Tradeoffs and synergies in California pest and nutrient management

In agroecosystem management in the western US, climate change will likely result in the combined challenge of increased pest pressure and physiological stress. At the same time, cropping systems are searching for ways to maintain productivity without degrading air, water and soil quality. Management strategies to respond to these challenges, such as choosing drought tolerant varieties and reducing or replacing N fertilizer with alternative soil amendments each pose tradeoffs for profit and sustainability. For example, while many useful strategies already exist to increase crop resilience, social and economic obstacles often prohibit their implementation. This presentation reviews the tradeoffs and synergies in different management systems in California in which our research group participates. In almonds, surveys found that one variety possessed traits indicating more conservative water use and was highly resistant to pests, but also yielded less and was difficult to process commercially, making it unlikely to be widely adopted as a solution. One example of a synergy in agricultural intensification is using stabilized food hydrolysate derived from recycled supermarket organics. Food hydrolysate is based on collecting unsold food from supermarkets and digesting it with enzymes to produce a stabilized product consisting of amino acids, simple sugars, fatty acids, and minerals. In greenhouse trials, food hydrolysate was as effective as nitrate fertilizers in stimulating plant growth and in a raised bed experiment, increased the activity of beneficial bacterial feeding nematodes compared to controls. The results of these studies, placed within the larger sociopolitical context of the California drought and increasing regulation of fertilizer, reveal the complex tradeoffs involved in water, nutrient, and pest management decisions.