Lawn Care Tips: Do a soil test NOW by calling your local K-State Research & Extension Office; Apply the right amount of a slow release or natural organic fertilizer at the right time (usually in May or September thru November); Apply fertilizer to unsaturated soils, never right before a rainstorm. Aerate compacted soils; Keep fertilizer away from waterways and never over water lawns; Sweep or blow fertilizers off hard surfaces so they won't wash down storm drains; and Learn more at the Healthy Lawn Expo on Saturday, March 23! What is a harmful algae bloom (HAB)? What causes it? - Blue green algae (Cyanobacteria) occurs naturally in ponds, lakes, reservoirs, and other still or slow-flowing bodies of water (see picture above.) However, in the summer heat, excess nutrients in the water – like nitrogen and phosphorus - can cause blue-green algae to explode into harmful algae blooms. How do excess nutrients enter the water? - Nitrogen and phosphorous are the main elements in commercial fertilizers. If farmers, landscapers, and landowners apply excess fertilizers, then during rainstorms the chemical excess runs into and accumulates in bodies of water.