Adaptive Management of Cannery Waste Water Applications in Northern California.

Agricultural land application is a method commonly used by food processing companies to dispose of factory process liquid and solid-wastes (Overcash et al., 2005). These wastes commonly contain varying levels of oxygen-demanding organics, nitrogen, and salts, especially sodium (Na). Land application of effluent and bio-solids can bring mixed remediation results depending on land availability, chemical nature of the waste applied, method of land application, crop produced, and soil properties. Overall, these activities rely on plant growth and removal (bio-mining), bio-degadation, and dilution to maintain regulated levels of nutrients/wastes and positive ecosystems function and services.

This research investigates the effects of high Na cannery water application (delivering ~ 860 kg/ha/year-Na) and the switch from NaOH to KOH as the primary fruit processing salt on soil properties at a site in Northern California. This research represents both long-term soil monitoring and experimental treatments looking at the additions of gypsum, nutrients - NPK, K2SO4, Wood Ash-Ca. Soils were sampled 4-6x year across the two year trial tracking pH, OM, and extractable Na, K, Ca, & Mg. A systemic change occurred between year 1 & 2 with the processing facility switching salts a year early than expected making K the dominant monovalent cation.

A major story both longer term and related to treatments is the pronounced effect of repeated Na rich water applications on soil properties and the resilience of the system. Annually exchangable Na can rise to >>800 ppm only to return to a working baseline of ~ 100 ppm with as winter rains flush excess salts. Changes in water chemistry starting year two provided early indications of systemic changes in exchangeable cations and other properties that should benefit soil health and primary productivity and provide operational flexibility at this site over time.