Aquatic Weeds Associated With Agricultural Water Supply

Water quantity and quality are both significant issues related to agriculture, and nowhere are these two issues more critical than in drought-beleaguered California. Water flows from surface-storage reservoirs, rivers, and lined canals through smaller irrigation ditches and aqueducts. The shallow ditches and canals are often occluded during the growing season with dense growths of nuisance aquatic plants and algae, which clog intakes and outflows, impede flow rates, and displace water. Aquatic plants significantly reduce the flow of water through these distributary systems. The goals of the irrigation conveyance portion of the project are to quantify the impact of dense vegetation on water conveyance, and to evaluate weed control options for both de-watered canals and flooded canals to improve weed management at reduced cost or environmental impact. Once the water reaches the intended users, the water quality may impact the crop condition or affect crop protection. For one crop, excess nutrients in the water may contribute to the growth of a novel problem. In water-seeded rice, dense growths of algae may reduce seedling survivorship and condition. This research will examine the nutrient loads and sources, as well as other factors contributing to the eruption of algal blooms in seeded rice fields. The management options for controlling algae in rice fields will be investigated, with the goal of reducing copper loadings resulting from the use of inorganic granular copper sulfate.