Effect of microalgae application on soil algal species diversity, cation exchange capacity and organic matter after herbicide treatments

Abstract

Soil microalgae live on small communities that change structure depending on many factors. Some of these factors include soil pH, agricultural practices as well as pesticide and herbicide treatments.  The size and activity of these soil microbial communities is an indicator of health, quality and fertility necessary for sustainable agriculture.  Methods:A commercial proprietary suspension of microalgae GOgreen®was applied at different concentrations through a center pivot irrigation system to a crop of cultivated corn (Zea mays) during six months.  Experimental plots of 0.5 acres each were planted in four rows. Corn (34,000 plants/acre) was planted in May and harvested in November allowing each plot to be studied for 6 months. In addition, one plot was planted for a second year to study the effects of consecutive planting and harvesting on algae populations in the soil. Soil samples were collected at a depth of 6 inches. Microalgae species identification was based on morphological criteria. Soil analysis included organic matter content (OM), pH and cation exchange capacity (CEC).Results:Treatment with GOgreen®has significant and measurable positive effects on soil OM content, CEC, pH and microalgae species diversity.Conclusions:  It was demonstrated through this study that GOgreen®increased diatom numbers and microalgae species diversity showing a restorative effect on soil quality after herbicide treatment in heavily farmed soil. Additionally, GOgreen®lowers the pH in soils with a pH higher than 7.0 emerging as an economical alternative that is safe for humans and the environment.