have other water
conservation options, including reconfiguring fields to reduce runoff velocity
and thus erosion. Our research has shown that that winter cover
crops (WCC) and CT can behave differently in California compared to other areas. On a
farm scale, WCC significantly reduces winter runoff but also may affect subsoil
water recharge and soil moisture content at the time of planting. The potential
for winter WCC to alter the water budget of subsequent crops under furrow
irrigation systems poses important questions, considering future water supply
concerns. Additional research is needed to develop conceptual models that
correlate water inputs and load reductions with alternative agricultural
management practices in California.
Such information would be beneficial to water quality stakeholders hoping to
address future quality and supply issues.